Papers by Keyword: Kinetic Studies

Abstract: Chitosan and clay materials of 50:50 ratio, produced and characterized from periwinkle shells and clay soil, was applied to capture CO₂ from gas mixture at elevated temperatures (50^OC to 250^OC) in a column bed, packed with the particles of dimension length 1.5 (m), and inner diameter 0.02 (m). The composition of gas mixture are 0.003, 0.002, 0.05, 0.15, 0.02, and 0.76 for CH_4, C₂H_6, H_2, CO_2, H₂O vapour, and N_2, respectively at condition of pressure 49 (kPa), temperature 250^OC, and flow rate 75 (L/min) from exhaust column into the column bed for adsorption process. The kinetic and isotherm models are adopted and simulations performed from the experimental data to determine suitable adsorption parameters for the process. Also, Aspen plus and statistical optimization tool to simulate the experimental data are utilized to determine the optimal yield and conditions of factors. The coefficient of determination of 0.992 showed that the quadratic model is best suitable for the combination of parameters and fitted well, while the optimization result gave significant difference among the bed height, temperature and time and their interactions. The result revealed that the adsorption process best followed Elovich kinetic and fitted well in the Freundlich multilayer adsorption isotherm with parameters 0.0187 (mg/g.hr), 175.932, and 1.5 for the kinetic constant, adsorption constant, and intensity respectively. The root means square errors and deviation values gave negligible values of 0.166; 0.045, and 0.0345; 0.0094 for the design/simulation; optimization models applied, when compared to the experimental data. The regression results of the factors analysis showed that the model R² of 0.995 is more reliable and fitted well than the modified R² of 0.985 and the estimated R² of 0.965. The central composite design for the optimization of the process gave maximum yield of 0.9411 at suitable combine time and temperature factors effect. Aspen plus simulation result gave yield of 0.9831 CO₂ removed from optimal conditions of time, temperature, and bed height of 2.8 (hrs), 155.6°C, and 3.44 (cm) respectively. It was noticed that N₂, CH₄, C₂H₆, and water vapour were removed from the gas mixture of yields 0.9972, 0.9832, 0.9831, and 0.9947 respectively.

Abstract: In this study, sorption efficiency of coated (C-) and uncoated (U-) zinc oxide nanoparticles (ZnO-NPs) in aqueous solution onto raw sago hampas (RSH) and acetylated sago hampas (ACSH) was studied. Physical and chemical characteristics of both the sorbate and sorbents were analysed using various characterization techniques. The mechanism of the sorption process was evaluated using equilibrium isotherms, kinetic and thermodynamic studies. From the study, maximum percentage removal of both sorbate ions were achieved at an equilibration time of 100 minutes with an optimum sorbate mass of 2.0 g per 50 ml. The study recorded a maximum % removal of 85.1% & 87.6% for C-and U-ZnO-NPs (< 50 nm) onto RSH and 90.0% & 91.1% onto ACSH. Langmuir isotherm fitted well for the sorption process with the highest efficiency of 0.793 mg/g recorded for C-ZnO-NPs onto RSH. Pseudo-second model best described the sorption process. An exothermic and non-spontaneous sorption process was realised in all the sorption studies except that of U-ZnO-NPs (< 50 nm) onto ACSH which became spontaneous as temperature increased. Based on the findings from the multiple approaches employed, both sorbents could be proposed as viable alternatives to act as a green sorbent in the removal of ZnO-NPs from water and wastewater.

Abstract: This In this study, the Ca-Al layered double hydroxide was used as a potential adsorbent for the removal of Congo red from aqueous solutions. The effects of Initial concentration and contact time on the adsorption properties of Congo red by Ca-Al LDHs were studied. The removal rate of Conge red reached to 59.416 mg/g under room temperature with 0.2g of adsorbent, initial concentration of 50 ppm, adsorption time of 210 min, shaking speed of 90r/min. The experimental equilibrium data for the removal of Congo red were evaluated by various isotherm models. The pseudo-second-order kinetic models were found to fit the adsorption kinetics, and the equilibrium data were appropriately fitted to Langmuir and Freundlich model adsorption isotherm.

Abstract: Concern about environmental protection has increased over the years and the presence of volatile organic compounds (VOCs) in water poses a threat to the environment. In this study, coconut shell activated carbon (PHAC) was produced by potassium hydroxide activation via microwave for benzene and toluene removal. Equilibrium data were fitted to Langmuir, Freundlich and Tempkin isotherms with all the models having R² > 0.94. The equilibrium data were best fitted by Langmuir isotherm, with maximum adsorption capacity of 212 and 238mg/g for benzene and toluene, respectively. The equilibrium parameter (R_L) falls between 0 and 1 confirming the favourability of the Langmuir model. Pseudo-second-order kinetic model best fitted the kinetic data. The PHAC produced can be used to remediate water polluted by VOCs.