Effect of hexavalent chromium on the environment and removal techniques: A review.

Despite the importance of chromium (Cr) in most anthropogenic activities, the subsequent environmental adulteration is now a source of major concern. Cr occurs in numerous oxidation states, with the furthermost stable and frequently occur states being Cr(0), Cr(III) and Cr(VI). Cr(0) and Cr(III) are vital trace elements while Cr(VI) is dispensable and noxious to living organisms. Predominantly in plants, Cr at low concentrations of about 0.05-1 mg/L assist to boost growth as well as increase productivity. However, accumulation of Cr could represent a potential threat to living organisms. Cr absorption, displacement and accretion depend on its speciation, which also determines its toxicity which is often diverse. Indications of its toxicity include; reduction of seed germination, retardation of growth, reduction of yield, inhibition of enzymatic activities, weakening of photosynthesis, nutrient, oxidative disparities and genetic mutation in plants as well as several injurious diseases in animals and humans. In this study, we have presented a comprehensive review as well as an informative account of the influence of Cr on the environment drawn from researches carried out over the years following an analytical approach. Uniquely, this work presents a review of the effects and remediation of Cr from soil and wastewater drawn from several evidence and meta-data-based articles and other publications. Accordingly, the write-up is intended to appeal to the consciousness of the general public that the significance of Cr notwithstanding, its environmental toxicity should not be taken for granted.

Prediction and optimizing of methylene blue sequestration to activated charcoal/magnetic nanocomposites using artificial neutral network and response surface methodology.

Green synthesized magnetic nanoparticles (MNPs) linked with activated charcoal (AC) (AC/Fe3O4 NCs) were exploited for methylene blue (MB) confiscation in this study. The AC/Fe3O4 NCs produced were characterized using TEM, FTIR, UV/Vis and XRD spectrometry. The Response-Surface-Methodology (RSM) was utilized to improve the experimental data for the MB sorption to AC/Fe3O4 NCs, with 20 experimental runs implemented through a central composite design (CCD) to assess the effect of sorption factors-initial MB concentration, pH and sorbent dosage effects on the response (removal-effectiveness). The quadratic model was discovered to ideally describe the sorption process, with an R2 value of 0.9857. The theoretical prediction of the experimental data using the Artificial-Neural-Network (ANN) model showed that the Levenberg-Marquardt (LM) had a better performance criterion. Comparison between the modelled experimental and predicted data showed also that the LM algorithm had a high R2 of 0.9922, which showed NN model applicability for defining the sorption of MB to AC/Fe3O4 NCs with practical precision. The results of the non-linear fitting (NLF) of both isotherm and kinetic models, showed that the sorption of MB to AC/Fe3O4 NCs was perfectly described using the pseudo-second-order (PSOM) and Freundlich (FRHM) models. The estimated optimum sorption capacity was 455 mg g-1. Thermodynamically, the sorption of MB to AC/Fe3O4 NCs was shown to be non-spontaneous and endothermic.

Fluoride ions sorption using functionalized magnetic metal oxides nanocomposites: a review.

Fluoride is an anionic pollutant found superfluous in surface or groundwater as a result of anthropogenic actions from improper disposal of industrial effluents. In drinking water, superfluous fluoride has been revealed to trigger severe health problems in humans. Hence, developing a comprehensive wastewater decontamination process for the effective management and preservation of water contaminated with fluoride is desirable, as clean water demand is anticipated to intensify considerably over the upcoming years. In this regard, there have been increased efforts by researchers to create novel magnetic metal oxide nanocomposites which are functionalized for the remediation of wastewater owing to their biocompatibility, cost-effectiveness, relative ease to recover and reuse, non-noxiousness, and ease to separate from solutions using a magnetic field. This review makes an all-inclusive effort to assess the effects of experimental factors on the sorption of fluoride employing magnetic metal oxide nanosorbents. The removal efficiency of fluoride ions onto magnetic metal oxides nanocomposites were largely influenced by the solution pH and ions co-existing with fluoride. Overall, it was noticed from the reviewed researches that the maximum sorption capacity using various metal oxides for fluoride sorption was in the order of aluminium oxides >cerium oxides > iron oxides > magnesium oxides> titanium oxides, and most sorption of fluoride ions was inhibited by the existence of phosphate trailed by sulphate. The mechanism of fluoride sorption onto various sorbents was due to ion exchange, electrostatic attraction, and complexation mechanism.

A Methodical Review on the Applications and Potentialities of Using Nanobiosensors for Disease Diagnosis.

Presently, with the introduction of nanotechnology, the evolutions and applications of biosensors and/or nanobiosensors are becoming prevalent in various scientific domains such as environmental and agricultural sciences as well as biomedical, clinical, and healthcare sciences. Trends in these aspects have led to the discovery of various biosensors/nanobiosensors with their tremendous benefits to mankind. The characteristics of the various biosensors/nanobiosensors are primarily based on the nature of nanomaterials/nanoparticles employed in the sensing mechanisms. In the last few years, the identification, as well as the detection of biological markers linked with any form of diseases (communicable or noncommunicable), has been accomplished by several sensing procedures using nanotechnology vis-à-vis biosensors/nanobiosensors. Hence, this study employs a systematic approach in reviewing some contemporary developed exceedingly sensitive nanobiosensors alongside their biomedical, clinical, or/and healthcare applications as well as their potentialities, specifically for the detection of some deadly diseases drawn from some of the recent publications. Ways forward in the form of future trends that will advance creative innovations of the potentialities of nanobiosensors for biomedical, clinical, or/and healthcare applications particularly for disease diagnosis are also highlighted.

Greenhouse Gas Emission: Perception during the COVID-19 Pandemic.

The period 2020/2021 was an unprecedented and historic time for industrial, economic, and societal activities all over the world with great challenges to human health, the ecosystems, and other aspects of human endeavors owing to the COVID-19 or SARS-CoV-2 (CV-19) pandemic which is now a topical aspect of research interest. Despite the negative impacts of the CV-19 pandemic, there are also positive reports during the CV-19 pandemic such as the reduction of gas flare, reduction in the burning of fossil fuels from automobile exhaust and a reduction in the other ensuing factors of greenhouse gases emissions (which is one of the major drives for global warming and climate change as well as other environmental effluences). Hence, this brief perspective review study is centered on greenhouse gas (GHG) emission. The study employs a methodical approach to analyze some already available research studies from existing publications and databases on GHG emission using the perception during the CV-19 pandemic. The specific findings from this review show that, from the meteorological perspective, the global response to the catastrophe ensuing from the CV-19 pandemic has a great influence on the reduction of GHGs, the reduction in the burning of fossil fuels from automobiles and industrial devices, and the reduction in the other ensuing factors of GHG emission. Hence, it will not be far from the truth to conclude that there is a possible positive connection between the CV-19 pandemic and GHG emissions. The study has a direct impact on the environment owing to the negative and positive environmental consequences of the CV-19 pandemic. Suggestions and recommendations in the form of future prospects of GHG emission vis-à-vis global warming and climate change are also discussed. Furthermore, suggestions on how to improve food security and agriculture during a pandemic such as the CV-19 outbreak period are highlighted.

Estudo comparativo das técnicas radiográficas e doses entre o Brasil e a Austrália / Comparative study of radiological techniques and doses between Brazil and Australia

OBJETIVO: O objetivo deste trabalho é fazer um estudo comparativo das técnicas radiográficas entre o Brasil e a Austrália e avaliar as doses de radiação para os exames radiológicos mais comuns. MATERIAIS E MÉTODOS: A dose de entrada na pele (DEP) e a dose efetiva (DE) foram obtidas com o uso do programa DoseCal. Em ambos os países, o estudo foi realizado em hospitais de grande porte da rede pública. Quatro tipos de exames foram avaliados: tórax, abdome, pelve e coluna torácica em três projeções (ântero-posterior, póstero-anterior e lateral). Na Austrália, todos os equipamentos são digitais e operam no sistema PACS. No Brasil, os aparelhos são convencionais. RESULTADOS: Os valores médios da DEP e da DE são consideravelmente mais altos no Brasil, exceto para os exames de tórax, cujos resultados indicaram índices menores. As maiores diferenças encontradas foram para os exames de pelve (26 vezes maior no Brasil) e de coluna torácica (43 vezes maior no Brasil). O mesmo acontece para os valores da DE. CONCLUSÃO: Nos hospitais australianos, os programas de controle e garantia de qualidade (PCGQ) fazem parte da rotina nos serviços de radiologia. Contam com equipamentos digitais de última geração e os serviços possuem uma equipe de física médica atuante. Esse conjunto de iniciativas resulta na produção de imagens radiográficas de alta qualidade, com baixas doses e índices de rejeição próximos a zero. Tais resultados apontam para a necessidade de se estimular a implantação de PCGQ em toda a rede hospitalar brasileira. No entanto, analisando os resultados de DEP nos exames de tórax, concluímos que doses baixas também são possíveis no Brasil se forem empregadas técnicas radiográficas adequadas.

OBJECTIVE: To compare radiological techniques used in Brazil and in Australia, and to evaluate radiation doses of the most common x-ray procedures. MATERIALS AND METHODS: The entrance skin dose (ESD) and the effective dose (ED) were obtained with the software DoseCal. In both countries the study was conducted in large public hospitals. Four distinct procedures were evaluated: chest, abdomen, pelvis and thoracic spine in three views (anterior-posterior, posterior-anterior and lateral) In Australia, all x-ray equipment are digital and linked with PACS whereas in Brazil conventional equipment is used. RESULTS: The mean values of ESD and ED were consistently higher in Brazil, except for chest x-rays. The higher differences were seen in pelvis (26 fold higher in Brazil) and thoracic spine (43 fold higher in Brazil) radiographs. CONCLUSION: All Australian hospitals have quality assurance programs (QAP) implemented on a permanent basis, the most advanced digital equipment and count with an effective medical physics service. These factors are determinant for high quality images, low rejection rates and low doses imparted to patients when compared to Brazilian standards. Theses results reinforce the need of implementation of quality assurance programs in Brazil. However, when analyzing the results of ESD for chest x-rays, we concluded that low doses can also be achieved in Brazil with the use of appropriate x-ray techniques.