Bentonite Impregnation Ammonium-Assisted as Eco-Friendly Dye Adsorbent: Analyses of Kinetics and Thermodynamics in Cationic Dye Adsorption

The original Java bentonite has been improved by a new method of multi-step impregnation using over-concentrated ammonium under nature temperature. The achieved materials were characterized using SEM-EDX, XRD, FTIR, and BET analysis and then applied in cationic dye adsorption. The specific case in peak XRD analysis of ammonium impregnation was detected at 18°, and the spectra at 532.3 and 470.6 cm-1 of the FTIR analysis were detected as the ammonium vibration and oscillation bending. Surface structure analysis from SEM-EDX showed the smooth and expanded material achieved, supported by surface area analysis of BET, which described the increase of surface area materials from 61.791, 73.089, and 178.710 m2/g for the bent, bent-Na, and bent-NH, respectively. The highest adsorption capacity on bentonite impregnated by ammonium was achieved at 526.316 mg/g and 128.205 mg/g for rhodamine B and malachite green, respectively. The adsorption mechanism was feasible in endothermic and fitted to pseudo-second-order and Langmuir isotherm adsorption model. The new method of ammonium impregnation on bentonite successfully improved the adsorption ability.