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The bentonite derived from Huangshan County was used as adsorbent for the adsorption of uranium (U(VI)). The effect of environmental factors, such as contact time, pH, ionic strength, HA and reaction temperature, on U(VI) adsorption on bentonite surface was investigated in detail. The adsorption capability of bentonite for U(VI) is obviously rest with pH value and ionic strength. The presence of HA in solution strongly enhance and reduce the adsorption of U(VI) on bentonite at low and high pH, respectively. The Langmuir and Freundlich models were applied to simulate the adsorption isotherms of U(VI) at three different temperatures of 298 ± 1, 318 ± 1 and 338 ± 1 K, respectively. The thermodynamic parameters (ΔH 0 , ΔG 0 and ΔS 0 ) calculated from the temperature-dependence adsorption isotherms indicates that U(VI) adsorption on bentonite is an endothermic and spontaneous process. At pH < 7, the adsorption of U(VI) was dominated by the outer-sphere surface complexation and ion exchange with H + /Na + on bentonite surfaces; At pH > 7, the inner-sphere surface complexation was the main adsorption mechanism. Based on the experimental analysis results, bentonite is an appropriate material for the enrichment and solidification of U(VI) ions. The results are important for the radioactive waste management. [ABSTRACT FROM AUTHOR]

Different types of acid pretreatment are known to influence the removal of certain components from pine wood sawdust, due to differences in the acid hydrolysis, which also predetermine the final formation and adsorptive properties of the produced activated carbon (AC) through subsequent potassium hydroxide activation. AC made by using phosphorous acid as an acid pretreatment had the largest absorption capacity of methylene blue (MB) dye due to its highest acidity. Subsequently, the effects on the adsorption variables for this AC such as initial pH, MB concentration, contact time and temperature were investigated. The resulting adsorption process was classified as pseudo-second-order kinetic model, and the Langmuir isotherm model better described the equilibrium data in comparison with the Freundlich isotherm model. The outcome showed that a lower temperature had an increased adsorption capacity of sawdust-derived AC pretreated with phosphorous acid, which allowed maximum adsorption capacities of 303.03 mg/g at 30 °C, implying that the adsorption was an endothermic process. Phosphorous acid pretreatment and activation processes proved to be an effective strategy to prepare highly porous AC from sawdust, with high potential to cationic dye removal from liquid phases. [ABSTRACT FROM AUTHOR]

Research on low-polluting, economical, and reliable antibiotic adsorption materials is of great significance for reducing pollution in the pharmaceutical and aquaculture industries. Herein, N, P co-doped carbon material (PCC500) with a high specific surface area of 1400 m2/g and a high mesoporous ratio of 89.9% were prepared from cabbage waste by H 3 PO 4 hydrothermal combined with activation. PCC500 showed good adsorption performance for various antibiotics, including chloramphenicol (CHL), tetracycline (TC), ofloxacin (OFX) and erythromycin (ERY). 99% removal efficiency and 247 mg/g adsorption capacity of TC on PCC500 were obtained at 298 K (C 0 = 50 mg/L), and 471 mg/g of the maximum adsorption capacity of was achieved at 318 K. The adsorption kinetics and thermodynamic analysis indicated that there was chemisorption during the adsorption process. A series of characterizations including SEM, EDS, N 2 adsorption and desorption, FTIR, XPS showed that the abundant pore structure and P, N functional groups are important factors affecting the adsorption performance, and the graphite-N and C3-PO structures in PCC500 could be the important active sites responsible for antibiotic chemisorption. Moreover, PCC500 exhibits good resistance to impurity ions and cyclic stability. [Display omitted] • N, P co-doped mesoporous carbon was prepared from Cabbage waste by a simple method. • A high mesoporous ratio of 89.87% and a large SSA of 1400 m2/g were obtained. • PCC500 showed good adsorption performance for four antibiotics. • The chemisorption sites for antibiotics adsorption were revealed. [ABSTRACT FROM AUTHOR]