Bioremediation of Nigrosine anionic dye from wastewater employing copper nanocomposite-modified Cucumis melo seed powder: a comparison of performance evaluation between defatted and surface modified adsorbent

Bioremediation of environmental pollutants is a hot research area due to its effectiveness and ease of use. This approach is utilized in current work by employing both simple adsorbent (SA) and nanoparticle-loaded adsorbent (NpLA) for the mitigation of Nigrosine dye, having high chemical stability and high color intensity. The structural and morphological characterization was studied by UV–Vis (ultraviolet–visible) spectrophotometer, FTIR (Fourier transform infrared spectroscopy), SEM (scanning electron microscopy), BET (Brunauer–Emmett–Teller), TGA (thermogravimetric analysis), and XRD (X-ray diffraction). The surface area of the adsorbent was found to be 1.728 m² g⁻¹. Optimized parameters were determined by batch experiments and adsorption efficiency was found to be 93% for SA at 20 ppm (dye concentration), 50 min (contact time), 2 g L⁻¹ (adsorbent dose), and at (acidic pH) 3. In the case of NpLA, a maximum adsorption efficiency of 96% was achieved at 100 ppm (dye concentration), 40 min (contact time), 1.5 g L⁻¹ (sorbent dose), and at acidic pH, 3. Both linear and non-linear forms of adsorption isotherms were applied to experimental data and kinetic study was done. The maximum multilayer adsorption capacity was found to be 0.8761 mg g⁻¹. Thus, the results concluded that NpLA is the effective and eco-friendly adsorbent for removing Nigrosine dye from the aqueous solutions. Many strategies for handling and recycling spent adsorbent can be experimented with, the most common recycling methods being leaching and electroplating, and handling methods comprising stabilization/solidification before being dumped into the ecosystem, having a high environmental impact. A valuable alternative includes mixing the spent adsorbent with raw material to produce ceramic materials, which can be used as construction material.