Sustainable Dye Removal A Review of Low-Cost Natural Adsorbents for Wastewater Treatment

Background: Wastewater discharge into natural watercourses causes pollution of surface and groundwater, making it unsuitable for drinking and increasing industrial treatment costs. Color is a major pollutant, as even small amounts of dyes make water visually unappealing. Adsorption is a widely used physicochemical treatment method, where wastewater is mixed with an adsorbent to remove contaminants. Materials and Methods: this study used natural adsorbents—Moringa seed and lemon seed powders—to remove methylene blue dye from synthetic textile wastewater. The seeds were sourced from local markets and farms, dried, and sieved. Adsorption experiments were conducted by varying contact time, initial dye concentration, pH, and adsorbent dosage. Results: Lemon seed powder achieved 86% color removal at pH 7 with a 30-minute equilibrium time, while Moringa seed powder achieved 50% removal at pH 6 with a 60-minute equilibrium time. Experimental data fit both Langmuir and Freundlich adsorption isotherms. Conclusion: Lemon seed powder proved significantly more effective than Moringa seed powder for methylene blue removal. Both materials show potential as low-cost, eco-friendly adsorbents that can reduce wastewater treatment expenses.