Haider J. Al-Lawati

Ciprofloxacin adsorption from aqueous solution onto chemically prepared carbon from date palm leaflets

A chemically prepared carbon was synthesized from date palm leaflets via sulphuric acid carbonization at 160 degrees C. Adsorption of ciprofloxacin (CIP) from aqueous solution was investigated in terms of time, pH, concentration, temperature and adsorbent status (wet and dry). The equilibrium time was found to be 48 hr. The adsorption rate was enhanced by raising the temperature for both adsorbents, with adsorption data fitting a pseudo second-order model well. The activation energy, Ea, was found to be 17 kJ/mol, indicating a diffusion-controlled, physical adsorption process. The maximum adsorption was found at initial pH 6. The wet adsorbent showed faster removal with higher uptake than the dry adsorbent, with increased performance as temperature increased (25-45 degrees C). The equilibrium data were found to fit the Langmuir model better than the Freundlich model. The thermodynamic parameters showed that the adsorption process is spontaneous and endothermic. The adsorption mechanism is mainly related to cation exchange and hydrogen bonding.

A sequential injection spectrophotometric method for the determination of penicillamine in pharmaceutical products by complexation with iron(III) in acidic media

A simple, robust and sensitive sequential injection spectrophotometric method for the assay of penicillamine (PA) in pharmaceutical formulations is developed. The method was based on the complex formation when PA is reacted with iron(III) solution in hydrochloric acid media. The deep blue colored PA-iron(III) complex produced is monitored at a maximum wavelength of 600 nm. A five level orthogonal array design coupled to genetic algorithm was employed to obtain the optimum experimental conditions for the determination of PA using peak absorbance as the measure of the systems performance criterion. A linear dynamic range for the determination of PA of 25-300 ppm was obtained with a sampling frequency of 50 h(-1) and a relative standard deviation of less than 0.98%. The method was successfully applied to the determination of PA in pharmaceutical formulations.

Adsorption of fexofenadine and diphenhydramine on dehydrated and activated carbons from date palm leaflets

Dehydrated carbon (DC) was prepared from date palm leaflets via sulfuric acid treatment at C in the presence of air. Acidified DC was converted to activated carbon (AC) at C under nitrogen atmosphere. DC shows low surface area (48 m2 g−1), whereas activated carbon possesses high surface area (405 m2 g−1). Both carbons were tested for the adsorption of fexofenadine (FEX) and diphenhydramine (DPH) at different initial pH, concentration and temperature. Maximum adsorption took place at pH 4.0 for FEX and pH 8.0 for DPH. Adsorption kinetics was found to follow well pseudo second-order kinetic model with increased adsorption as temperature increased within the range of 25–C. Activation energy, Ea, was 12–17.5 kJ mol−1 indicating physical adsorption of both drugs. Drug uptake was found to increase with temperature rise in the range of 25–45°C. Thermodynamic parameters showed that the adsorption of drugs is spontaneous and endothermic in nature with physical adsorption dominating the removal processes. Despite having very low surface area, DC shows competitive adsorption capability for AC. Drug desorption from loaded carbons showed better performance from DC than from AC. The effect of the presence of KCl on adsorption of FEX and DPH was also studied.

Determination of the pseudoephedrine content in pharmaceutical formulations and in biological fluids using a microbore HPLC system interfaced to a microfluidic chemiluminescence detector

A novel automated precolumn derivatization followed by separation using liquid chromatography for the determination of pseudoephedrine (PSE) by a microfluidic chemiluminescence detector has been developed. An on-line derivatization procedure was utilized by converting PSE into a highly light emitting species in a Ru(bipy)3(2+)-peroxydisulphate chemiluminescence (CL) system by derivatizing it with a 1.0 M formaldehyde solution. The derivatized analyte was directly injected into a microbore high-performance liquid chromatography (HPLC) system coupled to an on-chip chemiluminescence detector. The newly developed highly selective, sensitive and fast HPLC-CL method was validated and successfully applied for the analysis of PSE in pharmaceutical formulations and a human urine sample. The selectivity of the method is not only due to the HPLC separation but is also due to the highly selective detection principle of the Ru(bipy)3(2+)-peroxydisulphate CL system used. There was no interference observed from the common preservatives and excipients used in pharmaceutical preparations, which did not show any significant CL signal. The retention time of PSE was less than 3 min, and the detection limits and quantification limits were found to be 5.7 and 26.0 µg L(-1), respectively.

Spectrofluorimetric determination of aluminium in water samples using N-((2-hydroxynaphthalen-1-yl)methylene) acetylhydrazide

Abstract A sensitive and selective spectrofluorimetric method has been developed for the rapid determination of aluminium. This method is based on the formation of a complex between aluminium and N-((2-hydroxynaphthalen-1-yl)methylene) acetylhydrazide (HNMA). The fluorescence of the complex is monitored at an emission wavelength of 450 nm with excitation at 385 nm. Optimum complex formation occurred in Tris buffer at pH 6.0. Under the optimum conditions, linear calibration curves were obtained from 50 to 800 ppb. The detection limit was 9.2 ppb (ng mL−1). The maximum relative standard deviation of the method for an aluminium standard of 200 ppb was 2.5%. The effects of surfactants and interference from other ions were studied. The method was successfully applied for the determination of aluminium ions in water samples.

HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY DETERMINATION OF ANILINES WITH FLUORESCENT DETECTION AND PRE-COLUMN DERIVATIZATION

A simple, sensitive, and rapid reverse-phase high-performance liquid chromatography (RP-HPLC) method for the determination of anilines in water is proposed. The use of 2,7-diethylamino-2-oxo-2H-chromen-3-yl-benzothiazole-6-sulfonylchloride (coumarin 6-SO2Cl) as a fluorigenic-labeling reagent was investigated. The label reacted with aniline within 30 min under mild conditions (ambient temperature, pH 9.0) to give sulfonamides that were separated by RP-HPLC employing fluorescence detection with an excitation wavelength of 470 nm and an emission wavelength of 520 nm. The optimum conditions for fluorescence, derivatization, and chromatographic separation were established. The calibration curves were linear for the range 0–800 ppb. The proposed method was applied for the determination of anilines in spiked drinking water samples and irrigation water samples with recoveries of 90.0–103.9% and relative standard deviations of 1.2–4.7%, respectively. This method showed good accuracy and repeatability that can be used for the quantification of aniline in real samples.

Spectrofluorimetric determination of Zn2+ ions in aqueous medium using 5-(4-flourophenyl)-quinolin-8-ol

Abstract A spectrofluorimetric method based on complex formation between Zn2+ ions and 5-(4-flourophenyl)-quinolin-8-ol has been developed for the rapid determination of trace levels of zinc ions. The method is sensitive and selective. The complex formed emit strongly at 535 nm with excitation wavelength at 394 nm. Complexation formation was optimized by studying the effect of pH, molar ratio of the metal to the ligand and the type of buffers. The study indicated that maximum complexation resulted when the pH of the mixture was maintained at 8.0 with 0.2 M carbonate buffer and metal to ligand was at a stoichiometric ratio of 1:2. Under the optimum conditions, the detection limit was 3 ppb. Appropriate validation of the method, yielded acceptable relative standard deviations of less than 2% (n = 5). The method was applied to the trace determination of Zn2+ ions in tap water, mineral water, fresh milk and cream samples successfully.

Competitive removal of heavy metals from spiked hospital wastewater on acidic and chelating dehydrated carbons

ABSTRACT Date palm leaflets were carbonised using sulphuric acid dehydration, producing acidic dehydrated carbon (DC) that was converted to chelating dehydrated carbon (CDC) using ethylene diamine functionalisation. Both carbons were surface characterised and tested for competitive removal of Cd2+, Cu2+, Co2+, Ni2+ and Zn2+ from metal mixtures in hospital wastewater (HWW) and deionised water (DW). Sorption kinetics data follow pseudo-second-order model. Equilibrium sorption data follow the Langmuir model with better performance for CDC than DC. Sorption of metals from metal mixture from DW is clearly higher than from HWW because of the high content of organic moieties in HWW.

Nanotechnology: a clean and sustainable technology for the degradation of pharmaceuticals present in water and wastewater

Abstract Pharmaceuticals, newly recognized classes of environmental pollutants, are becoming increasingly problematic contaminants of either surface water or ground water around industrial and residential communities. Pharmaceuticals are constantly released into aquatic environments, mainly due to their widespread consumption and complicated removal in wastewater treatment plants. Heterogeneous photocatalysis appear to be one of the most destructive advanced oxidation processes (AOPs) for organic contaminants and are possible to obtain complete mineralization of organic pollutants into eco-friendly end products under visible and solar light irradiation. In this study, flower-like In2S3 hierarchical nanostructures were successfully prepared via a facile solution-phase route, using thioacetamide as both sulfur source and capping agent. X-ray diffractometry (XRD) of the flowers revealed that the cubic structure of In2S3; morphological studies examined by scanning electron microscopy (SEM) showed the synthesized In2S3 nanostructure was flower-like hierarchitecture assembled from nanoscale flakes. X-ray photoelectron spectroscopy (XPS) analysis confirmed the stoichiometry of In2S3 nanoflowers. Furthermore, the photocatalytic activity studies revealed that the prepared indium(III) sulfide(In2S3) nanoflowers exhibit an excellent photocatalytic performance, degrading rapidly the aqueous pharmaceutical solution of Lisinopril under visible light irradiation. These results suggest that In2S3 nanoflowers will be a promising candidate of photocatalyst working in thevisible light range.

Adsorption of lisinopril and chlorpheniramine from aqueous solution on dehydrated and activated carbons

Date palm leaflets were used as a precursor to prepare dehydrated carbon (DC) via phosphoric acid treatment at 150°C. DC, acidified with H3PO4, was converted to activated carbon (AC) at 500°C under a nitrogen atmosphere. DC shows very low surface area (6.1 m2/g) while AC possesses very high surface area (829 m2/g). The removal of lisinopril (LIS) and chlorpheniramine (CP) from an aqueous solution was tested at different pH, contact time, concentration, and temperature on both carbons. The optimal initial pH for LIS removal was 4.0 and 5.0 for DC and AC, respectively. However, for CP, initial pH 9.0 showed maximum adsorption on both carbons. Adsorption kinetics showed faster removal on AC than DC with adsorption data closely following the pseudo second order kinetic model. Adsorption increases with temperature (25°C–45°C) and activation energy (Ea) is in a range of 19–25 kJ mol/L. Equilibrium studies show higher adsorption on AC than DC. Thermodynamic parameters show that drug removal is endothermic and spontaneous with physical adsorption dominating the adsorption process. Column adsorption data show good fitting to the Thomas model. Despite its very low surface area, DC shows ~70% of AC drug adsorption capacity in addition of being inexpensive and easily prepared.