Brenda Moodley

Pharmaceutical residues in water and sediment of Msunduzi River, KwaZulu-Natal, South Africa

The little data about pharmaceutical residue contamination in African water bodies motivated our study on the occurrence of pharmaceutical residues in the water and sediment of Msunduzi River in the KwaZulu-Natal province of South Africa; and in the Darvill wastewater treatment plant found in Msunduzi catchment. Samples collected along the River and wastewater treatment plant were extracted and analysed for pharmaceutical residues selected based on statistics of drug usage in South Africa i.e. antipyretics, antibiotics, caffeine, an antiepileptic and an antipsychotic drug were determined using HPLC-MS/MS. In all the matrices investigated, the antipyretic ibuprofen had the highest concentration of up to 117 μg L(-1), 84.60 μg L(-1) and 659 ng g(-1) in wastewater, surface water and sediment respectively. Antibiotics were detected in generally low concentrations of<10 μg L(-1) in surface water samples and up to 34.50 μg L(-1) in wastewater; moreover they were not completely removed during wastewater treatment. The percentage removal efficiency of the studied group was 6.55-98.00% for antipyretics, 73.33-98.90% for antibiotics, 48.80% for the anti-epileptic drug and 86.40% for Caffeine. Clozapine exhibited a negative removal. In surface water, Henley dam exhibited a high concentration of the pharmaceutical residues and the highest concentration of metronidazole in sediment (up to 1253.50 ng g(-1)) detected. Metronidazole was only detected in sediment and bio-solids.

Occurrence and distribution pattern of acidic pharmaceuticals in surface water, wastewater, and sediment of the Msunduzi River, Kwazulu‐Natal, South Africa

The paucity of information on the occurrence of pharmaceuticals in the environment in African countries led the authors to investigate 8 acidic pharmaceuticals (4 antipyretics, 3 antibiotics, and 1 lipid regulator) in wastewater, surface water, and sediments from the Msunduzi River in the province of KwaZulu-Natal, South Africa, using solid-phase extraction (SPE) and liquid chromatography-mass spectrometry (LC/MS). The method recoveries, limits of detection (LOD), and limits of quantification were determined. The method recoveries were 58.4% to 103%, and the LODs ranged between 1.16 ng/L and 29.1 ng/L for water and between 0.58 ng/g and 14.5 ng/g for sediment. The drugs were all present in wastewater and in most of the surface water and sediment samples. Aspirin was the most abundant pharmaceutical observed, 118 ± 0.82 μg/L in wastewater influent, and the most observed antibiotic was nalidixic acid (25.2-29.9 μg/L in wastewater); bezafibrate was the least observed. The distribution pattern of the antipyretic in water indicates more impact in suburban sites. The solid-liquid partitioning of the pharmaceuticals between sediment and water, measured as the distribution coefficient (log KD ) gave an average accumulation magnitude of 10× to 32× in sediments than in water. The downstream distribution patterns for both water and sediment indicate discharge contributions from wastewater, agricultural activities, domestic waste disposal, and possible sewer system leakages. Although concentrations of the pharmaceuticals were comparable with those obtained from some other countries, the contamination of the present study site with pharmaceuticals has been over time and continues at present, making effective management and control necessary.

Preconcentration of molybdenum, antimony and vanadium in gasolsine samples using Dowex 1-x8 resin and their determination with inductively coupled plasma-optical emission spectrometry.

Strong ion exchangers (Dowex 50W-x8 and Dowex 1-x8) were used for the separation and preconcentration of trace amounts of Mo, Sb and V in gasoline samples. Dowex 1-x8 resin was found to be suitable for the quantitative retention of these metal ions from organic matrices. The elution of the metal ions from Dowex 1-x8 resin was achieved by using 2.0 mol L(-1) HNO3 solution. The Dowex 1-x8 preconcentration and separation method gave an enrichment factor of 120 with limits of detection equal to 0.14, 0.05 and 0.03 μg L(-1) for Mo, Sb and V, respectively. The limits of quantification were found to be 0.48, 0.18 and 0.10 μg L(-1) for Mo, Sb and V, respectively. Under optimized conditions, the relative standard deviations of the proposed method (n=20) were <4%. The accuracy of Dowex 1-x8 preconcentration procedure was verified by the recovery test in the spiked samples of gasoline sample. The Dowex 1-x8 preconcentration method was applied to Conostan custom made oil based certified reference material for the determination of Mo, Sb and V. The results of the paired t-test at a 95% confidence level showed no significant difference. The separation and preconcentration procedure was also applied to the gasoline samples collected from different filling stations.

Synthesis, Characterization, and Adsorption Kinetic Studies of Ethylenediamine Modified Cellulose for Removal of Cd and Pb

Surface functionalization of cellulose using ethylenediamine was performed to improve its binding capacity for Cd and Pb. Adsorption kinetics at pH 6.0 and 25°C revealed the Langmuir model to better describe the binding phenomena based on linear regression correlation coefficient (R2) values of 0.998 and 0.986 with adsorption capacities of 0.0136 and 0.0179 mmol g−1 for Cd and Pb, respectively, using raw cellulose and 0.128 and 0.242 mmol g−1 with ethylenediamine-modified cellulose. The Freundlich model gave binding capacities of 2.32 × 10−3 and 2.08 × 10−3 mmol g−1 for Cd and Pb, with R2 values of 0.979 and 0.942, respectively.

Synthesis, characterisation and application of imidazolium based ionic liquid modified montmorillonite sorbents for the removal of amaranth dye

The removal of amaranth dye using montmorillonite modified with an ionic liquid (IL) was investigated. An ionic liquid (1-methyl, 3-decahexyl imidazolium) was synthesised, and characterised by nuclear magnetic resonance (1H and 13C NMR), Fourier transform infrared (FT-IR) spectroscopy, high resolution mass spectroscopy (HR-MS) as well as thermal gravimetric analysis and differential thermal (TGA/DCS) analysis. The ionic liquid was thereafter used to modify sodium montmorillonite (Na+-Mt) to form a hydrophobic montmorillonite that has a positively charged surface, by adding IL in excess of the cation exchange capacity (CEC) of Na+-Mt. Energy dispersive X-ray analyser (EDX) was used to determine the chemical composition of Na+-Mt. Modified montmorillonite (Mt-IL) and Na+-Mt was characterised using FT-IR, scanning electron microscopy (SEM), X-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET) method, and used in the adsorption study of an anionic amaranth dye. A higher CEC of the Mt-IL (112 meq per 100 g) than Na+-Mt (89 meq per 100 g) was observed. The effects of sorbent dosage, dye concentration, solution pH and contact time were investigated in order to determine optimal experimental conditions. Optimum adsorption was obtained at pH 2 and adsorption data was better described by the pseudo-second-order kinetics and Langmuir adsorption isotherm. A maximum adsorption capacity of 263.2 mg g−1 was calculated. The thermodynamic parameters ΔG°, ΔH° and ΔS° were also investigated at temperatures of 313, 303 and 293 K. Column studies were performed on the modified material and the data generated was applied to the Thomas model where high column adsorption capacities of 393.7, 580.9 and 603.6 mg g−1 at different concentrations were obtained.

Multicomponent synthesis of pyridines via diamine functionalized mesoporous ZrO2 domino intramolecular tandem Michael type addition

A new and straightforward synthetic method was developed for the facile synthesis of heterocycle-fused pyridine derivatives in aqueous media from Knoevenagel condensation between an aromatic aldehyde and an active methylene compound. This was followed by Michael type addition of a ketone to the activated double bond of the arylidene via intramolecular cyclization in the presence of diamine functionalized [N-(2 amino ethyl)-3-amino propyl trimethoxy silane (AAPTMS)] mesoporous ZrO2 (AAPTMS/m-ZrO2) to synthesize fused pyridines in high yield. This one-pot conversion, which involves multiple steps and requires no toxic/organic solvents, produced new C–C and C–heteroatom bonds with all reactants efficiently utilized.

Pre-concentration of trace elements in short chain alcohols using different commercial cation exchange resins prior to inductively coupled plasma-optical emission spectrometric detection.

Chelex-100, Dowex 50W-x8 and Dowex MAC-3 exchange resins were investigated for separation and pre-concentration of trace amounts of Cd, Cr, Cu, Fe, Mn, Pb, Ti and Zn in alcohols with respect to retention and desorption characteristics. Dowex 50W-x8 was found to be the best sorbent with percentages recoveries >95%. In addition, Chelex-100 appeared to be suitable for the pre-concentration of Cu, Fe and Zn, whereas Dowex MAC-3 was selective for Cu and Fe. Therefore, Dowex 50W-x8 was used for further investigations. The relative standard deviations <4% (n=20), limits of detection and quantification were 0.1-1.2 μg L(-1) and 0.3-1.5 μg L(-1), respectively. The SPE method was validated against a certified reference material and the results were in agreement with certified values. The accuracy of the optimized method was verified by the recovery test in the spiked alcohol samples. The accuracy and spike recovery test for different metal ions were in the range 98-102% and 95-105%, respectively. The optimized method was applied to the separation and pre-concentration of metal ions in different commercial alcohol samples.

A solid phase extraction procedure based on electrospun cellulose-g-oxolane-2,5-dione nanofibers for trace determination of Cd, Cu, Fe, Pb and Zn in gasoline samples by ICP-OES

Cellulose-g-oxolane-2,5-dione nanofibers were prepared as an adsorbent for simultaneous separation and preconcentration of trace amounts of Cd, Cu, Fe, Pb and Zn ions in gasoline samples prior to ICP-OES detection. The nanofibers were chemically and morphologically characterized by FTIR, solid-state 13C NMR, BET and SEM techniques. The influences of experimental parameters such as pH, HNO3 concentration on metal ion elution from the nanofibers, flow rate and sample volume were investigated. The metal ions were retained on 0.5 g of the adsorbent at pH 6 and recovered with 5.0 mL of 2.0 mol L−1 HNO3. The adsorption capacities for the adsorbent were 273.1, 183.6, 195.5, 236.2 and 182.4 mg g−1 for Cd, Cu, Fe, Pb and Zn, respectively. The relative standard deviation was <3% (n = 15), limits of detection and quantification were 0.13–0.68 μg L−1 and 0.42–2.2 μg L−1, respectively, and the maximum preconcentration factor was 60. It was observed that cellulose-g-oxolane-2,5-dione nanofibers can be used for more than 30 adsorption–elution cycles without decreasing the extraction efficiency. The accuracy of the method was confirmed by analyzing a certified reference material and by performing the spike recovery test. The accuracy and recovery for different metal ions were in the range of 97–102% and 96–99%, respectively. The optimized method was applied for the separation and preconcentration of metal ions in gasoline samples.

Method Development for Flow Adsorption and Removal of Lead and Copper in Contaminated Water Using Electrospun Nanofibers of Chitosan Blend

This study reports column flow adsorption capacity for Pb and Cu of 56.54 mgg−1 and 5.75 mgg−1, respectively, using electrospun nanofibers (70–264 nm) of chitosan:polyacrylamide blend ratio 77:23 with glutaraldehyde cross-linking. The Freundlich isotherms gave a better fit than Langmuir. The fibers were applied in contaminated pond water and pulp wastewater, for removal of Pb and Cu, with removal efficiencies of 100% (Pb) and 98.6% (Cu) in pond water; and 97.2% (Pb) and 99.5% (Cu) in wastewater. The regeneration efficiencies (recovery %) were 64% (Pb) and 89% (Cu) in pond; 72% (Pb) and 90% (Cu) for pulp, respectively, using an adsorbent mass of 0.05 g.

Sesquiterpene lactones from the aerial parts of Vernonia blumeoides growing in Nigeria.

Four eudesmanolide sesquiterpene lactones (1-4) were isolated from the aerial parts of Vernonia blumeoides used in Nigerian ethnomedicine for the treatment of diarrhea and malaria. Compound 1 demonstrated limited but interesting antibacterial activity against Bacillus, Staphylococcus and Streptococcus species. The crystal structure of 1 allowed the absolute configuration of the stereocentres in the molecule to be assigned.