A new spectrophotometric method for determination of residual polydiallyldimethylammonium chloride flocculant in treated water based on a diazotization-coupled ion pair

Polydiallyldimethylammonium chloride (polyDADMAC) is a water-soluble cationic polyelectrolyte used for water treatment. Its residues in treated water are contaminants as they react with chlorine to produce a carcinogenic compound. Commonly-used techniques for quantification of the polycation, such as colloidal and potentiometric titration as well as 1H NMR, have poor sensitivity and detection limits. This paper describes a more sensitive UV spectrophotometric method for quantitative determination of residual polyDADMAC in treated water, through formation of an ion pair with (4-hydroxy-1-napthylazo) benzene-sulphonic acid (dye). The ion pair, which is a colloidal solid material, was characterised by FTIR, 13C NMR and 1H NMR techniques. The colloid materials formed with different concentrations of polyDADMAC were dissolved in either N,N-dimethylformamide or 1,4-dioxane, followed by determination with UV spectrophotometry. The wavelength of maximum absorption (ëmax) was found to be dependent on the solvent used, with 1,4-dioxane showing a better linear range of 0.1–1.8 mg..-1 polyDADMAC. Varying the pH of the solutions had no significant effect on ëmax

Elemental composition of blood and hair of mentally–ill patients using ICPOES techniques

Elemental concentrations of blood and hair of 40 mentally-ill patients and 40 controls (healthy subjects) were determined by Inductively Coupled Plasma Optical Emission Spectrophotometer (ICP-OES) in order to find out the metal burden of the patients with their level of significance and possible relationship of such elements with mental illness. Generally, higher concentrations of trace elements were obtained in the hair than in the blood. A concentration range of 90 - 400 ìg/g was obtained for Mg, K and Fe in hair of patients and controls, 80-7400 ìg/g was obtained in their blood; other elements range 0.001-30 ìg/g in both blood and hair of patients and controls. Comparative study of statistical significance of median values between different groups was determined by applying a non parametric test (Mann-Whitney) showed that concentrations of Ba, Be, Cr, Li, Mg, Fe and K were significantly higher in patients’ blood, while Al, Ba, Be, Na, Cd, Cr, Li, K, Mn,Mg and Sr were significantly higher in patient’s hair. Concentrations of most elements are higher in the hair and blood of the mentally ill patients than in the healthy controls. Deficiency of Cu and Zn might be causally related to the illness

Comparative Studies of the Speciation Patterns of Nickel and Chromium in Surface-, Ground- and Wastewater Systems in Botswana

Results of speciation stdies of nickel and chromium in wastewater, surface and groundwater systems using flame atomic absorption spectrometry (FAAS), graphite furnace atomic absorption spectrometry (GFAAS) and differential pulse adsorptive cathodic stripping voltammetry (DPAdCSV) are presented. Dimethylglyoxime (DMG) and diethylenetriaminepentaacetic acid (DTPA) were used as complexing agents forDPAdCSVdetermination of nickel and chromium, respectively, at a hanging mercury drop electrode (HMDE). Total nickel was in the range 3091–3201 mg L–1 in wastewater from an electroplating plant, 8.1–14.4 μg L–1 in surface water (freshwater) and 6.38–16.95 μg L–1 in groundwater. Total chromium was in the range 34.99–37.03 mg L–1 in electroplating wastewater and 15.8–571.0 mg L–1 in tannery effluents. Trace levels of chromium were detected in surface water (3.09–17.42 μg L–1) and groundwater (18.01–36.39 μg L–1). While most of the metal forms were found to be present in the CSV-labile fraction in the wastewater from the electroplating plant (mean of 67.9% for Ni and 79.8% for Cr), less than 5% of the total metal was present as CSV-labile fraction in tannery effluents, surface and groundwater samples. The tannery effluent was found to have very high complexation capacity (about 3 mg of Cr /L of effluent, i.e. 57.8 μM Cr). This complexing capacity of tannery effluent may have a potential application in environmental remediation.Keywords: Speciation, metals, complexation capacity, water systems, adsorptive cathodic stripping voltammetry

Fate, behaviour, and implications of ZnO nanoparticles in a simulated wastewater treatment plant

Increased use of engineered nanoparticles (ENPs) has resulted in their entry into municipal wastewater treatment plants (WWTPs) as their final sinks. However, the adverse impact of ENPs on the bacterial activity in the activated sludge WWTPs is not yet well understood, despite their increased release into such systems. In this study, the impacts on WWTPS associated with the disposal of zinc oxide (ZnO) ENPs was investigated using a simulated WWTP developed as per the prescribed Organization for Economic Co-operation and Development (OECD 303A) specifications. Analyses were done to determine zinc concentrations at various stages of the setup, mainly in the raw wastewater and treated effluent, using inductively coupled plasma optical emission spectrometry (ICP-OES). The results obtained indicated low levels of zinc residue (about 50–200 μg/L) in the treated effluent compared to relatively high concentrations of Zn in the sludge (about 3 000 mg/kg). Results reported herein imply precipitation of ZnO ENPs during wastewater treatment processes and hence its high levels in the sludge. The presence of solid Zn in the sludge was determined using X-ray diffraction spectroscopy (XRD). Overall, no significant impact of ZnO ENPs on the performance of the simulated WWTP was observed, in terms of the removal levels of chemical oxygen demand (COD) during the treatment processKeywords: wastewater, activated sludge, nanoparticles, zinc oxide, OECD 303

The Free-Radical Copolymerization of Difurylmethane with Maleic Anhydride

The copolymerization of difurylmethane with maleic anhydride in the presence of azobisisobutyronitrile as an initiator has been investigated at 65 ºC, 72 ºC and 85 ºC in different solvents. Reaction feeds containing 85 mol % and higher of difurylmethane yielded a soluble alternating copolymer in which the furan residue entrained in the polymer chain formed 2,5 linkages and had 3,4 unsaturation. The 1:1 difurylmethane- maleic anhydride adduct was readily prepared, and at the above temperatures and in the presence of the radical initiator partially underwent retro-Diels-Alder reaction. Copolymerization of the difurylmethane and maleic anhydride thus formed yielded the unsaturated alternating copolymer. Copolymers prepared from reaction feeds with proportions of difurylmethane lower than 85 mol % had higher cross-link density and exhibited higher thermodecomposition temperatures. South African Journal of Chemistry Vol.55 2002: 1-1

Determination of levels of copper in Kamiti river along coffee farms in Kiambu, Kenya

Copper‐based fungicides are extensively used in the control of coffee pests and diseases because they are relatively cheap and effective. This practice presents serious environmental implications owing to the toxic nature of copper. We report here an assessment on the effects of the use of copper‐based fungicides on River Kamiti, which flows along coffee growing areas of Kiambu District, Kenya. The levels of copper in the river were determined using flame atomic absorption spectrophotometry (FAAS) and were found to range from 0.3 to 2.38 x 10‐2 mgL‐1. It was observed that high levels of copper coincided with coffee spraying seasons and a high amount rainfall, indicating that these contributed to increased seepage of copper in the river. Active pulping factories on both sides of the geographical regions were also found to be a source of the same. Statistical analysis on the experimental data of copper levels from the study sites showed that there was no significant difference between the regions implying that the sampling sites were not the source of variation. Although there is clear evidence that coffee farming introduces copper into the river, the levels of copper in Kamiti river were found to be within acceptable limits and this would be attributed to dilution effects. However, at specific points, the levels of copper were very high threatening the survival of aquatic animals, thus the use of copper compounds is of environmental concern.Key words: Copper, fungicides, river wate

Determination of Lipophilic Extractives in Ionic Liquid Extracts of Eucalyptus Pulp by Gas Chromatography - Mass Spectrometry

Lipophilic wood extractives composition is currently a big concern of pulp and paper industries as well as for the environmentalists due to their negative impacts on the quality of pulp and the environment. Because of the shortcomings of different extraction procedures using volatile organic solvents in capturing residual lipophilic extractives in pulp, this study reports on the use of ionic liquids as an effective approach for such extraction. The capacity of two ionic liquids; 1- butyl-3-methylimidazolium acetate and 1-butyl-3-methylimidazolium chloride to recover wood extractives was compared and it was observed that ionic liquid with chloride anion recovered a higher amount of extractives. The effect of temperature of the added precipitating solvent during cellulose regeneration on the recovery of extractives was also studied. Recovery of extractives increased with increasing temperature of the added precipitating solvent and equilibrium was reached at 90oC. Fatty acids (saturated, unsaturated and α-hydroxyl acids), sterols (β-sitosterol and stigmastanol), steroid hydrocarbons and ketones were the main compounds determined from bleached pulp using gas chromatography mass spectrometry. On the basis of the fact that ionic liquids are biodegradable and non-volatile, this approach of analysis is definitely a highly green process for the determination of lipophilic extractives in pulp.Key words: Dissolving pulp, Extractives, Gas chromatography-mass spectrometry, Green solvent, Ionic liqui

Effect of metal poisoning and the implications of gender and age on the elemental composition in patients with mental behavioural disorders

The objective of this work was to investigate the possible correlation between the exposure to selected toxic metals and the behavioural disorder of mentally ill patients. The study also sought to establish if gender and age of the patient had an effect on the pattern of the elemental distribution in their head hair and blood samples. To achieve this, the concentrations of a number of selected toxic metal elements were determined in 60 mentally ill patients and 43 healthy individuals (control) in Ile-Ife area, in Nigeria, using inductively coupled plasma spectrophotometer-optical emission spectrometer (ICP-OES). The behavioural disorder cases investigated were 8 bipolar, 2 post partum psychosis, 43 schizophrenia and 7 non-specific cases. The concentration ranges of Cu, Zn, Ca, Li, V, Be (for both males and females), Cd and Sr (for females only) as analyzed from the patients’ head hair with behavioural disorders, were found to be similar with those of the controls. However, the concentration ranges of Al, Ba, Mg, Cr and Cd, Sr (for males only) were higher in patients than in the controls, while those for K and Fe were found to be higher in the controls than in the patients for both males and females. Blood samples analysis showed that, nearly all the elements were higher in the female (patients and control) than in the males; a possible indication that women may be at greater risk than men. It was also shown that, age may have an influence on the accumulation of some specific elements. The accuracy of the analytical results was experimentally demonstrated by NCS DC 73347 certified reference material that was analyzed along the standards while the significance of the data obtained was tested statistically at both p = 0.01 and 0.05.Key words: Toxic metals, behavioural disorder, gender, age, inductively coupled plasma-optical emission spectrometer

Geochemical scaling potential simulations of natural organic matter complexation with metal ions in cooling water at Eskom power generation plants in South Africa

The modified database in the pH, redox equilibrium calculations code (PHREEQC) with a Tipping and Hurley database (T_H.DAT) coupled with the Windermere’s humic acid model (WHAM) was used to simulate scale formation potential in cooling water circuitry, at Eskom power generating stations in South Africa. This study reports a semi-empirical simulative approach in which organic matter fractions, metals and anions in raw and cooling water were used as modelling experimental inputs. By using the saturation index profiles of Ca2+/ Mg2+ with fulvic acid in a modified Tipping and Hurley (T_H.DAT) database, fulvate complex species such as CaFulvate, MgFulvate, and geochemical modelling predictions, mineral phases that potentially precipitate are discussed. Speciation calculations showed that the increase in fulvic acid levels decreased saturation indices of scaling metal phases due to reduced levels of Ca2+ and Mg2+ in the water. Furthermore, if the concentrations of fulvic acid are known, semi-empirical calculations using the geochemical PHREEQC code with a modified T_H.DAT arepossible. Consequently, mineral phase equilibria outputs may give an indication of how the pH and temperature is to be manipulated to optimally predict and control the incidence of scaling