Repurposing Co-Fe LDH and Co-Fe LDH/Cellulose micro-adsorbents for sustainable energy generation in direct methanol fuel cells

Abstract

Spent adsorbents need to be recycled as well as valorized to obtain long-term benefits from the adsorption of contaminants from wastewater. Co-Fe LDH and Co-Fe LDH/cellulose-layered double hydroxide (LDH) were prepared for crystal violet (CV) adsorption. FT-IR, XRD, SEM, TEM, and, zeta potential analyses confirmed the micro-composites. The parameters examined in this study were the initial pH, initial concentration, adsorbent dose, contact time, adsorption isotherm, and adsorption kinetics. The removal percent was 97.5 % and 88 % for Co-Fe LDH and Co-Fe LDH/cellulose, respectively. A maximum adsorption capacity was 69.4 and 50.0 mg g−1 for Co-Fe LDH and Co-Fe LDH/cellulose, respectively, at pH = 9. The Langmuir-Freundlich model can adequately explain the isotherm processes of LDH and LDH/cellulose; R2 was 0.96 and 0.95, respectively. The spent adsorbents (Co-Fe LDH/CV and Co-Fe LDH/Cellulose/CV) were applied once again as catalysts for electro-oxidation in direct-methanol fuel cells. Due to its high stability in the basic medium (NaOH), the waste material was exploited as an active catalyst to support methanol oxidation. It displayed a better efficiency of 74.75 % and a current density of 76 mA/cm2 at 50 mV/s in 1 M methanol for Co-Fe LDH/CV. The suggested technique opens up a completely new channel for reusing waste into high-value materials for application in electrocatalytic energy generation.