Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India.
Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India.
Chemosphere. 2021 Oct;281:130706. doi: 10.1016/j.chemosphere.2021.130706. Epub 2021 May 10.
Chitosan was fabricated via gelation method using CaBr.xHO/methanol solution and was studied as a potential adsorbent (MCh) in adsorbing anionic synthetic dyes like Bromophenol blue (BB), Direct blue 6 (DB) and Congo red (CR) from single (one dye species at a time) and multi (having two dyes; binary and all three dyes; tertiary) adsorptive systems. Physico-chemical modifications of MCh surface prior and post modification and dye adsorption were evaluated using scanning electron microscopy, Energy-dispersive X-ray spectroscopy, powder X-ray diffraction analysis, surface area analysis and Fourier-transformed infrared spectroscopy. Influential parameters influencing the adsorption process viz. initial pH of dye solution, MCh dosage, adsorption temperature and initial concentration of dye species were optimised. Adsorptive studies involving single adsorptive setups verified formation of sorbate's (dye species) monolayer over the sorbent's (MCh) surface via chemisorption; as established by Langmuir isotherm and pseudo-second order kinetics model analysis. Theoretical maximum adsorption capacities of MCh for BB, DB and CR was found to be 81.301 mg/g, 163.934 mg/g and 75.758 mg/g, respectively. Meanwhile, for all multi-adsorptive systems, competitive Langmuir isotherm model verified antagonistic behaviour of an individual dye over other dye adsorption over MCh surface in their respective adsorptive systems. Thermodynamics of the sorbate-sorbent interaction was exothermic, spontaneous, with elevated degree of disorderedness; concluding the interaction as thermodynamically favourable. Co-existing metal cations and anionic salts had minimal effect on MCh's adsorption efficiency. Phytotoxicity assay via germination of Vigna mungo seeds verified the efficacy of the adsorbent in eliminating the dye species from single and multi-adsorptive systems.
壳聚糖通过凝胶法使用 CaBr.xHO/甲醇溶液制备，并被研究为一种潜在的吸附剂（MCh），用于从单一组分（一次一种染料）和多组分（两种染料；二元和三种染料；三元）吸附体系中吸附阴离子合成染料，如溴酚蓝（BB）、直接蓝 6（DB）和刚果红（CR）。在修饰前后和染料吸附前后，使用扫描电子显微镜、能量色散 X 射线光谱、粉末 X 射线衍射分析、表面积分析和傅里叶变换红外光谱评估 MCh 表面的物理化学修饰。优化了影响吸附过程的参数，如染料溶液的初始 pH 值、MCh 用量、吸附温度和染料初始浓度。单一组分吸附装置的吸附研究验证了通过化学吸附在吸附剂（MCh）表面形成单层的吸附物（染料）；这是通过 Langmuir 等温线和拟二级动力学模型分析确定的。MCh 对 BB、DB 和 CR 的理论最大吸附容量分别为 81.301、163.934 和 75.758mg/g。同时，对于所有多组分吸附体系，竞争 Langmuir 等温模型验证了在各自的吸附体系中，单个染料对其他染料吸附的拮抗行为。吸附剂-吸附质相互作用的热力学是放热的、自发的，无序度增加，这表明相互作用在热力学上是有利的。共存的金属阳离子和阴离子盐对 MCh 的吸附效率影响很小。通过绿豆种子发芽进行的植物毒性试验验证了吸附剂从单一组分和多组分吸附体系中消除染料的功效。
