废玻璃/铝渣人工沸石对水中Ca2+的吸附

利用废玻璃和铝渣制备沸石，进而表征沸石结构特征并研究其对水中Ca2+的吸附性能。采用批式实验考察不同温度下沸石用量、初始pH、振荡频率、接触时间对吸附量的影响，并研究吸附过程热力学、动力学特征。结果表明，吸附量随沸石用量增加而减小、随接触时间延长而增大。初始pH和振荡频率对吸附量影响较显著。温度变化对平衡吸附量影响不大，但升高温度可显著缩短吸附平衡时间。最佳工艺参数为：沸石用量20 g·L-1，初始pH 6~8，振荡频率150 r·min-1，接触时间60 min，此时吸附量约16 mg·g-1。Langmuir等温线最符合沸石吸附水中Ca2+过程，表明该过程是均质单分子层吸附。动力学特征最符合准二级动力学方程，证实该过程主要受离子交换、颗粒外液膜扩散和颗粒内扩散控制。该沸石对水中Ca2+吸附过程是物理吸附和化学吸附并存的自发、吸热、熵增过程。该沸石可较好地去除水中Ca2+，故具有一定软化硬水能力。

Aqueous calcium ion adsorption performance of artificial zeolite made from waste glass and aluminum slag

The zeolite was made from waste glass and aluminum slag, and its structure and performance on aqueous calcium ion adsorption was studied. At different temperatures, the impacts of zeolite dosage, initial pH, vibrating frequency and contact time on the adsorption capacity were investigated through batch experiments, as well as the corresponding thermodynamic and kinetic characteristics. The results show that the adsorption capacity decreased with the increase of zeolite dosage, while increased with the extension of contact time. Both the initial pH and the vibrating frequency have significant effects on the adsorption capacity. Although the temperature had little effect on the equilibrium adsorption capacity, the increased temperature could significantly shorten the adsorption equilibrium time. The optimal process parameters were following: zeolite dosage of 20 g·L-1, initial pH of 6~8, vibrating frequency of 150 r·min-1, contact time of 60 min, and the adsorption capacity under this condition was approximately 16 mg·g-1. The calcium ion adsorption on the zeolite was fitted well to the Langmuir isotherm, indicating a homogeneous monolayer adsorption process. The dynamic data fitted well to the pseudo-second-order kinetic model, which demonstrated that a process was mainly dominated by ion exchange, extra-particle liquid membrane diffusion and intra-particle diffusion. The above adsorption was an endothermic, entropy-increasing and spontaneous process with the coexistence of physisorption and chemisorption. With the capability of efficient removal of calcium ion from water, the zeolite could be used to soften hard water.