啤酒酵母废菌体吸附Pd2+的物理化学特性

以啤酒酿造厂的啤酒酵母废菌体为生物吸附剂,研究死的啤酒酵母菌体从PdCl₂溶液中吸附Pd²⁺的物理化学特性.结果表明,该菌体吸附Pd²⁺受吸附时间、溶液pH值、菌体浓度和Pd²⁺起始浓度等因素的影响.菌体吸附Pd²⁺是个快速的过程,吸附45min时吸附量达最大,但在最初的3min内,吸附量可达到最大吸附量的92%.在5～60℃范围内,吸附作用不受温度影响.吸附作用的最适pH值为3.5.在Pd²⁺起始质量浓度为30～300mg/L范围内和菌体质量浓度为2g/L的条件下,菌体对Pd²⁺的吸附作用符合Langmuir和Freundlich等温吸附模型.在pH=3.5,Pd²⁺与菌体质量比为0.2和30℃条件下吸附60min,吸附量达94.5mg/g.从废钯催化剂处理液回收钯,吸附量为32.2mg/g.XPS分析表明,该菌体能吸附水溶液中的Pd²⁺.TEM结果表明,在无外加电子供体时,死的啤酒酵母废菌体能够吸附和还原溶液中的Pd²⁺成Pd⁰微粒,Pd⁰微粒可进一步形成有一定形状的钯晶粒;该菌体还能使吸附在γ-Al₂O₃上的Pd²⁺还原成Pd⁰.

Physio-chemical Properties of Adsorbing Pd2+ by Saccharomyces Cerevisiae Waste Biomass

Saccharomyces cerevisiae waste biomass procured from the beer brewery, was used as the adsorbent for Pd²⁺. The physico-chemical properties of adsorbing Pd²⁺by the biomass were investigated. The results indicate that the adsorption of Pd²⁺by the biomass was affected by adsorption time, pHvalue, adsorbent concentration and Pd²⁺initial concentration in the solution. The biosorption is a rapid process, the capacity of the adsorption after 45 min reached the maximum, and 92.0% of the maximal capacity was obtained at the first 3 min of the adsorption. The optimum pH value was 3.5. In the range of 5-60 ℃, the biosorption was not affected by temperature. The isotherMOf the adsorption of Pd²⁺by the biomass followed Langmuir and Freundich models under the conditions of initial Pd²⁺mass concentration(30-300 mg/L) and biomass mass concentration(2g/L). Biosorptive capacity of 94.5 mg/g was obtained under the conditions of pH=3.5, mass ratio of an initial Pd²⁺to biomass being 0.2 and at 30 ℃ for 60 min of the adsorption. Palladium was removed from the treated solution of waste palladium catalyst with 32.2 mg/g of biosorptive capacity. The results of X-ray photoelectron spectrometer analysis indicate that the biomass could adsorb Pd²⁺ions from the aqueous solution. The observation in the transmission electron microscope shows that without the extra-electron donor, the waste biomass of Saccharomyces cerevisiae could adsorb and reduce Pd²⁺ions in the solution to microbial Pd⁰particles, which could become well-formed palladium crystals, as well as Pd²⁺ions adsorbed on the γ-Al₂O₃could be reduced to Pd⁰particles by the biomass.