Paradelo Remigio, Al-Zawahreh Khaled, Barral María Teresa
CRETUS Institute (Cross-Research in Environmental Technologies), Soil Science and Agricultural Chemistry Department, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
Department of Earth Sciences and Environment, Faculty of Natural Resources and Environment, The Hashemite University, Zarqa 13133, Jordan.
Materials (Basel). 2020 May 9;13(9):2179. doi: 10.3390/ma13092179.
Utilization of composts as low-cost adsorbents is an important application in the field of environmental remediation, but these materials have not yet been extensively used for dye removal. In this work, we have studied the characteristics of adsorption of methylene blue onto two composts (a municipal solid waste compost and a pine bark compost). Kinetics and equilibrium batch experiments testing the influence of adsorbent particle size, solution pH and ionic strength were performed. Both composts have a high adsorption capacity for methylene blue, similar to other low-cost adsorbents. Kinetics of adsorption followed a pseudo-first-order model, with maximum adsorption reached after a contact time of two hours. Equilibrium adsorption followed a Langmuir model in general. Reduction of particle size only increased adsorption slightly for composted pine bark. Increase in ionic strength had no effect on adsorption by municipal solid waste compost, but increased adsorption by composted pine bark. Modification of pH between 5 and 7 did not influence adsorption in any case. Overall, the results suggest that electrostatic interaction between the cationic dye and the anionic functional groups in the composts is not the only mechanism involved in adsorption. In conclusion, the use of composts for dye removal is a likely application, in particular for those composts presenting limitations for agricultural use.
将堆肥用作低成本吸附剂是环境修复领域的一项重要应用，但这些材料尚未广泛用于去除染料。在这项工作中，我们研究了亚甲基蓝在两种堆肥（城市固体废物堆肥和松树皮堆肥）上的吸附特性。进行了动力学和平衡批量实验，测试了吸附剂粒径、溶液pH值和离子强度的影响。两种堆肥对亚甲基蓝都有很高的吸附容量，与其他低成本吸附剂相似。吸附动力学遵循准一级模型，接触两小时后达到最大吸附量。平衡吸附总体上遵循朗缪尔模型。对于松树皮堆肥，减小粒径仅略微增加吸附量。离子强度的增加对城市固体废物堆肥的吸附没有影响，但增加了松树皮堆肥的吸附量。在5至7之间改变pH值在任何情况下都不会影响吸附。总体而言，结果表明阳离子染料与堆肥中阴离子官能团之间的静电相互作用不是吸附过程中唯一涉及的机制。总之，使用堆肥去除染料是一种可能的应用，特别是对于那些在农业使用方面存在局限性的堆肥。
