Removal of Heavy Metals and Other Cations from Wastewater Using Zeolites

Abstract

Zeolites from abundant natural deposits were investigated by the Bureau of Mines for efficiently cleaning up mining industry wastewaters. Twenty-two zeolites were analyzed by X-ray diffraction and inductively coupled plasma analysis (ICP). These included clinoptilolite, mordenite, chabazite, erionite, and phillipsite. The zeolites were primarily in the sodium or calcium form, but potassium and magnesium counter ions were also present. Bulk densities of a sized fraction (minus 40, plus 65 mesh) varied from 0.48 to 0.93 g/cc. Heavy metal ion exchange loading values on two clinoptilolites ranged from 1.6 meq/g for lead to 0 meq/g for mercury in single ion tests. The selectivity series was determined to be Pb>Cd>Cs>Cu(II)>Co(II)>Cr(III)>Zn>Ni(II)>Hg(II). Sodium was the most effective exchangeable ion for ion exchange of heavy metals. Wastewater from an abandoned copper mine in Nevada was used to test the effectiveness of clinoptilolite for treating a multiion wastewater. Aluminum, Fe(III), Cu(II), and Zn in the copper mine wastewater were removed to below drinking water standards, but Mn(II) and Ni(II) were not. Calcium and NH₄ were absorbed preferentially to all heavy metal cations except Pb. Adsorbed heavy metals were eluted from zeolites with 3-pct NaCl solution. Heavy metals were concentrated in the eluates up to 30-fold relative to the waste solution. Anions were not adsorbed by the zeolites.     

Removal of Divalent Metal Cations and Their Mixtures from Aqueous Streams Using Micellar-Enhanced Ultrafiltration

ABSTRACT

Micellar-enhanced ultrafiltration (MEUF) is a novel membrane-based separation technique that can be used to remove multivalent metal cations from aqueous streams. In this technique an anionic surfactant is added to the aqueous stream containing the metal cations to be removed. The surfactant forms highly charged aggregates called micelles onto which the metal cations adsorb or bind. The aqueous stream is then passed through an ultrafiltration membrane with pores small enough to block the passage of the micelles and adsorbed metal cations. In this study, MEUF has been shown to remove divalent cadmium, zinc, copper, and calcium ions and their mixtures with rejections of at least 96%. A previously developed equilibrium binding model describes the results successfully. Under reasonable conditions the flux rates are not substantially below that of pure water, indicating the feasibility of MEUF for industrial application.     

改性沸石去除水中有机污染物的研究进展

概述了沸石的物理、化学性质及结构特征,介绍了采用沸石处理有机污染物时所采用的不同改性方法以及改性后对不同有机物的去除效果。综述了沸石在改性和处理有机污染物过程中所涉及到的反应机理及相关理论,总结了沸石改性和应用方面存在的问题及今后研究的方向。     

The Selective Removal off Nitrogenous-Type Compounds from Fuels by Using Zeolites

Abstract

Several zeolites were tested for the selective removal of nitrogenous compounds from an organic solution. A model compound study showed that the extent of sorption from a complex mixture is a function of the nature of the nitrogenous compounds. A correlation between the extent of sorption and the size of a compound suggests that diffusion is the controlling parameter. A capacity of 10 wt% was obtained for the model compound study. The zeolites were also tested for the removal of nitrogenous compounds from a coker naphtha and from a hydroprocessed naphtha. The low capacities relative to the model compound study of ?1 wt% and ?3 wt% obtained for the coker and the hydroprocessed naphthas, respectively, suggest the sorption of nonnitrogenous compounds.     

Catalytic Activity of ZSM-11 Zeolites Modified with Metal Cations for the Ethane Conversion

ZSM-11 zeolite samples differing by their active sites (H⁺ and different metal cations) have been studied in the transformation of ethane into aromatic hydrocarbons. A relationship between Lewis sites increasing–aromatization capacity and possible reaction steps have been suggested.     

Liquid Membrane Separations of Metal Cations Using Macrocyclic Carriers

Abstract

The selectivity in water and methanol solvents of macrocyclic crown ether ligands toward univalent and bivalent cations is well known. Incorporation of these ligands into chloroform liquid membranes separating water and salt solution phases results in a system showing selective cation transport. The cation transport rates of single cations across these liquid membranes have been correlated with equilibrium constant values for cation-macrocycle interaction in methanol. This correlation has been extended to binary cation mixtures of Cs⁺ with Li⁺, Na⁺, K⁺, and Rb⁺. A model for cation transport from these cation mixtures has been reduced to an equation which gives good agreement between measured and predicted transport rates across our liquid membranes.     

Chromate Removal from Water Using Surfactant-Enhanced Crossflow Filtration

Abstract

Removal of chromate from water was investigated using the surfactant enhanced crossflow filtration technique in which the cationic surfactant, cetyl trimethylammonium bromide (CTAB), was the carrier for the metal ions. The variation of chromate and surfactant rejections, and permeate flux with time were measured as a function of CTAB/chromate concentration ratio, while maintaining a constant transmembrane pressure drop, membrane pore size, and pH of the feed solution. The method was found to be effective in removing chromate from water. It was observed that the efficiency of chromate removal increased with increasing CTAB/ chromate ratio. It was also found that the chromate concentration had a significant effect on the CTAB concentration in the permeate and on the time taken to establish the secondary membrane which consists of a highly viscous surfactant phase in the hexagonal state in the absence of chromate. In the presence of chromate, permeate flux increased at the same CTAB concentration although the surfactant and chromate rejections decreased, indicating lowering of the secondary membrane resistance to permeate flow. These conclusions were confirmed by deadend filtration experiments which showed that the fouling index decreased by the addition of chromate while the opposite was valid when sodium chloride was present in the surfactant/water/electrolyte ternary system.     

Effect of Divalent Metal Cations on Contaminant Removal by Bicarbonate-Form Anion Exchange Resin

This work investigated the role of divalent metal cations (Mg²⁺, Ca²⁺, and Cd²⁺) and subsequent precipitation or complexation on decreased contaminant removal by bicarbonate-form anion exchange resin (AER-HCO₃) relative to chloride-form AER (AER-Cl). The results showed that the removal of dissolved organic carbon and nitrate was lower for AER-HCO₃ than AER-Cl, and contaminant removal by AER-HCO₃ was affected by the presence of metal cation. For instance, magnesium and cadmium exhibited the greatest and least interference, respectively, with contaminant removal by AER-HCO₃. The results suggested that precipitation was not the cause of decreased contaminant removal by AER-HCO₃, and instead implied that complex formation between the contaminant and divalent metal was responsible for differences in removal by AER     

Desulfurization Over Metal Zeolites

Abstract

Metal oxides supported on zeolites have been demonstrated to be effective regenerable desulfurization agents for high temperature removal of hydrogen sulfide from fossil fuels. Metals of interest are iron and zinc. Zeolites of particular interest are commercially available zeolites with high hydrothermal stability such as synthetic mordenite and rare earth stabilized faujasite Y. The metals used as desulfurization agents are introduced by cation exchange. Zinc faujasite Y is of particular interest because of the demonstrated ability to reduce the hydrogen sulfide to several PPM concentration range in the desulfurized fuel in the temperature range of 500 to 650 C.     

Removal of Heavy Metal Ions from Water by Cross-Linked Potato Di-Starch Phosphate Polymer

Potato di-starch phosphate polymer was synthesized by cross-linking potato starch with phosphorus oxy-chloride in basic medium and was then dispersed (0.2-1%) in aqueous solutions of divalent heavy metal ions (Cu²⁺, Ni²⁺, Zn²⁺, and Pb²⁺), to investigate their removal efficiency by the starch and was found to increase with increase in the polymeric starch content and increase in the heavy metal ion concentration. The removal order was found to be Pb²⁺ (78.1%) > Cu²⁺ (58.5%) > Zn²⁺ (20.5%) > Ni²⁺ (17.3%) against the constant polymeric starch content. UV-Visible, Fluorescence, FT-IR, SEM, and CHN techniques were used for characterization of different complexes formed.     

Removal of Cu2+ from Water Using Liquid-Liquid Microchannel Extraction

The very good extraction selectivity of Cu²⁺ from water was demonstrated with a new microchannel equipment, by employing di-(2-ethylhexyl)phosphoric acid (D2EHPA) as an extractant and kerosene as a solvent. The effects of different experimental parameters on the extraction efficiency E, the volumetric mass transfer coefficient K_La, and the entrainment were experimentally investigated. The results showed that the extraction efficiency increased with increasing temperature, extractant concentration, phase ratio (organic/aqueous), and pH. The total flow rate, phase ratio, and pH were found to have a great effect on the mass transfer, whereas the temperature and the extractant concentration showed little effect.     

天然水凝胶材料在水体中重金属离子处理的研究进展

水凝胶材料由于其良好的金属离子吸附性能,从而在废水处理和环境保护等领域起到了重要作用。本文综述了天然水凝胶材料的开发及其在水处理(重金属离子去除方面)应用上的研究进展。详细讨论了天然水凝胶类型及其不同结构对重金属离子处理性能的影响。最后,对废水处理的水凝胶材料进行了展望。     

沸石对主流烟气中挥发性亚硝胺及NOx的吸附去除

采用程序升温脱附(TPD)及程序升温表面反应(TPSR)技术研究了NaY、NaZSM—5、NaA等分子筛对NO2、亚硝胺和香烟主流烟气的吸附作用。沸石对NO2、亚硝胺NPYR具有独特的吸附和催化能力,孔径、比表面是影响吸附量的重要因素。沸石对于主流烟气中NOx和亚硝胺的吸附比例关系受到孔径的制约。     

利用橡胶助剂废水脱除硫化氢工艺

对促进剂M生产中产生的硫化氢提出了治理方案。方案主要是利用防老剂RD生产车间的碱性工艺废水进入水膜除尘器,喷淋烟气。硫化氢充气燃烧后生成的SO2被碱液吸收,达到以废治废,脱除SO2的目的。     

Removal of Perchlorate from Contaminated Water Using a Regenerable Polymeric Ligand Exchanger

Abstract

A polymeric ligand exchanger (PLE), DOW 3 N‐Cu, has been investigated for perchlorate (ClO₄ ^?) removal from contaminated water. Batch kinetic tests revealed that the perchlorate sorption equilibrium for DOW 3 N‐Cu can be reached within 20 hours and perchlorate removal by DOW 3 N‐Cu follows standard ion exchange stoichiometry. Fixed‐bed column runs showed that 12,388 bed volumes of perchlorate‐free water can be obtained when DOW 3 N‐Cu was used to treat a simulated contaminated water with an influent perchlorate concentration of 200 µg/L. It was found that the regeneration of spent DOW 3 N‐Cu is pH dependent. It was shown that addition of ethanol and a surfactant Tween 80 to a 4% NaCl/2% NaOH regenerant solution increased the regeneration efficiency of spent DOW 3 N‐Cu by 11 and 5 percent, respectively. Nearly 90% of perchlorate capacity of saturated DOW 3 N‐Cu was recovered using 35 bed volumes of a regenerant containing 4% (w/w) NaCl, 2% NaOH, 5% Tween 80, and 5% ethanol.     

Removal of Manganese and Iron from Drinking Water Using Hydrous Manganese Dioxide

ABSTRACT

This paper examines the use of synthetic manganese dioxide as a material for the removal of Mn⁺⁺ and Fe⁺⁺ from drinking water. Three different types of Mn02 were prepared. One involved the production of the dioxide from permanganate and hydrogen peroxide, the second involved the use of the permanganate and manganous ions and the third used a formulation the included all three reagents. Tests showed that the first type of dioxide was by far the best for both iron and manganese removal and that the mechanism for the process was by ion exchange. Other tests indicated that the dioxide exchanger could be regenerated partially by contact with chlorine gas or hypochlorite which is commonly available as a process chemical at water treatment works.     

Removal of Some Heavy Metal Ions Using Grafted Polyurethane Foam

Polyurethane (PU) was modified by grafting a mixture of two monomers acrylonitrile/acrylic acid (AN/AAc) by gamma irradiation method. Effects of various parameters such as, concentration of comonomer composition, grafting yield, gamma irradiation doses, dose rates and pH of adsorbent on the adsorption capacity were studied. Characterizations of the grafted polyurethane (PU-g-AN/AAc) were investigated using infrared (IR) spectroscopic analysis, X-ray diffraction (XRD) and scanning electron microscope (SEM). Moreover, the adsorption capacities of some heavy metals such as, Zn(II), Fe(II), Ca(II), Ni(II), Cu(II) and Pb(II) onto PU-foam and PU-g-AN/AAc were studied. The efficiency of such grafted polyurethane foams for uptaking different previous metal ions was determined and compared with that of natural granular activated carbon (GAC). The uptaking of metal ions was remarkably affected by the pH of the solution, the valances of metal ions, atomic weight and its initial concentrations. Equilibrium isotherms and interruptible diffusivities were investigated through batch experiments in analyzing the uptaking of aqueous solutions of metal ions onto PU foam, grafted PU, and granular activated carbon. The Frundlich constants k and 1/n have been determined for each metal ion to represent both the ability and the affinity of that ions towards the uptaking materials, respectively.     

用海藻类生物吸附剂去除废水中的重金属离子——一种经济型新技术

Heavy metal pollution from industrial wastewater is a worldwide environmental issue. Biosorption of heavy metals by using biosorbents derived from various types of biomass has been shown to be effective for the uptake of heavy metal ions. In this study, biosorbents derived from the biomass of a group of marine macroalgae were used for the removal and recovery of heavy metal ions from aqueous solutions. Results indicated that the biosorbents have high uptake capacities and affinities for a number of heavy metal ions. The uptake capacities of the biosorbents were in the range of 1.0 to 1.5mmol·g-1 for divalent heavy metal ions. The kinetics of the uptake process was fast and the process can be used in both batch and fixed-bed operations. It appears that the biosorption process by using biosorbents from marine macroalgae can be an efficient and cost effective technology for the treatment of heavy metal containing wastewater.     

Oxidation of Phenol,o-nitro Phenol,o-chloro Phenol and Trichloroethylene Present in Water Using Surfactant Immobilized Manganate and Impregnated Metal Cations

Oxidation of trichloroethylene and derivatives of phenol, which are toxic compounds present in water, to harmless species has been carried out in the presence of modified clays such as HDTMA-immobilized-interlayer-Mn(VII) (surfactant immobilized manganate clay) and Mⁿ⁺-bent-Mn (VII) (metal cations like Al, Cr, Fe, Cu, Ni, Mn & Zn impregnated on manganate clays), by treating the toxic compounds with HDTMA-immobilized-interlayer-Mn(VII) clay and Mⁿ⁺-bent-Mn (VII) clays. The oxidation reaction was monitored by measuring the absorbance after every hour using a UV-Visible spectrophotometer at a definite wavelength.