Removal of chromium (VI) ions from polluted water using kaolinite-supported Fe/Al oxide(hydroxide) composite nanoadsorbents

Hexavalent chromium (Cr (VI)) contamination of surface and groundwater has become a major environmental concern owing to the diverse applications of Cr(VI)) in several industries. In the current study kaolinite-supported and size-controlled Fe/Al oxide(oxyhydroxide) nanocomposites (Kaolinite@Fe/Al nanocomposites) were synthesized for efficient removal of Cr(VI) from aqueous solution. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) analysis of the nanocomposites revealed that the nanocomposites were uniformly dispersed, with an average particle size of ~ 25 nm. Batch adsorption studies were carried out to study the effect of (Kaolinite@Fe/Al nanocomposites) on the removal of chromium (VI) from 100 mg/L Cr(VI) contaminated water over a wide pH range (3–10) at various adsorbent dosages. The result demonstrated that the nanocomposites’ adsorption efficiency increased with increasing adsorbent dosage. When the Kaolinite@Fe/Al nanocomposites dosage was increased from 1.0 to 3.0 g/L, the Cr(VI) removal percentage increased from 65.4 % to ∼99.0 %. This is due to the greater surface area and availability of more adsorption sites at higher dosages of the adsorbent. There was a significant removal of Cr(VI) in the pH range 3–6 reaching up to 99.0% Cr(VI) removal, however, removal efficiency decreased drastically beyond pH 6. Chromium (VI) exists as CrO4 2−, HCrO4 − and Cr2O7 2− oxyanionic species while the surface of the adsorbent becomes highly protonated, owing to the variable surface charge imparted by Al/Fe oxides/hydroxides favouring remarkable uptake of Cr(VI) in the anionic form. The experimental data fitted Langmuir adsorption model well with a maximum adsorption capacity of 70.71 mg/g. The results of the study demonstrate that Kaolinite@Fe/Al nanocomposites may have a promising potential for remediation of Cr(VI) contaminated wastewater and industrial effluents.The Water Research Commission (WRC) grant for externally funded Postdoctoral Fellowship and the National Research Foundation (NRF) of South Africa.http://www.aidic.it/cetam2023Chemical Engineerin

Adsorption of As (III) from contaminated water on activated carbon-supported nanoscale zero-valent iron particles

Arsenic (As) contamination is a major concern due to its toxicity and tendency to accumulate and bio-magnify within the food chain, causing wider damage to the ecosystem. In the current study, activated carbon-supported nanoscale zerovalent iron (AC-nZVI) particles, were produced using chemical reduction of ferric chloride hexahydrate in the presence of activated carbon as a scaffold to avoid agglomeration and improve their dispersity. Detailed transmission electron microscopy (TEM), and scanning electron microscopy (SEM) characterization of the as-synthesized nanoparticles showed monodispersed nanoparticles of approximate size 45 ±10 nm. Their potential application for removal of As(III) from contaminated water was investigated in batch adsorption experiments at various adsorbent dosages and pH values. The results of the study demonstrated that AC-nZVI particles exhibited 82.5% removal of As (III) ions (initial concentration 100 mg/L) at an adsorbent dosage of 2 g/L. The adsorption performance increased with increasing adsorbent dosage and removed 99% As(III) at an adsorbent dosage of 5g/L. The Langmuir and Freundlich adsorption models were fitted to the experimental data, and it was found that the Langmuir isotherm fitted the data better than the Freundlich isotherm with a maximum adsorption capacity of 27.83 mg/g of adsorbent. In the current study As(III) exists predominately as uncharged species H3AsO30 under the designed pH range of 4-8, therefore the effects of solution pH on As (III) adsorption were hardly observed. The results of the study demonstrated that activated carbon-supported zerovalent iron particles can have tremendous potential application for the effective removal of As(III) from industrial wastewaters.http://www.aidic.it/cetam2023Chemical Engineerin

Dopaminergic drugs and the risk of hip or femur fracture: a population-based case–control study

SUMMARY: The effect of dopaminergic medication on the risk of hip/femur fractures is not clear. Our results showed a nearly twofold increased risk of hip/femur fractures in current dopaminergic drug users. Concomitant use of antidepressants further increased this risk. Fracture risk assessment may be warranted in elderly users of dopaminergic drugs. INTRODUCTION: Dopaminergic drugs, often used in the treatment of Parkinson's disease, have several pharmacological effects that may increase or decrease the risk of falling and fractures. Thus, the effect of dopaminergic medication on the risk of hip/femur fractures is not clear. The objective of the study was to examine the effect of dopaminergic medication and concomitant use of psychotropics on the risk of hip/femur fractures taking into account the timing of dopaminergic drug use. METHODS: A population-based case-control study in the PHARMO database was conducted for the period 1991 to 2002. Cases were patients aged 18 years and older with a first hip or femur fracture and matched to four control patients by year of birth, sex and geographical region. RESULTS: The study population included 6,763 cases and 26,341 controls. Current use of dopaminergic drugs (1-30 days before the index date) was associated with an increased risk of hip/femur fractures compared to never use (OR(adj) 1.76, 95% CI = 1.39-2.22), but this excess risk rapidly dropped to baseline levels when treatment had been discontinued >1 year ago. Concomitant use of antidepressants among current dopaminergic drug users further increased the risk of hip/femur fractures (OR(adj) 3.51, 95% CI = 2.10-5.87) while there was no additional risk with concomitant use of other psychotropics. CONCLUSIONS: Although the observed association between dopaminergic drugs and fracture risk may not be entirely causal, due to absence of information on the (severity of the) underlying disease, fracture risk assessment may be warranted in elderly users of dopaminergic drugs

Hyper-IgG4 disease: report and characterisation of a new disease

BACKGROUND: We highlight a chronic inflammatory disease we call 'hyper-IgG4 disease', which has many synonyms depending on the organ involved, the country of origin and the year of the report. It is characterized histologically by a lymphoplasmacytic inflammation with IgG4-positive cells and exuberant fibrosis, which leaves dense fibrosis on resolution. A typical example is idiopathic retroperitoneal fibrosis, but the initial report in 2001 was of sclerosing pancreatitis. METHODS: We report an index case with fever and severe systemic disease. We have also reviewed the histology of 11 further patients with idiopathic retroperitoneal fibrosis for evidence of IgG4-expressing plasma cells, and examined a wide range of other inflammatory conditions and fibrotic diseases as organ-specific controls. We have reviewed the published literature for disease associations with idiopathic, systemic fibrosing conditions and the synonyms: pseudotumour, myofibroblastic tumour, plasma cell granuloma, systemic fibrosis, xanthofibrogranulomatosis, and multifocal fibrosclerosis. RESULTS: Histology from all 12 patients showed, to varying degrees, fibrosis, intense inflammatory cell infiltration with lymphocytes, plasma cells, scattered neutrophils, and sometimes eosinophilic aggregates, with venulitis and obliterative arteritis. The majority of lymphocytes were T cells that expressed CD8 and CD4, with scattered B-cell-rich small lymphoid follicles. In all cases, there was a significant increase in IgG4-positive plasma cells compared with controls. In two cases, biopsies before and after steroid treatment were available, and only scattered plasma cells were seen after treatment, none of them expressing IgG4. Review of the literature shows that although pathology commonly appears confined to one organ, patients can have systemic symptoms and fever. In the active period, there is an acute phase response with a high serum concentration of IgG, and during this phase, there is a rapid clinical response to glucocorticoid steroid treatment. CONCLUSION: We believe that hyper-IgG4 disease is an important condition to recognise, as the diagnosis can be readily verified and the outcome with treatment is very good

Biosurfactant enhanced bioremediation of polycyclic aromatic hydrocarbon contaminated environmental media

Polycyclic aromatic hydrocarbons (PAHs) are a diverse class of toxicants that are ubiquitously and persistently present in the environment. These compounds present a risk for human health and the environment, as they are mutagens, carcinogens and teratogens. Bioremediation has shown promise as a potentially effective and low-cost treatment option, but concerns about the slow process rate and bioavailability limitations have hampered more widespread use of this technology. In the fundamental work of this thesis a series of experiments was designed utilizing the biosurfactant produced by Pseudomonas aeruginosa LBP5, LBP9 and CB1. Specifically, these experiments were designed to determine if the presence of various levels of partially purified biosurfactants produced by the isolates, would affect the degradation of a range of PAHs. The biodegradation and biotransformation of PAHs were studied in three bioremedial systems: soil slurry, liquid culture experiments with enriched consortium on PAHs from petroleum contaminated sites and Bioslurry reactor study with autochthonous consortium. Biosurfactant-producing and polycyclic aromatic hydrocarbon degrading microorganisms were isolated from petroleum-contaminated crane service station soil and creosote contaminated wood treatment plant soils in Pretoria area. Bacterial isolates LBP9 and LBP5 isolated from crane service station soil and isolates CB1, CN2, CN3, CN5 isolated from creosote contaminated soil were found to be the most efficient biosurfactant producing strains. The biosurfactant produced by the strains LBP9, LBP5 and CB1 were extracted and characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR FTIR) and Thin layer chromatography (TLC). Evaluation of the ability of the LBP9 biosurfactant for applications in enhancing biodegradation of mixed polycyclic aromatic hydrocarbons (PAHs) with a consortium of bacteria indicated that the biosurfactant was able to enhance the removal of significant amount of PAHs from the liquid culture medium at different concentrations. In this study at 400 mg/L amendment of lipopeptide the solubility of Phenanthrene, Fluoranthene and Pyrene was increased to 19.4, 33 and 45.4 times their aqueous solubility, respectively, and the extent of substrate utilization rate of the PAHs was enhanced up to 3 fold in the sole substrate microcosms. A second goal of these experiments was to discern the efficacy of exogenous lipopeptide application and stimulation of in situ biosurfactant production through biostimulation / nutrient amendments in the removing of polycyclic aromatic hydrocarbons (PAH) from creosote PAH contaminated soil. This work also suggests that it may be more practical to stimulate indigenous biosurfactant production within a soil than to add pre-purified compound. In general, the results presented in the studies show the potential of biosurfactants in assisting the bioremediation of polycyclic aromatic hydrocarbon contaminated environmental media in a reasonable timeframe.Dissertation (MEng)--University of Pretoria, 2015.tm2015Chemical EngineeringMEngUnrestricte

Fabrication and Application of Ag, Black TiO2 and Nitrogen-Doped 3D Reduced Graphene Oxide (3D Black TiO2/Ag/N@rGO) Evaporator for Efficient Steam Generation

The scarcity of fresh water, which is aggravated by rapid economic development and population growth, is a major threat to the modern world. Solar-driven interfacial desalination and steam generation is a promising strategy that localizes heat at the air-water interface through appropriate thermal management and demonstrates efficient photothermal performance. In the current study, Ag, black TiO2, and nitrogen-doped 3D reduced graphene oxide (3D black TiO2/Ag/N@rGO) hierarchical evaporator was fabricated, and its morphology, elemental composition, porosity, broadband solar absorption potential, photothermal performance, and interfacial desalination potential were assessed. The 3D solar evaporator showed efficient solar absorption over the entire broadband UV-visible near-infrared (UV-Vis NIR) region and demonstrated 99% photothermal conversion efficiency and potential freshwater generation of 1.43 kg·m−2 h−1. The specific surface area and porosity analyses demonstrated an ultrahigh specific surface area, high pore volume, and a mesoporous structure, with a predominant pore diameter of 4 nm. The strong photothermal performance can be attributed to the nitrogen doping of the rGO, which boosted the electrocatalytic and photothermal activity of the graphene through the activation of the excess free-flowing π electrons of the sp2 configuration of the graphene; the broadband solar absorption potential of the black TiO2; and the localized surface plasmon resonance effect of the AgNPs, which induced hot electron generation and enhanced photothermal conversion. Hence, the high photothermal conversion efficiency attained can be attributed to the synergistic photothermal performances of the individual components and the high interfacial surface area, abundant heat, and mass transfer microcavities of the 3D hierarchical porous solar absorber, offering multiple reflections of light and enhanced solar absorption. The study highlights the promising potential of the 3D evaporator for real-word interfacial desalination of seawater, helping to solve the water shortage problem sustainably

Biosurfactant assisted bioremediation of petroleum and polycyclic aromatic hydrocarbons in aquatic and soil media

Petroleum hydrocarbons are organic pollutants of major concern due to their wide distribution, persistence, complex composition, and toxicity. They can bioaccumulate in food chains where they disrupt biochemical or physiological activities and can affect genetic integrity of many organisms, resulting in carcinogenesis, mutagenesis and impairment of reproductive capacity. Polycyclic aromatic hydrocarbons (PAHs) have been recognized as priority pollutants due to their carcinogenic, mutagenic and teratogenic properties. Bioremediation, which utilizes the metabolic versatility of microorganisms such as bacteria and fungi to degrade or detoxify hazardous wastes into harmless substances has been recognized as a sustainable, economic, environmentally friendly and versatile alternative for the remediation of many contaminated environments; however its effectiveness is limited by low bioavailability of nonaquous phase and soil-bound PAHs and petroleum hydrocarbons due to their low aqueous solubility, high hydrophobicity and strong sorption to soil. The purpose of this study was to investigate the PAHs and petroleum hydrocarbons bioavailability and subsequent biodegradation enhancement potential of biosurfactants. Biosurfactants have steadily gained increased significance in environmental applications such as bioremediation dueto several advantages over surfactants of chemical origin, such as biodegradability, environmental compatibility, low toxicity, high selectivity and specific activity at extreme temperature, pH and salinity. A series of experiments was designed to investigate the bioavailability and subsequent biodegradation enhancement potential of the biosurfactants produced by the bacterial strains Bacillus subtilis CN2, Ochrobactrum intermedium CN3, Paenibacillus dendritiformis CN5 and Bacillus cereus SPL_4 in liquid culture and soil microcosms with PAH-enriched microbial consortium from chronically contaminated sites. The biosurfactants exhibited a high level of thermal stability, tolerance to extreme levels of salinity and a positive effect for increasing pH. They were identified after Fourier Transform Infrared (FT-IR) spectrometry, Thin Layer Chromatography (TLC) and Liquid Chromatography/Tandem Mass Spectrometry (LC MS/MS) analyses. The biosurfactants physicochemical characterization displayed vast structural diversity and potent surface active properties of surface tension reduction and emulsion formation with a range of hydrocarbons. The lipopeptide biosurfactants produced by CN3 and CN2 enhanced degradations of used motor oil and petroleum sludge in liquid culture. In a shake flask pyrene degradation study, lipopeptide supplementations at 600 and 300 mg L-1 enhanced pyrene degradation to 83.5% and 67% respectively in 24 days compared to 16% degradation in its absence. However, degradation of pyrene was reduced to 57% as the lipopeptide supplementation was raised to 900 mg L 1. This demonstrates that the biodegradation of pyrene was found to increase with an increase in the lipopeptide concentration up to a threshold level. In a soil bioremedial study, microcosms supplemented with 0.2 and 0.6% (w/w) lipopeptide, 51.2% of 4-ring and 55% of 5- and 6-ring PAHs, 64.1% of 4-ring and 79% of 5- and 6-ring PAHs were removed respectively, compared to, 29% of 4-ring and 25.5% of 5- and 6-ring PAHs removal in the surfactant free control after 64 days of incubation. However, there was no statistically significant change in the degradation rates of low molecular weight PAHs in surfactant amended and surfactant free controls. The degradation of 5 and 6 ring PAHs was significantly enhanced (p < 0.05) in the higher surfactant dosage compared to the lower dosage. The results of this work demonstrated that the use of biosurfactants is a viable option to reduce clean-up time and for effective remediation of soil and aqueous media contaminated with polycyclic aromatic and petroleum hydrocarbons. The study demonstrated potential applications of microbial surfactants and provided an insight for further investigation of their large scale production for commercial applications.Thesis (PhD)--University of Pretoria, 2016.Chemical EngineeringPhDUnrestricte

Pulmonary Sarcoidosis following Etanercept Treatment for Ankylosing Spondylitis: A Case Report and Review of the Literature

Antitumor necrosis factor therapies have revolutionized the treatment of some inflammatory diseases. However, the use of these agents is associated with the development of many paradoxical autoimmune diseases. Less well-recognized is the association with sarcoidosis. We report a 55-year-old female with long-standing ankylosing spondylitis who developed persistent dry cough and dyspnea while receiving etanercept therapy. High-resolution computed tomography scanning showed mediastinal lymphadenopathy and multiple nodules in both lung fields developed two months after the administration of etanercept. Lymph node biopsy was not practicable. Histopathological examination of minor salivary gland biopsy revealed noncaseating granulomata, and the serum angiotensin-converting enzyme was very elevated. All infectious studies were negative. Etanercept was discontinued plus a course of corticosteroids with a clinical improvement, and a follow-up high-resolution computed tomography scanning 4 months later showed evident regression of mediastinal lymph nodes and pulmonary nodules. Potential pathogenic mechanisms of this paradoxical effect of tumor necrosis factor-alpha blocking agents are discussed