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Abstract: Hemp (Cannabis sativa L.) bast was used to prepare activated carbon fibers by phosphoric acid activation at 400–600°C. The pyrolysis process, textural and chemical properties for the samples were investigated by means of TG/DTA, SEM, cryogenic N2 adsorption, FTIR and XPS. Dye adsorption on the resultant sample was also measured. The textural properties of the activated carbon fibers were found to be strongly dependent on the activation temperature. Activated carbon fibers exhibited narrow pore size distributions with maxima in the micropore and small mesopore regions. BET surface area, total pore volume, micropore volume and mesopore volume increased with the increase of activation temperature up to 450°C and then decreased with further heating, and a sample with maximum surface area of 1142m2 g−1 and total pore volume of 0.67cm3 g−1 was obtained. Phosphoric acid facilitated the conservation of porous structure, led to the creation of tremendous porosity, and resulted in various P-containing functional structures on the surface and in the bulk phase of the resultant samples. The adsorption of acid blue 9 on the sample could be favorably described by Langmuir isotherm, and the adsorption kinetics was found to be well fitted by the intraparticle diffusion model. [ABSTRACT FROM AUTHOR]

Abstract: Water pollution caused by ammonia nitrogen has attracted a great attention as its toxicity affects both the environment and human health. The objective of this paper was to investigate the adsorption behavior of NH4 +-N from aqueous solution by activated carbons prepared from rice husk. The physico-chemical properties of the activated carbon were characterized by Brunauer-Emmett-Teller (BET) test, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). It was found that the NH4 +-N adsorption on the rice husk derived carbons was dependent on adsorbent dosage and solution pH. The adsorption kinetics and isotherms of NH4 +-N by rice husk carbon were also investigated, and good correlation coefficients were obtained for the pseudo-second order kinetic equation. Dubinin-Radushkevitch (D-R) adsorption isotherm model could better describe the adsorption behavior of NH4 +-N on the rice husk carbon. Calculated by D-R model, the adsorption course of NH4 +-N on the rice husk carbon was favored chemical ion-exchange mechanism. Moreover, the activated carbon adsorbed NH4 +-N was highly fertilizer conservation especially for the nitrogen element. It was proposed that the amount of removed NH4 +-N from aqueous solutions would increase evidently treated by rice husk carbon if combined with biological method. [Copyright &y& Elsevier]

[Display omitted] • A functionalized material (CTAB-Pd/GAC) was synthesized as the catalyst. • CTAB could reduce the consumption of Pd for the catalyst. • Adsorption performance of catalyst was controlled by the amount of CTAB load. • Selective adsorption performance of the catalysts to 2,4-DCBA was enhanced. • The adsorption-desorption for 2,4-DCBA and BA was a dynamic process. The CTAB-Pd/GAC catalyst was obtained by functionalizing palladium/granular activated carbon (Pd/GAC) with cetyltrimethylammonium bromide (CTAB), which was used for the electrocatalytic reductive dechlorination of 2,4-dichlorobenzoic acid (2,4-DCBA). The degradation rate of 2,4-DCBA by 40 mg g−1 CTAB-Pd/GAC was 9.8 × 10−3 (min−1 g−1 Pd), which was 11 folds than that by Pd/GAC (0.9 × 10−3 min−1 g−1 Pd), and the value of q e, 2,4-DCBA / q e, BA was 2.33 as compared to 0.67 for Pd/GAC. The combined result of dechlorination and adsorption experiments suggested that the functionalization by CTAB would enhance the 2,4-DCBA concentration on the surface of CTAB-Pd/GAC, and accelerate the degradation rate. However, the removal efficiency of 2,4-DCBA would decrease when the CTAB load reached 80 mg g−1, due to the excessive adsorption capacity for dechlorinated product. Density functional theory (DFT) calculations also proved that CTAB would increase adsorption capacity of catalyst and selective adsorption behavior of 2,4-DCBA, which accelerated the degradation rate of 2,4-DCBA. [ABSTRACT FROM AUTHOR]