Sahar M. Ahmed

A comparative adsorption study with different agricultural waste adsorbents for removal of oxamyl pesticide

AbstractThe use of cheap and eco-friendly adsorbents prepared from abundantly available pomegranate peel (Pomegranate activated carbons, PAC) and Banana peel (Banana activated carbons, BAC) compared with Commercial activated carbons (ACs) were used for the removal of an insecticide and nematicide oxamyl from aqueous solutions. The ACs were characterized by Fourier transform infrared spectroscopy, Scanning electron microscope, Transmission electron microscopy, and energy dispersive. The effects of initial pesticide concentration and contact time on the biosorption of oxamyl onto the three different adsorbents were investigated. The equilibrium data of kinetic studies were attained at 180 min. The experimental results show increasing adsorption of adsorbents with increasing oxamyl concentrations. The experimental isotherms data were analyzed using Freundlich, Temkin, and Dubinin–Radushkevich isotherm equations. The best experimental data were obtained for all adsorbents by the Freundlich isotherm model with...

Synthesis and Surface Properties of Novel N-Alkyl Quinoline-Based Cationic Gemini Surfactants

Two series of cationic dimeric (gemini) surfactants are prepared with respect to key surfactants properties, such as surface activity and solubilization. The influence of both the dimerization and the spacer group is examined in order to establish structure-property relationships. The surface tension and critical micelle concentration can be markedly reduced compared to the monomeric surfactants in the pure state. The critical micelle concentration (cmc) of each series has been determined using equilibrium surface tension measurements. Furthermore, air/water interface parameters including effectiveness (πcmc), efficiency (PC20), maximum surface excess (Γ max ), and minimum surface area (A min ) have been also derived using Gibbs adsorption equation at 25°C. Standard free energies of micellization and adsorption were calculated. Solubilization behaviors of the synthesized surfactants were measured towards paraffin oil as solubilized material using light transmission technique.

Egyptian apricot stone (Prunus armeniaca) as a low cost and eco-friendly biosorbent for oxamyl removal from aqueous solutions.

In this work, activated carbon was prepared from apricot stone (ASAC) waste to remove the insecticide oxamyl from aqueous solutions. The effect of different parameters such as adsorbent dose, the initial oxamyl concentration and contact time were investigated. Adsorption isotherm, kinetics and thermodynamics of oxamyl on ASAC were studied. Equilibrium data were fitted to the Langmuir, Freundlich, Temkin and DubininRadushkevich (D-R) isotherm models. Langmuir isotherm provided the best fit to the equilibrium data with maximum adsorption capacity of 147.05 (mg/g). Kinetic studies were also undertaken in terms of pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic models for oxamyl on ASAC. The adsorption process follows the pseudosecond order kinetic with high coefficients correlation. The thermodynamic parameters ∆Go, ∆Ho and ∆So determined, showed that the adsorption of oxamyl onto ASAC was feasible, spontaneous and endothermic. The results showed that ASAC is an efficient adsorbent for the adsorptive removal of oxamyl from aqueous solutions. Original Research Article American Journal of Experimental Agriculture, 4(3): 302-321, 2014 303

Hydrolysis of Pesticides in Wastewater Catalyzed by Cu(II) Complexes of Silyl Based Cationic Micelles

The effect of cationic surfactant micelles, namely hexadecyl trimethyl silane ammonium chloride (A), dodecyl trimethyl silane ammonium chloride, (B) and their copper (II) ion complexes on the hydrolysis of the pesticides: diazinon, cypermethrin, and carbaryl was studied. The rate of the pesticides decay in water was significantly accelerated in presence of these cationic micellar solutions. Furthermore, the copper (II) ion complexes of these micellar were found to be much more effective in hydrolysis of these pesticides. The results indicate that the complexes with a 1:1 ratio of both ligands to the metal ions are the active species in catalytic hydrolysis of carbaryl pesticide. Kinetic study is explained.

Synthesis and Biological Activity of Alkyl Pyridinium Aldoxime Based Surfactants

Abstract A series of N-alkyl pyridinium aldoxime surfactants was synthesized by the reaction of pyridinium aldoxime with long chain alkyl halides (decyl, dodecyl, tetradecyl and hexadecyl bromide). The chemical structure of the synthesized compounds was confirmed by elemental analysis and FTIR spectra. Surface tension was measured in aqueous solutions for different concentrations at 25 °C. Various surface properties of the synthesized surfactants were evaluated, particularly the critical micelle concentration (CMC), effectiveness (πCMC), efficiency (PC20) as well as the maximum surface excess (Γmax) and minimum surface area (Amin). Also, the micellization and adsorption at liquid/air interfaces were investigated. The synthesized cationic surfactants were evaluated for their biocidal activity. Good antibacterial and antifungal activities were recorded against Gram-positive bacteria (Bacillus subtilis ATCC 6633, Micrococcus luteus ATCC 25922), followed by Gram-negative bacteria (Escherichia coli ATCC 23282, Pseudomonas aeruginosa ATCC 10145), yeast (Candida albicans IMRU 3669) and filamentous fungus (Aspergillus niger ATCC 16404).

The effect of cationic surfactant additives on flow properties of crude oil

ABSTRACT Pretreatment of the crude oil with flow improver or pour point depressants has received the greatest acceptance due to its simplicity and economy. Three cationic surfactants Bola form based on urea were prepared by quaternization reaction with alkyl dihalides of different chain length (hexayl, decyl-, and dodecyl-dibromide). The prepared compounds (U6, U10, and U12) were evaluated as surface active agents as well as pour point depressant for crude oil compared to monosurfactant (U12a) corresponding to (U12). The surface parameters of each synthesized surfactant were calculated from their surface tension profile including the critical micelle concentration, maximum surface excess (Γmax), and the minimum surface area (Amin). The free energies of micellization (ΔG°mic) and adsorption (ΔG°ads) were also calculated. Its pour point and viscosity decreased significantly after adding surfactants. FTIR studies of crude-surfactant mixture showed remarkable decrease in concentration of viscosity enhancing groups such as alkanes, alcoholic, and acidic groups, indicating the effectiveness of both the surfactants.

Alkaline Hydrolysis of TNT in Micellar System

The influence of micellar and Ca(OH)2 water system on the rates of alkaline hydrolysis of 2,4,6-trinitrotoluene (TNT) was studied and evaluated quantitatively via capillary gas chromatography (CGC) and high performance liquid chromatography (HPLC). The critical micelle concentrations and rate constants of reactions in the micellar phase were determined in micellar solutions of cationic, anionic or nonionic systems. An increase in the rates of alkaline hydrolysis of TNT was observed. Alkaline hydrolysis of TNT using mixture of nonionic surfactant micelles and anionic surfactant showed higher degradation than that with a cationic surfactant.

Synthesis and Some Applications of Schiff Base Surfactants

Schiff bases derived from the condensation reaction of benzaldehyde or anizaldehyde and diethylenetriamine were prepared. The products were neutralized with palmatic acid to pH 7. The chemical structures of the prepared compounds were confirmed using elemental analysis, FTIR, and 1H NMR spectroscopy. Various surface properties of the synthesized surfactants were evaluated particularly, critical micelle concentration, effectiveness, efficiency, maximum surface excess, and minimum surface area. These surfactants were also evaluated as corrosion inhibitors and biocide agents Gram positive and Gram negative bacterial strains. The rheological properties and the filter loss for oil-based mud (invert-emulsion mud) were evaluated. The result showed that they were good emulsifiers and filter loss control agents for oil-base mud. It was determined that they have good corrosion inhabitation for low carbon steel alloy and good bactericidal effect.

Effect of gemini surfactant additives on pour point depressant of crude oil

ABSTRACT Efficiencies of cationic gemini surfactant additives in improving the pour point depressant of crude oil were investigated. The length of alkyl chain is a major factor affecting the improvement of the pour point depression. The adsorption behavior of these gemini surfactants at air/solution and oil/solution interfaces were investigated by measuring the surface tension and interfacial tension as functions of concentration. It is found that there is a good relation between surface properties especially interfacial tension of the gemini surfactants and their efficiency in depressing the pour point. Also, the surface parameters and free energies of micellization and adsorption confirm the decreasing and improving of pour point depression. Crystallization study in crude oil revealed the relationship between the structure and activity of gemini surfactant additives. It is found that the x-ray diffraction patterns of waxes with additives are remarkably different from those without additives. The mechanism of the depressants action has been suggested according the adsorption of each additive. Adsorption of the additive on the surface of the wax particles inhibits their growth and alters the crystal habits through micelle core. Pretreatment of the crude oil with pour point depressants has received the greatest acceptance due to its simplicity and economy. GRAPHICAL ABSTRACT

Photocatalytic degradation of TNT in wastewater using Fe doped TiO2 nanoparticles

Catalysts Characterization Laboratory, Petroleum Refining Division, Egyptian Petroleum Research Institute (EPRI), 1 Ahmed El Zomour St., Nasr City, PO Box 11727, Cairo, Egypt, Tel. +20 2 22736349; Fax +20 2 22747433; emails: sehamshaban@yahoo.com (S.A. Shaban), saharahmed92@hotmail.com (S.M. Ahmed), doaadesouki@hotmail.com (D.S. El-Desouki), nohaaboulgheit@yahoo.com (N.A.K. Aboul-Gheit), samiraepri@hotmail.com (S.M. Abdel-Azim)