Diffusion-Driven discrepancies in LBM adsorption modeling: A comparative study of active and passive scalar approaches for adsorption processes

Addressing mathematical discrepancies in the adsorption model of Hashem et al. (2024): A technical commentary

Adsorption models and heat of adsorption of adsorbed ortho di-methyl benzene species on silica by using Temperature Programmed Adsorption Equilibrium methods

In recent years, there has been an increasing interest in finding innovative solutions for the efficient removal of contaminants from water, soil, and air. The present study reviews the adsorptive removal of catechol (C), resorcinol (R), hydroquinone (HQ), and their derivatives from various adsorbents. As an effective, efficient, and economic approach for water purification, adsorbents and adsorption processes have been widely studied and applied in different aspects for a long time. The role of various adsorbent materials like activated carbon, activated carbon cloth, carbon nanotubes, polymeric resins, organic clays, Fe(OH)2, and TiO2 was discussed together with that of other experimental parameters. In all the synthetic resins, particularly, aminated hypercrosslinked polymers have good adsorption capability for phenols. These polymeric adsorbents are suitable for industrial effluents containing C, R, HQ, and their derivatives. The adsorption capacities of the adsorbents reviewed here vary significantly depending on the characteristics of the individual adsorbent, the extent of chemical modifications, and the concentrations of solutes.

The model and mechanism of adsorptive technologies for wastewater containing fluoride: A review

Investigation of vapor condensation on a flat plate and horizontal cryogenic tube using lattice Boltzmann method

The law of specific surface energy variation during the adsorption process is an important basis for studying the mechanisms of coal gas adsorption. Based on the theory of adsorption energy, eight coal samples with different ranks were analyzed using an isothermal adsorption experiment at three different temperatures (30, 40, and 50 °C) and six different pressures (0.1, 0.2, 0.6, 1.0, 1.4, and 1.8 MPa). Then, the single-layer adsorption model and multilayer adsorption model were used to calculate the energy variation during the adsorption process. Just like the adsorption capacity, it is clear that the specific surface energy is inversely proportional to temperature and proportional to gas pressure. The energy difference between the single-layer adsorption and the multilayer adsorption calculation is large. Therefore, the adsorption energy was calculated based on the calorific value, and the comparative analysis shows that the specific surface energy based on the multilayer adsorption model can better reflect the gas adsorption capacity than the single-layer adsorption model. The mechanisms of gas adsorption were explored, such as intermolecular force, energy variation, and specific surface area. The adsorption energy was simulated, which indicated that the energy variation is affected by both coal physical properties and internal chemical structure.

To realize the effective utilization of reed for adsorption of methylene blue (MB), modified reed activated carbon (M-RAC) was prepared using reed as raw material and MgCl<sub>2</sub> and FeCl<sub>3</sub> as activators. The four parameters of M-RAC dosage, MB concentration, adsorption time, and oscillation velocity during the adsorption process were optimized by the response surface methodology (RSM). The adsorption performance of M-RAC on MB under the optimal process was determined and analyzed by three different adsorption models. The results showed that the adsorption capacity of M-RAC on MB was 436.33 mg/g when the M-RAC dosage was 0.17 g, the MB concentration was 550 mg/L, the adsorption time was 105 min, and the oscillation velocity was 154 r/min. The experimental data were consistent with the Langmuir model and Pseudo-secondorder kinetics, which indicated that the adsorption process was a monolayer chemical adsorption process. The thermodynamic study confirmed that the increase in temperature favored the adsorption of M-RAC on MB, and the adsorption process was a spontaneous and heat-absorbing reaction. The analysis of the Fourier transform infrared (FTIR) spectroscopy showed that the absorption peaks of hydroxyl functional groups in the prepared M-RAC were higher, and the C-O characteristic peaks were enhanced. The results suggest that M-RAC is a potential biochar adsorbent for effectively removing MB dye from wastewater.

Development of a schiff base-chitosan-vanillin/hydroxyapatite composite for effective brilliant green dye removal: Characterization, adsorption modeling, and cost analysis.

Standard purification systems have mainly demonstrated the inefficient removal of neonicotinoid insecticides with high persistence in the environment. In the present work, a new magnetic adsorbent composed of Fe3O4 and CuO nanoparticles impregnated with activated carbon (AC) has been used to remove imidacloprid (IMCP) as the most common neonicotinoid insecticide from the water solutions. Various techniques such as Fourier Transform infrared spectroscopy, x-ray diffraction, field emission scanning electron microscopy, energy-dispersive x-ray diffraction, and vibrating sample magnetometer were employed to characterise the fabricated composite. The main affecting parameters, including adsorbent amount, solution pH, agitating time, initial pesticide concentration, and temperature, were examined to obtain the optimised conditions. According to the obtained results from kinetic and isotherm modelling, the adsorption mechanism of IMCP on Fe3O4/CuO@AC nanocomposite (NC) is a combination of chemisorption and physisorption phenomena. The presence of heterogeneous sites for IMCP adsorption was shown by fitting the experimental data to the Freundlich isotherm model. In addition, the adsorption process was well consistent with the pseudo-second-order kinetic model, which indicates that chemisorption is the determining step in the adsorption process. Thermodynamic data showed the exothermic and spontaneous nature of the adsorption process. Under optimal conditions (initial concentration of pesticide 10 mg L−1, pH = 7, and contact time of 10 min), 99.6% of IMCP was effectively removed, indicating the excellent ability of the adsorbent to adsorb this insecticide from aqueous solutions.

Adsorption of Ni(II) on spent coffee and coffee husk based activated carbon

Equilibrium, kinetic and thermodynamic study of diazinon adsorption from water by clay/GO/Fe3O4: Modeling and optimization based on response surface methodology and artificial neural network

Comparative evaluation of BiOCl–NPls–AC composite performance for methylene blue dye removal from solution in the presence/absence of UV irradiation: Kinetic and isotherm studies

Cs and Cs-O co-adsorption on Zn-doped GaAs nanowire surfaces: A first-principles calculations

In this study, to remove Cr(VI) from the solution environment by adsorption, the almond shell was pyrolyzed at 400 and 500 °C and turned into biochar (ASC400 and ASC500) and composite adsorbents were obtained by coating these biochars with chitosan (Ch-ASC400 and Ch-ASC500). The resulting biochars and composite adsorbents were characterized using Fourier transform infrared (FTIR) spectroscopy; Brunauer, Emmett, and Teller (BET) surface area; scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX); and the point of zero charge pH (pHpzc) analyses. The parameters affecting the adsorption were examined with batch adsorption experiments and the optimum parameters for the efficient adsorption of Cr(VI) in 55 mg L−1 solution were determined as follows; adsorbent dosages: 5 g L−1 for biochars, 1.5 g L−1 for composite adsorbents, contact time: 120 min, pH: 1.5. It was seen that the temperature did not affect the adsorption much. Under optimum conditions, Cr(VI) adsorption capacities of ASC400, ASC500, Ch-ASC400, and Ch-ASC500 adsorbents are 11.33, 11.58, 37.48, and 36.65 mg g−1, respectively, and their adsorption percentages are 95.2%, 97.5%, 94.3%, and 94.0%, respectively. Adsorption data were applied to Langmuir, Freundlich, Scatchard, Dubinin-Radushkevic, and Temkin isotherms and pseudo-first-order kinetic model, pseudo-second-order kinetic model, intra-particle diffusion model, and film diffusion model. The adsorption data fitted well to the Langmuir isotherm and pseudo-second-order kinetic models. From these results, it was determined that chemical adsorption is the dominant mechanism. Also, both intra-particle diffusion and film diffusion is effective in the adsorption rate. For all adsorbents, the Langmuir isotherm proved to be the most appropriate model for adsorption. The maximum monolayer adsorption capacities calculated from this model are 24.15 mg g−1, 27.38 mg g−1, 54.95 mg g−1, and 87.86 mg g−1 for ASC400, ASC500, Ch-ASC400, and Ch-ASC500, respectively. The enthalpy change, entropy change, and free energy changes during the adsorption process were calculated and the adsorption was also examined thermodynamically. As a result, adsorption occurs spontaneously for all adsorbents.

The prospective of maize cob powder (MCP) as an effective adsorbent for the removal of malachite green (MG) and congo red (CR) dyes from aqueous solution was investigated. The presence of functional groups and pores on maize cob powder were confirmed by FTIR and SEM analysis. Batch adsorption studies were conducted and various parameters such as contact time, adsorbent dosage, initial dye concentration, pH and temperature were examined to observe their effects in the dyes adsorption process. The optimum conditions for the adsorption of MG and CR onto the adsorbent (MCP) was found to be: contact time (60mins), pH (10.0) and temperature (303 K), adsorbent dose (1 g) for an initial MG dye concentration of 50 mg/L and contact time (80mins), pH (2.0) and temperature (343 K) for an initial CR dye concentration of 50 mg/L and adsorbent dose 1.0 g respectively. The experimental equilibrium adsorption data fitted best and well to the Freundlich isotherm model for CR dye adsorption and Langmuir Isotherm for MG adsorption. The maximum adsorption capacity was found to be 13.02 mg/g and 9.41 mg/g for the adsorption of MG and CR dyes respectively. The kinetic data conformed to the pseudo-second-order kinetic model. Thermodynamic quantities such as Gibbs free energy (ΔG0), enthalpy (ΔH0) and entropy (ΔS0) were evaluated and the negative values of ΔG0, ΔH0 and ΔS0 obtained indicated the spontaneous and exothermic nature of the MG adsorption process while positive enthalpy (ΔH0) indicated an endothermic nature of CR adsorption process.