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A recent study published in the Journal of Water Process Engineering introduces a new composite adsorbent for removing hexavalent chromium (Cr(VI)) from wastewater, addressing a significant environmental concern. Researchers developed this adsorbent by combining coffee grounds biochar (CGB) and sodium alginate (SA), leveraging the strengths of both materials.

The CGB, rich in oxygen-containing functional groups, effectively reduces Cr(VI) to the less toxic trivalent chromium (Cr(III)). When combined with SA, known for its excellent gel-forming and ion-binding properties, the resulting composite, SACGB, demonstrated superior adsorption capabilities. The study showed that SACGB could achieve a maximum Cr(VI) adsorption capacity of 30.66 mg/g, with a removal efficiency of 99.79% under optimal conditions.

Key findings included the reduction of 58.97% of Cr(VI) to Cr(III) on the adsorbent’s surface, and the composite’s ability to maintain 93% removal efficiency despite interference from other metal ions. Importantly, SACGB’s performance in actual wastewater met industrial discharge standards, making it a viable option for practical applications.

The composite remained effective over multiple recycling cycles and contained no biotoxic components, underscoring its sustainability. The study highlights SACGB as an economical and efficient adsorbent for Cr(VI) removal, promoting the principles of circular economy and waste valorization. This research paves the way for developing similar eco-friendly adsorbents, crucial for addressing heavy metal pollution in wastewater.