Study On Modification Of Persimmon Biosorbent And Adsorption Behaviors For Platinum Group Metals

Faced with current situations of low grade, complicated composition and difficult extraction of platinum group metal resource, how to enrich and recover platinum group metals from multi-metals solution containing platinum group metals is the key problem for circulation utilization of platinum group metal.Biosorption as a noval metals recovery techonolgy has many advantages, including abundant resource, low cost, high metal binding capacity and without second pollution, which make biosorption have a wide application prospect.In this paper, waste persimmon powder (PP) was chosen as the raw material to prepare modified persimmon biosorbents CPP and GPP by Formaldehyde Condensation Modification and Glycine Amphoteric Modification, respectively. Design of experiments (DOE) was used to optimize modification conditions. The effects of various parameters, including solution initial pH (pHi), the amount of sorbent, temperature, hydrochloric acid concentration, chloride ion concentration, adsorption time and metal ion concentration on the adsorption process in the single (Pt/Pd) systems were investigated by using batch adsorption techniques. Also, the effect of eluent on the elution process was tested. For the binary system of Pt-Ni and Pd-Ni, the influences of solution pHi, hydrochloric acid concentration, chloride ion concentration and nickel concentration on the selective adsorption performance of Pt or Pd were studied.The combined effects of modified agent amount, modified time and modified temperature on the modified persimmon biosorbent were investigated by using DOE experimental method and the optimize modification condition ranges were determined as follows:the amount of modifier for30%-40%, moderation time for100-150min, modification temperature for313-333K. The adsorption behavior for the recovery of Pt(Ⅳ) and Pd(Ⅱ) from the single Pt(Ⅳ) or Pd(Ⅱ) ion solutions and the binary Pt-Ni or Pd-Ni solutions were discussed respectively. Controlling low hydrochloric acid concentration, low chloride ion, pHi for2.0, temperature for343K, the adsorption%of Pt(Ⅳ) and Pd(Ⅱ) were over 90%and95%, respectively. The adsorption results in the binary system of Pt-Ni and Pd-Ni were obtained:low hydrochloric acid concentration, low chloride ion and low solution pHi can realize complete separation Pt or Pd from high concentration of nickel solution.Based on adsorption results and the analysis on persimmon biosorbents before and after adsorption by SEM, FT-IR and XPS, the Pt(IV) adsorption process by persimmon biosorbents were supposed to be typical adsorption-coupled reduction mechanism; the Pd(Ⅱ) adsorption process by persimmon biosorbents were supposed to be surface complexation mechanism.This paper provides important fundamental data for the effective utilization of waste persimmon powder and new method for recovery of platinum group metals from complex solutions.