Silver-Molybdate@KaoliniteNanocomposites for efficient and reusable inorganic cation decontamination from wastewater: a cost-effective sustainable approach for Cr(VI) and Cu(II) elimination

Abstract

The persistent threat of toxic heavy metals like Cr(VI) and Cu(II) in water systems demands advanced, cost-effective solutions beyond conventional adsorbents such as activated carbon, clay minerals, and ion-exchange resins, which often suffer from limited adsorption capacity, slow kinetics, poor stability under acidic or basic conditions, and high regeneration costs. Here, we engineer a robust Ag2MoO4@Kaolinite nanocomposite to overcome these limitations, delivering exceptional adsorption performance and reusability. Advanced characterizations (XRD, FT-IR, SEM, and TEM) confirm the nanocomposite’s optimized structure and active sites. In batch tests, the material achieves > 90% removal of Cr(VI) (pH 2) and Cu(II) (pH 6), reducing Cr(VI) concentrations from 50 mg/L to below 0.5 mg/L and Cu(II) from 50 mg/L to below 2.5 mg/L at optimal adsorbent doses, outperforming traditional methods. Comparative plots of absolute residual concentrations as a function of adsorbent dose are provided to clearly illustrate the treatment efficacy and compliance with water quality standards. Adsorption follows pseudo-second-order kinetics and the Langmuir isotherm, indicating chemisorption-driven monolayer uptake. Remarkably, the nanocomposite retains 82–88% efficiency after five regeneration cycles, demonstrating unmatched durability compared to conventional adsorbents that typically lose significant capacity within fewer cycles. Its stability across diverse conditions (variable doses, concentrations, and competing ions) ensures real-world applicability. A breakthrough in cost-efficiency synthesis at just $64.50–89.00 per 100 g and 91–98% operational savings over conventional systems positions this innovation as a scalable, economically viable solution. By merging high performance with sustainability, Ag2MoO4@Kaolinite bridges the gap from lab-scale promise to industrial adoption, offering a transformative tool for combating heavy metal pollution.