Recovery of silver by using hydrogel and investigating adsorption kinetics

There are various methods available for recovering precious metals such as solvent extraction by using organic solvent, ion exchange by using chelating agents, natural zeolit or activeted carbon, electrowinning by passing electric current, biosorption by using biomass for removing metal ions from solution, precipitation by adding more active metal, and adsorption by using varied adsorbents for removing metal ions. Adsorption is a commonly used method for recovery of silver. Alternatively ion exchange, biosorption and solvent extraction have been developed for the recovery of silver from solution. Comparatively, the adsorption seems to be the most suitable method for the recovery of silver in the case of low concentration due to low cost and high efficiency. In this thesis that is presented, silver was recovered from wastewater by using biocomposites, which are prepared by using chitosan, cellulose, polyacrylamide as adsorbents and kinetics of the system were be investigated by determining the proper conditions for this operation. These were done to investigate X-Ray Diffraction (XRD) on behalf of the obtaining information about the crystal structure, to observe Scanning Electron Microscopy (SEM) to get the information about the surface/cross sectional properties of used hydrogels. After the adsorption, the remaining precious metals concentrations were measured by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES). In the present thesis, the proper conditions were determined about amount of adsorbent at 0.05, 0.10, 0.15, 0.20, 0.25 gram, shaking rate at 100, 150, 200, 250, 300 ppm, adsorption time, initial concentration of adsorban at 50, 25, 17, 12.5 10 ppm, pH values at 1.0, 3.0, 5.0, 8.0, 10.0 and temperature values at 20, 30, 40, 50, 60°C. Moreover; kinetics of the adsorption system were described as reaction rates and were investigated whether Freundlich ve Langmuir ve Brunauer-Emmet-Teller Adsorption Isotherm Models are fitted.