Rice husk extracted lignin–TEOS biocomposites: Effects of acetylation and silane surface treatments for application in nickel removal☆

A novel lignosilicate (LS) composite was synthesized from pre-extracted (hot water, 80% ethanol, 0.3 N NaOH) lignin of rice husk (RH) using TEOS as matrix. The extracted lignins were subjected to surface modification by acetylation followed by in situ synthesis of lignosilicate (LS) composites by sol-gel method for application in nickel removal. LS were characterized by FT-IR, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), particle size distribution (PSD) and atomic absorption spectroscopy (AAS). FT-IR studies showed acetyl group in the range of 1680-1690 cm-1 whereas for adsorbed Si-O-Ni2+ the band appeared at 870 cm-1. Findings suggest that alkali extracted LS with mean PSD of 14.89 nm are thermally more stable (Tm = 337 °C) than ethanol (ELS) and hot water (HLS) extracted LS, and exhibit potential for Ni2+ removal (38.74%). SEM and PSD (D50) analyses confirmed their rough surfaces and dispersive nature, respectively, suitable for metal biosorption.