Green-synthesized Nanoparticles for Industrial Effluent Remediation: A Systematic Review

Abstract

The contamination of water bodies by industrial effluents is a major environmental challenge. Nanotechnology, particularly the use of nanoparticles (NPs), has emerged as a promising approach for wastewater remediation. However, conventional NP synthesis often relies on toxic reagents and energy-intensive processes, conflicting with sustainability goals. In this context, green synthesis, using biological agents such as plant extracts, microalgae, and microorganisms, has gained attention as an eco-friendly and cost-effective alternative. This systematic review aims to analyze recent advances in the application of biogenic NPs for industrial effluent treatment. The study followed the PICO (Population, Intervention, Comparison, Outcome) protocol to structure the research question, and a systematic search across scientific databases resulted in the selection of 13 high-impact studies. The findings demonstrate the high efficiency of various NPs, including ZnO, Ag, Fe₃O₄, and ternary heterojunctions, in removing recalcitrant pollutants such as toxic metals (e.g., Cr and CN⁻) and organic dyes. Adsorption and photocatalysis were identified as the main removal mechanisms, with degradation efficiencies often exceeding 90%. Key operational parameters, such as pH, contact time, and nanomaterial dosage, significantly influence process performance. Additionally, the studies report good stability, reusability, and low ecotoxicity of biogenic NPs, reinforcing their environmental and technical viability. Overall, green synthesis represents a sustainable and effective platform for developing advanced wastewater treatment technologies aligned with green chemistry and circular economy principles.