Removal of hazardous dyes and waterborne pathogens using a nanoengineered bioadsorbent from hemp – Fabrication, characterization and performance investigation

Abstract

Water is essential to human life. Improvements to clean safe water using sustainable energy efficient methods are among the top engineering achievements credited with advancing human civilization. Hemp, a lignocellulosic abundant biomass with multiple functional groups, has the potential to be applied in varied fields. In this study, a hemp hurd nanocomposite (HHNC) adsorbent was developed by embedding silver nanoparticles within hemp hurd following a simple, rapid and "green chemistry" method. The feasibility of using this hemp-based nanoadsorbent impregnated with silver nanoparticles is explored herein for the simultaneous degradation of Brilliant green (BG), a cationic dye, and Congo red (CR) an anionic dye, and for inhibiting the growth of bacteria from wastewater. The changes in surface chemistry and surface morphology of synthesized HHNC before and after adsorption was explored. The adsorption results of both dyes showed that adsorption data followed the Langmuir isotherm model and pseudo-second-order kinetic model. The Langmuir adsorption capacity qmax was calculated to be ∼256 mg g − 1 and ∼455 mg g − 1 for BG and CR, respectively. The thermodynamics study demonstrated the adsorption process to be endothermic and spontaneous in nature. HHNC exhibited adsorptive removals of 88.6% and 99.4% for CR and BG dyes, respectively, at pH 6.5 and at room temperature. The recovery efficiency was > 82% for CR and > 94% for BG after 6 cycles of reuse. The minimum inhibitory concentration (MIC) value for AgNPs in HHNC was 12.7 µg/ml for E. coli and S. aureus. Thus, the results indicate that HHNC, being an environmentally-friendly adsorbent, exhibits excellent potential to remove organic dyes of substantial molecular structures and a competent disinfectant for drug-resistant bacteria.