Papers by Keyword: Adsorption Equilibrium

Abstract: The relative adsorption coefficient, a novel parameter was introduced to describe the dominant adsorption ability of ions in cation membrane for all vanadium redox flow battery instead of traditional selectivity coefficient. The parameter as a function of membrane property and vanadium ions in membrane was derived from the relative potential differences in membrane between an isothermal adsorption and an ideal equivalent adsorption. The adsorption isotherms of three kinds of commercial membranes were measured for VO²⁺/H⁺ electrolyte system. The results show the reasonable rules that the relative adsorption coefficients increase as the VO²⁺ contents are increased whereas decrease as the H⁺ contents are increased in electrolyte.

Abstract: A novel Al–Si–Fe–Ca composite material for phosphate removal in wastewater treatment was made by using Al (OH)₃,Fe₂O₃,CaO and silica powder as raw materials. Sorption data modelling with a pH range of 3–12, P concentrations of 3,5,7,9, 11,13, 15mg L⁻¹, and an ambient temperature of 23°C indicated that an optimal removal of P occurred at pH 6.0. A maximum removal of 99.68% was found for 11mg L⁻¹ (pH of 6). Langmuir isotherm best described theadsorption processwith a maximumadsorption capacity of 8.60mg g⁻¹. Three kinetic models (apseudo-first-order, a pseudo-second-order (PSO) and Elovich) were also applied,and the results showed that the PSOmodel best described the data. SEM and EDAX analysis confirmed that P was adsorbed to the surface of the composite material. This study demonstrates that the composite adsorbent is suitable for use in wastewater treatment, with P removal of the solids being preferential and spontaneous.

Abstract: The adsorption behavior of Reactive Blue (RB2) dye from aqueous solution on chitosan/diatomite biocomposite adsorbent was studied. The effects of biocomposite adsorbent ratio and pH on removal of RB2 were examined, and optimum experimental conditions were identified. Biocomposite adsorbent had the largest adsorption efficiency when the ratio was 10 wt%. The maximum percentage removal of RB2 was 96.36% which obtained at pH 4.0. Adsorption equilibrium showed adsorption amount of RB2 improved with increase in the amount of NaCl, indicating that the addition of inorganic salt was an advantage of the removal of RB2.

Abstract: Adsorption isotherms are often required for understanding mobility, fate and bioavailability of contaminants in soils. Those about Pb (II) and Cd (II) on Andosols and Kanto loam were investigated in this work. Results show that adsorption increased with cation equilibrium concentration (10^-4 - 1 meq L^-1) and solution pH (5 - 7), and also that most adsorption isotherms can be simulated precisely with the ion-exchange-based Urano model. The applicability of model in predicting adsorption equilibriums of cations on soils in circumneutral aqueous solution (pH 5 - 7) were experimentally confirmed. There is an exception as to the Pb (II) adsorption on Andosols with the solid-to-liquid phase ratio higher than 1:100, there adsorption isotherms at pH 5 and pH 7 crossed, and the measurement precision decreased. The Urano model equation becomes inapplicable. Further experiment where humus substances (HS) were added indicated that the abnormal phenomenon can be attributed to dissolved HS and their complexation with Pb (II). The dissolution of HS with solution pH has enhanced Pb (II) concentration in solution but hardly reduced the total amount of adsorption on soil.

Abstract: This study evaluated the performance of a photoreactor packed with TiO2/Quartz and ZrO2/Quartz, ZnO/Quartz, initiated by UV irradiation. The experimental results showed that the concentration of VOCs increased and the degration efficiency decreased at the same residence time. Additionally, as the residence time increased, degration efficiency increased. According to the Langmuir-Hinshelwood Model’s predicted results, the reaction rate constant (kc) was 50.1, 7.2, and 3.0 ppm min-1 for TiO2/Quartz, ZrO2/Quartz and ZnO/Quartz, respectively. In contrast, the adsorption equilibrium constant (K) was 10.0, 21.9, and 2.4 ppm-1 with the previous catalyst, individually.