BIOGENIC SILVER NANOPARTICLES AS SUSTAINABLE NANOCATALYSTS FOR THE SIMULTANEOUS REMEDIATION OF ORGANIC POLLUTANTS AND INORGANIC HEAVY METALS IN WASTEWATER

Abstract

The rapid release of organic pollutants and inorganic heavy metals into aquatic environments has become a major global environmental concern due to rapid industrialization, urbanization and agricultural activities. Conventional wastewater treatment technologies often face problems of simultaneous removal of multiple pollutants owing to their high operational cost, incomplete degradation efficiency and secondary pollution. In recent years, biogenic silver nanoparticles (AgNPs) have been recognized as promising sustainable nanocatalysts due to their unique physicochemical properties, excellent catalytic performance, environmental compatibility, and eco-friendly synthesis routes. Unlike chemically synthesized nanoparticles, biogenic AgNPs are synthesized using plant extracts, microorganisms, algae or other biological resources, which minimizes the use of hazardous chemicals and promotes green nanotechnology. The present review aims to carry out an extensive assessment of synthesis, characterization, catalytic mechanisms and environmental applications of biogenic silver nanoparticles as a simultaneous remediation tool of organic pollutants and inorganic heavy metals in wastewater treatment systems. We used a systematic review methodology to collect and critically appraise peer-reviewed studies published in the top scientific journals. A thorough review was done on relevant literature regarding green synthesis techniques, characterization of nanoparticles, catalytic degradation of organic contaminants, mechanisms of heavy metal adsorption and environmental sustainability. The collected studies were compared to point out recent developments, current challenges and future research opportunities in the area of biogenic nanocatalysis.The literature reviewed depicts that biogenic silver nanoparticles possess extraordinary catalytic activity, high surface area, excellent electron transfer capacity and strong adsorption efficiency and are very effective for degrading persistent organic pollutants such as dyes, pharmaceuticals, pesticides, phenolic compounds along with their removal of toxic heavy metals such as lead, cadmium, chromium, mercury and arsenic. The catalytic performance of these nanoparticles depends on the particle size, morphology, surface functional groups, the conditions for synthesis, and the biological source used in fabrication. Moreover, biogenic AgNPs have higher stability, reusability, antimicrobial activity and lower environmental toxicity than many of the conventionally synthesized nanomaterials. However, there are several challenges such as large scale production, long term environmental safety, nanoparticle recovery, standardization of the process and the full toxicity assessment under real wastewater conditions. Overall, the biogenic silver nanoparticles represent a novel environmentally sustainable nanocatalytic platform for integrated wastewater remediation. Their ability to degrade organic pollutants while adsorbing or transforming inorganic heavy metals offers a significant potential for next generation water treatment technologies. Future works should be dedicated to the development of scalable green synthesis techniques, lifecycle and ecotoxicological assessment, strategies for catalyst regeneration, pilot-scale applications, and interdisciplinary collaboration in order to achieve the practical implementation of biogenic silver nanoparticles for sustainable environmental protection and global water resource management.

Keywords: Biogenic silver nanoparticles; Green synthesis; Nanocatalysis; 4‑Nitrophenol reduction; Dye photocatalytic degradation; Heavy‑metal adsorption; Wastewater remediation