Subscriber access provided by WEBSTER UNIV
Separations
Extremely Effective Boron Removal from Water by Stable Metal Organic Framework ZIF-67 Jingli Zhang, Yaona Cai, and Kexin Liu Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/acs.iecr.8b05656 • Publication Date (Web): 20 Feb 2019 Downloaded from http://pubs.acs.org on February 26, 2019
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 25 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Industrial & Engineering Chemistry Research
Extremely Effective Boron Removal from Water by Stable Metal Organic Framework ZIF-67 Jingli Zhang†,‡., Yaona Cai†,‡, Kexin Liu†,‡ †
School of Environmental and Municipal Engineering, Tianjin Chengjian University, Tianjin
300384, China ‡
Tianjin Key Laboratory of Aquatic Science and Technology, Tianjin Chengjian University,
Tianjin 300384, China;
ABSTRACT: The development of adsorbents with high adsorption capacity is a great challenge. The ZIF-67 nanocrystal prepared was applied to boron removal for the first time. The results indicated that well-defined rhombic dodecahedral cobalt-based ZIF-67 synthesized at room temperature exhibited good stability. Under pH of 4 and temperature of 25oC, ZIF-67 exhibited an extraordinarily high boron adsorption capacity of 579.80 mg·g-1 at initial boron concentration of 0.5 mol·L-1, the highest boron adsorption capacity ever reported. The intraparticle diffusion and the film diffusion both were the rate controlling steps. The adsorption of boron to ZIF-67 was mainly due to electrostatic interaction, π-π stacking interaction and the coordination bonding and the boric acid molecules successfully crystallized on the ZIF-67 surface. At the fifth cycle the adsorption capacity of ZIF-67 exhibited 94.1% of the first cycle. ZIF-67 is a promising sorbent for boron removal. Keywords: Metal-organic Framework; ZIF-67; Boron; Adsorption; Regeneration
Corresponding author. Tel.: +86 22 23085117, E-mail:
[email protected].
E-mail:
[email protected] (Yaona Cai),
[email protected] (Kexin Liu) 1
ACS Paragon Plus Environment
Industrial & Engineering Chemistry Research 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 2 of 25
1. Introduction Boron is a microelement widely distributed in earth’s hydrosphere and geosphere.1,2 In nature, boron is always found as compounds with other elements.3 Boron and its compounds are widely used in many industries such as glass, electronics, ceramics, porcelains, semiconductors, pharmaceuticals, insecticides, catalysts and cleaning products.4 The glass industry is the biggest consumer among them and consumes more than half of the total production of boron compounds. significant role in plant, animal and human being growth.
6,7
5
Boron plays a
However, both incompleteness and
increment of boron in daily intake can induce toxic effects.7 Long-term utilization of water and food sources with high-strength boron can cause health problems including neurological effects, mental deficiency, cardiovascular disease, and reproductive disorders.8 The concentration of boron in drinking water is stipulated ≤2.4 mg·L−1 by the World Health Organization and ≤1.0 mg·L−1 by European Union. Various processes such as adsorption,9,10 precipitation,11 ion exchange,12 filtration,13 and phytoremediatio,14 have been used to remove boron from water. Among those processes, adsorption has been extensively studied due to its advantages such as low cost, effective boron uptake and easy regeneration and convenient preparation. Many adsorbents for boron removal from aqueous solution have been used including Fe(Ⅲ) modified bentonite clay,9 selective ion exchange resins,15 chelating resins,16 fibers,17 activated carbon,18 oxides and hydroxides,19 layered double hydroxides,20 eggshell (agricultural waste)21 and silica-supported N-methyl-d-glucamine adsorbent.22 Among those adsorbents, resins23-27 were much studied due to large static boron isotopic separation factor and favorable recovery ability in the last decade. As well known, an important parameter to evaluate the sorbent is its adsorption capacity. Metal−organic frameworks (MOFs), constructed by the 2
ACS Paragon Plus Environment
Page 3 of 25 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Industrial & Engineering Chemistry Research
coordination of metal ions and polyatomic organic bridging ligands to create open crystalline frameworks with permanent porosity, are widely studied in gas adsorption, separations and catalysis applications. Zeolitic imidazolate frameworks (ZIFs) with imidazolate linkers, the most widely-explored MOFs in the literature, are topologically isomorphic with zeolites. ZIFs are found to be a good alternative due to their high adsorption capacity, low cost and thermal stability in the aqueous environment,28 especially ZIF-8 (Zn(II)) and ZIF-67 (Co(II)).29,30 ZIF-8 shows high adsorption capacity of 247.44 mg·g-1 for boron at 45 °C and good reusability.31 In comparison with the metal ion Zn(II) in ZIF-8, the metal ion Co(II) with unsaturated electronic configuration of 1s22s22p63s23p63d7 in ZIF-67 is probably easier to form the coordination bonding with adsorbate. In this work, ZIF-67 was synthesized at room temperature and applied for boron removal. Powder X-ray diffraction (PXRD), scanning electronic microscopy (SEM) and thermogravimetric analysis were employed to characterize the structure of ZIF-67. The ZIF-67 adsorption and regeneration was investigated in batch experiments. 2. Materials and methods 2.1. Materials Ultrapure deionized water (DI water, 1.2 μg·L-1 TOC, 18.2 MΩ cm at 25 oC) was employed in this study. All reagents were of analytical grade and used without further purification. All aqueous solutions prepared were stored in polyethylene/polypropylene containers to prevent boron solution pollution from glassware. 2.2. Preparation of ZIF-67 The ZIF-67 nanocrystals were synthesized according previous report32,33 with a minor modification. In brief, 12 mmol of cobalt nitrate hexahydrate and 48 mmol of 2-methylimidazole were dissolved in 3
ACS Paragon Plus Environment
Industrial & Engineering Chemistry Research 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 4 of 25
0.120 L methanol, respectively. The two solutions were mixed and stirred for 24 h after 30 min sonication. And then the purple precipitate was collected by filtration and washed with ethanol for three times. Finally, the obtained powders were dried at room temperature for 24 h. 2.3. Analytical methods The synthesized ZIF-67 was characterized using a field emission scanning electron microscopy (FESEM, JEOL JSM-7800F, Japan). Powder X-ray diffraction (PXRD) patterns were recorded at room temperature by an Ulitma IV diffractometer (Rigaku, USA) with monochromatized Cu Kα radiation (40 kV, 40 mA). Diffraction data were collected in 2θ scan range from 5 to 50° with a step size of 0.02°. Thermogravimetric analysis (TGA) was performed on a PerkinElmer Diamond 6300 TG/DTA thermal analysis instrument (USA). The boron concentration was determined by using Azomethine H. UV-vis spectrophotometric method at the wavelength of 420 nm. The specific surface area and pore volume were determined by Brunauer-Emmett-Teller (BET) method, using a Quantachrome NovaWin version 10.01. Zeta potential is determined on a Malvern Instrument Zetasizer Nano-ZS at room temperature. 2.4. Boron adsorption Adsorption of boron to ZIF-67 was investigated by batch-type operation. In a typical adsorption process, ZIF-67 sample was added into boric acid solution in 0.2 L conical flask, and then the mixture was shaken up in the water bath shaker at a set temperature. The adsorption capacity of ZIF-67 at time t, Qt (mg·g-1), is calculated as follow34
Qt
(C0 Ct )v m
(1)
where Ct is the adsorbate concentration at time t, C0 is initial concentration, m is the ZIF-67 mass and v (L) is the solution volume. The adsorption capacity at equilibrium was denoted as Qe (mg·g-1). 4
ACS Paragon Plus Environment
Page 5 of 25 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Industrial & Engineering Chemistry Research
3. Results and discussion 3.1. Characterization The prepared ZIF-67 was characterized by SEM, XRD and TGA. The SEM image (Figure 1a) showed that the as-synthesized ZIF-67 was rhombic dodecahedron and its particle size was approximately 400-500 nm. After 11 day (Figure S1) preservation in air, the morphology of the as-synthesized ZIF-67 was unchanged, indicating that as-synthesized ZIF-67 had good stability under ambient conditions. The nitrogen adsorption–desorption isotherms of ZIF-67 (Figure 1b) showed that ZIF-67 was a typical microporous material with its specific surface area of 1776 m2·g−1, the pore volume of 0.72 cm3·g−1 and the average pore size of 1.98 nm with pore size of 1.2-3 nm. Figure 1c revealed that the XRD patterns of the as-synthesized ZIF-67 was well matched with the simulated patterns of 7.31°(011), 10.36°(002), 12.72°(112), 14.40°(022), 16.45°(013), 18.04°(222), 22.15°(114), 24.53°(233), 25.62°(224), 26.70°(134), 29.67°(044), 30.62°(334), 31.55°(244) and 32.43°(235),35 showing that the ZIF-67 nanocrystals were successfully synthesized and well-developed. A slight weight loss was noticed from 50 to 300 oC from the TGA curve in air (Figure 1d), possibly owing to the escape of guest molecules (methanol, ethanol, 2-methylimidazole and water) and gas molecules from the cavities.36 Subsequently, a significant weight loss was found in the range of 350-420 oC, which could be attributed to the decomposition of ligand.37 There was a weak weight loss at the temperature range of 250-500 oC and the significant weight loss appeared at range of 510-750 oC on the TGA curve in N2 in our previous report.32 Therefore, the as-synthesized ZIF-67 had good thermal stability in both air and nitrogen. 5
ACS Paragon Plus Environment
Industrial & Engineering Chemistry Research
3.2. Boron adsorption 3.2.1. Effect of dosage ZIF-67 was added into boric acid solution with the dosage of 1-4 g·L-1 for 24 h at 35 oC. As shown in Figure 2a, the boron adsorption capacity decreased with the increase of ZIF-67 dosage. When the dosage of ZIF-67 increased, the equilibrium concentration Ce decreased. At higher dosages, the equilibrium adsorption capacity Qe was significantly decreased partly because of the aggregation of ZIF-67 adsorption sites. 800
a
b
Adsorption
Desorption
600 dV(d) (x10-2cm3/nmg·g)
N2 volume (cm3/g)
700
500 400 300 200 100
14 12 10 8 6 4 2 0 0
1
2
3
4
5
Pore size (nm)
0 0.0
0.2
0.4
0.6
0.8
1.0
P/P0
c
110
ZIF-67 regenerated
d
100
ZIF-67 as-synthesized
m (%)
90
Intensity (a.u.)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 6 of 25
80 70 25-1000 °C -2.587 mg (-53.08%)
60
ZIF-67 simulated
50 40
0
10
20
30
40
50
0
200
2 °
400
600
800
1000
T (°C)
Figure 1. Characterization of the prepared ZIF-67: (a) SEM images at 1 day and (b) N2 adsorption-desorption isotherms (Pore size distributions at lower right corner); (c) XRD patterns; (d) TGA curve in air.
6
ACS Paragon Plus Environment
Page 7 of 25
3.2.2. Effect of initial pH ZIF-67 was added into a series of boric acid aqueous solutions with the different initial pH for 24 h at 35 oC. The pH of boric acid solutions was adjusted by adding 0.1 mol·L-1 hydrochloric acid or 0.1 mol·L-1 sodium hydroxide. The adsorption capacity of ZIF-67 (3 g·L-1) at various initial pH was shown in Figure 2b. The adsorption capacity increased with the increase of the solution initial pH up to 4 and then decreased gradually at higher pH values. The effects of pH on the adsorption were similar under the dosages of 1, 2, 3 and 4 g·L-1. The optimum pH value was 4 for the adsorption of boron adsorption onto ZIF-67. 340
0.470
120 0.465 100 0.460
80
(mg/g)
140
b
300
0.475
160
320
max
Qmax Ce
180
0.480
Q
a
Ce (mol/L)
200
Qmax (mg/g)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Industrial & Engineering Chemistry Research
280 260 240 220 200 180 160
1.0
1.5
2.0
2.5
3.0
3.5
4.0
2
4
Dosage (g/L)
6
8
10
pH
Figure 2. Boron adsorption in boric acid solution at temperature of 35 oC (a) ZIF-67 dosage of 1, 2, 3 and 4 g·L-1; (b) pH of 2, 3, 4, 5, 6, 8 and 10 at ZIF-67 dosage of 3 g·L-1.
3.2.3. Adsorption kinetics To further investigate the adsorption kinetics of boron to ZIF-67, ZIF-67 (3 g·L-1) was added into a series of boric acid aqueous solutions (pH: 4) with the initial boron concentrations of 0.05, 0.1, 0.2, 0.3 and 0.5 mol·L-1 for 24 h at 35 oC. The boron concentration in the supernatant was monitored at time t and Qt was calculated.
7
ACS Paragon Plus Environment
Industrial & Engineering Chemistry Research 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 8 of 25
The adsorption capacity Qt of boron on ZIF-67 was shown in Figure 3a. The boron adsorption capacity increased rapidly at the beginning and then reached to equilibrium gradually. The equilibrium adsorption capacity Qe increased from 13.67 to 395.52 mg·g-1 when the initial boron concentration was changed from 0.05 to 0.5 mol·L-1. In order to study the adsorption mechanism and the potential rate controlling steps, three kinetic models, pseudo-second order model, intraparticle diffusion model and Boyd’s kinetic model,38 were used to fit the experimental data. The pseudo-first order model was not adopted because the pseudo-second-order kinetic model is better for the adsorption behavior in the liquid phase.39 The pseudo-second order model can be expressed as t 1 t 2 Qt k2Qe Qe
(2)
where k2 (g·mg-1h-1) is the adsorption rate constant. The linear plots of t/Qt against t based on the kinetic data were shown in Figure 3b. Boron adsorption on ZIF-67 was well described by pseudo-second order model. The pseudo-second order model based on the adsorption capacity in the solid phase was in agreement with chemisorption being the rate controlling step. That showed that there was share or exchange of electrons between boric acid and ZIF-67. The experimental data of equilibrium capacity were greater than the calculated values (Table S1), especially for high initial concentration, indicating that there probably existed other processes in addition to adsorption. In general, there are three consecutive stages in adsorption process: 1) the first stage, the adsorbate diffuses from the bulk solution to the external surface of adsorbent; 2) the second stage, the adsorbate on the external surface of adsorbent transfers in the internal pores or/and branched pores in the adsorbent particle, that is called intraparticle or pore diffusion; and 3) the third stage, the adsorbate is adsorbed at an active site on the surface of material (chemical reaction via ion-exchange, 8
ACS Paragon Plus Environment
Page 9 of 25 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Industrial & Engineering Chemistry Research
complexation and/or chelation).40 The intraparticle diffusion model was used to fit the experimental data to evaluate whether it was involved into the adsorption process of boron on ZIF-67 and the model can be expressed as
Qt k p ,i t 0.5 C
(3)
where kp,i (mg·g-1·h-0.5) is the intraparticle diffusion rate constant at phase i, C is related to the thickness of the boundary layer and the external mass transfer in the adsorption.41 The linear plots of Qt against t-0.5 based on the experiment data showed that the boundary layer diffusion of boric acid molecules and the diffusion from solution to the external surface of ZIF-67 were performed 42 in liquid-phase adsorption (Figure 3c and Table S1). The concentration of residual boron decreased gradually and the adsorption rate slowed down to equilibrium.43 The regression line of the second stage did not pass through the origin, showing that the intraparticle diffusion was not the only controlling step for the adsorption rate.44 In order to find the rate-determining step, the kinetic data were analyzed using the Boyd kinetic model, which is represented as follows 2
2Qt Bt 3Qe
for Qt/Qe < 0.85
(4)
Bt 0.4977 ln(1
Qt ) for Qt/Qe > 0.85 Qe
(5)
where B (h-1) is the rate coefficient. The B values were summarized in Table S1 and the linear plots of Bt versus t were shown in Figure 3d for various initial boron concentrations. If this plot is a straight line through the origin the adsorption is controlled by particle diffusion. Otherwise, it is controlled by the film diffusion. The film diffusion was the rate-limiting step for boron adsorption on ZIF-67 because the straight line did not pass through the origin.
9
ACS Paragon Plus Environment
Industrial & Engineering Chemistry Research
3.2.4. Adsorption isotherms The isotherm experiments were carried out by adding ZIF-67 (3 g·L-1) into a series of boric acid aqueous solution with the initial boron concentration of 0.05, 0.1, 0.2, 0.3 and 0.5 mol·L-1 (mixture pH: 4) at temperatures of 25, 35 and 45 oC, respectively. The adsorptions of boron on ZIF-67 at different temperatures were shown in Figure 4a. The boron adsorption capacities increased with the decrease of temperature, indicating that the adsorption of boron on ZIF-67 was favorable at low temperatures. 1.6
a
400
b
1.4 1.2 t/Q (hg/mg) t
Qt (mg/g)
300
200
1.0 0.8 0.6 0.4
100
0.2
0
0.0
0
5
10
15
20
25
0
5
10
15
400
6.0
c
350
5.0
300
25
d
4.0 Bt
250 200
3.0
150
2.0
100
1.0
50 0
20
t (h)
t (h)
Qt (mg/g)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 10 of 25
0.0 0
1
2
3
4
5
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
t (h)
t0.5 (h0.5)
Figure 3. (a) Effect of contact time on boron adsorption on ZIF-67 (ZIF-67 dosage of 3 g·L-1, temperature of 35 oC); (b) Fitting by pseudo-second order model; (c) Fitting by intraparticle diffusion model; and (d) Fitting by Boyd’s kinetic model. ( 0.3 mol·L-1,
0.05 mol·L-1,
0.1 mol·L-1,
0.2 mol·L-1,
0.5 mol·L-1) 10
ACS Paragon Plus Environment
Page 11 of 25 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Industrial & Engineering Chemistry Research
To further investigate the adsorption isotherm of boron to ZIF-67, the three isotherm models, Langmuir isotherm model,45 Freundlich isotherm model and Henry isotherm model, were employed to describe the boron adsorption. The Langmuir isotherm model, which assumes that adsorption takes place as a monolayer on a homogenous surface, can be expressed as Ce C 1 e Qe K L Qmax Qmax
(6)
where KL, the Langmuir isotherm constant, is related to the adsorption bonding energy, and Qmax is the estimated maximal adsorption capacity. Fitting results were seen in Figure 4b and the correlation coefficients at different temperature were lower than 0.2 (Table S2), suggesting that Langmuir isotherm model cannot fit the data well. Freundlich isotherm model is widely used to describe the adsorbent-adsorbate interaction and the adsorption process on heterogeneous surfaces with different functional groups. Freundlich isotherm model can be expressed as follow
1 log Qe log K F log Ce n
(7)
where KF is the Freundlich isother constant, and 1/n is a constant that indicates the adsorption capacity of the adsorbent and the intensity of the adsorption process. KF and 1/n indicate the magnitude of the adsorption driving force. Fitting results were seen in Figure 4c. KF and 1/n could be obtained from the intercepts and slopes from the plots of logQe versus logCe as summarized in Table 1. Considering 1/n < 1 at all tested temperatures, an affinity should exist between boron and ZIF-67, which might be the electrostatic attraction.46 The equilibrium constants derived from various isotherms such as Langmuir, Frumkin, Henry isotherms, can be used for calculation of free energy changes (ΔG) of adsorption. Henry model was employed to describe the boron adsorption isotherms on ZIF-6 and can be expressed as follow 11
ACS Paragon Plus Environment
Industrial & Engineering Chemistry Research
Qe K p Ce
(8)
where Kp (ml g-1) is the distribution constant. The linear plots of Qe versus Ce based on the isotherm data were shown in Figure 4d and Kp were summarized in Table 1. The data could fit the Henry isotherm model well and the correlation coefficients were larger than 0.96 for all tested temperatures.
a
35
500
30
400
25
Ce/Qe (g/L)
Qe (mg/g)
600
300 200
b
20 15
100
10
0
5 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40
Ce (mol/L)
Ce (mol/L)
-1.2 -1.4
600
c
d
500
-1.6 Qe (mg/g)
-1.8 logQe
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 12 of 25
-2.0 -2.2
400 300
-2.4
200
-2.6
100
-2.8 0
-3.0 -1.6
-1.4
-1.2
-1.0
-0.8
-0.6
-0.4
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 Ce (mol/L)
logCe
Figure 4. (a) Boron adsorption isotherms on ZIF-67 at different temperatures (pH of 4); (b) fitting of boron adsorption isotherms on ZIF-67 by Langmuir model; (c) Freundlich model; and (d) Henry model.(
25°C,
35°C,
45°C)
The adsorption capacities of materials found in literature and this study were showed in Figure 5a (details seen in Table S3). ZIF-67 exhibited the highest adsorption capacity of 579.80 mg·g-1 at 25 oC,
12
ACS Paragon Plus Environment
Page 13 of 25
which was much higher than any other adsorbent ever reported. The adsorption ability of ZIF-67 was much better than that (247.44 mg·g-1) of isostructural ZIF-8, indicating that Co(II) made great contribution in boron adsorption. Figure 5b showed that the boric acid molecules crystallize on the ZIF-67 surface.
600 500 400 300 200
a
b
1 Activated Carbon 2 Fly ash 3 Mg-AI Layered double hydroxides 4 Iron oxide/hydroxide-based nanoparticles 5 MIL-96(AI) 6 UIO-66 7 Calcium alginate gel beads 8 Glucamine-functionalized hydrogel beads 9 ZIF-8 10 ZIF-67
25C 35C 45C
600 500 400
Qe(mg/g)
700
Qmax (mg/g)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Industrial & Engineering Chemistry Research
300 200 100 0 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 Ce(mol/L)
100 0
1
2
3
4
5
6
7
8
9
10
Figure 5. (a) Boron adsorption capacities of adsorbents; (b) ZIF-67 adsorbed with boron at 25 oC (initial boron concentration of 0.5 mol·L-1 and ZIF-67 dosage of 3 g·L-1).
3.2.5. Adsorption thermodynamics The feasibility of the adsorption process was evaluated by the thermodynamic parameters including Gibbs free energy change (ΔG, kJ·mol-1), enthalpy change (ΔH, kJ·mol-1), and entropy change (ΔS, kJ·mol-1 k-1), which were obtained through Eq. (9)
ln K p
VS VH R RT
(9)
where R (8.314 J·mol-1·K-1) is the universal gas constant, T (K) is Kelvin temperature, Kp is the distribution coefficient which can be obtained from Henry model. According to Eq. (9), the linear plot of lnKp versus 1/T was shown in Figure 6. The data fitted well with a correlation coefficient of 0.996. The parameters of the adsorption of boron on ZIF-67 were given in Table 1. All ΔG values at
13
ACS Paragon Plus Environment
Industrial & Engineering Chemistry Research
various temperatures were negative, demonstrating that the adsorption of boron on ZIF-67 was spontaneous. When the temperature was decreased, ΔG was more negative, showing that the adsorption of boron to ZIF-67 was easier at the low temperature. The negative ΔH (-31.39 kJ mol-1) suggested that the adsorption process was exothermic reaction. The negative value of ΔS suggested the randomness decrease (boric acid molecules) at the solid/liquid interface during the adsorption of boron on ZIF-67. 5.2 5.0
lnKp
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 14 of 25
4.8 4.6 4.4 4.2 3.10
3.15
3.20
3.25
3.30
3.35
1/T ( )
Figure 6. Van’t Hoff plot.
Table 1 Thermodynamic parameters of two isotherm models for boron adsorption on ZIF-67. Freundlich model 1/n KF R2
T (oC) 25 35 45
Henry model Kp R2 (mL·g-1)
0.93 1.56 1.06
0.16 0.93 0.20 0.97 0.08 0.97
165.39 113.17 74.69
ΔG
ΔS
ΔH
(KJ mol-1) (KJ·mol-1·k-1) (KJ·mol-1) 0.97 -12.68 0.96 -12.17 0.98 -11.42
-0.06
-31.39
3.3. Adsorption mechanism The adsorption of the substrate on MOFs is mainly related to electrostatic interaction, acid-base 14
ACS Paragon Plus Environment
Page 15 of 25 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Industrial & Engineering Chemistry Research
interaction, π-π stacking interaction, hydrogen bonding and ligand binding in the liquid phase.47 Under pH of 4 and temperature of 25 oC, ZIF-67 exhibited an extraordinarily high boron adsorption capacity of 579.80 mg·g-1, the highest boron adsorption capacity ever reported. Firstly, the highest boron adsorption is mainly related to the electrostatic interaction between ZIF-67 nanocrystals and boric acid. The speciation of boric acid depends on its concentrations.48 The polyborate species prevail at concentrations higher than 20 mmol·L-1. In the 0.5 mol·L-1 boron aqueous solution, there exist B5O6(OH)4-, B3O3(OH)4-, B4O5(OH)2-, B(OH)4- and B(OH)3, these species can be interconverted,49,50 and their distribution are controlled by pH. The pristine ZIF-67 exhibited positive surface charges at pH ≤10 in water (Figure 7a). With the initial pH increased from 4 to 9, the functional groups on ZIF-67 nanocrystal surface might be deprotonated, thus resulting in the decrease of positive charge density on ZIF-67 nanocrystals. The electrostatic interaction between ZIF-67 nanocrystals and borate ions with negative charge decreased with the pH increase. Boron acid is a weaker acid (0.5 mol·L-1, pH=4.43) and B(OH)3 is not easy to transform polymeric borate ions at low pH of 2 and 3. Boron exist three different chemical states on the adsorbed MOFs
51.
Secondly, the π–π stacking interaction, a weaker interaction than electrostatic interaction, occurred between the 2-methylimidazole ligand and polymeric borate ions containing six membered rings such as B3O3(OH)4-, B5O6(OH)4- and B4O5(OH)42- (Figure 7b).52 Thirdly, the coordination bonding between open metal ion sites in ZIF-67 and borate ions through OH groups. As a result, the concentration of boron acid adsorbed on ZIF-67 becomes higher and the boric acid molecules successfully crystallized on the ZIF-67 surface (Figure 5b). The pristine ZIF-8 exhibited negative surface charges at pH < 9.153 and there is an electrostatic repulsion between ZIF-8 and boric acid molecules. In addition, the characteristics of ZIF-8 (Figure 7c) are different to its isostructural
15
ACS Paragon Plus Environment
Industrial & Engineering Chemistry Research
ZIF-67 (Figure 7d). The cell lengths of ZIF-67 are longer than that of ZIF-8 and the cell of ZIF-67 is larger than that of ZIF-8 (Table S4), indicating that the larger pore size is conducive to the entry of adsorbents and pore volume of ZIF-67 can accommodate more adsorbents. The adsorption capacity of ZIF-67 was much higher than that (247.44 mg·g-1) of isostructural ZIF-8.
50
Zeta potential (mV)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 16 of 25
40
a b
30 20 10 0 -10 2
4
6
8
10
12
pH
c
d
Figure 7. (a) Zeta potentials of ZIF-67 at various pH; (b) Polymeric borate ions B3O3(OH)4-, B4O5(OH)42- and B5O6(OH)
4
-
from left to right; simulation structure of (c) ZIF-8 and (d) ZIF-67
(Task: locate, Method: metropolis, Quality: customized, Force field: Universal).
3.4. Regeneration and recycling The regeneration and reusability of the ZIF-67 are crucial for practical application, especially for
16
ACS Paragon Plus Environment
Page 17 of 25
cost control. The reusability of ZIF-67 was evaluated by a multiple cycle test. The desorption experiment was carried out as follows. The exhausted ZIF-67 was added into hydrochloric acid solutions (0.1 L , pH: 4), and then the mixtures were stirred at 35 oC for 4 h with hydrochloric acid renewed once at 2 h. The regenerated ZIF-67 was washed with ethanol (2×0.01 L) and dried at room temperature for 24 h. The adsorption conditions in every cycle were the same. At the fifth regeneration cycle, the adsorption capacity of ZIF-67 could still exhibit 94.1% of the original capacity (Figure 8a), showing that the acid-washing was a feasible and effective method to remove boron from the used ZIF-67. ZIF-67 had no significant change from its XRD pattern (Figure 1c) and morphology (Figure 8b) at the fifth regeneration cycle. Therefore, ZIF-67 is a stable, effective and recyclable sorbent for boron removal.
100
Recovery Rate (%)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Industrial & Engineering Chemistry Research
a
b
80 60 40 20 0
1
2
3
4
5
Cycle
Figure 8. (a) Recycling of ZIF-67 on boron adsorption; (b) SEM images of the ZIF-67 desorption.
4. Conclusions Well-defined rhombic dodecahedral cobalt-based ZIF-67 (size: 400-500 nm) was synthesized at room temperature. ZIF-67 exhibited the highest uptake capacity of 579.80 mg·g-1 at the optimal pH of 4, which was much higher than any other adsorbent ever reported. The adsorption kinetics
17
ACS Paragon Plus Environment
Industrial & Engineering Chemistry Research 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 18 of 25
analysis indicated that intraparticle diffusion and film diffusion were the rate-limiting steps. Adsorption of boron on ZIF-67 was a spontaneous and exothermic process. The adsorption of boron to ZIF-67 was mainly due to electrostatic attraction, π–π stacking interaction and the coordination bonding between open metal ion sites in ZIF-67 and polymeric borate ions and then the molecules successfully crystallize on the ZIF-67 surface. The adsorbent was easily regenerated by using hydrochloric acid and the boron adsorption capacity exhibited 94.1% of the first cycle at the fifth cycle. The high uptake capacity and the good stability of ZIF-67 indicated that it is a promising adsorbent for boron removal.
Supporting Information SEM image of ZIF-67 at 11-day preservation in air, parameters of kinetic models, thermodynamic parameters of Langmuir model, experimental conditions of the boron adsorption capacities of the various adsorbents and cell parameters for simulation structures of ZIF-67 and ZIF-8.
Acknowledgments This work was supported by the National Natural Science Foundation of China (grant number 51078265) and by the Research Fund of Tianjin Key Laboratory of Aquatic Science and Technology (TJKLAST-PT-2016-07).
Literature Cited (1) Hilal, N.; Kim, G. J.; Somerfield, C. Boron removal from saline water: a comprehensive review. Desalination 2011, 273, 23-35.
18
ACS Paragon Plus Environment
Page 19 of 25 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Industrial & Engineering Chemistry Research
(2) Bodzek, M. The removal of boron from the aquatic environment-state of the art. Desalin. Water Treat. 2016, 57, 1107-1131. (3) Wang, B.; Guo, X.; Bai,; P. Removal technology of boron dissolved in aqueous solutions - a review, Colloid. Surface A 2014, 444, 338-344. (4) Nasef, M. M.; Nallappan, M.; Ujang, Z. Polymer-based chelating adsorbents for the selective removal of boron from water and wastewater: a review. React. Funct. Polym. 2014, 85, 54-68. (5) Theiss, F. L.; Ayoko, G. A.; Frost, R. L. Removal of boron species by layered double hydroxides: a review. J. Colloid Interface Sci. 2013, 402, 114-121. (6) Howe, P. D. A review of boron effects in the environment. Biol. Trace Elem. Res. 1998, 66, 153-166. (7) Abdelnour, S. A.;
El-Hack, M. E. A.;
Swelum; A. A.; Perillo, A.; Losacco, C.
The vital
roles of boron in animal health and production: A comprehensive review. J. Trace Elem. Med. Bio. 2018, 50, 296-304 [8] Wolska, J.; Bryjak, M. Methods for boron removal fromaqueous solutions—A review. Desalination 2013, 310, 18–24. (9) Vhahangwele, M.; Mugera, G.W.; Hlanganani, T. Adsorption of As, B, Cr, Mo and Se from coal fly ash leachate by Fe3+ modified bentonite clay. J. Water Reuse Desal. 2016, 6, 382-391. (10) Demirçivi, P.; Saygılı, G. N. Comparative study of modified expanded perlite with hexadecyltrimethylammonium-bromide and gallic acid for boron adsorption. J. Mol. Liq. 2018, 254, 383-390. (11) Lin, J. Y.; Shih, Y. J.; Chen, P. Y.; Huang, Y. H. Precipitation recovery of boron from aqueous solution by chemical oxo-precipitation at room temperature. Appl. Energ. 2016, 164,
19
ACS Paragon Plus Environment
Industrial & Engineering Chemistry Research 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 20 of 25
1052-1058. (12) Kobya, M.; Öncel, M. S.; Demirbas, E.; Celen, M. Arsenic and boron removal from spring and groundwater samples in boron mining regionsof Turkey by electrocoagulation and ion-exchange consecutive processes. Desalin. Water Treat. 2017, 93, 288-296. (13) Chiang, A. C. T.; Lin, J. C. T.; Wijayanti, D. R.; Lee, D. J. Boron removal with UTC-series reverse osmosis filtration. J. Taiwan Inst. Chem. E. 2013, 44, 317-321. (14) Turker, O. C.; Baran, T. A combination method based on chitosan adsorption and duckweed (Lemna gibba L.) phytoremediation for boron (B) removal from drinking water. Int. J. Phytoremediat. 2018, 20, 175-183. (15) Jung, S.; Kim, M. J. Optimal conditions for recovering boron from seawater using boron selective resins. Korean J. Chem. Eng. 2016, 33, 2411-2417. (16) Wang, B.; Lin, H.; Guo, X.; Bai, P. Boron removal using chelating resins with pyrocatechol functional groups. Desalination 2014, 347, 138-143. (17) Ting, T. M.; Nasef, M. M. Modification of polyethylene-polypropylene fibers by emulsion and solvent radiation grafting systems for boron removal. Fiber. Polym. 2017, 18, 1048-1055. (18) Zelmanov, G.; Semiat, R. Boron removal from water and its recovery using iron (Fe3+) oxide/hydroxide-based nanoparticles (NanoFe) and NanoFe-impregnated granular activated carbon as adsorbent. Desalination 2014, 333, 107-117. (19) Sasaki, T.; Sakai, Y.; Hongo, T.; Iizuka, A.; Yamasaki, A. Preparation of a solid adsorbent derived from concrete sludge and its boron removal performance. Ind. Eng. Chem. Res. 2012, 51, 5813-5817. (20) Yilmaz, A. E.; Boncukcuoglu, R.; Bayar, S.; Fil, B. A.; Kocakerim, M. M. Boron removal by
20
ACS Paragon Plus Environment
Page 21 of 25 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Industrial & Engineering Chemistry Research
means of chemical precipitation with calcium hydroxide and calcium borate formation. Korean J. Chem. Eng. 2012, 29, 1382-1387. (21) Al-Ghouti, M. A.; Khan, M. Eggshell membrane as a novel bio sorbent for remediation of boron from desalinated water. J. Environ. Manage. 2018, 207, 405-416. (22) Xu, L.; Liu, Y.; Hu, H.; Wu, Z.; Chen, Q. Synthesis, characterization and application of a novel silica based adsorbent for boron removal. Desalination 2012, 294, 1-7. (23) Zhang, N.; Lyu, J.; Bai, P.; Guo, X. Boron isotopic separation with pyrocatechol-modified resin by chromatography technology: experiment and numerical simulation. J. Ind. Eng. Chem. 2018, 57, 244-253. (24) Alharati, A.; Swesi, Y.; Fiaty, K.; Charcosset, C. Boron removal in water using a hybrid membrane process of ion exchange resin and microfiltration without continuous resin addition. J. Water Process Eng. 2017, 17, 32-39. (25) Tiwari, A.; Choi, K. M.; Lee, S. M.; Tiwari, D. Rapid and efficient removal of boron from deep sea water using synthesized polymer resin. Desalin. Water Treat. 2014, 57, 2134-2141. (26) Floquet, C. F.; Sieben, V. J.; MacKay, B. A.; Mostowfi, F. Determination of boron concentration in oilfield water with a microfluidic ion exchange resin instrument. Talanta 2016, 154, 304-311. (27) Korkmaz, M.; Özmetin, C.; Cirtlik, A.; Siğirci, Ş. I. Full factorial design of experiments for boron removal from solutions by purolite S 108 resin converted to hydroxyl form. Particul. Sci. Technol. 2016, 35, 742-748. (28) Li, Y.; Zhou, K.; He, M.; Yao, J. Synthesis of ZIF-8 and ZIF-67 using mixed-base and their dye adsorption. Microporous Mesoporous Mater. 2016, 234, 287-292.
21
ACS Paragon Plus Environment
Industrial & Engineering Chemistry Research 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 22 of 25
(29) Yang, Q.; Lu, R.; Ren, S.; Chen, C. Chen, Z.; Yang, X. Three dimensional reduced graphene oxide/ZIF-67 aerogel: Effective removal cationic and anionic dyes from water. Chem. Eng. J. 2018, 348, 202-211. (30) Yang Q.; Ren S.; Zhao, Q.; Lu, R.; Zheng, H. Selective separation of methyl orange from water using magnetic ZIF-67 composites. Chem. Eng. J., 2018, 333, 49-57. (31) Lyu, J.; Zhang, N.; Liu, H.; Zeng, Z.; Zhang, J.; Bai, P.; Guo, X. Adsorptive removal of boron by zeoliticimidazolate framework: kinetics, isotherms, thermodynamics, mechanism and recycling. Sep. Purif. Technol. 2017, 187, 67-75. (32) Zhang, Z.; Zhang, J.; Liu, J.; Xiong, Z.; Chen, X. Selective and competitive adsorption of azo dyes on the metal-organic framework ZIF-67. Water Air Soil Poll. 2016, 227, 471- 483. (33) Hasan, Z.; Cho, D. W.; Chon, C. M.; Yoon, K.; Song, H. Reduction of p-nitrophenol by magnetic Co-carbon composites derived from metal organic frameworks. Chem. Eng. J. 2016, 298, 183-190. (34) Din, A. T. M.; Hameed, B. H.; Ahmad, A. L. Batch adsorption of phenol onto physiochemical-activated coconut shell. J. Hazard.Mater. 2009, 161, 1522-1529. (35) Lin, K. Y. A.; Yang, H.; Lee, W. D. Enhanced removal of diclofenac from water using a zeolitic imidazole framework functionalized with cetyltrimethylammonium bromide (CTAB). Rsc. Adv. 2015,5, 81330-81340. (36) Schejn, A.; Balan, L.; Falk, V.; Aranda, L.; Medjahdi, G.; Schneider, R. Controlling ZIF-8 nano- and microcrystal formation and reactivity through zinc salt variations, CrystEngComm 2014, 16, 4493-4500. (37) Lin, K. Y. A.; Lee, W. D. Self-assembled magnetic graphene supported ZIF-67 as a recoverable
22
ACS Paragon Plus Environment
Page 23 of 25 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Industrial & Engineering Chemistry Research
and efficient adsorbent for benzotriazole. Chem. Eng. J. 2016, 284, 1017-1027. (38) Zhou, Q.; Zhu, L.; Xia, X.; Tang, H. The water – resistant zeolite imidazolate framework 67 is a viable solid phase sorbent for fluoroquinolones while efficiently excluding macromolecules. Microchim. Acta. 2016, 183, 1839-1846. (39) Xie, L.; Liu, D.; Huang, H.; Yang, Q.; Zhong, C. Efficient capture of nitrobenzene from waste water using metal-organic frameworks. Chem. Eng. J. 2014, 246, 142-149. (40) Torad, N. L.; Hu, M.; Ishihara, S.; Sukegawa, H.; Belik, A. A.; Imura, M.; Ariga, K.; Sakka, Y.; Yamauchi, Y. Direct synthesis of MOF-derived nanoporous carbon with magnetic Co nanoparticles toward efficient water treatment. Small 2014, 10, 2096-2107. (41) Ho, Y. S. Second-order kinetic model for the sorption of cadmium onto tree fern: a comparison of linear and non-linear methods. Water Res. 2006, 40, 119-125. (42) Crini, G.; Peindy, H.; Gimbert, F.; Robert, C. Removal of c.i.basic green 4 (malachite green) from aqueous solutions by adsorption using cyclodextrin-based adsorbent: kinetic and equilibrium studies. Sep. Purif. Technol. 2007, 53, 97-110. (43) Luo, P.; Zhao, Y.; Zhang, B.; Liu, J.; Yang, Y.; Liu, J. Study on the adsorption of neutral red from aqueous solution onto halloysite nanotubes. Water Res. 2010, 44 1489-1497. (44) Cheng, Z.; Liu, X.; Han, M.; Ma, W. Adsorption kinetic character of copper ions onto a modified chitosan transparent thin membrane from aqueous solution. J. Hazard. Mater. 2010, 182, 408-415. (45) Tran, H. N.; Lin, C. C;. Woo, S. H.; Chao, H. P. Efficient removal of copper and lead by Mg/Al layered double hydroxides intercalated with organic acid anions: adsorption kinetics, isotherms, and thermodynamics. Appl. Clay Sci. 2018, 154, 17-27.
23
ACS Paragon Plus Environment
Industrial & Engineering Chemistry Research 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 24 of 25
(46) Hasan, Z.; Jhung, S. H. Removal of hazardous organics from water using metal-organic frameworks (MOFs): plausible mechanisms for selective adsorptions. J. Hazard. Mater. 2015, 283, 329-339. (47) Tang, Y. P.; Luo, L.; Thong, Z.; Chung, T. S. Recent advances in membrane materials and technologies for boron removal. J. Membrane Sci. 2017, 541, 434-446. (48) Baskan, M. B.; Atalay, N. Boron removal from aqueous solution by batch adsorption using box-behnken design. Desalin. Water Treat. 2015, 55, 2095-2102. (49) Zhou, Q.; Zhu, L.; Xia, X.; Tang, H. The water – resistant zeolite imidazolate framework 67 is a viable solid phase sorbent for fluoroquinolones while efficiently excluding macromolecules. Microchim. Acta 2016, 183, 1839-1846. (50) Hasan, Z.; Jhung, S. H. Removal of hazardous organics from water using metal-organic frameworks (MOFs): Plausible mechanisms for selective adsorptions. J. Hazard. Mater. 2015, 283, 329-339. (51) Lyu, J.; Liu, H.; Zeng Z.; Zhang, J.; Xiao, Z.; Bai, P.; Guo, X. Metal−organic framework UiO-66 as an efficient adsorbent for boron removal from aqueous solution. Ind. Eng. Chem. Res., 2017, 56, 2565–2572. (52) Guan, Z.; Lv, J.; Bai, P.; Guo, X. Boron removal from aqueous solutions by adsorption - a review. Desalination 2016, 383, 29-37. (53) Chen, L. Y. Synthesis, characterization and evaluation of novel composites based on ZIF-8. Henan Normal University, 2017. (A Dissertation for Master degree in Chinese)
24
ACS Paragon Plus Environment
Page 25 of 25 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Industrial & Engineering Chemistry Research
Abstract Graphics
Regeneration
High boron adsorption
ZIF-67
H3BO3 ⇋
25
ACS Paragon Plus Environment