Study On Adsorption And Desorption Of Ag～+ And Coordination Compound Of Silver In Silver-containing Wastewater

Silver-containing wastewater is discharged by silver-gilt industry, photographic industry, chemical analysis in laboratory and so on. It is not only pollution to environment but also waste to resources if we let it out into nature without reclamation. In traditional methods of reclamation of silver there are some disadvantages such as causing great consumption of energy, resulting in secondary pollution, and having little effect on trace silver. The method of adsorption-desorption-electrolysis was chosen to recover the silver contained in wastewater in this thesis. In order to compare with the adsorbing effect of the two kinds of materials, Ag⁺, [Ag(NH₃)₂]⁺, [Ag(S₂O₃)₂]^3- were chosen as adsorbents, and diatomite, bentonite, zeolite, and microzyme were chosen as adsorates. The influences of experimental conditions such as time, pH, initial concentration of adsorbents and adsorates on adsorbing effect were studied. Furthermore, the situation of which [Ag(NH₃)₂]⁺, [Ag(S₂O₃)₂]^3- were adsorbed onto zeolite and microzyme were studied. Their adsorbing mechanisms were also studied. The following conclusions can be obtained(1) When using diatomite, bentonite, zeolite, and microzyme to adsorb Ag⁺, the adsorbing effects were good. Comparing with the adsorbing ability, the order was microzyme> zeolite> diatomite> bentonite. The equilibriums that mineral materiales and microzyme biomass adsorbed Ag⁺ were reached within 5minutes. In the conditions of 5minutes, pH5.41, initial concentration of Ag⁺ of 108mg/L, mineral material dosage of 67g/L, agitating rate 500r/min and room temperature, the the removal rate that mineral materials adsorbsed Ag⁺ were up to 95.94%, 91.32%, and 97.61%, respectively, and the adsorbing quantities were 1.5542mg/g, 1.4794mg/g, and 1.5813mg/g, respectively. In the conditions of 5minutes, pH5.41, initial concentration of Ag⁺ of 216mg/L, biomass of 16.7g/L, room temperature, the removal rate that microzyme adsorbed Ag⁺ was up to 92.67%, and the adsorbing quantity was 15.0518mg/g.(2) When using zeolite and microzyme to adsorb [Ag(NH₃)₂]⁺, the adsorbing effects were also good. In the conditions of 5minutes, pH10.33, initial concentration of Ag⁺ of 108mg/L, biomass of 16.7g/L, zeolite dosage of 67g/L, room temperature, the removal rate of Ag⁺ were up to 73.33% and 99.3% respectively, and adsorbing quantity were 4.7423mg/g and 1.6087mg/g respectively. When zeolite adsorbed [Ag(S₂O₃)₂]^3-, adsorbing effect was not so well. Micozyme had good effect on adsorbing [Ag(S₂O₃)₂]^3- in acid solution. In the conditions...