Magnetic Graphene Oxide/Chitin Nanocomposites for Efficient Adsorption of Methylene Blue and Crystal Violet from Aqueous Solutions

Abstract

The present study is focused on the synthesis of prominent magnetic graphene oxide/chitin nanocomposites, which behaves as an adsorbent for organic dyes under visible light. The nanocomposites were characterized using physicochemical techniques such as X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, vibrating-sample magnetometer, scanning electron microscopy, and transmission electron microscopy. A band gap energy of 2.01 eV was evaluated from Tauc and Davis–Mott plots. Batch adsorption studies were performed on crystal violet and methylene blue dyes with varying parameters such as time, pH, concentration, dosage, and temperature, which resulted to excellent adsorption activities of 403.78 mg/g for crystal violet and 332.61 mg/g for methylene blue. The as-synthesized nanocomposite showed excellent recovery capability, retaining its adsorption efficiency even after nine cycles of regeneration. The adsorption equilibrium data fitted well into the pseudo-second-order model and Langmuir isotherm model, while the spontaneity and exothermic nature of the adsorption phenomenon are demonstrated by thermodynamic studies. A comparative adsorption study results to a selective adsorption of cationic dyes over anionic ones, which goes in conformity with the high negative value of zeta potential obtained at neutral pH.

Cellulose citrate: a convenient and reusable bio-adsorbent for effective removal of methylene blue dye from artificially contaminated water

“…The maximum zeta potential is À28.5 that is comparable to other similar adsorbents. [78][79][80][81] The zeta potential at neutral pH is À3.8 that is consistent with the affinity of the adsorbent for cationic molecules like MB. At high pH (higher than pH ZPC ) the absorption is mainly driven by electrostatic interactions between opposite charges.…”

Effective adsorption of crystal violet from aqueous solutions with effective adsorbent: equilibrium, mechanism studies and modeling analysis

“…Nowadays, organic dyes are one of the main sources of water pollution due to their wide application in industry such as for dyeing papers, textile fibers, plastics, leathers and pharmaceuticals [1]. According to a recent report, about 10 thousand various types are produced with a rate of more than 700 thousand tons/year, and most of the dyes available in the market [2]. Dyes such as malachite green (MG), methylene blue (MB) and crystal violet (CV) have a negative effect on water quality, and it is carcinogenic dyes that can potentially affect human as well as animal life [3][4][5].…”

A Biocompatible, pH-Sensitive, and Magnetically Separable Superparamagnetic Hydrogel Nanocomposite as an Efficient Platform for the Removal of Cationic Dyes in Wastewater Treatment

“…To compensate for these inadequacies, fabrication of environment-friendly materials with selective adsorption of dyes and easy separation capability has been attempted. 18 The hydrogels especially composed of renewable and sustainable sources have been used for treatment of colored water. 19 , 20 Hydrogels are three-dimensional cross-linked polymers containing hydrophilic groups, which enable them to absorb water.…”