Heavy Metals Retention on Recycled Waste Glass from Solid Wastes

ARTICLE pubs.acs.org/IECR

Heavy Metals Retention on Recycled Waste Glass from Solid Wastes Sorting Operations: A Comparative Study among Different Metal Species Andrea Petrella,† Mario Petrella,† Giancarlo Boghetich,† Teodora Basile,† Valentina Petruzzelli,† and Domenico Petruzzelli*,† †

Dipartimento di Ingegneria delle Acque e Chimica, Politecnico di Bari, 4, Via E.Orabona, 70125 Bari, Italy ABSTRACT: Heavy metals retention [Pb2+, Cd2+, Ni2+, and Cr(VI)] on recycled waste porous glass (RWPG) from solid wastes sorting operations was carried out. To the purpose metals containing solutions in the concentration range 2
4 mg/L, reproducing the average concentration present in, e.g., solid waste leachate from landfills or industrial effluents, were percolated onto columns loaded with RWPG beads with particle size in the range 0.35
1.0 mm and flow-rates between 0.23 and 0.75 L/h. Metals retention mechanism was associated with ion exchange with overall capacities in the following order: Pb2+ > Cd2+ > Ni2+ > Cr(VI) in consideration of the hydrated ion radius and free energy of hydration of the metal ions. The rate controlling step was identified with the ions interdiffusion in the Nernst liquid film around particles. The metals exhausted beads were embedded into cement conglomerates as inert materials thus minimizing metals release in the environment. The prepared mortar specimen showed improved thermal properties as compared to conventional (sand based) composites.

the EU countries.15,16 Thanks to the RWPG porous structure, lightness, and thermal insulation properties, the material may be effectively reused in the building industry as inert (aggregate) in the concrete and mortars formulation.17
20 Through laboratory columns loaded with RWPG beads, the sorption properties of the reference waste derived material toward different metal ions, i.e., lead, cadmium, nickel, and chromium(VI), present in solutions simulating typical industrial wastewater, were evaluated. Thermodynamic and kinetic aspects of the metal retention phenomena on RWPG were evaluated which were essentially based on ion exchange. In this context, the process parameters for larger scale applications were defined and the effects on RWPG retention capacity and rates examined. The final destination of the heavy metals laden sorbents was the building industry as lightweight aggregates for mortars and concrete formulations.17
20

1. INTRODUCTION The increasing industrial use of heavy metals over the past decades has led to a corresponding incremental release of metals in the environment.1
4 Insufficiently or partially treated industrial effluents induce unacceptable sanitary risk and environmental hazards in all natural compartments (air, soil, water, biota).1,3,5 Typically, lead, cadmium, copper, chromium, zinc, and nickel ions may be introduced into natural waters from metals smelting, chemical, leather tanning, electroplating, and metal finishing operations.6
10 Special concern is focused on heavy metals due to their biopersistence, whereas their generalized toxicity for humans and other animals has an important impact on socioeconomic activities.11
13 Recent improvements in the analytical methods for trace metals detection,14 together with a better substantiation of their sanitary and environmental impacts, leads to the enforcement of more stringent standards for the maximum allowable concentrations released in water bodies as well as in other environmental compartments.11
13 The purpose of the present work is to evaluate behavior of recycled waste porous glass (RWPG) as a cheap sorbents for heavy metals removal from wastewaters.12,13 On the other hand, recycling of (municipal and industrial) solid wastes after sorting operations is very hectic in the context of the waste minimization policies with recovery of valuable, e.g., secondary raw materials for reuse.15,16 On these premises, recycling of waste glass from different socioeconomic activities (in the form of RWPG), as a sorbent for heavy metals present in industrial effluents and/or leachates from landfills, leads to a dual advantage in terms of a) conservation of secondary raw materials for reuse and b) environmental control of persistent pollutants in the environment. The essential biopersistence and chemical inertia of glass materials leads to long-term accumulation in the environment and, accordingly, recycling and reuse operations must be favored in the ambit of the current waste minimization policies applied in r 2011 American Chemical Society

2. EXPERIMENTAL SECTION Recycled waste porous glass from municipal/industrial solid wastes sorting operations was kindly supplied by Maltek Industrie S.r.l., Terlizzi, Bari, Italy. To the purpose, waste glass, i.e., sodium
calcium silicate/oxides derivatives (Table 1) was crushed and mixed with foaming (porosizing) agents such as CaCO3 and binders (granulating agents) such as diatomite, caustic soda, or potash, and the mixture melted at 900
1300 °C. After decomposition of the carbon dioxide releasing compounds (foaming agents) in the molten mass, it is induced the formation of controlled porosity materials which, after granulation and quenching, leads to the formation of glass beads with a bulk Received: September 27, 2011 Accepted: November 19, 2011 Revised: November 14, 2011 Published: November 19, 2011 119

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density in the range 0.2
0.5 kg/dm3. Finally, RWPG beads are sieved at controlled bead size. Figure 1A shows the appearance of typical RWPG samples, together with the corresponding SEM micrographs (Figure 1B and C). A lightweight mostly closed porous structure is evidenced for the reference materials. Figure 1C inset shows the X-ray diffraction (XRD) spectrum carried out on RWPG samples. Sodium and calcium silicate/ oxides derivatives are detected in an otherwise amorphous background. SEM micrographs were obtained with a Mod.XL Scanning Electron Microscope from Philips Co., Eindhoven, Holland, whereas X-ray diffractions (XRD) were carried out by the use of a PW 1830 voltage generator equipped with a PW 1050/04

goniometer and a PW 3710 data acquisition system, from Philips Co., Eindhoven, Holland. Dynamic (column) experiments on RWPG beads were carried out at 298 K by the use of jacketed glass columns (I.D. = 1.0 cm; H = 50 cm) loaded with 8 g of different bead size range samples. Elution was carried out by the use of metals containing solutions, representative of typical industrial wastewater composition, on different bead size range materials (0.5
1.0, 0.35
0.7, and 0.5
0.75 mm). On 0.5
1 mm bead size range, experiments were carried out at variable flow-rates ranging 0.23
0.75 L/h and overall metals concentration in the range 2
4 mg/L. Experiments on the other bead size range were carried out at 0.23 L/h and 2 mg/L. All dynamic experiments were extended to exhaustive column breakthrough (effluent equal to influent concentrations). Table 2 summarizes the complex of tests carried out. Synthetic solutions (tap water) were prepared from reactive grade Pb(NO3)2, Cd(NO3)2 3 4H2O, Ni(NO3)2 3 7H2O, and K2Cr2O7, from Carlo Erba, Milan, Italy. Effluent metals concentrations along column bed volumes (BV = v/vr) and time, t, were monitored by the use of FAAS on a Mod.AAnalyst 700 Spectrometer from Perkin-Elmer, CA, USA. Final destination of metals laden RWPG samples was cement mortars formulation as a succedaneum of conventional inert

Table 1. RWPG Composition oxides

% by weight

SiO2

71

CaO

9

Na2O

14

Al2O3

3

MgO

2

K2O

1

Figure 1. RWPG material: A) beads at different grain size; B) SEM of a single bead; and C) RWPG internal bead texture with the corresponding XRD spectrum (inset). 120

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Table 2. Summary of the Experimental Tests Carried out on RWPG Materials influent concentration

bead size

flow-rate

metal specie

(mg/L)

(mm)

(L/h)

2+

2 2

0.35
0.7 0.5
0.75

0.23 0.23

2

0.5
1.0

0.23

2

0.35
0.7

0.23

2

0.5
0.75

0.23

2

0.5
1

0.23

2

0.5
1

0.40

2

0.5
1

0.60

3 4

0.5
1 0.5
1

0.23 0.23

2

0.35
0.7

0.23

2

0.5
0.75

0.23

2

0.5
1

0.23

2

0.5
1

0.44

Ni

Cd2+

Pb2+

Cr2O7=

2

0.5
1

0.75

2

0.5
1

0.23

Figure 2. Breakthrough curves for lead, cadmium, nickel, and chromium(VI) ions retention on RWPG (0.5
1 mm bead size, 0.23 L/h, 2 mgMe+2/ L, 298 K).

bead size range (0.5
1 mm), and metals concentration (2 mg/L); Figure 3 shows the corresponding breakthrough curves for lead and cadmium ions for experiments carried out at different bead size range (0.35
0.7 mm, 0.5
0.75 mm, and 0.5
1 mm), respectively, constant the flow-rate (0.23 L/h) and metals concentration (2 mg/L); Figure 4 shows the influence of flow-rate of elution for lead, cadmium, and nickel ions breakthrough at constant bead size range (0.5
1 mm) and concentration (2 mg/L). From a general overview of data it may be assumed that metal ions are mostly sorbed onto RWPG by strong electrostatic interactions at the negatively charged silicate/oxide functional groups present on the surface of the porous glass, after favorable (αMen+/Na+,Ca2+< 1) or unfavorable (αMen+/Na+,Ca2+> 1) ion exchange equilibrium with sodium/calcium ions which are massively present on the initial sorbent at concentrations exceeding 10%w, as determined by X-ray diffraction25

materials. To the purpose, controlled composition cement mortars, including metals containing RWPG as an aggregate, were prepared by the use of a class II CEM A-LL, 42.5R cement from Buzzi Unicem, Barletta, Italy, according to standard protocols by the use of a Hobart normalized mixer (USA).21 A RWPG volume exceeding 810 cm3 was added to the mortars according to standard protocols.22 Cube specimen (4  4  4 cm) were aged for 28 days at relative humidity >90% and then dried at 105 °C to constant weight. Specimen were submitted to jar test (Vittadini, Aqua, Milan, Italy) to evaluate potential release of Pb2+, Cd2+, and Ni2+ species, which was carried out after filtration and analysis of the supernatant solution. Single stage tests in demineralized water, with a liquid to solid ratio exceeding 10 L/kg, were carried out under continuous stirring (10 rpm) for 24 h according to standard protocols for solid wastes testing.23 As for thermal conductivity determinations of the cement mortars, cylindrical specimen (H = 5 cm; ϕ = 10 cm) were aged for 28 days at a relative humidity exceeding 90% and then dried (105 °C) to constant weight and stabilization at room temperature. The tests were carried out by the use of the ISOMET 2104 system from Applied Precision Ltd. (Slovakia) provided with a heating probe to produce a constant thermal flow for about 7 min and then stopped. By temperature detection along time at the opposite side of the specimen, thermal conductivity was determined. Conventional (sand based) mortars were also prepared as control. Mechanical resistance to compression (Rc) of specimens was detected after mechanical inflection tests on prismatic samples 40  40  160 mm prepared in steel molds and cured according to UNI EN 1015-11.24 Tests were carried out by means of a press system from MATEST, Milan, Italy. Conventional sand based mortars were also prepared as control.

RWPG
ðNaþ =Ca2þ Þn þ Menþ T RWPG
Menþ þ nðNaþ =Ca2þ Þ

ð1Þ

At a minor extent, metal sorption may also occur through weak electrostatic, i.e. van der Waals interactions, based on other (nonspecific) functionalities, supposedly present on the solid phase.26,27 From comparison of the breakthrough curves shown in Figure 2 it is evident that negatively charged dichromate ions are rejected from the solid-phase by Donnan exclusion,25 whereas cation species (Cd2+, Ni2+, Pb2+) are retained, at a different extent, on the basis of the variable retention capacity figures reported in Table 3 Variable retention capacities toward metal ions may be explained in terms of steric hindrance to ions permeation through the porous structure of the glass itself. The average width of the openings in the silicate lattice should be sufficiently large to allow free migration of the hydrated metal ions involved in the ion exchange reaction.28 In this context, the respective hydrated crystalline radius and the relative free energies of hydration of different cations may play a relevant role in terms of metals retention per unit mass of RWPG material, in truly agreement with data reported in Table 3 where lead ions show the lower hydrated radius with cadmium the larger one. On the other hand, the free energy of hydration for nickel is larger than the corresponding for lead ions. On these premises, lead ions, having the most favorable compromise between permeation (smaller hydrated radius) and

3. RESULTS AND DISCUSSION 3.1. Thermodynamics. Figures 2
5 show comparative breakthrough curves for different metal ion species. Specifically, Figure 2 shows comparison of the breakthrough curves for different metal ions for experiments carried out at constant flow-rate (0.23 L/h), 121

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Figure 4. A) Lead ion breakthrough curves for RWPG beads at variable flow-rates (0.23, 0.44, 0.75 L/h; 0.5
1 mm; 2 mg Pb2+/L). B) Cadmium ion breakthrough curves for RWPG beads at variable flow-rates (0.23, 0.40, 0.60 L/h; 0.5
1 mm; 2 mg Cd2+/L).

Table 3. Metals Retention Capacities of RWPG and Relevant Ionic Properties Functional to Ionic Retention Phenomenaa retention capacity

hydrated radius

free energy of

(mgMen+/gRWPG)

(Å)

hydration (kJ/meq)

Ni2+

0.40

4.04


2065.8

Cd2+

0.68

4.26


1799.5

Pb2+ Cr2O7=

1.03 ∼0

4.01 -


1495.6 -

metal species

Figure 3. A) Lead, B) cadmium, and C) nickel ions retention on RWPG at different particle size (0.35
0.7, 0.5
0.75, and 0.5
1 mm; 0.23 L/h, 2 mgMe+2/L).

a Flow-rate: 0.23 L/h; bead size: 0.5
1 mm; influent metals concentration: 2 mg/L; T = 298 K.

the flow-rate (0.23 L/h) and the influent metal ions concentration (2 mg/L). In all cases, a strong influence of RWPG particle size was observed in terms of retention capacity. The larger bead size (0.5
1 mm) showing a higher porosity exceeding (21%)29 shows a corresponding higher metals retention capacities, thus confirming that the most active silicate exchanging functionalities are localized on the surface of RWPG materials. The smaller beads size samples (0.35
0.7 mm), showing a lower porosity exceeding 15%29 and a corresponding lower exposed surface area, hindering the availability of the ion exchanging sites for metals retention, show a lower retention capacities. Moreover, based on literature data,30,31 ion clogging phenomena (e.g., a kind of ionic surface polarization) in the liquid film around the rigid inorganic glassy structure of the particle may control full availability of the surface functional groups of smaller particles thus

electrostatic interactions (easier ionic dehydration), will engage functional groups more quantitatively as compared to e.g., cadmium showing a larger hydrated radius and a definitely more difficult dehydration of ions. As a consequence, cadmium shows a lower retention capacity as compared to lead (Figure 2). Moreover, although nickel shows almost the same ionic radius as compared to lead (Table 3), the controlling factor determining the entity of ionic retention onto the silicate functional groups is associated with a more difficult dehydration. Accordingly, nickel ion show the lowest retention capacity as compared to all the other ions investigated. Figure 3 shows metals breakthrough curves for lead, cadmium, and nickel ions retention onto RWPG materials at different bead particle size (0.35
0.7, 0.5
0.75, and 0.5
1.0 mm), constant 122

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Figure 6. A) Time dependent breakthrough curves for cadmium ions retention on RWPG glass beads columns at variable flow-rates (0.23, 0.40, and 0.60 L/h; 0.5
1 mm; 2 mg Cd2+/L). The inset shows correlation of the half exchange time of exchange, t0.5 (C/C0 = 0.5 in the breakthrough curves), vs flow-rate.

In dynamic systems, when the ion exchange equilibrium is favorable toward the entering specie initially present in the liquid-phase (i.e, αMen+/Na+ < 1) any preferred ion behind the exchange boundaries (i.e., the width of the conversion band between the initial and final ionic form of the exchanger), sooner or later, will catch up with the same boundary. Similarly, any ion ahead of the boundary will ineluctably be included in the same band. The end result is a sharpening of the breakthrough curve during column elution. In other words, any measure which increases the ion exchange rate and decreases the rate of motion of the exchange boundary will lead to a selfsharpening of the breakthrough curve.26 As a consequence, from direct comparison of lead and cadmium ions breakthrough curves shown in Figure 4, it is confirmed the affinity (selectivity) of RWPG material toward lead rather than cadmium ions, after the evident self-sharpening of the lead breakthrough curves. This is an indirect confirmation of what previously postulated for the system at hand based on different considerations related to the hydrated ionic radius and the free energies of hydration of the ions. 3.2. Kinetics. Extensive literature data indicate that sorption kinetics in liquid
solid phase heterogeneous systems are controlled by mass transfer phenomena with rate determining steps associated with the interdiffusion of the interacting ions in- and out- of the contacting phases. The overall kinetic rate determining steps may be associated with the following: a) the resistance to ion interdiffusion in the solid phase (particle diffusion control, pdc) and b) the resistance to ion interdiffusion in the limiting stationary (Nernst) liquid-film around the particle (film diffusion control, fdc).32 The differential rate equations of ion exchange are too complex to be solved analytically, and, accordingly, simplifications based on the assumption of local equilibrium during column operations have to be done together with other assumptions related to the concentration of the entering species being much smaller than the initial amount of counterions present in the sorbent (i.e., trace elution). Accordingly, the uptake of the trace component, independently from the presence of other components, may reasonably be described by a linear isotherm. On these premises, the rates of particle and film diffusion controlled ion exchange may be approximated by the assumption of “linear driving force” relations thus allowing for the following analytical

Figure 5. Time dependent breakthrough curves for A) lead, B) cadmium, and C) nickel ions retention on RWPG columns loaded with different bead size materials (0.35
0.7, 0.5
0.75, and 0.5
1 mm; 0.23 L/h, 2 mgM+2/L). In the insets: Correlation of the half exchange times, t0.5 (C/C0 = 0.5 in the breakthrough curves), vs average bead radius.

limiting full ion retention. As clearly evidenced in Figure 3, higher retention capacities toward metals were observed at 0.5
1 mm as compared to the smaller bead size range where a smaller area above the breakthrough curves of the corresponding metals is observed. Figure 4 shows the influence of flow-rate on lead and cadmium retention behavior, constant the bead size in the range (0.5
1 mm) and influent metals concentration (2 mg/L). At longer contact times (i.e., lower flow-rates) retention performance are drastically improved toward both lead and cadmium ions. Kinetic factors, which are going to be better substantiated in the sections to follow, will explain such behavior. One point is worth discussing here referring to lead ions breakthrough curve showing a “self-sharpening” at lower flow-rates. 123

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Table 4. Jar Test on the RWPG-Cement Composites To Evaluate Potential Release of Metals (μg/L)

solution for particle diffusion control ð2Þ

where X is the amount of species i in the exchanger per unit volume of bed (mol/Lr); ^ is the solid-phase diffusion coefficient; and ro is the bead size radius. The asterisk refers to data at equilibrium. The half exchange time of reaction (X = 0.5Xo) is easily obtained from eq 2 t0:5 ¼ 0:15ro 2 =^

ð3Þ

The corresponding rate equation for film diffusion control is dXi =dt ¼ 3D=2ro δðCi
Ci Þ ð4Þ where X s the amount of species i in the exchanger per unit volume of bed (mol/Lr); C is the liquid-phase concentrations (mol/L); D is the liquid-phase diffusion coefficient (m2/s); ro is the bead radius; C0 is the initial liquid-phase concentration of the entering specie; and δ is the film thickness. Asterisks refer to equilibrium data. The half exchange time at C = 0.5C0 is easily obtained from eq 4 t0:5 ¼ 1:33ro δ=DC0

maximum allowable

after jar test

concentration (μg/L)

Cd2+ Ni2+

Cd2+ > Ni2+ based on the application of the ion hydration free energy model for the ion exchange retention. Film diffusion control was the rate determining step of the ion exchange reactions. Thanks to the porous structure of RWPG, the heavy metals laden exhausted sorbents were reused in the construction industry as lightweight thermal insulators for masonries and plasters without relevant adverse effects on constructions and the environment. 124

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’ ACKNOWLEDGMENT The authors wish to thank Prof. Pietro Stefanizzi, Polytechnic University of Bari, for thermal measurements of cement mortars.

(21) Italian Organization for Standardization (UNI). CementComposition, specifications and conformity criteria for common cements. UNI: Milan, Italy, 2001; EN 197-1. (22) Italian Organization for Standardization (UNI). Methods of testing cement-Part 1: Determination of strength. UNI: Milan, Italy, 2005; EN 196-1. (23) Italian Organization for Standardization (UNI). Characterization of waste-Compliance test for leaching of granular waste materials and sludges. UNI: Milan, Italy, 2004; EN 12457-2. (24) Italian Organization for Standardization (UNI). Methods of test for mortar for masonry: Determination of flexural and compressive strength of hardened mortar. UNI: Milan, Italy, 2001; EN 1015-11. (25) Petrella, A.; Petruzzelli, V.; Basile, T.; Petrella, M.; Boghetich, G.; Petruzzelli, D. Recycled porous glass from municipal/industrial solid wastes sorting operations as a lead ion sorbent from wastewaters. React. Funct. Polym. 2010, 70, 203–209. (26) Helfferich, F. Ion exchange; McGraw Hill: New York, 1962; Chapter 9. (27) Turkova, J. Journal of chromatography library. Affinity Chromatography; Elsevier Science Ltd.: UK, 1978. (28) Strohmaier, K. G.; Vaughan, D. E. W. Structure of the First Silicate Molecular Sieve with 18-Ring Pore Openings, ECR-34. J. Am. Chem. Soc. 2003, 125, 16035–16039. (29) DIN V 18004, 2004, part 5, Use of building products in construction works. Tests methods for aggregates according to DIN V 20000-103 and DIN V 20000-104. (30) Ingleziakis, V. J.; Grigoropoulou, H. Effects of operative conditions on the removal of heavy metals by zeolite in fixed bed reactors. J. Hazard. Mater. B 2004, 112, 37–43. (31) Manliu, E.; Loizidou, M.; Spyrellis, N. Uptake of lead and cadmium by clinoptilolite. Sci. Total Environ. 1994, 149, 139–144. (32) Helfferich, F. Ion Exchange; McGraw Hill: New York, 1962; Chapter 6. (33) Italian Organization for Standardization (UNI). Specification on mortar for masonry-Mortar for interior and exterior plaster. UNI: Milan, Italy, 2004; EN 998-1. (34) Italian Organization for Standardization (UNI). Specification on mortar for masonry-Masonry Mortars. UNI: Milan, Italy, 2004; EN 998-2. (35) Italian Law Decree no. 36, January 13, 2003. (36) Carslaw, H. S.; Jaeger, J. C. Conduction of heat in solids, 2nd ed.; Clarendon Press: Oxford, 1959.

’ AUTHOR INFORMATION Corresponding Author

*Phone: +39(0)805963777. Fax +39(0)805963635. E-mail: [email protected].

’ REFERENCES (1) Moore, J. W.; Ramamoorthy, S. Monitoring and criteria for impact assessment of metals. Heavy metals in natural waters; SpringerVerlag: New York, 1984. (2) Duffus, J. H. “Heavy metals” a meaningless term? (IUPAC Technical Report). Pure Appl. Chem. 2002, 74, 793–807. (3) Ferguson, J. E. The heavy elements: chemistry, environmental impact and health effects; Pergamon Press: Oxford, 1990. (4) Bowen, H. J. M. The environmental chemistry of the elements; Academic Press: London, 1979. (5) An, H. K.; Park, B. Y.; Kim, D. S. Crab shell for the removal of heavy metals from aqueous solution. Water Res. 2001, 35, 3551–3556. (6) Gupta, V. K. Equilibrium uptake, sorption dynamics, process development, and column operations for the removal of copper and nickel from aqueous solution and wastewater using activated slag, a lowcost adsorbent. Ind. Eng. Chem. Res. 1998, 37, 192–202. (7) Leinonen, H.; Lehto, J. Ion exchange of nickel by iminodiacetic acid chelating resin Chelex 100. React. Funct. Polym. 2000, 43, 1–6. (8) Lin, S. H.; Lai, S. L.; Leu, H. G. Removal of heavy metals from aqueous solution by chelating resin in a multistage adsorption process. J. Hazard. Mater. 2000, 76, 139–153. (9) Kenawy, I. M. M.; Hafez, M. A. H.; Akl, M. A.; Lashein, R. R. Determination by AAS of some trace heavy metal ions in some natural and biological samples after their preconcentration using newly chemically modified chloromethylated polystyrene-PAN ion-exchanger. Anal. Sci. 2000, 16, 493–500. (10) Pehlivan, E.; Altun, T. The study of various parameters affecting the ion exchange of Cu2+, Zn2+, Ni2+, Cd2+, and Pb2+ from aqueous solution on Dowex 50W synthetic resin. J. Hazard. Mater. 2006, 134, 149–156. (11) UNEP, United Nations Environmental Programme, Industry and Environment Office, Paris, 1989. (12) Ramalbo, R. S. Introduction to wastewater treatment process; Academic Press Inc.: New York, 1977. (13) Benefield, L. D.; Judkins, J. F.; Weand, B. L. Process chemistry for water and wastewater treatment; Prentice-Hall Inc.: NJ, 1982. (14) Richardson, S. D. Water Analysis: Emerging Contaminants and Current Issues. Anal. Chem. 2009, 81, 4645–4677. (15) Council Directive 91/156/EEC of the Council of the European Community of 18 March 1991 on waste. (16) Italian Ministry for Environment and Territory, D.M. no. 186, April 5, 2006. (17) Petrella, A.; Petrella, M.; Boghetich, G.; Petruzzelli, D.; Ayr, U.; Stefanizzi, P.; Calabrese, D.; Pace, L. Thermo-acoustic properties of cement-waste-glass mortars. Constr. Mater. 2009, 162 (CM2), 67–72. (18) Petrella, A.; Petrella, M.; Boghetich, G.; Petruzzelli, D.; Calabrese, D.; Stefanizzi, P.; De Napoli, D.; Guastamacchia, M. Recycled waste glass as aggregate for lightweight concrete. Constr. Mater. 2007, 160 (CM4), 165–170. (19) Cioffi, R.; Maffucci, L.; Martone, G.; Santoro, L. Feasibility of manufacturing building materials by re cycling a waste from ion exchange process. Environ. Technol. 1998, 19, 1145–1150. (20) Pansini, M. Natural zeolites as cation exchangers for environmetal protection. Miner. Deposita 1996, 31, 563–575. 125

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