A review on the utilization of fly ash

The kinetics of sorption from a solution onto an adsorbent has been explored theoretically. The general analytical solution was obtained for two cases. It has been shown that at high initial concentration of solute (sorbate) the general equation converts to a pseudo-first-order model and at lower initial concentration of solute it converts to a pseudo-second-order model. In other words, the sorption process obeys pseudo-first-order kinetics at high initial concentration of solute, while it obeys pseudo-second-order kinetics model at lower initial concentration of solute. The theoretical results (derived equations) show that the observed rate constants of pseudo-first-order and pseudo-second-order models are combinations of adsorption and desorption rate constants and also initial concentration of solute. The obtained theoretical equations are used to correlate experimental data for sorption kinetics of some solutes on various sorbents. The predictions of the theory are in excellent agreement with the experimental data.

Kinetic models of sorption: a theoretical analysis.

https://cyberleninka.org/article/n/638974.pdf

Characteristics and adsorption capacities of low-cost sorbents for wastewater treatment: A review

Adsorption of phenolic compounds on low-cost adsorbents: A review.

Carbon black was employed as the catalyst for triiodide reduction on fluorine-doped tin oxide glass substrates (FTO-glass) used as counter electrodes in platinum-free dye-sensitized solar cells The fill factors were strongly dependent on the thickness of the carbon layer, and the light energy conversion efficiency also increased up to a thickness of 10 μm The charge-transfer resistance (R ct ) of the carbon counter electrode decreased with the thickness of the carbon layer The R ct for the thicker carbon layer is less than three times that for the platinized FTO-glass The highest cell efficiency was 91% under 100 mW cm -2 light intensity (1 sun AM 15 light, J sc = 168 mA cm -2 , V oc = 7898 mV, fill factor = 0685)

Highly Efficient Dye-Sensitized Solar Cells Based on Carbon Black Counter Electrodes

Electrochemical and electron spectroscopic studies of highly polished glassy carbon electrodes

Surface preparation of glassy carbon electrodes

Electrochemistry of bipyridyl derivatives of cobalt in solutions of anionic and cationic micelles

Rice husk ash (RHA) obtained from a rice mill in Kenya has been used as an inexpensive and effective adsorbent (and reagent) for the removal (and detection) of some phenolic compounds in water. The abundantly available rice mill waste was used in dual laboratory-scale batch experiments to evaluate its potential in: (i) the removal of phenol, 1,3-dihydroxybenzene (resorcinol) and 2-chlorophenol from water; and (ii) the detection of 1,2-dihydroxybenzene (pyrocatechol) and 1,2,3-trihydroxybenzene (pyrogallol) present in an aqueous medium. The studies were conducted using synthetic water with different initial concentrations of the phenolic compounds. The effects of different operating conditions (such as contact time, concentration of the phenolic compounds, adsorbent quantity, temperature, and pH) were assessed by evaluating the phenolic compound removal efficiency as well as the extent of their color formation reactions (where applicable). RHA exhibits reasonable adsorption capacity for the phenolic compounds and follows both Langmuir and Freundlich isotherm models. Adsorption capacities of 1.53 x 10(-4), 8.07 x 10(-5), and 1.63 x 10(-6) mol g(-1) were determined for phenol, resorcinol and 2-chlorophenol, respectively. Nearly 100% adsorption of the phenolic compounds was possible and this depended on the weight of RHA employed. For the detection experiments, pyrocatechol and pyrogallol present in water formed coloured complexes with RHA, with the rate of colour formation increasing with temperature, weight of RHA, concentration of the phenolic compounds and sonication. This study has proven that RHA is a useful agricultural waste product for the removal and detection of some phenolic compounds.

Adsorption and detection of some phenolic compounds by rice husk ash of Kenyan origin

Films with alternating layers of the anion cobalt phthalocyanine tetrasulfonate (CoIIPcTS4-) and cationic polydimethyldiallylammonium chloride (PDDA) were prepared by electrostatic layer-by-layer adsorption. Quartz crystal microbalance and optical studies demonstrated formation of smooth ultrathin films with a linear increase in thickness with the number of deposition steps. Films containing 1, 2, 3, 4, and 5 bilayers of CoIIPcTS4-/PDDA on a gold electrode gave reversible, reproducible steady state cyclic voltammetry for the CoII/CoI redox couple with midpoint potential at -0.28 V vs a saturated calomel reference electrode. Voltammetry was controlled predominantly by charge transport processes in the film, even for films containing only a bilayer of PDDA/CoIIPcTS4-. The peak reduction current increased with the number of layers and showed a tendency to saturation after a deposition of 4-5 bilayers. Copyright 1999 Academic Press.

Geoffrey N. Kamau

Papers

Electrochemical and electron spectroscopic studies of highly polished glassy carbon electrodes

Surface preparation of glassy carbon electrodes

Electrochemistry of bipyridyl derivatives of cobalt in solutions of anionic and cationic micelles

Adsorption and detection of some phenolic compounds by rice husk ash of Kenyan origin

Assembly of Electroactive Ordered Multilayer Films of Cobalt Phthalocyanine Tetrasulfonate and Polycations.