啤酒酵母废菌体吸附Pd^(2+)的物理化学特性

Physio-chemical Properties of Adsorbing Pd^(2+) by Saccharomyces Cerevisiae Waste Biomass

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 Pd Cl2 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 p H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 45 min时吸附量达最大 ,但在最初的 3 min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 p H值为 3 .5 .在 Pd2 + 起始质量浓度为 3 0～ 3 0 0 mg/L范围内和菌体质量浓度为 2 g/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 p H=3 .5 ,Pd2 +与菌体质量比为 0 .2和 3 0℃条件下吸附 60 min,吸附量达94.5 mg/g.从废钯催化剂处理液回收钯 ,吸附量为 3 2 .2 mg/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-Al2 O3 上的 Pd2 +还原成 Pd0 .

Saccharomyces cerevisiae waste biomass procured from the beer brewery, was used as the adsorbent for Pd 2+. The physico-chemical properties of adsorbing Pd 2+ by the biomass were investigated. The results indicate that the adsorption of Pd 2+ by the biomass was affected by adsorption time, pH value, adsorbent concentration and Pd 2+ 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 isotherm of the adsorption of Pd 2+ by the biomass followed Langmuir and Freundich models under the conditions of initial Pd 2+ mass concentration(30-300 mg/L) and biomass mass concentration(2 g/L). Biosorptive capacity of 94.5 mg/g was obtained under the conditions of pH=3.5, mass ratio of an initial Pd 2+ 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 Pd 2+ 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 Pd 2+ ions in the solution to microbial Pd 0 particles, which could become well-formed palladium crystals, as well as Pd 2+ ions adsorbed on the γ-Al 2O 3 could be reduced to Pd 0 particles by the biomass.