The removal of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) from aqueous solutions using agro-waste biomass of Vitis vinifera (grape) leaf litter was studied. Activated carbons were produced from the biomass and chemical activation achieved by using phosphoric acid (HPO) and potassium hydroxide (KOH) for the modification of the carbons' surface morphology. Activated carbons were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy and Brunauer-Emmett-Teller (BET) in order to understand removal mechanisms of the contaminants by activated carbons. The effect of solution concentration, pH, adsorbent dosage, contact time and temperature was evaluated to optimize the removal efficiency of activated carbons. Adsorption isotherm models were used to analyse the equilibrium data obtained, and kinetic models were applied to study sorption mechanisms. The results fitted well into Freundlich isotherm with both AC-KOH and AC-HPO having high K values. Maximum adsorption capacities for AC-HPO were 78.90 and 75.13 mg/g for PFOA and PFOS, respectively. Equilibrium was reached before 60 min on both adsorbents, and thermodynamic studies indicated that the process was exothermic and spontaneous. Surface morphology showed the abundance of microspores (>60%) with BET total surface area of 295.488 and 158.67 m/g for AC-HPO and AC-KOH activated carbons, respectively. Removal efficiencies were 95 and 90% for PFOA using AC-HPO and AC-KOH, respectively; corresponding values for PFOS were 94 and 88%. Adsorbents' removal capacities depended on the physicochemical characteristics of adsorbents.
Background: There is limited data on the association between diarrhoea among children aged under five years (U5D) and water use, sanitation, hygiene, and socio-economics factors in low-income communities. The study investigated U5D and the associated risk factors in the Zeekoe catchment in Cape Town, South Africa. Methods: A cross-sectional study was conducted in 707 households in six informal settlements (IS) two formal settlements (FS) (March–June 2017). Results: Most IS households used public taps (74.4%) and shared toilets (93.0%), while FS households used piped water on premises (89.6%) and private toilets (98.3%). IS respondents had higher average hand-washing scores than those of FS (0.04 vs. −0.14, p = 0.02). The overall U5D prevalence was 15.3% (range: 8.6%–24.2%) and was higher in FS than in IS (21.2% vs. 13.4%, respectively, p = 0.01). Water storage >12 h was associated with increasing U5D (OR = 1.88, 95% CI 1.00–3.55, p = 0.05). Water treatment (OR = 0.57, 95%CI 0.34–0.97, p = 0.04), good hand-washing practices (OR = 0.59, 95%CI 0.42–0.82, p = 0.002) and Hepatitis A vaccination (OR = 0.51, 95%CI 0.28–0.9, p = 0.02) had significant preventing effects on U5D. Conclusions: The study highlights that good hygiene practice is a key intervention against U5D in informal settlements. The promotion of hand-washing, proper water storage, and hygienic breastfeeding is highly recommended.
In this study, an analytical method for the routine determination of nine perfluorinated compounds (PFCs), using ultra performance liquid chromatography coupled to a quadrupole time-of-flight mass spectrometer (UPLC-QTOF-MS), was developed, validated, and used for their assay in surface water and sediments. The method yielded good linearity with a correlation coefficient (R) ranging between 0.991 and 0.999 for all the compounds investigated. Limits of detection (LOD) ranged between 0.02 and 0.08 ng/l, while the limit of quantification (LOQ) ranged from 0.065 to 0.261 ng/l. Recovery studies were carried out in replicate assays, and percentage recoveries ranged between 56 and 112% for the nine perfluorinated compounds investigated. The method was applied to determine levels of perflurooctanoic acid (PFOA) and PFOS in surface water and sediment samples collected along the Plankenburg River in Stellenbosch, South Africa. Samples were pre-treated, extracted, and cleaned up via offline solid-phase extraction (SPE) procedures, using hydrophilic-lipophilic balance (HLB) C-18 cartridges. Levels of PFOA and PFOS found in surface water ranged between (12.8 ± 4.24 and 62.62 ± 4.86 ng/l) and (
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