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Batch experiments were conducted to study the ability of activated palm kernel husk carbon (APKHC) to adsorb Pb(II) ions from aqueous solutions. The effects of various operational parameters, such as temperature (25–55°C), pH (1.0–5.0), contact time (0–120 min), and adsorbent dose (0.5–3.5 g/L) were examined. The results suggested that the adsorption of Pb(II) is exothermic and strongly dependent on pH. The optimum pH for Pb(II) removal is 5.0. The Pb(II) uptake by APKHC was fast and reached an equilibrium in 80 min. The Pb(II) removal efficiency increased with increasing APKHC dosage up to 2.0 g/L, and then reached a plateau with approximately 97% of Pb(II) removed. Experimental data were fitted using Langmuir and Freundlich isotherms. The Pb(II) adsorption can be described well by the Langmuir model with a maximum monolayer uptake capacity of 98.04 mg/g. Kinetic study results suggested that the adsorption process proceeded according to the pseudo-second-order kinetic model. In short, APKHC can be used as an effective economical adsorbent for Pb(II) removal. [ABSTRACT FROM PUBLISHER]

Coconut husk activated carbon (CHAC) was used as an adsorbent to remove hexavalent uranium (U(VI)) from aqueous solutions by adsorption. Batch experiments were conducted to investigate the effects of contact time, pH, initial U(VI) concentration, and adsorbent dosage on U(VI) adsorption. The adsorption process reached an equilibrium state after 150 min. The uptake of U(VI) was highly pH dependent, and the optimum adsorption was at near-neutral pH. High U(VI) removal efficiencies could be achieved by increasing CHAC dosages. The uranium adsorption capacity increased with increasing initial U(VI) concentrations. Above a certain point, any further increase in initial U(VI) concentration produced no significant change in uranium adsorption capacity. Langmuir and Freundlich models were employed to describe the adsorption isotherm of U(VI) by CHAC. The Langmuir model fitted the equilibrium data better than the Freundlich isotherm. The maximum U(VI) adsorption capacity of CHAC was 6.67 mg/g. Kinetics data were also examined in terms of adsorption kinetics using pseudo-first-order and pseudo-second-order kinetic models. The results suggested that the adsorption process followed the pseudo-second-order kinetics well. In summary, CHAC had significant potential for the removal of U(VI) from aqueous solutions. [ABSTRACT FROM AUTHOR]

In the title compound, [Ni(C14H8N2O5)(H2O)2] n, the NiII cation is six-coordinate with a slightly distorted octahedral coordination geometry and the 4-(isonicotinamido)phthalate ligand links the NiII centres into a three-dimensional structure with sra topology. The structure is also stabilized by N-H...O hydrogen bonding between the uncoordinated amide groups of the ligand and extensive O-H...O hydrogen bonding between the two coordinated water molecules. The magnetic and thermal stability properties of the title compound are also discussed. [ABSTRACT FROM AUTHOR]

In the title compound, {[Co(C14H8N2O5)(C10H8N2)]·3H2O} n, the CoII cation is five-coordinated with a slightly distorted trigonal-bipyramidal geometry, and the 5-isonicotinamidoisophthalate ligands link CoII atoms into a layered structure. These two-dimensional arrays are further pillared by rod-like 4,4′-bipyridine ligands to give a three-dimensional framework with pcu (primitive cubic) topology. The magnetic and adsorption properties of the title compound are also discussed. [ABSTRACT FROM AUTHOR]