渗滤液中Na+对生物膜形成初期吸附特性的影响

为了探究渗滤液微生物生物膜形成初期吸附特性, 设置4种Na⁺浓度采用耗散型石英晶体微天平(QCM-D), 结合刚性模型和黏弹性模型拟合分析, 探究吸附质量和黏弹性随时间变化.结果表明: 生物膜初期吸附存在可逆吸附和不可逆吸附过程, 150mmol/L的Na⁺促进了不可逆吸附的形成.Na⁺增加了溶液Zeta电位, 细菌表面所带净电荷量减小; 随Na⁺浓度由2.5mmol/L增加至50mmol/L, 表面吸附速率逐渐增加, 符合静电双层理论, Na⁺继续增加至150mmol/L, 吸附速率无显著变化.在不同浓度Na⁺溶液中, 吸附膜柔性大小顺序为: 150mmol/L>2.5mmol/L>10mmol/L≈50mmol/L.模型拟合结果表明, 膜黏弹性随吸附过程逐渐增加; 随Na⁺浓度增加, 吸附膜质量增加, 膜黏弹性先升高后不变.

Effects of Na+ in leachate on initial adsorption of biofilm

A quartz crystal microbalance with dissipation (QCM-D) was used to investigate the initial adsorption behavior of biofilm under four kinds of Na⁺ concentrations. The rigid model and viscoelastic model were fitted to explore the changes in adsorption mass and viscoelasticity with time. The results indicate that both reversible and irreversible adsorption processes occurred in the initial adsorption of biofilm. The formation of irreversible adsorption was promoted when Na⁺ concentration was 150mmol/L, due to increased zeta potential and net charge reduction in bacterial surfaces. With an increase in Na⁺ concentration from 2.5mmol/L to 50mmol/L, the adsorption rate increased gradually, which is consistent with the electrostatic double-layer theory. No significant change in the adsorption rate was observed when the concentration was increased to 150mmol/L. The softness of the absorbed layer in the 150mmol/L group was the highest, followed by the 2.5, 10 and 50mmol/L groups. An increase in the viscoelasticity of the layer was also observed during the early adsorption process. With an increase in Na⁺ concentration, the adsorption mass kept increasing and the viscoelasticity first increased and then remained unchanged.