Sequestration of Cr(VI) onto polyethyleneimine-derivatized cellulose and its effect on the enzymatic degradation and microbiome viability

The extremely hazardous nature of Cr(VI) necessitates its sequestration in a sustainable and effective manner. Cellulose-derived materials, known for their eco-friendly properties, are widely employed in environmental remediation. To improve its adsorption capabilities for heavy metals, cellulose is often derivatized with moieties like amine, thiol, carboxylic acid, etc. The current work compares the efficacy of cellulose derivatized with polyethyleneimine-a nitrogen-rich biocompatible polymer-obtained via two synthetic approaches, resulting in adsorbents termed PEI-MAAC and PEI-DAC. PEI-MAAC represents cellulose grafted with methacrylic acid followed by PEI immobilization, while PEI-DAC involves PEI immobilization on dialdehyde cellulose. The adsorption of Cr(VI) over the two categories of adsorbents is initially optimized for key parameters, including pH, adsorbent dosage and metal concentration. Further analysis of adsorption isotherms and kinetics revealed the superior efficacy of PEI-DAC. To evaluate the environmental impact of these Cr(VI)-adsorbed cellulose-derived materials, their enzymatic degradation behavior and effects on the soil microbiome have been explored. It has been found that the Cr(VI) adsorption retards the enzymatic degradation rate of these materials, while no significant adverse effects on the soil microbiome have been observed. The study highlights the potential of cellulose-derived materials as sustainable candidates for heavy metal sequestration and environmental remediation.