煅烧紫贻贝壳粉对Cd^(2+)和Pb^(2+)的吸附热力学研究

Thermodynamics of the Adsorption of Cadmium(Ⅱ) and Lead(Ⅱ) Ions in Calcined Purple Mussel Shells

贻贝是我国的重要的海产经济贝类,但由于养殖规模的增大而随之产生的废弃贻贝壳资源成为了关注的热点。研究发现贻贝壳是一种环境友好型的生物吸附剂,本文通过高温煅烧处理,进一步优化了贻贝壳的吸附性能,采用SEM、BET、XRD和IR表征手段对贻贝壳的微结构、孔径及组成进行了分析;同时探讨了贝壳粉吸附剂对Cd^(2+)和Pb^(2+)的吸附热力学性能。结果发现贻贝壳粉经高温煅烧后,其主要成分为Ca O,且比表面积显著增大,比表面积达7.8965 m^2/g,形成诸多纳米孔径,直径在0.5~1.1 nm,吸附性能提高。贻贝壳吸附剂用量和溶液p H对Cd^(2+)和Pb^(2+)的吸附量影响较大,吸附剂对Cd^(2+)的吸附量明显高于对Pb^(2+)的吸附量,且吸附剂对Cd^(2+)和Pb^(2+)的吸附均符合Freundlich等温吸附模型。由此可知,煅烧后的紫贻贝壳是一种优良廉价的生物吸附剂,可将其开发成一种针对性去除废水中重金属Cd^(2+)的新型吸附剂。

The mussel is an important economic shellfish in China, but massive amounts of discarded shells due to increases in the scale of cultivation have become a focus of public attention. Studies have demonstrated that mussel shell is an environment-friendly bioadsorbent. In this study, the adsorption properties of mussel shell were optimized using the calcination method, and the microstructure, pore size, and composition of mussel shell were analyzed using scanning electron microscopy（SEM）, Brunauer-Emmett-Teller（BET） analysis, X-ray diffraction（XRD）, and infrared（IR） spectroscopy. The adsorption thermodynamic properties of the shell powder to cadmium（Ⅱ） and lead（Ⅱ） were also explored. The results showed that the main component of mussel shell powders after calcination was calcium oxide. The specific area of mussel shell powders was significantly increased up to 7.8965 m^2/g, many nanometer-sized pores were formed with a diameter of 0.5~1.1 nm, and the adsorption capacity of the mussel shell powders was enhanced. The adsorbent dosage and solution p H had a greater influence on the amounts of adsorbed cadmium（Ⅱ） and lead（Ⅱ）, the amount of adsorbed cadmium（Ⅱ） was significantly higher than that of adsorbed lead（Ⅱ）, and both adsorptions followed the Freundlich isotherm equation. Therefore, calcined mussel shell is an excellent low-cost biological adsorbent that can be developed into a new adsorbent targeting the heavy metal cadmium（Ⅱ） in wastewater.