This study reports the usage of chemically impregnated coconut coir waste (CICCW) as a low-cost adsorbent for the desulfurization of feed diesel. The characterization of the developed adsorbent was focused on quantitative analysis (carbon yield %, proximate, ultimate, carbon surface functionalities, BET surface area and porosity distribution, and particle size analysis), qualitative analysis (FTIR), and optical analysis (SEM). BATCH EXPERIMENTS with feed diesel having a total sulfur concentration of 2,050 mg L-1 were conducted to optimize the ADSORPTION parameters such as adsorbent dose, temperature, and contact time. The ADSORPTION process shows an optimum dose of 1 g/20 mL, and the equilibrium is attained in 3 h. The ADSORPTION of sulfur onto the adsorbent at optimum temperature 293 K is regulated by external mass transfer (diffusion into mesopores) followed by a steady ADSORPTION phase with intra-particle diffusion in micropores. A Fickian mechanism controls the diffusion of sulfur molecules from the solution onto the surface of the adsorbent. Freundlich ADSORPTION isotherm illustrates the equilibrium ADSORPTION data very well. The negative value of ΔGo (-27.61 kJ mol-1) and ΔSo (-44.56 J K-1 mol-1) indicates the feasibility, spontaneity of the ADSORPTION process and justified the decrease in the randomness of adsorbed sulfur molecules onto the adsorbent surface, respectively. The exhausted CICCW can be effectively regenerated by methanol and reutilized for three ADSORPTION–desorption cycles. The approximate cost of preparation of the adsorbent was USD 10.714 per kg. These results clearly proved the feasibility of the developed low-cost adsorbent (CICCW) as a good candidate for the desulfurization of feed diesel.

Chitosan has the ability to adsorb substantial quantities of dyestuff from aqueous solution. Currently, it may be a useful adsorbent for the effluent of textile mills. The design procedure for BATCH study has been investigated for dyestuffs. The effect of several factors governing the dye ADSORPTION such as dosage, temperature, pH and particle size have been investigated. The BATCH ADSORPTION kinetic study satisfied the model proposed by increasing dosages at generalized rate constant (6.26 to 5.64 k/min), intra-particle diffusion (kp=3.13 to 4.63 mg/g, 0.5 min) and Langergren’s rate constant (kp=0.1952 to 0.1663 per min). ADSORPTION was found to increase on increasing temperature (30oC, 45oC and 60oC), increasing pH (6.7, 8.5 and 9.5) and on decreasing particle size (1.651 mm, 0.384 mm and 0.177 mm). Maximum amount of dye ADSORPTION occurred at temperature level 60oC (29.9 mg/g); at pH level 9.5 (29.8 mg/g) and particle size 0.177 mm (30.0 mg/g). Also, desorption studies are evaluated at different temperatures and pH.

The study examines the possibility of removing Methyl Orange (MO) from aqueous solutions using crude bentonite. SEM-EDX (scanning electron microscopy) and XRD (X-Ray Diffraction) analyses were performed to characterize the material. BATCH EXPERIMENTS were performed on the ADSORPTION process to study the effect of contact time, pH, concentration, and temperature. The results indicate that the equilibrium reaches after 2 h of contact. The MO ADSORPTION followed the Langmuir-Freundlich and Baudu models with a maximum ADSORPTION capacity of 308 mg/g. The adsorbed capacity of the material is best at pH=3. The ADSORPTION capacity increases with temperature.  In addition, the Central Composite Design (CCD) in Response Surface Methodology (RSM) and Artificial Neural Network (ANN) were used to evaluate the simultaneous interactions of independent variables. The results suggest that the initial concentration was the dominant parameter in the ADSORPTION process. The monolayer model with two energies derived from statistical physics can be adapted to interpret the ADSORPTION data. Physical ADSORPTION forces were predicted to be responsible for the removal of the dye. This study provides new information on the ADSORPTION mechanisms of pollutants commonly found in water.