Preparation of Mesoporous Silica from Electrolytic Manganese Slags

Subscriber access provided by University of Sussex Library

Article

Preparation of Mesoporous Silica from Electrolytic Manganese Slags by Using Amino-Ended Hyperbranched Polyamide as Template Daohong Zhang, Daiyong Xiao, Qian Yu, Sufang Chen, Shenghui Chen, and Menghe Miao ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.7b02268 • Publication Date (Web): 11 Sep 2017 Downloaded from http://pubs.acs.org on September 21, 2017

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 free 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 accessible to all readers and 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.

ACS Sustainable Chemistry & Engineering 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 23

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

ACS Sustainable Chemistry & Engineering

Preparation of Mesoporous Silica from Electrolytic Manganese Slags by Using Amino-Ended Hyperbranched Polyamide as Template Daohong Zhang1*, Daiyong Xiao1, Qian Yu1, Sufang Chen2*, Shenghui Chen1, Menghe Miao3 1

Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission &

Ministry of Education, Hubei Province, South-Central University for Nationalities, 182 Minzu Road, Wuhan, Hubei Province, 430074, China 2

Key Laboratory for Green Chemical Process of Ministry of Education, Wuhan Institute of

Technology, LiuFang Campus, No.206, Guanggu 1st Road, Donghu New & High Technology Development Zone, Wuhan, Hubei 430205, China 3

CSIRO Manufacturing, 75 Pigdons Road, Waurn Ponds, Victoria 3216, Australia

*Corresponding

authors.

E-mail:

[email protected]

Zhang);[email protected] (Dr. Sufang Chen).

ACS Paragon Plus Environment

(Prof.

Dr.

Daohong


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

Abstract Large quantities of waste slags are produced during the preparation of electrical manganese, causing serious pollution to the environment. The recycling and utilization of electrolytic manganese slags (EMS) is a serious challenge to the industry. Here, we report the utilization of EMS in preparation of high-performance mesoporous silica using amino-ended hyperbranched polyamide (AEHPA) as template. The effects of AEHPA content and molecular weight on properties of mesoporous silica, including the specific surface area, pore diameter, pore volume, size and distribution, have been investigated. Based on 0.3 wt% AEHPA-2 during preparing silica, the specific surface area, pore volume and pore diameter of the produced amorphous mesoporous silica are 451.34 m2·g-1, 0.824 cm3·g-1 and 7.09 nm, respectively, showing remarkable improvements over the silica without AEHPA with specific surface area (271.05 m2·g-1), pore volume (1.167 cm3·g-1) and pore diameter (17.43 nm). The formation mechanism of mesoporous silica has been supposed and substantiated by FT-IR, XRD, XPS spectra and SEM micrographs. This preparation method of mesoporous silica from EMS may open a new avenue for recycling and utilization of manganese slag.

Keywords ： Electrolytic manganese slags; Mesoporous silica; Hyperbranched polymers; Recycling and utilizing.


Page 2 of 23

Page 3 of 23

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


INTRODUCTION Electrolytic manganese slags (EMS) is a category of acidic filtered by-product from the extraction of electrolytic manganese. The rapid development of electrolytic manganese brings great benefits. But simultaneously, about 6-9 tons of the solid waste is produced while producing per ton electrolytic manganese 1, and especially some heavy metal elements and compounds in EMR can pollute surrounding soil and receiving water bodies. 2 Therefore, the large quantity of by-product EMS solid waste poses a heavy burden to the environment and an urgent challenge to the industry3. China has been the top contributor to the production of electrolytic metal manganese, accounting for over 98.5% of the total world capacity in 2014.4,5 The recycling of EMS has become a major problem for the industry. Many scientists and engineers have studied recycling of EMS and made progresses in many approaches, including synthesis of zeolite,6 geo polymers,7 road beds, soil fertilizer, autoclaved bricks, ground granulated blast-furnace slag cement, cementing material, chemical raw materials8-11 and metal recovery.12,13 These methods are very difficult to be applied industrially due to low efficiency, high cost of production and low value of the resultant products. The recycling of EMS is still limited to laboratory scales while the increasing quantity of EMS is being stacked near to the factories, causing potential pollution from the heavy metals of EMS as rain soaks EMS over a long period of time. It is thus imperative to find a viable recycling method so as to end the pollution caused by EMS.14



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 23

Mesoporous silica have been widely used in catalysis and chromatography fields due to their high surface area, high hydrothermal stability, tunable pore sizes and volumes, and diverse surface functionality.15-17 Mesoporous silica can be used to carry, transport and protect macromolecules,18 and as a basis for the synthesis of complex porous structures.19,20 Mesoporous silica can also be used as supramolecular aggregates in life science, biomedicine, and catalytic reactions,21 and it is a good nanocarrier of biological macromolecules and polymers.22 Mesoporous silica is usually prepared using templates-based methods, including small molecules and polymers templates. Tetraethyl-orthosilicate, ionic surfactant and cellulose, are mainly small molecule templates.23,24 Polymers templates include polyethylene glycol, polypyrrole,

ultrathin

polymer

films,

polymer

microspheres

dual-templates

cetyltrimethyl ammonium bromide and P123, and so on.25-27 It is easy to form a homogeneous reactive system with simple morphology by using a small molecule as template. Polymers, on the other hand, can tune the microstructure of nanomaterials and synthesize more complicated target products using a more complex process. During the synthesis of mesoporous silica, both small molecules and polymers have positive function for stabilizing the material.28 The cavities inside hyperbranched polymers and the large number of reactive ended-groups can stabilize and disperse nanoparticles29,30. Moreover, the cavities can provide a place for reactions between the small molecules. Therefore, hyperbranched polymers are ideal templates for controlling the morphology and properties of nanomaterials.31 Main synthesis methods of silica include hydrothermalreaction,32 chemical vapor


Page 5 of 23

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


deposition, microemulsion, sol-gel and chemical precipitation.33 Both chemical vapor deposition method and sol-gel method involve expensive raw materials and high energy

consumption.34

The

microemulsion

method35

needs a

complicated

post-treatment process, involving the difficult removal of organics and potential environmental pollution, although it is convenient in controlling the particle size of silica. The chemical precipitation method

36

is of large particle size and wide

distribution, and the method shows low energy consumption, high extraction efficiency, simplicity of process and easy industrialization. Here, we research recycling and utilization of electrolytic manganese slags by using the chemical precipitation method. Amino-ended hyperbranched polyamide (AEHPA) is used as template to prepare high-performance silica with high quality by taking advantage of its liquidity and availability of functional amino groups37. The size, distribution, pore property and specific surface area of the silica particles can be controlled by changing the content and molecular weight of the AEHPA). The obtained mesoporous silica shows a higher surface area and higher content of silicon dioxide than the conventional method without AEHPA, indicating potentially industrial value of recycling electrolytic manganese slags.

EXPERIMENTAL SECTION Materials. Electrolytic manganese slags (EMS) was supplied by Citic Dameng Mining Industries Reagent Co., Ltd, and its overall elemental composition

38

is

composed of 4.46 wt% Mn, 1.32 wt% Al, 15.06wt% Si, 6.75wt% Fe, 9.94wt% Ca, 1.06wt% Mg, 0.78wt% K, 0.14wt% Na, 0.07wt% P and 0.02wt% Zn. Sodium



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

hydroxide, sulfuric acid, hydrofluoric acid, diethylenetriamine (DETA), methyl acrylate (MA), ethylenediamine (EDA), methanol and ethanol were supplied by Sinopharm Chemical Reagent Co., Ltd. All chemical reagents were of analytical grade and used as received. Preparation of amino-ended hyperbranched polyamide. Three types of amino-ended hyperbranched polyamides (AEHPA-n, n=1, 2 and 3) were synthesized using different molar ratios among ethylenediamine, diethylenetriamine and methyl acrylate according to Scheme 1.37 0.25 mol diethylenetriamine and 0.25 mol methyl acrylate were added into a 250 mL three-neck flask equipped with a mechanical stirrer, a nitrogen inlet, and a water trap attached with a condenser. The mixture was reacted for about 12 h at 0-5 oC, and then an appropriate content of ethylenediamine was added dropwise into the flask according to three different molar ratios (2:2:1, 6:6:1 and 14:14:1) among diethylenetriamine, methyl acrylate and ethylenediamine, respectively. The mixture was heated gradually to about 70 oC to react for 1h and then heated to about 130 oC to react for 7 h under nitrogen atmosphere. Three types of yellowish liquid products were obtained with near yield of about 96%.


Page 6 of 23

Page 7 of 23

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


Scheme 1. Synthesis scheme of AEHPA and ideal chemical structure of AEHPA-2. The three products were named as AEHPA-1, AEHPA-2 and AEHPA-3 in sequence, and their theoretical molecular weights are calculated to be 374, 1002 and 2258 g/mol according to their molar ratios, and their amino-ended numbers are 4, 8 and 16. The ideal chemical structure of AEHPA-2 is presented in Scheme 1. Preparation of mesoporous silica. 200 g EMS was washed by using 500 mL deionized water for four times followed by filtering. The residue was dried for about 2 h at 120 oC to obtain dried EMS powder. 20 g dried EMS powder and 95 g 40 wt% sodium hydroxide solution were added into a 250 mL three-necked flask equipped with a mechanical stirrer and a condenser. The reaction was conducted at 140 oC for 12 h. The filtrate (sodium silicate solution) was obtained after the resultant solution was filtered. Sodium silicate solution was added into a 250 mL three-necked flask equipped with a mechanical stirrer and heated gradually to about 80 oC. Then 0.06 g AEHPA-2 as a template was added to the flask. An appropriate content of 10 wt% sulfuric acid solution was added dropwise into the flask for neutralizing the solution to pH 5~6, and then the solution was reacted for about 2 h at 80 oC, resulting in the formation of white emulsion. The white emulsion was filtered to form a white filter cake. Deionized water was used to wash the filter cake several times until the filtrate contains no sulfate ion as tested using barium chloride solution. 4.13 g mesoporous silica was obtained after the resultant cake was dried at 120 oC for 3 h. The silica quality has been measured according to the standard method (HG/T 3061-2009) about silica, and the results include that the SiO2 content is about 93.1wt% (≥90wt%), and



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 23

manganese content is about 38.5 mg/kg (≤40 mg/kg), and ferric content is about 479.3mg/kg (≤500 mg/kg) and copper content is about 8.2 mg/kg (≤10 mg/kg ), indicating highest equality of mesoporous silica according to HG/T 3061-2009. Characterization of mesoporous silica. The particle size distribution was measured by laser particle analyzer (OMEC, Ltd., Zhuhai, China). The morphology of mesoporous silica was examined by scanning electron microscope (SEM, Hitachi, Co., SU8010, Japan). The specific surface area, pore volume and pore size distribution of the mesoporous silica were determined by N2 adsorption-desorption isotherms (BET, Quantachrome,

Co.,

Autosorb-1-C-TCD-MS,

UAS).

X-ray

photoelectron

spectroscopy (XPS) patterns of mesoporous Silica particles were measured on a Multilab 2000 (VG, England). FT-IR measurements were performed on a Bruker Vector 33 spectrometer using sealed cell (KBr 0.5mm). X-ray diffraction (XRD) patterns were obtained using a Bruker-D8 diffractometer with monochromatized Cu Kα radiation (λ=1.54Å) at 40 kV and 40 mA.

RESULTS AND DISCUSSION Effect of AEHPA molecular weight on the properties of mesoporous silica. The mesoporous materials were characterized for specific surface area, pore volume and pore size. The N2 sorption spectra of the mesoporous silica prepared using AEHPA and without using AEHPA are shown in Figure 1. Their properties are presented in Table 1.


Page 9 of 23

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


Figure 1. (a) N2 adsorption-desorption isotherms and (b) pore distribution curves of mesoporous silica with different molecular weights of AEHPA-n (n=1, 2, 3). From Table 1 and Figure 1, the specific surface area, pore volume and pore diameter of the produced mesoporous silica by using AEHPA-2 as template are 451.34 m2·g-1, 0.824 cm3·g-1and 7.09 nm, respectively, compared with specific surface area (271.05 m2·g-1), pore volume (1.167 cm3·g-1) and pore diameter (17.43 nm) of the silica prepared without AEHPA. This suggests significant increase in specific surface area and decreases both in pore volume and in diameter. These distinct changes may be attributed to the cavities inside hyperbranched polymers and the hydrogen-bond interaction between the amino of AEHPA and the hydroxyl group of the silicon precursor29,30. The mesoporous silica with AEHPA exhibited narrow pore size distributions, which confirms that the mesopores remain accessible by nitrogen even after the polymerization.39 As shown in Table 1, with the increase of AEHPA molecular weight, the specific surface area of mesoporous silica increases first and then decreases. When the moderate molecular weight AEHPA-2 was used as template for preparing mesoporous silica, the specific surface area was the largest. Presumably the molecular weight of the AEHPA template has a significant influence on the specific surface area and pore diameter of the mesoporous silica.



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 23

Table 1. Effect of AEHPA molecular weight on the property of mesoporous silica molecular weight Without AEHPA 0.3wt%AEHPA-1 0.3wt%AEHPA-2 0.3wt%AEHPA-3

BET Surface Area (m2·g-1) 271.05 352.22 451.34 381.87

Pore Volume (cm3·g-1) 1.17 0.88 0.82 0.82

Pore Size (nm) 17.43 10.15 7.09 8.60

According to Brunauer-Deming-Deming-Teller (BDDT) and International Union of Pure and Applied Chemistry (IUPAC) adsorption isotherms system,40,41 all the samples with AEHPA show IV type isotherms in Figure 1a. The number of adsorption layers is limited when it reaches the saturated vapor pressure. The N2 isotherms exhibit a capillary condensation step at P/Po=0.6~0.9, as indicated by the hysteretic loop. The isotherms rose rapidly and accompanied by hysteresis in the relative moderate pressure due to the existence of capillary condensation. The hysteresis loop of the mesoporous silica with AEHPA belongs to H1 type. The pores show irregular size distribution with complex structure, showing typical “worm-like mesoporous channel” and pipe type hole with uneven distribution. The hysteresis loops take flat oval shape, which are typical physical adsorption curves for mesoporous materials.42 The sample without AEHPA shows type II isotherms and type H3 hysteresis loop, indicating formation of a disordered material. In principle, the preparation of mesoporous silica by using AEHPA-2 as template can increase the specific surface area, which can affect the particle size distribution of the silica particles43. The particle size distribution of the mesoporous silica is shown in Figure 2. The average diameter (Figure 2a) of the silica without AEHPA is approximately 25.72 µm. However, the average diameters of the mesoporous silica


Page 11 of 23

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


with AEHPA-1, AEHPA-2 and AEHPA-3 are 19.96, 18.60 and 18.89 µm, respectively. With the increase of molecular weight of AEHPA, the particle diameter first decreases and then increases slightly as shown in Figure 2b-d. Because the molecular weight of AEHPA-1 is much smaller than AEHPA-2 in the system, the AEHPA is not enough to form a protective film and stabilizes the silicon precursor, resulting in wide distribution of particle size. However the even larger molecular weight AEHPA-3 has higher viscosity than the smaller molecular weight AEHPA-2, resulting in self-aggregation to form uneven templates with various sizes which leads to some large diameter silica particles.

Figure 2. The particle size distribution of silica by using different AEHPA as templates. (a) without AEHPA, (b) AEHPA-1, (c) AEHPA-2 and (d) AEHPA-3. Effect of AEHPA-2 content on the specific surface area of mesoporous silica. As shown in Table 1, mesoporous silica with high specific surface area can be prepared using the intermediate molecular weight AEHPA-2 as template. The effect of



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

AEHPA-2 content on the properties of mesoporous silica is showed in Table 2 and Figure 3.

Figure 3. (a) N2 adsorption-desorption isotherms and (b) pore distribution curves of mesoporous silica with different contents of AEHPA-2. As shown in Table 2, with the increase of AEHPA-2 content, the specific surface area of mesoporous silica increases first and then decreases with the maximum value achieved when the AEHPA-2 content was 0.3 wt%. Compared with the silica without AEHPA-2, the specific surface area of 0.3 wt% AEHPA-2 increases by 66.5%. At the same time, the pore volume and pore diameter of mesoporous silica reached their respective minimum values, corresponding to decreases of 29.4% and 59.3%, respectively. With further increase of AEHPA-2 content, the specific surface area of the produced mesoporous silica declined slightly. The reason for the decrease is that the high content of AEHPA-2 leads to high viscosity, which is unfavorable for forming mesoporous silica particles with high specific surface area.44 Figure 3 shows the dependence of N2 adsorption-desorption isotherms and pore distribution curves of mesoporous silica on the AEHPA-2 content. When the AEHPA-2 content is less than 0.1 wt%, the BDDT and IUPAC of the mesoporous


Page 12 of 23

Page 13 of 23

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


silica belong to type II and type H3 isotherms, respectively (Figure 3a), and the mode of pore size is 12.764 nm (Figure 3b and Table 2), indicates a kind of large pore diameters materials arising out of such interstitial cavities (textural pores). When the AEHPA-2 content is higher or equal to 0.3 wt%, the BDDT and IUPAC of the mesoporous silica belongs to type IV and type H1 isotherms, respectively (Figure 3a), and the mode of pore size is about 7~8 nm at the maximum probability (Figure 3b and Table 2). The N2 isotherms exhibit a capillary condensation step at P/Po=0.6~0.9, and the mesoporous silica prepared by using AEHPA as template is used to maintain the mesoporous structure.45 Table 2. Effect of AEHPA content on the property of mesoporous silica content without AEHPA-2 0.1wt%AEHPA-2 0.3wt%AEHPA-2 0.5wt%AEHPA-2 0.7wt% AEHPA-2 0.9wt%AEHPA-2

BET Surface Area (m2·g-1) 271.05 337.60 451.34 421.79 399.28 404.87

Pore Volume (cm3·g-1) 1.167 0.834 0.824 0.797 0.769 0.824

Pore Size (nm) 17.428 12.764 7.090 7.147 8.276 8.146

0.3 g sample was dispersed in 40 mL of distilled water and was allowed to undergo supersonic wave at room temperature. After 2 minutes, particle size distribution and average particle size of silica in water were measured using a laser particle analyzer. Average particle sizes and particle size distributions of mesoporous silica with different AEHPA-2 contents are shown in Figure 4. With the increase of AEHPA-2 content, the average particle size of mesoporous silica decreases sharply first and then increases slightly, reaching its minimum value when the AEHPA-2 content is 0.3 wt%.



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

Compared with the average particle size (25.72 µm) of the silica without AEHPA-2, that value of 18.60 µm for 0.3 wt% AEHPA-2 represents a decrease of 27.68%. The average diameters of the samples obtained by using 0.1wt%, 0.5wt%, 0.7wt% and 0.9wt% AEHPA-2 are 23.70, 21.18, 21.37 and 21.41 µm, respectively. The particle size distribution of mesoporous silica becomes substantially narrow with the addition of AEHPA-2, and its minimum value appears at 0.3 wt% (Figure 4c).

Figure 4. The particle size distribution of silica obtained by different contents of AEHPA-2. (a) without AEHPA-2, (b) 0.1wt%AEHPA-2, (c) 0.3wt%AEHPA-2, (d) 0.5wt%AEHPA-2, (e) 0.7wt%AEHPA-2 and (f) 0.9wt%AEHPA-2. The small average particle size and narrow particle size distribution of mesoporous silica may be attributable to a surfactant effect of the amino of AEHPA. The hydrogen-bond interaction between the amino of AEHPA and the hydroxyl


Page 14 of 23

Page 15 of 23

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


groups of silicon precursor29,30 forms a protective film on the surface of silicon precursor. When the content of AEHPA is lower than 0.3wt% in the system, the AEHPA is not enough to form a protective film to stabilize the silicon precursor, resulting in aggregation of the silica during acidolysis and thus a wide particle size distribution (Figure 4a-b). Too much AEHPA (0.5-0.9 wt%) in the system may form a thick protective film, resulting in excessive silicon precursor molecules in the film to form large size particles and wide particle size distribution of mesoporous silica (Figure 4d-f). The incorporation of 0.3 wt% AEHPA-2 seemingly reaches a balance that gives the minimum average particle size and particle size distribution in Figure 4c.

Scheme 2. The formation mechanism of mesoporous silica. Formation mechanism of mesoporous silica. The possible formation mechanism of mesoporous silica is presented in Scheme 2. (1) Firstly, both the amino-ended groups of AEHPA-2 (Scheme 2a) and the hydroxyl groups of sodium silicate have strong hydrogen bonding force and form a protective film (Scheme 2b)



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

on the surface of the silicon precursor (named AEHPA@Na2SiO3 complex). (2) During acidolysis of the complex, dehydration of hydroxyl groups condenses the AEHPA@Na2SiO3 complex and forms silica micelles (Scheme 2c). The protective film on the outer layer of the silica micelles effectively prevent their aggregation. (3) Sufficient water is used to wash the silica micelles for removing Na+ and SO42-, simultaneously, and all the AEHPA template agent on the surface of the silica micelles is also removed and cavities are formed (Scheme 2d). (4) When the silica micelles are dried at about 120 oC, the mesoporous silica (Scheme 2e) is formed after the free water is removed completely. Their FT-IR spectra of all samples in Figure 5a appear similar peaks at 3450 cm-1 and 1640 cm-1 (s, -OH), 1095 cm-1 (b, Si-O), 799 cm-1 (b, -OH), and 465 cm-1 (s, Si-O-Si), and the characteristic peaks of AEHPA-n have been not observed, indicating that the templates AEHPA-n have been removed completely after formation of mesoporous silica. This is substantiated by the disappearance of N1s peak at binding energy of about 399 eV in Figure 5c-d. The XRD spectra of all samples in Figure 5b show that there is no obvious diffraction peak in 0o~5o, suggesting that the prepared silica may be amorphous silica wormlike mesoporous channels but not ordered mesoporous structures.


Page 16 of 23

Page 17 of 23

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


Figure 5. (a) FT-IR, (b) XRD, (c) XPS and (d) N1s XPS spectra of various mesoporous silica. To investigate the microstructure of mesoporous silica obtained by templates AEHPA-n, their SEM micrographs have been shown in Figure 6. Compared with the compact structure embedded big particles about silica without AEHPA-n in Figure 6a, the size of mesoporous silica particles decreases and the microstructure becomes loose and porous due to the usage of templates AEHPA-n in Figure 6b-d. With an increase of AEHPA-2, the loose and porous microstructure increases first and then decreases from Figure 6c and Figure 6e-f, and the mesoporous silica (Figure 6c) obtained by 0.3wt% AEHPA-2 indicating highest surface area, being agreement with the result in Table 2 and the formation mechanism of the mesoporous silica in Scheme 2.



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

Figure 6. SEM micrograph of mesoporous silica obtained by AEHPA as templates. (a) without AEHPA-n, (b) 0.3wt% AEHPA-1, (c) 0.3wt% AEHPA-2, (d) 0.3wt% AEHPA-3, (e) 0.1wt% AEHPA-2 and (f) 0.5wt% AEHPA-2.

CONCLUSION Electrolytic manganese slags (EMS) could be used to prepare high-performance mesoporous silica by using amino-ended hyperbranched polyamide (AEHPA) as template. The effects of AEHPA content and molecular weight on the properties of resulting amorphous mesoporous silica were investigated, including the specific surface area, pore diameter and pore volume. When 0.3 wt% AEHPA with intermediate molecular weight was used, the resultant mesoporous silica shows a specific surface area of 451.34 m2·g-1, a pore volume of 0.824 cm3·g-1 and a pore diameter of 7.09 nm, compared with specific surface area (271.05 m2·g-1), pore volume (1.167 cm3·g-1) and pore diameter (17.43 nm) without the use of AEHPA. These indicate a significant increase in specific surface area and decreases in both pore volume and pore diameter. The reported preparation method of mesoporous


Page 18 of 23

Page 19 of 23

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


silica from EMS may open an avenue of recycling and utilizing manganese slags, and the mesoporous silica with high specific surface area may be used as catalyst supports.

ACKNOWLEDGES We gratefully acknowledge the financial support of the National Natural Science Foundation of China (21403158, 51573210 and 51373200) and Key Project in the National Science &Technology Pillar Program during the Twelfth Five-year Plan Period (2015BAB01B03).

REFERENCES (1) Tangmeng, L.; Zhong, H.; Xingrong, Y.; Mingqiang, Y.; Jinzhong, L., Research of resource utilization of electrolytic manganese slag. China's Manganese Ind. 2012, 1, 1-6 DOI: 10.14101/j.cnki.issn.1002-4336.2012.01.007 (2) Li, C.; Zhong, H.; Wang, S.; Xue, J., Leaching behavior and risk assessment of heavy metals in a landfill of electrolytic manganese residue in western hunan, China. Hum. Ecol. Risk Assess. 2014, 20, 1249-1263 DOI: 10.1080/10807039.2013.849482 (3) Wu, S.; Wang, J.; Liu, L.; Wang, H.; Zhao, P., Review on comprehensive utilization of electrolytic manganese slag. Inorg. Chem. Ind. 2016, 4, 22-25 (4) Zhou, C.; Du, B.; Wang, N.; Chen, Z., Preparation and strength property of autoclaved bricks fromelectrolytic manganese residue. J. Clean. Prod. 2014, 84, 707-714 DOI: 10.1016/j.jclepro.2014.01.052 (5) Xu, F.; Jiang, L.; Dan, Z.; Gao, X.; Duan, N.; Han, G.; Zhu, H., Water balance analysis and wastewater recycling investigation in electrolytic manganese industry of China — A case study. Hydrometallurgy 2014, 149, 12-22 DOI: 10.1016/j.hydromet.2014.05.002 (6) Li, C.; Zhong, H.; Wang, S.; Xue, J.; Zhang, Z., A novel conversion process for waste residue: Synthesis of zeolite from electrolytic manganese residue and its application to the removal of heavy metals. Colloids Surfaces A 2015, 470, 258-267 DOI: 10.1016/j.colsurfa.2015.02.003 (7) Zhao, R.; Han, F. L., Preparation of geopolymer using electrolytic manganese residue. Key Eng. Mater. 2014, 591, 130-133 DOI: 10.4028/www.scientific.net/KEM.591.130 (8) Wu, F. F.; Wang, S.; Guo, S. Y.; Zhong, H., Adsorption of methylene blue by porous ceramics prepared from electrolytic manganese residues. Desalin. Water Treat. 2016, 57, 27627–27637 DOI: 10.1080/19443994.2016.1172514 (9) Shu, J.; Liu, R.; Liu, Z.; Chen, H.; Du, J.; Tao, C., Solidification/stabilization of electrolytic manganese residue using phosphate resource and low-grade MgO/CaO. J. Hazard. Mater. 2016, 317, 267-274 DOI: 10.1016/j.jhazmat.2016.05.076 (10) Chen, H.; Liu, R.; Liu, Z.; Shu, J.; Tao, C., Immobilization of Mn and NH4+-N from electrolytic manganese residue waste. Environ. Sci. Pollut. R. 2016, 23, 12352-12361 DOI:



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

10.1007/s11356-016-6446-2 (11) Chen, H. L.; Liu, R.; Long, Q.; Liu, Z. In Carbonation precipitation of manganese from electrolytic manganese residue treated by CO2 with alkaline additives, International Conference on Machinery, Materials Engineering, Chemical Engineering and Biotechnology, 2016 DOI: 10.2991/mmeceb-15.2016.142 (12) Shu, J.; Liu, R.; Liu, Z.; Chen, H.; Tao, C., Enhanced extraction of manganese from electrolytic manganese residue by electrochemical. J. Electro. Chem. 2016, 780, 32-37 DOI: 10.1016/j.jelechem.2016.08.033 (13) Shu, J.; Liu, R.; Liu, Z.; Chen, H.; Tao, C., Simultaneous removal of ammonia and manganese from electrolytic metal manganese residue leachate using phosphate salt. J. Clean. Prod. 2016, 135, 468-475 DOI: 10.1016/j.jclepro.2016.06.141 (14) Wu, N.; Jiao, Y.; Zeng, P.; Cheng, H.; Zhang, J.; Song, M., Present situation and prospect of electrolytic manganese slag recovery and reutilization. Guangdong Chem. Ind. 2016, 9, 134-135 (15) Luo, F.; Feng, F.; Hou, L.; You, W.; Xu, P.; Li, X.; Ge, X.; Wu, Y. In The exploration of mesoporous silica as a stationary phase support for semi-packed micro-fabricated gas chromatographic (GC) columns, IEEE International Conference on MICRO Electro Mechanical Systems, 2017 DOI: 10.1109/MEMSYS.2017.7863598 (16) Han, N.; Wang, Y.; Bai, J.; Liu, J.; Wang, Y.; Gao, Y.; Jiang, T.; Kang, W.; Wang, S., Facile synthesis of the lipid bilayer coated mesoporous silica nanocomposites and their application in Micropor. Mesopor. Mater. 2016, 219, 209-218 DOI: drug delivery. 10.1016/j.micromeso.2015.08.006 (17) Corell, E. P.; Garcíabennett, A.; Roslis, J. V.; Argüelles, F. A.; Andrés, A., Application of mesoporous silica materials for the immobilization of polyphenol oxidase. Food Chem. 2017, 217, 360-362 DOI: 10.1016/j.foodchem.2016.08.027 (18) Zeng, X.; Yu, S.; Ye, L.; Li, M.; Pan, Z.; Sun, R.; Xu, J., Encapsulating carbon nanotubes with SiO2: a strategy for applying them in polymer nanocomposites with high mechanical strength and electrical insulation. J. Mater. Chem. C 2015, 3, 187-195 DOI: 10.1039/C4TC01051E (19) Mohapatra, S., Plasmonic properties of Ag nanoparticles embedded in GeO2-SiO2 matrix by atom beam sputtering. Phys. Chem. Chem. Phys. 2016, 18, 3878-3883 DOI: 10.1039/c5cp05345e (20) Dong, Z.; Yu, G.; Le, X., Gold nanoparticles modified magnetic fibrous silica microsphere as a highly efficient and recyclable catalyst for the reduction of 4-nitrophenol. New J. Chem. 2015, 39, 8623-8629 DOI: 10.1039/c5nj00713e (21) Yang, C.; Fu, L.; Zhu, R.; Liu, Z., Influence of cobalt species on the catalytic performance of Co-N-C/SiO2 for ethylbenzene oxidation. Phys. Chem. Chem. Phys. 2016, 18, 4635-4642 DOI: 10.1039/c5cp06779k (22) Zhang, L.; Liu, T.; Chen, Y., Magnetic conducting polymer/mesoporous SiO2 yolk/shell nanomaterials: multifunctional nanocarriers for controlled release of doxorubicin. Rsc Adv. 2016, 6, 8572-8579 DOI: 10.1039/c5ra23580d (23) Sui, X. Y.; Xu, J.; Wang, C. H.; Zhou, C. L.; Liu, R. X., Preparation of hollow silica microspheres with nanoporous shells by soft template method. Key Eng. Mater. 2014, 602-603, 63-66 DOI: 10.4028/www.scientific.net/KEM.602-603.63 (24) Cao, K. L.; Wu, Y.; Wang, J.; Hui, X. Y.; Wang, X. T., Preparation and characterization of silica nanotubes with cellulose as template. Appl. Mech. Mater. 2016, 851,61-65 DOI: 10.4028/www.scientific.net/AMM.851.61


Page 20 of 23

Page 21 of 23

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


(25) Li, M.; Liu, N.; Wu, Z.; Li, Y.; Li, S.; Xu, W.; Luo, Z.; Liu, Y., A facile and novel route for dual-template method synthesis of mesoporous silica material Al-Ce-SBA-15. Mater. Lett. 2016, 185, 85-88 DOI: 10.1016/j.matlet.2016.08.072 (26) Prabhakar, N.; Zhang, J.; Desai, D.; Casals, E.; Gulinsarfraz, T.; Näreoja, T.; Westermarck, J.; Rosenholm, J. M., Stimuli-responsive hybrid nanocarriers developed by controllable integration of hyperbranched PEI with mesoporous silica nanoparticles for sustained intracellular siRNA delivery. Inter. J. Nano. 2016, 11, 6591-6608 DOI: 10.2147/IJN.S120611 (27) Deze, E. G.; Papavasiliou, A.; Papageorgiou, S. K.; Katsaros, F. K.; Kouvelos, E. P.; Romanos, G. E.; Boukos, N.; Xin, Q.; Nyalosaso, J. L.; Cool, P., Metal loaded nanoporous silicas with tailor-made properties through hyperbranched polymer assisted templating approaches. Micropor. Mesopor. Mater. 2016, 235, 107-119 DOI: 10.1016/j.micromeso.2016.07.051 (28) Jeon, H.; Lee, C. S.; Patel, R.; Kim, J. H., Well-organized meso-macroporous TiO2/SiO2 film derived from amphiphilic rubbery comb copolymer. ACS Appl. Mater. Interfaces 2015, 7, 7767-7775 DOI: 10.1021/acsami.5b01010 (29) Prida, V. M.; Vega, V.; García, J.; González, L.; Rosa, W. O.; Fernández, A.; Hernando, B., Functional Fe–Pd nanomaterials synthesized by template-assisted methods. J. Magn. Magn. Mater. 2012, 324, 3508-3511 DOI: 10.1016/j.jmmm.2012.02.077 (30) Pan, L. Y.; Zhang, Y. L.; Wang, H. Y.; Liu, H.; Luo, J. S.; Xia, H.; Zhao, L.; Chen, Q. D.; Xu, S. P.; Gao, B. R., Hierarchical self-assembly of CdTe quantum dots into hyperbranched nanobundles: suppression of biexciton Auger recombination. Nanoscale 2011, 3 (7), 2882-2888 DOI: 10.1039/clnr10121h (31) Yin, J. Y.; Liu, H. J.; Jiang, S.; Chen, Y.; Yao, Y., Hyperbranched Polymer Functionalized Carbon Dots with Multistimuli-Responsive Property. Acs Macro Letters 2013, 2 (11), 1033-1037 DOI: 10.1021/mz400474v (32) Kumar, S.; Malik, M. M.; Purohit, R., Synthesis methods of mesoporous silica materials. Mater. Today: Proceedings 2017, 4, 350–357 DOI: 10.1016/j.matpr.2017.01.032 (33) Sun, D.; Sui, X. Y.; Zhou, C. L.; Han, N. H.; Liu, F. T., Synthesis of silica aerogel using silica sol by ambient drying method. Key Eng. Mater. 2017, 726, 199-203 DOI: 10.4028/www.scientific.net/KEM.726.199 (34) Alam, M. N.; Potiyaraj, P., Synthesis of nano zinc hydroxide via sol–gel method on silica surface and its potential application in the reduction of cure activator level in the vulcanization of natural rubber. J.Sol-Gel Sci. Tech. 2017, 81, 903-911 DOI: 10.1007/s10971-016-4248-0 (35) Zhou, X.; Chi, K.; Duan, A.; Zhao, Z.; Dong, H.; Gong, Y.; Song, S.; Wang, X.; Xu, C., Hierarchically structured porous silica spheres by microemulsion/vesicle templating for hydrodesulfurization of fluid catalytic cracking diesel. Part. Part. Syst. Char. 2016, 33, 190-203 DOI: 10.1002/ppsc.201500166 (36) Dong, L. I.; Wang, F. H.; Hong, Z., Preparation of ultrafine silica nanoparticles by a precipitation method. J. Beijing Univ. Chem. Tech. 2016, 43, 33-39 DOI: 10.13543/j.bhxbzr.2016.01.005 (37) Zhang, D.; Liu, T.; Chen, S.; Miao, M.; Cheng, J.; Chen, S.; Du, D.; Li, J., Influence of the molecular weights of amino-ended hyperbranched polyamide template on the morphology of self-assembled ZnS nanoparticles. Macromol. Res. 2016, 24, 892-899 DOI: 10.1007/s13233-016-4132-3 (38) Li, J.; Jiao, X.; Du, D.; Ye, H.; Peng, Q., Mineralogical properties of electrolytic manganese



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

slag from guangxi, Bull. Chin. Ceram Soc., 2017, 36, 947-952 DOI: 10.16552/j.cnki.issn1001-1625.2017.03.033 (39) Chung, P. W.; Kumar, R.; Pruski, M.; Lin, S. Y., Temperature responsive solution partition of organic–inorganic hybrid poly(n-isopropylacrylamide)-coated mesoporous silica nanospheres. Adv. Funct. Mater. 2010, 18, 1390-1398 DOI: 10.1002/adfm.200701116 (40) Shu, Z.; Chen, Y.; Zhou, J.; Li, T.; Sheng, Z.; Tao, C.; Wang, Y., Preparation of halloysite-derived mesoporous silica nanotube with enlarged specific surface area for enhanced dye adsorption. Appl. Clay Sci. 2016, 132, 114-121 DOI: 10.1016/j.clay.2016.05.024 (41) Atashin, H.; Malakooti, R., Magnetic iron oxide nanoparticles embedded in SBA-15 silica wall as a green and recoverable catalyst for the oxidation of alcohols and sulfides. J. Saudi Chem. Soc. 2017, 21, S17–S24 DOI: 10.1016/j.jscs.2013.09.007 (42) Beck, J. S.; Vartuli, J. C.; Roth, W. J.; Leonowicz, M. E.; Kresge, C. T.; Schmitt, K. D.; Chu, C. T. W.; Olson, D. H.; Sheppard, E. W.; Mccullen, S. B., A new family of mesoporous molecular sieves prepared with liquid crystal templates. J. Am.Chem.Soc 2016, 114, 10834-10843 DOI: 10.1021/ja00053a020 (43) He, Q.; Cui, X.; Cui, F.; Guo, L.; Shi, J., Size-controlled synthesis of monodispersed mesoporous silica nano-spheres under a neutral condition. Micropor. Mesopor. Mater. 2009, 117, 609-616 DOI: 10.1016/j.micromeso.2008.08.004 (44) Kejik, M.; Moravec, Z.; Barnes, C. E.; Pinkas, J., Hybrid microporous and mesoporous organosilicate covalent polymers with high porosity. Micropor. Mesopor. Mater. 2017, 240, 205-215 DOI: 10.1016/j.micromeso.2016.11.012 (45) Xia, H.; Wan, G.; Yang, F.; Wang, J.; Bai, Q., Preparation of monodisperse large-porous silica microspheres with polymer microspheres as the templates for protein separation. Mater. Lett. 2016, 180, 19-22 DOI: 10.1016/j.matlet.2016.05.044


Page 22 of 23

Page 23 of 23

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


Mesoporous silica with high specific surface area was prepared by electrolytic manganese slags and hyperbranched polymers, which shows high-value recycling of manganese slags and application potential. 32x15mm (300 x 300 DPI)


Preparation of Mesoporous Silica from Electrolytic Manganese Slags

Recommend Documents