A novel recovery technology of trace precious metals from waste water by combining agglomeration and adsorption
(School of Chemical and Energy Engineering, South China University of Technology, Guangzhou 510640, China)
Abstract: A novel and efficient technology for separating and recovering precious metals from waste water containing traces of Pd and Ag was studied by the combination of agglomeration and adsorption. The recovery process and the impacts of operating conditions such as pH value of waste water, adsorption time, additive quantity of the flocculant and adsorbent on the recovery efficiency were studied experimentally. The results show that Freundlich isothermal equation is suitable for describing the behavior of the recovery process, and the apparent first-order adsorption rate constant k at 25 ℃ is about 0.233 4 h−1. The optimum technology conditions during the recovery process are that pH value is 8−9; the volume ratio of flocculant to waste water is about 1׃(2 000−4 000); the mass ratio of adsorbent to waste water is 1׃(30−40); and processing time is 2−4 h. Finally, the field tests were done at the optimum technology conditions, which show that the total concentration of Pd and Ag in the waste water below 11 mg/L can be reduced to be less than 1 mg/L.
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