Carbon dots crosslinked chitosan/cellulose sponge capture of methyl blue by an adsorption process

Abstract For environmental protection, organic dyes and solvents of industrial wastewater must be eliminated. Here, a citric acid‐based carbon dots (CA‐CDs) crosslinked chitosan/microcrystalline cellulose (CS/MCC/CA‐CDs) sponge was synthesized to study its adsorption performance for methyl blue (MB) dye. The morphology of the sponge was a tangled fibre with a bundle formed by hydrogen bonds between CA‐CDs and the CS/MCC composite matrix. The abundant amount of tangled fibre bundle units can offer plentiful active adsorption sites to collect the dye molecules. The adsorption capacity of the CS/MCC/CA‐CDs sponge toward MB was 306.8 mg/g at pH 10 and a temperature of 298 K. In addition, the pseudo‐second‐order kinetic model was matched with the adsorption kinetic experimental data, and the adsorption isotherm data can be described by the Langmuir models. This study proposed that the CS/MCC/CA‐CDs sponge adsorbent creates tremendous potential application value in wastewater treatment due to its fast kinetics, high adsorption capacity, simple preparation, and eco‐friendly properties.