Nickel Phosphide and Biochar Synergy for Effective Tetracycline Removal

A nickel phosphide/biochar composite efficiently removes tetracycline from wastewater by activating persulfate. The composite, synthesized using phytic acid, achieves a 94.55% removal rate via surface-bound radicals. Biochar enhances catalytic selectivity, offering a cost-effective solution to mitigate antibiotic pollution and resistance in aquatic environments.

May 26, 2024

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Wang, et al (2024) The critical roles of surface-bound radicals in the nickel phosphide/biochar-persulfate catalytic oxidation system for tetracycline removal: The synergistic catalysis between nickel phosphides and biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More. *Chemical Engineering Journal.* https://doi.org/10.1016/j.cej.2024.151915

In the pursuit of efficient wastewater treatment, a recent study published in the Chemical Engineering Journal presents a novel approach using a nickel phosphide/biochar (NixP/biochar) composite for the catalytic removal of tetracycline (TC). This composite was synthesized using phytic acid (PA) as a biomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More phosphorus source, resulting in Ni12P5 as the predominant crystalline phase.

The study highlights the composite’s remarkable efficiency in activating persulfate (PS) for TC removal, achieving a 94.55% removal rate within 180 minutes. This performance surpasses that of other metal-based phosphide/biochar composites like Fe, Cu, and Co. The NixP/biochar system demonstrated consistent effectiveness across varying TC concentrations and complex water matrices.

Central to this process are the surface-bound radicals, primarily SO4-• and •OH, which are the key reactive oxygen species (ROSs) driving the degradation of TC. The biochar component enhances the catalytic selectivity of nickel phosphides by modulating their electronic structures, particularly favoring Ni2P and Ni12P5 phases, while reducing the selectivity for P-centered Ni3P.

Density functional theory (DFT) calculations further explain that electron donations from nickel, phosphorus, and carbon facilitate the homolysis of persulfate, producing surface-bound SO4-• radicals that trigger subsequent ROS generation. This synergy between nickel phosphides and biochar not only enhances catalytic activity but also ensures stability and resistance to interference from various water contaminants.

This innovative approach offers a cost-effective and environmentally friendly solution for the removal of recalcitrant antibiotics from wastewater, potentially aiding in the fight against antibiotic resistance and promoting safer aquatic environments.