School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China.
School of Environmental and Chemical Engineering, Zhaoqing University, Zhaoqing 526061, China.
Ecotoxicol Environ Saf. 2021 Feb;209:111760. doi: 10.1016/j.ecoenv.2020.111760. Epub 2020 Dec 22.
In this study, a simple to produce, low-cost and environment-friendly sludge based adsorbent, prepared from municipal dewatered sludge and modified by calcium oxide (CaO), is described. The enhancement effect of CaO modification on the adsorption capacity and mechanical strength of sludge based adsorbents (CaO-SA), and the modification mechanism of CaO on activated sludge are discussed. Also, the Cd(II) adsorption conditions are optimized using surface optimization experiment. The results indicated that CaO had a good effect on improving the adsorption capacity and mechanical strength of the sludge-based adsorbent. The CaO-SA adsorbent showed best performance with respect to the mechanical strength and Cd(II) adsorption capacity when prepared under 5% CaO dosage and 60 °C drying temperature. CaO modification can increase the specific surface area and calcium ion content of the sludge-based adsorbent and remove the proton of the carboxylic acid in the sludge. The Box-Behnken experimental design results revealed that the importance of operating conditions for CaO-SA adsorption of Cd(II) can be arranged in the order of adsorption time > dosage> pH> temperature. The results also indicated that the interactions between adsorption time and CaO-SA dosage, adsorption time and pH, adsorption time and temperature are all important factors affecting the Cd(II) adsorption. The optimal conditions (adsorption time of 90 min, CaO-SA dosage of 1 g/L, pH of 5 and adsorption temperature of 40 °C) for CaO-SA to adsorb Cd(II) were obtained by surface optimization, at which the Cd(II) adsorption rate could reach a value of 99.74%.
本研究制备了一种简单、廉价且环保的基于污泥的吸附剂，该吸附剂由城市脱水污泥和氧化钙（CaO）改性而成。探讨了 CaO 改性对污泥基吸附剂（CaO-SA）吸附容量和机械强度的增强作用，以及 CaO 对活性污泥的改性机制。此外，通过表面优化实验对 Cd(II)吸附条件进行了优化。结果表明，CaO 对提高污泥基吸附剂的吸附容量和机械强度有很好的效果。当 CaO 用量为 5%、干燥温度为 60°C 时，CaO-SA 吸附剂的机械强度和 Cd(II)吸附容量最佳。CaO 改性可以增加污泥基吸附剂的比表面积和钙离子含量，并去除污泥中羧酸的质子。Box-Behnken 实验设计结果表明，CaO-SA 吸附 Cd(II)的操作条件的重要性可以按吸附时间>用量>pH 值>温度的顺序排列。结果还表明，吸附时间与 CaO-SA 用量、吸附时间与 pH 值、吸附时间与温度之间的相互作用都是影响 Cd(II)吸附的重要因素。通过表面优化，得到了 CaO-SA 吸附 Cd(II)的最佳条件（吸附时间 90min、CaO-SA 用量 1g/L、pH 值 5 和吸附温度 40°C），此时 Cd(II)的吸附率可达 99.74%。
