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

Abstract

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.

Keywords

• Rice husk (RH)
• Lignin–TEOS biocomposites
• Sol–gel chemistry
• Differential scanning calorimetry (DSC)
• Metal removal
• FTIR