Facile Green Preparation of Lignocellulosic Biosorbent from Lemongrass Leaf for Cationic Dye Adsorption

Lignocellulosic biosorbents for wastewater treatment are generally powders. However, powdered biosorbents require the time and energy taken up in grinding and sieving. In this work, lignocellulosic biosorbents were prepared in fiber form from lemongrass leaf (LGL), through a simple, green procedure using various chemical treatment conditions. Scanning electron microscopy (SEM) revealed the reduced diameter of treated fibers and thermogravimetric analysis (TGA) revealed increased thermal stability due to the partial elimination of lignin and hemicellulose. Based on the eco-friendly preparation and adsorption capacity, the most suitable fibrous biosorbent for dye adsorption was LGL treated with 5 wt% NaOH (TLGL5). The Langmuir isotherm model indicated maximum adsorption capacities of TLGL5 toward crystal violet (CV) and methylene blue (MB) of 76.92 mg g(-1) and 35.84 mg g(-1), respectively. CV and MB uptake by TLGL5 were compatible with the pseudo-second order model. Thermodynamic study indicated a spontaneous and endothermic adsorption reaction for both dyes. Using an aqueous acetic acid desorption solution, TLGL5 could be used for four adsorption-desorption cycles. Based on these findings, TLGL5 is a viable alternative adsorbent for the removal of dye from textile effluent.

Automated summary

In this study, lignocellulosic biosorbents in fiber form were prepared from lemongrass leaf through a simple and green process. The most suitable fibrous biosorbent for dye adsorption was found to be TLGL5 treated with 5% NaOH, showing maximum adsorption capacities towards crystal violet and methylene blue. The thermodynamic study indicated a spontaneous and endothermic adsorption reaction for both dyes, and TLGL5 showed good potential for multiple adsorption-desorption cycles.