Indian Journal of Chemical Technology, 2002

Salicylaldoxime immobilised silica gel was used as an effective solid phase surface, for the preconcentration, removal or recovery of zinc ion from aqueous phase. The efficiency was tested by the equilibrium sorption study both in batch and column operations. The efficiency increases with the shaking period, agitation speed, adsorbent dose, temperature and flow rate but is independent on the volume of the solution. Maximum adsorption was found to occur at pH 5.5. Alkali metal, alkaline earth metal and ammonium salts do not influence the adsorption process. Heavy metal ions viz. Cu(II), Ni(II), Co(II) and Fe(III) get adsorbed by the said process but at much different pH values. Complexing ligands like EDT A and cyanide markedly decrease the adsorption of Zn(II) by the said procedure. The adsorption data fits well the Langmuir adsorption isotherm model. The negative free energy change indicates that the process is favourable as well as spontaneous. The merit of the process lies with its high preconcentration factor. It is know n th at many metals are normall y present in natural water systems. The co nstituents in natural water exhibit properties th at may be class ifi ed as either conservati ve or no n-conservati ve. The fo rmer relates to concentrati o n of species th at remains at relati vely constant rati o to each other throughout the system. Thi s appli es mostly to the more abundant li ghter elements such as sodium, potass ium and calcium. The no n-conservative behaviour is shown by most other metals such as iro n, copper, zinc, lead , mercury which show concentration vari ation depending on variabl es such as positi on, time, temperature and most importantl y bio logical activity 1 .

2016

This study investigates Cu and Zn removal onto binary mixed mineral sorbents from simulated wastewater, relevant to streams impacted by acid mine drainage and effluents. Mixed suspensions of kaolinite/montmorillonite and kaolinite/goethite exhibited different sorption behavior from the single mineral components, reducing Cu and Zn removal (except Cu sorbed on montmorillonite/goethite) over the range of pH investigated. Cu and Zn removal by the electrolyzed systems showed a complex response to increased ionic strength, which increased solid concentration, leading to lower Cu and Zn sorption. Enhanced Cu sorption on the montmorillonite/goethite as age increased may be attributed to increased hydroxylation of the mineral surface resulting in the formation of new reactive sites.

This study investigates the reactivity and removal kinetics of Cu and Zn onto mixed mineral systems from aqueous solution related to acid mine drainage impacted areas. The sorbents used were kaolinite, Al-montmorillonite, goethite, and their mixtures. The effects of surface charge, proton coefficient, and sorption kinetics were studied at room temperature (23 ± 2 • C). Using an empirical model, mineral mixing reduced the exchange of protons for sorbing ions and the acidity of the reactive sites, thus impeding Cu and Zn removal by proton exchange. Based on the amount of Cu and Zn sorbed on the mixed mineral suspensions at ionic strength 0.01 to 0.1 M and pH 4, it is suggested that Cu and Zn removal from aqueous solution was by both inner and outer sphere complexation. Mineral mixing reduced the transfer rate of Cu relative to the single mineral suspensions in both slow and fast reaction phases. The behavior of the mixed suspensions in Cu and Zn sorption suggest that different reactive sites were involved at the onset of sorption, becoming similar to those of the single mineral components over time.

2018

The ability of a type of clay to adsorb Cu(II) and Zn(II) ions from aqueous solutions was studied and optimized. Different factors affecting adsorption were considered and studied individually. These factors include contact time, pH, initial metal ion concentration, clay dose and temperature. Langmuir, Freundlich and Temkin isotherm models were studied for the adsorption process. Depending on the values of correlation coefficients of the different models, it was concluded that the adsorption of Cu(II) ions was best described by Temkin model (R2=0.9904), where adsorption of Zn(II) followed both Langmuir (R2=0.9806) and Freundlich (R2=0.9840) models. Maximum adsorption capacities according to Langmuir isotherm were 20.08 and 17.60 mg/g for Cu(II) and Zn(II) ions, respectively. The increase of adsorption capacity with temperature for both metal ions indicted endothermic processes.

— Kinetic studies were conducted on the process of the dissolution of non-ferrous metals with the use of sulfur-containing material as a source of leaching agent-sodium thiosulfate. It is shown that with increasing concentrations of sodium hydroxide in solution in the range of 0.1-1.0 M, copper recovery is increased from 21.5 to 46.2 %. As the temperature increases from 25 to 45 0 C, copper dissolution rate in the initial moment of the time increases, then over time this figure gradually decreases with decreasing the copper content in the initial product. The value of the reaction order is 0.39. The calculated value of the activation energy in the process of leaching copper is 12.01 kJ / mol, which suggests that the analyzed process is proceeds in the diffusion mode. Keywords— complex and low-grade raw materials, the structure of condensed systems, structural-phase transitions, hydrometallurgy.

Eurasian Soil Science, 2009

The adsorption of Cu, Zn, and Pb from acetate solutions is accompanied by higher values of the affinity constants compared to the adsorption of the same cations from nitrate solutions. The observed differences are due to the formation of stable charged complexes of acetate ions with heavy metal cations, whose binding strength with the surface of soil particles is higher than that of free ions, and also due to the possible precipitation of poorly soluble metal compounds in a calcareous ordinary chernozem.

World Journal of Applied Chemistry, 2017

Sorption of Cu and Zn was investigated using single and mixed mineral systems under sulfidic-anoxic condition to treat wastewater obtained from disused mine pits at Parys Mountain in, United Kingdom. Water courses are the recipients of these contaminants. In these water courses fishing activities exist. Attempt was made to reduce the Cu and Zn levels intake in the watercourses using mineral systems of clays and goethite. These were tested with the mine waste water for characterization of copper and zinc removal at variable pH, solid concentration and contact time. In addition, levels of saturation of hydroxyl complexes were modeled. Batch reactions conducted at ambient temperature (23±2°C) reveal all systems of assorted minerals sorbed more Cu than Zn. In addition, Cu sorbed on iron sulfide exhibited increase in sorption with increasing pH. There was cross cutting effect of Cu and Zn sorbed on iron sulfide at pH 6 and Cu sorbed on goethite at about pH 7, These indicate similar metal removal characteristics. Differences in removal of copper and zinc ions may be assigned to outer sphere complexation and specific adsorption of copper and zinc ions. Non-promotive Cp effect (i.e. decrease in metal removal with increase in concentration of particle) was observed in all minerals. This effect may be assigned to increase in aggregation of the mineral particle size. Ageing characterization progresses as residence time was increased. This may be assigned thiol (=S-H) and hydroxyl (=Me-OH) groups and sites of reactions. There is no link to stable hydroxylation of copper and zinc species that could significantly contribute to the removal of these metals.

A method ./or the determination of operationa/ly-defined metal species at natural concentration levels has been developed. The method is based on a combination ol physical characterization by size ./i'actionation using ultra./iltration and chemica! characterization by retention studies on different solid sorbents. The aim (~l this study is to investigate the e.ffect ofpH on its pe!formance. A set of three columns packed with di{{erellt sorbents, name~IJ, cation-exchange resin Chelex-/OO, anion-exchange resin Dowex /-X8 and C-/8 reversed phase was developed. The retention of meta! species in each size '/;y/ction onto the sorbents at different pH conditions was investigated. Experiments were lx/formed with metals in the presence of model ligands, name~v, nitrilotriacetic acid (NTA) , ethylenediamine tetraacetic acid (EDTA), humic acid (HA) , 8-hydroxyquinoline-5-sulphonic acid (SOX) a/ld 8-hydroxyquinoline (OX). The applicabi/i~l' 0/ the method was investigated using synthetic river water samples ,spiked with ,species o/zinc.

In this study, the adsorption of Cu(II) and Ni(II) ions onto white clay of montmoril-lonite group obtained from the Kahramanmaras region was investigated. The effects of clay amount, initial metal ion concentration, pH, and temperature on the adsorption were studied. The results showed that the increases in the clay amount, initial metal ion concentration, pH and temperature led to the increases in the metal ion adsorp-tions. Besides, the competitive adsorption of Cu(II) and Ni(II) ions was studied at different pH and temperatures and it was shown that Cu(II) ions were more adsorbed than Ni(II) ions. As a result, it was observed that clay had a high adsorption capacity for metal ions. It was determined that the adsorption of Cu(II) and Ni(II) ions by clay was in the range of 92.3–100% adsorption and 90.26–97.82% under all experimental conditions, respectively. Many toxic heavy metals have been discharged into the environment as industrial wastes, causing serious soil and water pollution. Cadmium, Cu, Ni, Pb and Zn are especially common metals that tend to accumulate in organisms, causing numerous diseases and disorders 1,2. They are also common groundwater contaminants at industrial and military installations 3. A number of technologies for the removal of heavy metal ions from aqueous solutions have been developed over the years, which was recently confirmed 4. The most important of these techniques include chemical precipitation, filtration and re