The D2 adsorption and desorption kinetics on porous carbon materials are significantly faster (up to a factor of 1.9) than the corresponding H2 kinetics for specific pressure increments/decrements. This represents the first experimental observation of kinetic isotope quantum molecular sieving in porous materials due to the larger zero-point energy for the lighter H 2 , resulting in slower adsorption/desorption kinetics compared with the heavier D2. -(ZHAO, X.; VILLAR-RODIL, S.; FLETCHER, A. J.; THOMAS*, K. M.; J. Phys. Chem. B 110 (2006) 20, 9947-9955; Sch. Nat. Sci., Univ. Newcastle, Newcastle upon Tyne NE1 7RU, UK; Eng.) -W. Pewestorf 35-021
Calligonum crinitum, a desert plant, was used as a natural adsorbent for the removal of Pb(II) ions 10 from aqueous solutions. The sorption capacity of the sorbent was investigated through batch 11 adsorption,as a function of contact time, metal ion concentration, and pH. The surface chemistry of 12 the sorbent was probed using Fourier transform infrared spectroscopy, allowing an understanding of 13 been proven as an effective sorbent for the removal of Pb(II) ions from aqueous solutions, with 1 potential in water remediation processes.
Native Scottish wood samples were investigated as potential, locally sourced, raw materials for biochar production. Screening experiments identified pure softwood as the preferable feedstock. Influence of operational parameters, i.e. activating gas flow rate (CO2), heating ramp rate and contact time on final biochar characteristics, was investigated using design of experiments. Surface area and biochar yield were selected as response variables. Minitab was used to define experimental run conditions and suggested an optimal output at 60 min contact time and 15 °C/min ramp rate for maximum responses. The highest surface area (764 m2/g) was achieved at 850 °C from softwood, albeit with a low yield of 15%. Under optimised conditions, the observed surface area was 613 m2/g with ~ 18% yield. Pareto charts suggested no influence of gas flow rate on chosen responses, which correlated well with experimental data. Pore structure was a combination of micro- and mesopores with average pore widths of 3–5 nm and an average point of zero charge of 7.40 ± 0.02. Proximate analysis showed an increase in fixed carbon content from 20%, in the feedstock, to 80%, in the optimised biochar. Morphological analysis showed a layered carbon structure in the biochars. The results show the significance of the selected feedstock as a potential source of biochar material and the relevance of interplay of operational variables in biochar development and their final characteristics.
Despite their extensive and decade long application in wastewater treatment, activated carbon remains one of the most viable adsorbents, with substantive practical application, due to their high pollutant binding capacity. In this study, commercially available activated charcoal was applied in the uptake of aqueous cadmium [Cd(II)] ion. The effect of some process variables on the Cd (II) uptake was investigated via batch mode. Furthermore, the adsorbents' surface charge (pHPZC), surface morphology (using SEM) and available surface functional groups (using FTIR) were explained. The pH dependence of the present adsorption system was revealed, with the optimum pH was recorded at pH 5.0. Similarly, the Cd (II) uptake (mg/g) decreased with increasing adsorbent dosage due to possible active sites clogging, overcrowding and interference Furthermore, the isothermal and kinetics analyses of the experimental data, that were aptly validated using the hybrid error model, respectively depicted the Langmuir isotherm and pseudosecond-order kinetic model as the best fit. A Langmuir adsorption capacity of 682.5 mg g -1 was also recorded in the study. Consequently, the present adsorption system was characterized by an equilibrium timeframe of industrial practicability, hence the adsorbent was successfully applied for the aqueous Cd (II) uptake.
Three new ligands containing a bicyclo[2.2.2]oct‐7‐ene‐2,3,5,6‐tetracarboxydiimide unit have been used to assemble lantern‐type metal‐organic cages with the general formula [Cu4L4]. Functionalisation of the backbone of the ligands leads to distinct crystal packing motifs between the three cages, as observed with single‐crystal X‐ray diffraction. The three cages vary in their gas sorption behaviour, and the capacity of the materials for CO2 is found to depend on the activation conditions: softer activation conditions lead to superior uptake, and one of the cages displays the highest BET surface area found for lantern‐type cages so far.
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