Mohrazi Ava, Ghasemi-Fasaei Reza
Department of Soil Science, School of Agriculture, Shiraz University, Shiraz, Iran.
Environ Monit Assess. 2023 Jan 27;195(2):339. doi: 10.1007/s10661-022-10900-4.
Wastewater contains organic compounds, including dyes, which have potential risks to the environment. Hence, these compound needs to be eliminated from the aqueous solution. In the present study, chitosan-pectin composite (Cs-Pc) was used as an adsorbent to remove methylene blue dye (MB) from synthetic wastewater. To evaluate the parameters affecting adsorption, including the initial MB concentration, solution pH, contact time, and Cs-Pc dose, batch experiments were carried out. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FTIR), and pH point of zero charges (pH pzc) were applied for characterizations of Cs-Pc. The optimum conditions were obtained with an initial MB concentration of 50 mg L: solution pH ~ 11, Cs-Pc dose: 1.5 g L and 180 min contact time, which caused 97.77% of MB removal. In addition, the removal efficiency of MB was more influenced by pH than by sorbate dose. Also, Cs-Pc had a higher ability to remove MB than chitosan and pectin, probably due to its highly porous structure and rough surfaces that provides active sites and facilitate MB adsorption. The maximum removal efficiency and the adsorption capacity of MB onto Cs-Pc at 500 mg L concentration under optimum conditions were 98.67% and 328.02 mg g, respectively. The adsorption kinetics and isotherms were best described by pseudo-second-order and Freundlich equation, respectively. After four times of recycling, the removal efficiency of MB was above 96%. Electrostatic and pi-pi interactions are the main mechanisms for the removal of MB onto the adsorbent. So the application of Cs-Pc is promising for MB removal from polluted solutions not only due to its strong adsorbing capability but also due to its excellent ability to reuse.
废水含有有机化合物，包括染料，这些物质对环境具有潜在风险。因此，需要从水溶液中去除这些化合物。在本研究中，壳聚糖-果胶复合材料（Cs-Pc）被用作吸附剂，以去除合成废水中的亚甲基蓝染料（MB）。为了评估影响吸附的参数，包括初始MB浓度、溶液pH值、接触时间和Cs-Pc剂量，进行了批量实验。采用扫描电子显微镜（SEM）、能量色散X射线光谱（EDX）、傅里叶变换红外光谱（FTIR）和零电荷点pH值（pH pzc）对Cs-Pc进行表征。在初始MB浓度为50 mg/L、溶液pH值约为11、Cs-Pc剂量为1.5 g/L和接触时间为180分钟的条件下获得了最佳条件，此时MB的去除率为97.77%。此外，MB的去除效率受pH值的影响大于吸附质剂量的影响。而且，Cs-Pc去除MB的能力高于壳聚糖和果胶，这可能是由于其高度多孔的结构和粗糙的表面提供了活性位点并促进了MB的吸附。在最佳条件下，当MB浓度为500 mg/L时，MB在Cs-Pc上的最大去除效率和吸附容量分别为98.67%和328.02 mg/g。吸附动力学和等温线分别用伪二级方程和Freundlich方程进行了最佳描述。经过四次循环后，MB的去除效率仍高于96%。静电和π-π相互作用是吸附剂去除MB的主要机制。因此，Cs-Pc的应用不仅因其强大的吸附能力，还因其出色的再利用能力，在从污染溶液中去除MB方面具有广阔前景。
