Effect of TiO2 phase on the photocatalytic degradation of methylene blue dye

Please read abstract in the article.The National Research Foundation of South Africa and the University of Pretoria's Research Development Programme (RDP).http://www.elsevier.com/locate/pce2021-12-29hj2021Chemical Engineerin

Eco-friendly removal of methylene blue from aqueous medium using low cost sawdust-biochar adsorbent

This study reports on the facile synthesis and viability of sawdust-derived-biochar adsorbent for the effective removal of methylene blue dye pollutant from aqueous medium. The crystallinity, morphology and surface functional groups of the synthesised materials were determined using XRD, SEM and FTIR characterisation techniques. The adsorption efficiency of sawdust biochar was investigated by observing the removal of methylene blue dye (MB) from an aqueous system while varying process parameters like the adsorbent loading and initial concentration. Results showed that the sawdust biochar achieved remarkable removal of 98.7 % MB in 90 minutes and a complete removal after 120 minutes. The adsorption kinetics were best described by the pseudo-first-order kinetics model and had a R2 value higher than 0.97. Additionally, the Langmuir adsorption isotherm model, which points to monolayer adsorption, fit the results best and showed the material to have an adsorption capacity of 151.3 mg/g. Finally, the results obtained from this study depicts the efficiency of sawdust biochar in the removal of organic dye and points a way forward in achieving zero pollution and a toxic-free environment.http://www.aidic.it/cetam2023Chemical Engineerin

Palladium phytoremediation and phytomining potential of vetiver grass (Chrysopogon zizanioides)

Levels of palladium in the environment are on the rise due to anthropogenic activities. There is a need to remediate contaminated environments, while also recovering the precious metal (Pd(II)) in a cost-effective and environmentally friendly manner. The leading contributor of Pd and other catalytic metal pollution in the environment is the automotive industry where platinum group metals (PGMs) are used in catalytic converters. Recently, there is renewed interest in platinum and other PGMs due to their use in the cathode of fuel cells for hydrogen generation. In this study, the phytomining and phytoremediation potential of vetiver grass (Chrysopogon zizanioides) was investigated by assessing its removal and accumulation of Pd, and its tolerance towards elevated Pd concentrations. Vetiver grass was grown in Pd solutions with concentrations ranging from 10 – 120 ppm. The grass was harvested after a period of 20 d and separated into roots and shoots. The removal efficiency of Pd ranged from 80 % at 10 ppm initial concentration to 20 % at 120 ppm. The removal of Pd from the solution and accumulation in the plant was influenced by the initial Pd concentration. The highest accumulation achieved was 0.4 mg g-1 dry weight (DW) in the roots at 120 ppm. Low translocation factors < 1 suggested that Pd was mainly kept in the roots of vetiver grass. The toxicity of Pd to vetiver grass was observed at concentrations 20 ppm as demonstrated by the reduced growth and drying up of the aerial biomass of the grass. The results revealed that vetiver grass may have potential in the phytoremediation and recovery of palladium for reuse by burning and reprocessing of ash.The National Research Foundation of South Africa.http://www.aidic.it/cetam2023Chemical Engineerin

Plasmonic effect and bandgap tailoring of Ag/Ag2S doped on ZnO nanocomposites for enhanced visible-light photocatalysis

Please read abstract in the article.The National Research Foundation of South Africa and Sedibeng Water Chair.http://www.elsevier.com/locate/apt2023-05-04hj2023Chemical Engineerin

Photocatalytic activity of visible-light-driven ternary Ag/Ag2S/ZnO nanocomposites for phenol degradation in water

Silver sulphide (Ag2S) and zinc oxide (ZnO) nanoparticles were synthesized through a sol-gel method. The Ag constituent of the ternary was achieved by photodesposition of the binary Ag2S/ZnO resulting in a color change from brownish grey to purple indicating its formation. The synthesised particles were characterised using Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Energy-dispersive X-ray spectroscopy (EDX) to confirm its elemental presence and morphology. The crystallinity of the nanoparticles was determined using the X-ray diffractometer (XRD), and Brunauer–Emmett–Teller (BET) analysis surface area was 4.95 m2 g-1. The progressive degradation of phenol was analysed and results showed that under visible light, the ternary composite Ag/Ag2S/ZnO, exhibited the highest phenol degradation efficiency (95 %) compared to the constituent compounds, ZnO (37 %) and Ag2S/ZnO (83 %) after 6 h of visible light irradiation respectively. However, investigations have revealed that extrinsic factors such as pH of the solution, the initial concentration of phenol and photocatalyst dosage could significantly affect the overall system performance.https://www.cetjournal.it/index.php/cetpm2021Chemical Engineerin

Facile synthesis and characterisation of nanosized ZnO modified with Ag2S for visible-light-induced phenol degradation

This study investigates the synthesis, characterisation, and application of a visible-light activated binary nanocomposite catalyst for the degradation of phenol in water. Zinc oxide with a wide direct band gap (3.4 eV) is efficient under ultraviolet irradiation but shows less activity under visible light. Therefore, a sol-gel method was applied to modify it using silver sulphide whose band gap is much lower (1.1 eV) to shift the photosensitivity of the composite catalyst towards the visible light spectrum. The synthesised nanoparticles were characterised using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction which confirmed the purity of the synthesised material. At a catalyst loading of 1 gL-1, results showed that under visible light, the binary composite Ag2S/ZnO exhibited the highest phenol degradation efficiency of 50 % which was greater than ZnO that recorded a 16 % removal after 210 minutes of irradiation. These results support further development and application of visible-light-induced catalysts for photocatalytic degradation.https://www.cetjournal.it/index.php/cetpm2021Chemical Engineerin

Enterobiasis and strongyloidiasis and associated co-infections and morbidity markers in infants, preschool- and school-aged children from rural coastal Tanzania: a cross-sectional study.

Background. There is a paucity of data pertaining to the epidemiology and public health impact of Enterobius vermicularis and Strongyloides stercoralis infections. We aimed to determine the extent of enterobiasis, strongyloidiasis, and other helminth infections and their association with asymptomatic Plasmodium parasitaemia, anaemia, nutritional status, and blood cell counts in infants, preschool-aged (PSAC), and school-aged children (SAC) from rural coastal Tanzania.MethodsA total of 1,033 children were included in a cross-sectional study implemented in the Bagamoyo district in 2011/2012. Faecal samples were examined for intestinal helminth infections using a broad set of quality controlled methods. Finger-prick blood samples were subjected to filariasis and Plasmodium parasitaemia testing and full blood cell count examination. Weight, length/height, and/or mid-upper arm circumference were measured and the nutritional status determined in accordance with age.Results E. vermicularis infections were found in 4.2% of infants, 16.7%, of PSAC, and 26.3% of SAC. S. stercoralis infections were detected in 5.8%, 7.5%, and 7.1% of infants, PSAC, and SAC, respectively. Multivariable regression analyses revealed higher odds of enterobiasis in children of all age-groups with a reported anthelminthic treatment history over the past six months (odds ratio (OR): 2.15; 95% confidence interval (CI): 1.22 - 3.79) and in SAC with a higher temperature (OR: 2.21; CI: 1.13 - 4.33). Strongyloidiasis was associated with eosinophilia (OR: 2.04; CI: 1.20-3.48) and with Trichuris trichiura infections (OR: 4.13; CI: 1.04-16.52) in children of all age-groups, and with asymptomatic Plasmodium parasitaemia (OR: 13.03; CI: 1.34 - 127.23) in infants. None of the investigated helminthiases impacted significantly on the nutritional status and anaemia, but moderate asymptomatic Plasmodium parasitaemia was a strong predictor for anaemia in children aged older than two years (OR: 2.69; 95% CI: 1.23 ¿ 5.86).Conclusions E. vermicularis and S. stercoralis infections were moderately prevalent in children from rural coastal Tanzania. Our data can contribute to inform yet missing global burden of disease and prevalence estimates for strongyloidiasis and enterobiasis. The association between S stercoralis and asymptomatic Plasmodium parasitaemia found here warrants further comprehensive investigations