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Sabore field is characterised by a high level of artisan activities that contributes to water pollution by heavy metals; these heavy metals when present in drinking water can be deleterious to human health. Consequently, in 2018 we investigated the seasonal variations of the water samples from the Sabore vicinity to determine its suitability for drinking. Six metals (Mn, Cu, Cd, Zn, Ni, Pb) were studied, the health risk assessment was investigated using Hazard Index (HI), Hazard Quotient (HQ) and Cancer Risk (CR). The results showed that water from this locality have HI values > 1, Pb and Cd were top contributors to non-carcinogenic risk while Ni and Cd caused concern for carcinogenic health risk making it unsuitable for consumption. The seasonal spread of the metals shows that Mn varied from 148 to 976 µg/L; Cu from 923 to 1676 µg/L; Cd from 1.167 to 22.5 µg/L; Zn from 63 to 118 µg/L, Ni from 37 to 95 µg/L and Pb from 128 to 185 µg/L in the rainy season. For the dry season, Mn shows a spread of 1442–1802 µg/L; 344–776 µg/L for Cu; 57–82 µg/L for Cd; 48–187 µg/L for Zn; 147–242 µg/L for Ni and 79–256 µg/L for Pb. The increased concentration of some metals during the dry seasons could be attributed to the increased human activities around the field, increased evaporation rate, absence of rainfall and runoff water. The heavy metal content of water from some of the sites exceeded the stipulated permissible limits and poses serious health risk to its consumers. [ABSTRACT FROM AUTHOR]

Polysulphone/clay ion-exchange membranes were prepared by the phase inversion method using N-methyl-2 pyrrolidone as solvent. The aims of this work were to synthesize and investigate the effect of different natural clays from different locations on the morphology, hydrophilicity, structure, swellability, metal extraction from water and ion-exchange capacity (IEC) of the membranes prepared. The characterization techniques used were scanning electron microscopy, X‐ray diffractometry, Fourier transform infra-red spectroscopy and contact angle. The clays from locations 1 (N4) and 2 (N6) had a good dispersion in the polysulphone matrix and exhibited high IEC, swellability and hydrophilicity. The 2θof the polysulphone/clay membranes compared to polysulphone membrane was lower, indicating an increase in thed-spacing between layers of the clays and also intercalation of clay layer silicates in the polymer matrix. Extraction/adsorption of Pb2+by all the tested membranes was faster (10 min) compared to Cu2+, and it was approximately 100%. [ABSTRACT FROM AUTHOR]

ABSTRACT This study investigates the effect of solvent properties on the structural morphology and permeation properties of polysulfone/β-cyclodextrin polyurethane (PSf/β-CDPU) mixed-matrix membranes (MMMs). The membranes were prepared by a modified phase-inversion route using four different casting solvents [dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), dimethyl acetamide (DMA), and N-methyl-2-pyrrolidone (NMP)]. While DMSO-based membranes demonstrated particularly high permeability (ca 147 L/m2h.bar), their crystallinity was low compared to MMMs prepared using DMA, DMF and NMP due to the formation of thin active layers on their surfaces. Cross-sectional morphology revealed that the MMMs have a dense top skin with finger-like inner pore structures. Membranes prepared using NMP displayed the highest hydrophilicity, porosity, and crystallinity due to the low volatility of NMP; DMF membranes exhibited superior mechanical and thermal stability due to its (DMF) high hydrogen bonding (δ H) values. Thus, the morphological parameters, bulk porosity, and flux performance of MMMs have a significant inter-relationship with the solubility properties of each solvent (i.e., δ H, density, volatility, solubility parameter). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2005-2014, 2013 [ABSTRACT FROM AUTHOR]

Abstract: This paper discusses the solute and structural properties of polysulfone (PSf)/β-cyclodextrin (β-CD) polyurethane (PU) mixed-matrix membranes. Relative to a commercial PSf membrane, β-CD polyurethane (β-CDPU) was blended with PSf at concentration levels of 0–10% to prepare mixed-matrix membranes using a convectional phase-inversion technique. The surface morphology and the porous structure were evaluated by scanning electron microscopy (SEM). Dynamic mechanical analysis was used to determine the mechanical stability (stiffness) of the membranes: mixed-matrix membranes (MMMs) were found to be mechanically stable even at elevated temperatures (30–350°C). Pure water sorption results show a Fickian diffusion mode mechanism for the PSf membrane (n=0.50), PSf/5% β-CDPU shows an anomalous transport mechanism (n=0.80) while the PSf/8 %β-CDPU and PSf/10% β-CDPU membranes followed a non-Fickian diffusion mode (n=1.1). Pure water permeability and glucose rejection characteristics were carried out using a cross-flow system. These results reveal that pure water and solute permeability increase with an increase in pressure. The hydrophilicity and surface energy of the MMMs were determined using a sessile-drop (contact-angle) method. Mixed-matrix PSf/β-CDPU membranes were found to be more hydrophilic (<49°) compared to the PSf membrane in the case of PSf/5% β-CDPU, while for 8 and 10% PSf/β-CDPU the contact angle values did not differ significantly (60–66°). Higher pure water permeability and glucose rejection of up to 99.88% was also obtained. This study demonstrates that the crystal structure of MMMs lacks sorption sites to allow high mass transfer of water and glucose molecules through the membranes which resulted in higher glucose rejection. [Copyright &y& Elsevier]

Abstract: This work presents the preparation and characterization of polysulfone (PSf)/β-cyclodextrin (β-CD) polyurethane composite membranes using a modified phase inversion technique. β-CD polyurethane was blended with PSf at concentrations of 0–10% to prepare nanofiltration (NF) membranes for selective removal of Cd2+ ions from water at a working pH of 6.9. Mixed matrix β-CD polyurethane/PSf membranes were more hydrophilic with higher water permeability and higher Cd2+ rejection (up to 70%). However, the mixed matrix membranes were also rougher, less porous, took up more water, and were less mechanically stable. Further, FT-IR results indicate hydrogen bonding interactions between β-CD polyurethane and PSf, which suggests that the materials are compatible. Dead-end filtration tests suggest that mixed matrix membranes have higher water flux. This suggests that the combination of β-CD polyurethane with PSf can produce viable nanofiltration with improved flux without a compromise on its rejection ability. [Copyright &y& Elsevier]