Reyad Shawabkeh

Experimental study and modeling of basic dye sorption by diatomaceous clay

This paper presents a study on the adsorption of basic dye, methylene blue, from an aqueous solution onto diatomaceous earth (diatomite). The effect of initial dye concentrations, adsorbent particle size and concentration, and agitation speed on adsorption was investigated. Adsorption isotherms obtained at different solutions temperatures revealed an irreversible adsorption with a capacity of 42 mmol dye/100 g diatomite reached within 10 min. This value slightly increases with increasing the solution temperature. A proposed correlation to describe the irreversible adsorption isotherm was introduced, which resulted in a better fit to the experimental data than that of Langmuirs and Freundlichs. Two simplified kinetics models, pseudo-first order and pseudo-second order, were tested to investigate the adsorption mechanisms. It was found that the kinetics of adsorption of methylene blue onto the surface of diatomite at different operating condition are best described by the pseudo-first-order model.

Copper and strontium adsorption by a novel carbon material manufactured from pecan shells

Abstract A novel carbon material (PS276a) was produced from pecan shells, a waste product of the agricultural industry. Preparation of this material involved the impregnation of the pecan shell feedstock with a phosphoric acid solution. Activation was followed by a water wash and a sodium hydroxide treatment. The carbon produced was characterized by adsorption of N 2 and revealed a pore structure with an average pore diameter of 74.8 A. Equilibrium sorption isotherms prepared for this carbon demonstrate that it has a significantly higher capacity for copper and strontium sorption than that of a commercial material used for comparison. A maximum of 95 mg Cu 2+ and 180 mg Sr 2+ are adsorbed per gram of this carbon at pH 3.6 and 8.5, respectively. Demonstrated process advantages of this carbon material and preparation technique include low temperature manufacture, in-situ regeneration potential, and adsorbate recovery capability.

The Feasibility of Using Diatomite and Mn–Diatomite for Remediation of Pb2+, Cu2+, and Cd2+ from Water

Diatomite and manganese-oxide-modified–diatomite (Mn–diatomite) were tested as adsorbents for Pb2+, Cu2+, and Cd2+removal from water. Impregnating the surface of diatomite with 0.38 g of manganese oxide per gram diatomite shows an increase of 2.4-fold in the surface area of the modified diatomite. The adsorption capacities were 99, 51, and 26 mg/g Mn–diatomite for Pb2+, Cu2+,and Cd2+, respectively, obtained at solution pH 4, while values of 24, 21, and 16 mg/g diatomite were obtained at the same conditions and for the same metals. The obtained adsorption kinetics experimental data display that 95% of the original Pb2+ concentrated was adsorbed by Mn–diatomite within 10 min, while kinetic data for diatomite showed a lower rate for Pb2+ uptake. The filtration quality of diatomite was significantly enhanced with the surface modification by manganese oxide.

Absorption of phenol and methylene blue by activated carbon from pecan shells

Activated carbon is produced from pecan shells by chemical activation using phosphoric acid. This activation is followed by the treatment with sodium dodecyl sulfate to prepare the surface for the adsorption of phenol and methylene blue from aqueous solution. The results showed a great ability for methylene blue removal with sorption capacity of 410 mg/g at pH 9 and solution concentration of 35 mg/l, while moderate adsorption was obtained for phenol with a capacity of 18 mg/g at pH 11 and the same solution concentration. The increase or decrease in solution pH has a favorable effect on the sorption of both adsorbates. Langmuir and Freundlich models were used to fit the experimental data.

High-performance liquid chromatographic determination of simvastatin in medical drugs

A simple and rapid HPLC method for the determination of simvastatin using a C18-Hypersil column and acetonitril-phosphate buffer-methanol (5: 3: 1, v/v/v) as a mobile phase with detection at 230 nm was proposed. Commercial pharmaceutical tablets were analyzed with a linear range for simvastatin up to 1.884 mg % and a regression coefficient of 0.9995. The method is found to be precise, accurate, reliable, and selective.

The Synthesis and Characterization of Microporous, High Surface Area Activated Carbon from Palm Seeds

A high surface area, microporous activated carbon was prepared from palm seeds using chemical and physical activation methods. Samples of powdered palm seeds were treated with different concentrations of phosphoric and nitric acid at 160°C, followed by physical activation using CO2 at 550°C. The Brunauer-Emmett-Teller surface area analysis of the carbon treated with acids has a low surface area (27 cm2/g) using nitrogen at 77.35 K, whereas only mesopore structures were opened by an acid mixture. Further physical treatment by CO2 provided a high surface area of 1,440 m2/g and the pore volume distribution illustrated a micropore structure with a mean pore of 1 nm. Fourier transform infrared spectroscopy analysis illustrated the presence of carboxylic, phenolic, and lactoine groups on the surface of these activated carbon samples where the obtained zero point of charge (pHZPC) for this material was 4.89.

Rate of Biodegradation of Phenol by Klebsiella oxytoca in Minimal Medium and Nutrient Broth Conditions

ABSTRACT The rate of biodegradation of phenol by Klebsiella oxytoca strain was studied in the nutrient broth and M9 minimal medium. It was found that K. oxytoca degrade phenol at elevated phenol concentration where 75% of initial phenol concentration of 100 ppm will degrade within 72 h. This rate was increased with increasing the initial cell densities, increasing the aeration rate and increasing the time required for complete degradation. At phenol concentration above 400 ppm, the cells were unable to degrade the substrate efficiently due to the increasing concentration of phenol in the medium. The culture conditions were also showed a significant impact on the ability of these cells to remove phenol. The optimum solution pH and temperature were 6.8 and 37°C, respectively. The growth of these cells in the presence and absence of phenol was modeled and it was found that the Recatti equation best fit the growth in the absence of phenol whereas the Voltera equation accounted for the history of the cell population in the presence of phenol.

Synthesis and characterization of Cu–Zn/TiO2 for the photocatalytic conversion of CO2 to methane

ABSTRACT Different Cu–Zn/TiO2 catalysts were synthesized by using the wet impregnation method. The prepared catalysts were used for the conversion of CO2 into methane by photocatalysis. Various characterization techniques were used to observe the surface morphology, crystalline phase, Brunauer–Emmett–Teller (BET) surface area, presence of impregnated Cu and Zn, and functional group. Scanning electron microscope analysis showed spherical morphology, and slight agglomeration of catalyst particles was observed. BET analysis revealed that the surface area of the catalyst was decreased from 10 to 8.5 m2/g after impregnation of Cu and Zn over TiO2 support. Synergetic effect of Cu and Zn over TiO2 support (Cu2.6/TiO2, Zn0.5/TiO2 and Cu2.6–Zn0.5/TiO2) and the effects of Cu loading (0, 1.8, 2.1, 2.6 and 2.9 wt%) were also investigated at different feed molar ratios of H2/CO2 (2:1 and 4:1). The Cu2.6–Zn0.5/TiO2 catalyst showed a maximum conversion of 14.3% at a feed molar ratio of 4. The addition of Zn over the catalyst surface increased the conversion of CO2 from 10% to 14.3% which might be due to synergy of Cu and Zn over TiO2 support.

An Experimental and Kinetic Study of the Sorption of Carbon Dioxide onto Amine-Treated Oil Fly Ash

A new CO2 adsorbent is produced from waste oil fly ash (OFA). Ammonium hydroxide solution is used to convert OFA to activated carbon. Then, the product is used for the adsorption of CO2 from a nitrogen/carbon dioxide (N2/CO2) gas mixture. The OFA samples are characterized by several techniques. Chemical treatment of OFA considerably changed its surface morphology. In particular, its surface area, as determined by BET measurements, increased from 59 to 318 m2/g. The amine-functionalized ash had a monolayer adsorption capacity of 74.51 mg/g and was obtained at relative pressure, . A kinetics study showed that the CO2 adsorption capacity of OFA increased with increasing CO2 flow rates and concentrations and decreasing the relative humidity. Unlike physical adsorption, the chemisorption process resulted in increased adsorption capacity with increasing temperatures over the range 0–40°C. We also found that the adsorption process was endothermic (80–173 kJ/mol). The isotherm data for the adsorption process were fitted using different models. The saturation capacity determined from the Sips model, which corresponds to the sum of the saturation capacities of all of the adsorbed layers, was 540.3 mg/g of ash.

Kinetic study of effect of amine based corrosion inhibitor in reducing corrosion rate of 1018 carbon steel in seawater solution

Abstract The effect of an amine based inhibitor (CORTRON AR-505) on the corrosion of 1018 carbon steel in seawater was studied using weight loss, adsorption isotherm analysis, polarisation resistance and potentiodynamic polarisation techniques. AR-505 is adsorbed on the steel surface according to the Shawabkeh–Tutunji adsorption isotherm equation. A maximum adsorption capacity of 0·097 mg AR-505 was obtained to cover a monolayer of adsorption. Corrosion kinetics illustrated that inhibition efficiency has increased with increasing inhibitor concentration and solution pH, while it decreased with increasing solution temperature and stirring speed. Polarisation data fitted by the Butler–Volmer equation showed that the values of anodic and cathodic transfer coefficients are in the average of 0·84 and 0·15 respectively. Corrosion resistance measurements provided a rapid decrease in corrosion rate from 7 to 1 mm/year.