Removal of reactive dyes-based wastewater with moringa-coated cellulose microcrystals (CMC) produced from sugarcane bagasse

Abstract

Reactive dyes are mostly used for cotton dyeing, but due to the high amount of unfixed dyes present after the dyeing, various adsorbents have been developed to remove them effectively. This study aims to develop novel bioadsorbents based on cellulose microcrystals (CMC) derived from agri-food waste sugarcane bagasse (SB), with a yield of ∼15 %, which is then coated with cationic protein derived from Moringa oleifera (MO) to enhance absorbent performance. The performance of these absorbents – SBCMC and SBCMC/MO were tested for the removal of C.I. Reactive Red 180 dye from dyeing wastewater. Surface characterisation of bioadsorbents was carried out using FTIR spectroscopy, laser particle size analyser, Zetasizer, and FESEM imaging. Removal percentages of dyes by the adsorbents were carried out using a UV-Vis spectrophotometer in combination with different adsorbent dosages, time, pH and dye concentrations. The size of the CMC was found to be less than ∼10 μm for 50 % of particles and less than ∼20 μm for 90 % of particles. The removal efficiency was found to be higher for moringa-coated SBCMC, with an adsorption capacity of 99.61 mg/g at an initial dye concentration of 1000 ppm and a dosage of 5 g/l. This is attributed to neutralisation of anionic surface as evident through zeta potential, which is reduced from −15.39 to −2.105 mV and also in FESEM images. The experimental data were better fitted to the Freundlich isotherm model and the pseudo-second-order kinetic model. Comparison with other bioadsorbents showed that the developed SBCMC/MO bioadsorbent has a similar or better adsorption capacity, demonstrating the effectiveness of dye removal. This study encourages the use of waste and natural materials as renewable resources to remove dyes from wastewater.