Citrullus lanatus Seed Starch–Based Resin for Water Purification: Synthesis, Physicochemical Characterization and Batch Adsorption of Heavy Metals

The increasing contamination of water resources by heavy metal ions causes a significant environmental and public health challenge. In this study, a novel eco-friendly adsorbent synthesized from Citrullus lanatus (water-melon) seed starch. Water-melon seed starch ascorbic acid (WMSSAA) resin characterization was carried out by Fourier Transform Infrared (FTIR) spectrophotometry, Scanning Electron Microscopy (SEM) analysis as well as Thermogravimetric (TG) - Differential Thermal (DT) analysis. The WMSSAA resin was further investigated for removal of toxic heavy metal ions from the standard aqueous solutions by batch adsorption method. The distribution coefficient and percentage removal of heavy metal ions by WMSSAA resin were determined under the influence of pH range of 2-8. FTIR spectral data favors the formation of chemically modified resin. These data clearly reveal functionalities present on resin. Rough and uneven morphology of resin is confirmed by SEM analysis. The moderate to good thermal stability of resin has been investigated by TG-DTA. The functionality present on resin provides sites for significant adsorption of heavy metal ions Cd2+, Ni2+, Pb2+, Zn2+. Citrullus lanatus Seeds are agricultural waste. This work applies green chemistry principle through formation of active adsorbent from waste seeds. The work contributes towards sustainable waste water treatment protocol. The results demonstrated that the synthesized resin exhibited high adsorption efficiency, suggesting its potential as a low-cost and sustainable alternative for wastewater treatment.