Modified Chitosan for Silver Recovery—Kinetics, Thermodynamic, and Equilibrium Studies

Abstract

The aim of this study is to investigate the silver recovery from aqueous solutions. There are a variety of recovery methods, such as hydrometallurgical, bio-metallurgical, cementation, reduction, electrocoagulation, electrodialysis, ion exchange, etc. Adsorption represents a convenient, environment friendly procedure, that can be used to recover silver from aqueous solutions. In this paper we highlight the silver adsorption mechanism on chitosan chemically modified with active groups, through kinetic, thermodynamic, and equilibrium studies. A maximum adsorption capacity of 103.6 mg Ag(I)/g of adsorbent for an initial concentration of 700 mg/L was noticed by using modified chitosan. Lower adsorption capacity has been noticed in unmodified chitosan—a maximum of 75.43 mg Ag(I)/g. Optimum contact time was 120 min and the process had a maximum efficiency when conducted at pH higher than 6. At the same time, a way is presented to obtain metallic silver from the adsorbent materials used for the recovery of the silver from aqueous solutions.

2-Mercaptobenzimidazole derivative of chitosan for silver sorption – Contribution of magnetite incorporation and sonication effects on enhanced metal recovery

“…Chitosan-based materials offer interesting perspectives for chemical modification and synthesis of functionalized materials because of the presence of highly reactive groups (-OH, amine groups) [27][28][29][30][31]. In addition, chitosan can be also readily conditioned as magnetic composite for readily separation of micro-and nanoparticles from aqueous solutions.…”

Selective Reductive Removal of Silver Ions from Acidic Solutions by Redox-Active Covalent Organic Frameworks

“…Meantime, the adsorption isotherm analysis of COF-LZU1 toward silver ions was performed at different initial concentrations of silver ions (5–1200 ppm). The saturated silver ion adsorption capacity was calculated to be 175 mg g –1 (Figure b), which is very high in comparison with other common adsorption materials, such as active carbon (AC), clay, and chitosans . Further, the adsorption isotherm was also simulated with different models, as shown in the inset picture in Figure b.…”

“…Up to now, numerous methods and techniques have been developed by researchers for the removal and recovery of silver from wastewater, which include chemical precipitation, biosorption, cementation, adsorption, ion exchange, electrowinning, solvent extraction, etc. − Alternatively, adsorption is still regarded as a highly efficient, effortless operation, and low-cost way in the purification of heavy metal ions. Whereas, many studies have reported diverse adsorbents, aiming at selecting more efficient and ecofriendly strategies. − For example, metal oxides, activated carbons, clays, and chitosan materials have been used in silver removal from aqueous solutions. Subsequently, metal–organic frameworks (MOFs) − were garnered considerable attention owing to their adjustable porosity, easily functionalized groups, and high specific surface area.…”

A Green, Simple and Facile Way to Synthesize Silver Nanoparticles Using Soluble Starch. pH Studies and Antimicrobial Applications

“…Due to their intrinsic properties and multilayer actions, colloidal Ag-NPs have a broad spectrum of antimicrobial activity against different types of microorganisms, demonstrating a huge potential against even antibiotic-resistant microorganisms [ 29 , 30 , 31 , 32 , 33 ].…”