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SBA‐15/polypyrrole composite was synthesized by polymerizing pyrrole in the presence of SBA‐15. The samples were characterized using the following techniques: low‐angle XRD, wide‐angle XRD, FTIR, FESEM, TGA, HRTEM, and BET. From the low‐angle XRD analysis, it confirms the formation of a mesoporous hexagonal structure (p6 mm). From the HRTEM image, an orderly arrangement of mesopores is evident. Using adsorption techniques, our objective is to remove sunset yellow, indigo carmine, titan yellow, and orange G dye from aqueous solutions with SBA‐15/polypyrrole composite. The removal efficiency for all the dyes was greater than 90 %. The isotherm was verified to follow the Langmuir isotherm model. The maximum adsorption capacities for sunset yellow, indigo carmine, titan yellow, and Orange G were found to be 78.74 mg/g, 83.33 mg/g, 78.74 mg/g, and 106.38 mg/g, respectively. The adsorption kinetics followed a pseudo‐second‐order model, and the R2 value was greater than 0.99 for all the dyes. The thermodynamic parameters of ΔG°, ΔS°, and ΔH° showed negative values, indicating that the adsorption was spontaneous, decreased entropy, and was exothermic. The recycling of the SBA‐15/polypyrrole composite resulted in a 90 % removal efficiency for three cycles. Therefore, the present adsorbent could be applied to treat industrial effluents that contain these dyes. [ABSTRACT FROM AUTHOR]

Adsorption and photocatalytic decomposition of anionic and cationic surfactants are presented. Two different types of photocatalysts were studied, commercial TiO2‐P25 (Evonik) with pHpzc = 5.65 and nitrogen‐modified TiO2/N pHpzc = 6.7 (point of zero charge). Two different types of surfactants were used: anionic surfactant NaDBS (sodium dodecylbenzene sulfonate) and cationic surfactant BtCl (benzethonium chloride). Obtained adsorption isotherms of NaDBS and BtCl comply with the conditions of monolayer Langmuir model isotherms. The maximal anionic surfactant adsorption took place at acidic pH and it was higher for TiO2/N (196 mg g−1) than for commercial TiO2‐P25 (140 mg g−1). There was the opposite situation in the case of cationic surfactants, higher adsorption took place at alkaline condition and it was higher for TiO2/N (100 mg g−1) than for commercial TiO2‐P25 (85 mg g−1). Photocatalytic degradation has been found to be more effective in neutral and high than in low pH solutions for both surfactants. It is mainly the difference between charges of the surface of photocatalysts and ionic parts of individual surfactants that determined the effectiveness for each of them. [ABSTRACT FROM AUTHOR]

Adsorption and photocatalytic decomposition of anionic and cationic surfactants are presented. Two different types of photocatalysts were studied, commercial TiO2‐P25 (Evonik) with pHpzc = 5.65 and nitrogen‐modified TiO2/N pHpzc = 6.7 (point of zero charge). Two different types of surfactants were used: anionic surfactant NaDBS (sodium dodecylbenzene sulfonate) and cationic surfactant BtCl (benzethonium chloride). Obtained adsorption isotherms of NaDBS and BtCl comply with the conditions of monolayer Langmuir model isotherms. The maximal anionic surfactant adsorption took place at acidic pH and it was higher for TiO2/N (196 mg g−1) than for commercial TiO2‐P25 (140 mg g−1). There was the opposite situation in the case of cationic surfactants, higher adsorption took place at alkaline condition and it was higher for TiO2/N (100 mg g−1) than for commercial TiO2‐P25 (85 mg g−1). Photocatalytic degradation has been found to be more effective in neutral and high than in low pH solutions for both surfactants. It is mainly the difference between charges of the surface of photocatalysts and ionic parts of individual surfactants that determined the effectiveness for each of them. [ABSTRACT FROM AUTHOR]

In this study, a natural loess soil was evaluated as an adsorbent of Li+ in seawater. Only Li+ was adsorbed preferentially by loess over other cations in seawater despite having the lowest concentration. The adsorption studies of Li+ with loess were assessed using the batch equilibration method. In batch adsorption experiment, the various factors such as agitation time, initial concentration, and amount of dose were investigated. Adsorption isotherm and kinetic studies were performed to quantify the adsorption capacity and adsorption rate of Li+ by loess from seawater. The equilibrium data of adsorption were fitted by using the Freundlich and Langmuir isotherm models. It was seen that the Langmuir isotherm is better in describing the adsorption process of Li+ by loess due to its higher correlation coefficient R2 value. The maximum adsorption capacity of loess for Li+ obtained by Langmuir isotherm was 0.193 mg/g. The pseudo-first-order, the pseudo-second-order, and the intra-particle diffusion kinetic models were employed to analyze the time-dependent adsorption rate of Li+. It was found that the adsorption of Li+ closely follows the pseudo-second-order kinetic model, from which a very accurate estimation of the equilibrium adsorption capacity ( qe,cal) was achieved, as well as the higher R2. Because of its low-cost and high selectivity towards Li+, loess could be probably an applicable adsorbent for the recovery of Li+ from seawater. [ABSTRACT FROM AUTHOR]