Imran Muhammad Sajid, Javed Tariq, Areej Isham, Haider Muhammad Nouman
Department of Chemistry, University of Sahiwal, Sahiwal, 57000, Punjab, Pakistan E-mail:
Department of Chemistry, Government College University, Faisalabad, 38000, Punjab, Pakistan.
Water Sci Technol. 2022 Apr;85(8):2295-2317. doi: 10.2166/wst.2022.124.
The current study explores the effectiveness of coconut husk for crystal violet dye sequestration employing a batch experimental setup. Characterization of adsorbent was carried out via FTIR, and SEM techniques and results confirmed the involvement of -OMe, -COC- and hydroxyl functional groups in dye uptake, and the rough, porous nature of adsorbent and after adsorption dye molecules colonized these holes resulting in dye exclusion. Effects of various adsorption parameters such as pH, adsorbent dose, contact time, initial dye concentration, and temperature of solution were studied. Crystal violet adsorption on coconut husk was highly pH-dependent, with maximum removal occurring at basic pH. Maximum removal of dye, i.e., 81%, takes place at optimized conditions. Kinetic data was analyzed by pseudo-first, pseudo-second order and an intra-particle diffusion model. Results showed that the pseudo-second order kinetic model best described adsorption of crystal violet onto coconut husk. Langmuir, Freundlich, and D-R adsorption isotherms were also used to test their appropriateness to experimental data and the Freundlich isotherm fits best to data. Thermodynamic parameters showed that the current process was spontaneous, endothermic in nature with continuous decrease in entropy. Established practice is 79% applicable to tap water and in acidic medium nearly 80% of adsorbent was recovered, confirming the effectiveness and appropriateness of coconut husk for crystal violet dye exclusion from wastewater.
本研究采用间歇实验装置探讨了椰壳对结晶紫染料的吸附效果。通过傅里叶变换红外光谱（FTIR）和扫描电子显微镜（SEM）技术对吸附剂进行了表征，结果证实了 -OMe、-COC- 和羟基官能团参与了染料的吸附过程，并且吸附剂具有粗糙、多孔的性质，吸附后染料分子占据了这些孔洞，从而实现了染料的去除。研究了各种吸附参数，如pH值、吸附剂剂量、接触时间、初始染料浓度和溶液温度的影响。椰壳对结晶紫的吸附高度依赖于pH值，在碱性pH条件下去除率最高。在优化条件下，染料的最大去除率为81%。采用伪一级、伪二级动力学模型和颗粒内扩散模型对动力学数据进行了分析。结果表明，伪二级动力学模型能最好地描述结晶紫在椰壳上的吸附过程。还使用了朗缪尔等温线、弗伦德里希等温线和D-R吸附等温线来检验它们对实验数据的适用性，结果表明弗伦德里希等温线最适合该数据。热力学参数表明，当前过程是自发的，本质上是吸热的，且熵不断降低。既定实践表明，该方法对自来水的适用性为79%，在酸性介质中，近80%的吸附剂得以回收，这证实了椰壳从废水中去除结晶紫染料的有效性和适用性。
