Grass Waste: A Highly Biosorbent for the Removal of Malachite Green Dye From Aqueous Solution

Grass waste (GW), a low-cost agricultural waste, is a more effective adsorbent to remove malachite green MG dye. Treatments physical or chemical of GW by soaking in solution H2O2 (10%) for 4 hours at 25 °C. The removal of MG from bio-sorption GW was studied at several weights of GW (0.01–0.1 g), equilibrium time (2–120 min), initial concentration (10–100 mg/L), and pH solution (2–10). The effect of the factors on the adsorption efficiency was studied using the batch process. Increasing MG dye concentration, the adsorption efficiency of GW increased, but the removal percentage decreased from 10.599 mg/g to 110.99 mg/g to 94.11% to 83.08%. The data evidently displayed a removal percentage of MG of about 89.89% at a weight of GW of 0.08 g/100 mL. The adsorbent was characterized via SEM and TEM. Desorption of MG dye studies was performed with hydrochloric acid, sodium hydroxide, phosphoric acid, acidic acid, and H2O. A high removal percentage of 89.088% in acid medium 0.1 N hydrochloric acid. With the addition of HCl, the solution pH decreases, and hence, at a pH of 3, the GW surface becomes large and protonated, and the attachment among the molecules of dye and GW becomes weakened. The data revealed that bio-sorption GW adsorbent is potentially a very low-cost and eco-friendly adsorbent for the removal of MG dye.