An Investigation into the Use of Chitosan for the Removal of Soluble Silver from Industrial Wastewater

Abstract

Chitosan was examined as a means of removing soluble silver from industrial waste streams. Stirred-batch and column methods were used to remove free (hydrated) silver ion as well as the ammonia, thiocyanate, thiosulfate, and cyanide complexes of silver in simulated wastewater at an initial concentration of 50 ppm and in a pH range of 2-10. An actual sample of X-ray film development rinse water was also tested. Batch method results show 80-95% silver bound at pH 4-8 for Ag + and Ag(NH 3 ) 2 + , while 92% and 75% of Ag(S 2 O 3 ) 2 3and Ag(SCN) 3 2-, respectively, were bound at pH 2. Using a column containing 0.500 g of chitosan, 160 bed volumes of Ag + , 875 bed volumes of Ag(NH 3 ) 2 + , 715 bed volumes of Ag(S 2 O 3 ) 2 3-, and 190 bed volumes of Ag(SCN) 3 2solution were treated before silver ion concentration in the effluent reached 5 ppm. Chitosan did not significantly bind Ag(CN) 2at any pH tested. Chitosan treated 450 bed volumes of 40 ppm X-ray rinse water before effluent silver concentration reached 5 ppm. Capacity experiment results using the column method indicated 42 mg of silver bound per gram of chitosan. Four commercial resins, Amberlite IRA-67, IRA 458, IRC-718, and Duolite GT-73, were also tested as silver binding agents.

Use of chitosan for the removal of metal ion contaminants and proteins from water

“…Several investigators have reported the heavy metal binding capacities of chitin and chitosan (Muzzarelli et al, 1989;Bassi et al, 1999;Lasko and Hurst, 1999). 28…”

“…A study of the metal binding capacity of chitosan has shown good binding with metals such as copper and vanadium (Micera et al, 1986). Chitosan as a means of removing soluble silver from industrial waste streams has also been demonstrated (Lasko and Hurst, 1999). Commercially available chitosan's potential in the adsorption of heavy metals such as zinc, copper, cadmium and lead from aqueous solutions under various physicochemical conditions was investigated by Bassi et al (2000).…”

Preparation of chitosan–nylon-6 blended membranes containing silver ions as antibacterial materials

“…Owing to its biocompatibility, biodegradability, antibacterial and antifungal activities, chitosan has become, in the past 20 years, a much sought-after material for a variety of applications including biomedical devices, in wound healing, controlled drug delivery, 1 food packing, 2 heavy metal chelating agents 3,4 and waste removal. 5,6 To extend the applications of chitosan, several approaches have been used for the modification of chitosan, such as graft polymerization 7 and blending with other natural or synthetic polymers. 8,9 In particular, modification of chitosan by means of blending with other polymers is a convenient and effective method for practical utilization.…”

Sunlight-driven reduction of silver ion to silver nanoparticle by organic matter mitigates the acute toxicity of silver to Daphnia magna

“…However, high concentration of Ag + could still be observed in industrial wastewater and mine tailings owing to application in electronic, photographic industry and mining (Lasko and Hurst, 1999;Sanudowilhelmy and Flegal, 1992).…”