Giombo persimmon seeds (GPS) (Diospyrus kaki L) were used as a novel low-cost adsorbent for the removal of Toluidine Blue dye (TB) from aqueous solution by batch contact adsorption mode at 25˚C. The GPS adsorbent was characterized by specific surface area (Brunauer-Emmett-Teller), scanning electron microscopy, infrared spectroscopy (ATR-FTIR), thermal analysis, point of zero charge, and Boehm titration techniques. The effects of initial pH of solution, adsorbent dosage, contact time, and initial dye concentration on TB adsorption were investigated. Kinetic data were evaluated by pseudo-first-order, pseudosecond-order, and Elovich models. The equilibrium adsorption was analyzed by Langmuir, Freundlich, and Sips isotherms models. Desorption studies were also performed. The results indicated that the Elovich model agreed very well with the kinetic data. The equilibrium data of adsorption of TB onto GPS were better fitted using Sips isotherm. The maximum adsorption capacity was 34.73 mg g −1. Good regeneration (93.5%) of GPS adsorbent was obtained using 2.00 mol L −1 CH 3 COOH as eluent. The GPS adsorbent can be used in the future as an alternative low-cost adsorbent for the treatment of waters contaminated with TB dye.

In this study, Punica granatum husk (PGH), an agricultural powdered biowaste, was used as adsorbent for the removal of methylene blue (MB) dye from aqueous solutions. The effects of initial pH of solution, adsorbent dosage, contact time, and initial dye concentration on the MB adsorption were evaluated in batch adsorption mode at 298 K. Kinetic data were evaluated by pseudo-first-order, pseudo-second-order, and Elovich models. The equilibrium adsorption was evaluated by Langmuir, Freundlich, and Sips isotherm models. The applicability of PGH was also evaluated for simulated effluents. The results revealed that pseudosecond-order model agreed well with the experimental kinetic data. The adsorption of MB onto PGH was better fitted using Sips isotherm. The maximum adsorption capacity obtained by Sips model was 68.40 mg g −1 . Regeneration of PGH adsorbent was possible using 1.0 mol L −1 of HCl as eluent. PGH adsorbent is adequate for removal of MB from simulated textile and river effluents. The results obtained in this work show that PGH can be used as alternative adsorbent for MB removal from effluents.