Aim: This study assessed the levels of Pb, Cr, Cd and Zn in settled indoor dust and paint chips. Study Design: Samples were obtained from twelve selected residential houses within Nairobi County, Kenya.
Water samples were taken from five sampling points and their quality assessed through analysis of physical and chemical characteristics. Turbidity, temperature, conductivity, pH, dissolved oxygen and total suspended solids were determined on site during sample collection, using potable meters. Anions were determined using UV/Visible spectroscopy while heavy metals were determined using flame Atomic Absorption Spectroscopy (AAS) in accordance with AWWA standard methods. Turbidity was the highest recorded parameter during the wet season with a mean of 481.83 NTU. 53% of the parameters showed significant seasonal variation (P<0.5) with the mean concentration of 56 % of the parameters being higher during the wet season. The parameters that exceeded the WHO limit were turbidity, phosphates, lead, iron, nickel, chromium and cobalt indicating poor quality of water in River Sio. Poor agricultural practices, domestic and industrial wastewater are the main factors that contribute to pollution of the River. The study proposes proper land use, proper treatment and disposal of sewage and use of organic manure and biological control as means of preventing water and soil pollution.
In this paper, the influence of contact time, initial pH and metal ion concentrations on the adsorption properties of a freshwater green alga (Spirogyra sp.) biomass was studied. Several model solutions of selected heavy metals (Cd, Cu, Cr, Pb) were put into contact with the green algae-based sorbent for different time periods. After the treatment, the concentrations of heavy metals in model solutions were determined using flame atomic absorption spectrometry (FAAS) and inductively-coupled plasmaoptical emission spectrometry (ICP-OES). Fourier transform infrared spectroscopy (FTIR) was used to reveal which functional groups were responsible for the green algae biosorption properties. Adsorption capacities were found to be 22.52, 38.19, 35.59 and 94.34 mg/g for Cd, Cr, Cu and Pb, respectively, at contact times of 15-50 minutes and initial metal ion concentrations of 500-700 µg/g. The optimum pH for biosorption of Cd, Cr, Cu and Pb were 5.5, 5.8, 5.9 and 5.0, respectively. The biosorption process followed second order kinetics and fittedthe Langmuir isotherm model. Biomonitoring studies suggested the possible use of this freshwater green algaas a bioindicator, with mean concentration factors for the selected elements in the range of 367-7154.
The need for clean and safe consumable water is of paramount importance to any society since water is a crucial substance for the sustenance of life. Kibera slum is one of the leading slums in the world with a high population, leading to poor levels of sanitation and inadequate clean water supply. Consequently, the residents have to seek for alternative water supply. Motoine River flows through the slum, and thus acts as an alternative source of water. This study determined the concentration levels of heavy metals (Pb, Fe, Cu, Cr and Cd) and nutrients (nitrates, nitrites and phosphates) in Motoine River, Kibera in September 2014 and compared the variations downstream. The metals were determined using Atomic Absorption Spectroscopy (AAS) while the nutrients were determined using UV/Visible spectroscopy. Concentration levels of Cu, Cd and Cr were found to be lower than
Original Research Article
Synthesis and characterization of hexamine capped ZnSeO4 QDs (ZnSeO4-Hex) by heating up method (HU) was achieved. These, of two crystallite sizes, denoted QDsS1 and QDsS2; with crystallite diameters of 8.6 nm and 14.0 nm respectively. X-ray diffraction (XRD) pattern bared hexagonal close packed (hcp) crystal structure. Band gap for QDsS1 was 5.85 eV and for QDsS2 3.8 to 4.3 eV. Hexamine (C6H10N4) cap on ZnSeO4 QDs was elucidated by Fourier Transform Infrared Spectroscopy (FTIR) and Gas Chromatography-Mass Spectroscopy (GC-MS) results. Transmission Electron Microscopy (TEM) images revealed polycrystallites of different orientation, showing crystal grains separated by tilted grain boundary folds. These QDs were tested as optical chemical nano-sensors for carcinogenic organic pollutants: Anthracene (ANTH), Benzo (a) pyrene (BaP), pyrene (PRN) and pyridine (py). Results revealed that, when the organic pollutants interacted with the QDs, they caused characteristic changes in the way these nanoparticles interacted with characteristic fluorescence and absorbance spectrum
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