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Abstract: Adsorption of ammonia (NH3) onto activated carbons prepared from palm shells impregnated with sulfuric acid (H2SO4) was investigated. The effects of activation temperature and acid concentration on pore surface area development were studied. The relatively large micropore surface areas of the palm-shell activated carbons prepared by H2SO4 activation suggest their potential applications in gas adsorption. Adsorption experiments at a fixed temperature showed that the amounts of NH3 adsorbed onto the chemically activated carbons, unlike those prepared by CO2 thermal activation, were not solely dependent on the specific pore surface areas of the adsorbents. Further adsorption tests for a wide range of temperatures suggested combined physisorption and chemisorption of NH3. Desorption tests at the same temperature as adsorption and at an elevated temperature were carried out to confirm the occurrence of chemisorption due to the interaction between NH3 and some oxygen functional groups via hydrogen bonding. The surface functional groups on the adsorbent surface were detected by Fourier transform infrared spectroscopy. The amounts of NH3 adsorbed by chemisorption were correlated with the contents of elemental oxygen present in the adsorbents. Mechanisms for chemical activation and adsorption processes are proposed based on the observed phenomena. [Copyright &y& Elsevier]

Two Co(II)-based coordination polymers: [Co 2 (L) 2 (bib) 2 ] n (1) and {[Co 2 (L) 2 (bimb) 2 ]·2H 2 O·DMA)} n (DMA = N,N-dimethylacetamide) (2) using 4,4′-bis(thiomethylene) dibenzoic acid (H 2 L) as the first ligand, 1,4-bis(imidazol)-butane (bib) and 1,4-bis(imidazol-1-ylmethyl)benzene) (bimb) as the second ligands, were synthesized under the condition of solvothermal and characterized by X-ray single-crystal diffraction, elemental analysis, IR spectra and thermogravimetric analysis (TGA). X-ray single-crystal diffraction analysis exhibits that 1 and 2 belong to the triclinic crystal system, space group P -1. The central Co(II) ions exhibit a regular spatial tetrahedral structure which are coordinated by two O atoms from two L2− ligands and two N atoms from two N-donor ligands. Furthermore, the photocatalytic degradation properties and mechanism of 1 and 2 for methylene blue (MB) were investigated. The results show that the band gap (E g) of 1 and 2 is 3.78 eV and 3.82 eV, and the equipotential point (pH pzc) of 1 is 4.25. Both 1 and 2 show excellent photocatalytic degradation for MB. •OH is the main active substance causing MB degradation. The photocatalytic degradation for MB of 1 and 2 is in line with the first order kinetics equation. The pH pzc of complex 1 is 4.25. When pH < 4.25, 1 has a positive charge on the surface, and will generate electrostatic repulsion with MBH2+, inhibiting the adsorption of 1 to MB, so the degradation rate of MB is greatly reduced. When pH > 4.25, complex 1 has a negative charge on the surface and generates electrostatic attraction with MBH2+, which promotes the adsorption of 1 to MB, so the degradation rate of MB is greatly increased. Image 1 [ABSTRACT FROM AUTHOR]