Radiometric survey of sediments and health risk assessments from the southern coastal area of Delta State, Nigeria.

Over the years, the release of potential radiological components around the oil exploration environment has increased with potential health implications.Yet; the mechanism and health associated assessment have remained fuzzy to most experimental scientists. The current study determines the activity concentration of radionuclides in sediments and the corresponding health risk assessments from the hydrocarbon exploration environment of the southern coastal area of Delta State, Nigeria. A Sodium-iodide NaI(Tl) detector, with a well-calibrated multichannel analyzer (MCA) to ensure efficiency and energy was utilized. A total of seventy-five sediment samples (Five sediment samples each per community) were collected from the southern coastal area of Delta State, Nigeria. The mean activity concentrations of 40K, 238U, and 232Th of the sediment samples were 3361.48 ± 194.26 Bqkg-1, 40.11 ± 16.17 Bqkg-1, and 45.73 ± 19.27 Bqkg-1 respectively. The obtained mean values exceeded the world standard limit of 400 Bqkg-1, 35 Bqkg-1, and 30 Bqkg-1 respectively. Also, the computed mean radiological health hazard risk of radium equivalent activity (Raeq), representative level index (Iyr), external hazard index (Hex), internal hazard index (Hin), absorbed gamma dose rate (D), annual effective dose equivalent outdoor and indoor (AEDE) and lifetime cancer risk (ELCR) values are 363.94 ± 32.37 Bkgl-1, 2.9657 Bkgl-1, 0.9839, 1.0919, 175.82 nGyh-1, 2.1556 mSvyr-1, 0.8625 mSvyr-1, and 7.5447 mSvyr-1 respectively. The values were found to be slightly higher than the world standard limit. Therefore, the residents that are using the sediments of the southern coastal area for the construction of buildings as well as dwelling in houses built with such sediments are exposed to these radiological materials. This may pose a radiological health risk concern. The obtained results will serve as radiation and radiological baseline data for sediments of the southern coastal area of Delta State, Nigeria.

Application of coal fly ash based ceramic membranes in wastewater treatment: A sustainable alternative to commercial materials.

The continued increase in the global population has resulted in increased water demand for domestic, agricultural, and industrial purposes. These activities have led to the generation of high volumes of wastewater, which has an impact on water quality. Consequently, more practical solutions are needed to improve the current wastewater treatment systems. The use of improved ceramic membranes for wastewater treatment holds significant prospects for advancement in water treatment and sanitation. Hence, different studies have employed ceramic membranes in wastewater treatment and the search for low-cost and environmentally friendly starting materials has continued to engender research interests. This review focuses on the application of coal fly ash in membrane technology for wastewater treatment. The processes of membrane fabrication and the various limitations of the material. Several factors that influence the properties and performance of coal fly ash ceramic membranes in wastewater treatment are also presented. Some possible solutions to the limitations are also proposed, while cost analysis of coal fly ash-based membranes is explored to evaluate its potential for large-scale applications.

Photocatalytic degradation of tetracycline using surface defective black TiO2-ZnO heterojunction photocatalyst under visible light.

Fabrication of heterojunction and surface defective engineering, through the formation of oxygen vacancies, are among the various photocatalytic enhancement techniques. A combination of these techniques has the prospect of enhancing photocatalytic activities through improved light absorption capabilities and charge separation process of the photocatalysts. In this study, a heterojunction of black titanium oxide-zinc oxide (BTiO2-ZnO) nanocomposite was synthesized using the conventional sol-gel approach, coupled with aluminum foil-assisted NaBH4 reduction. The structure, morphology, surface properties, and optical characteristics of the synthesized material were studied using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), UV-vis absorption spectra, scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDS), and transmission electron microscope (TEM). The XRD confirmed the successful formation of BTiO2-ZnO heterostructure, while SEM revealed the structural morphology as pseudo-spherical with slight agglomeration. BTiO2-ZnO was found to be more efficient than BTiO2 and BZnO for the removal of tetracycline with degradation efficiencies of 63, 58, and 56 % respectively. The effects of process parameters such as the amount of photocatalyst, pollutant's concentration, and the initial solution pH on photocatalytic degradation study were systematically explored. The results confirm that the formation of the heterostructure from BTiO2 and BZnO could offer a facile route to improving the catalytic degradation of tetracycline. Therefore, this study offers a novel perspective on the design of efficient metal oxide photocatalyst systems that rely on the integration of defect engineering and heterojunction for the removal of organic contaminants.

Cascade perovskite single crystal for gamma-ray spectroscopy.

The halide lead perovskite single crystals (HLPSCs) have great potential in gamma-ray detection with high attenuation coefficient, strong defects tolerance, and large mobility-lifetime product. However, mobile halide ions would migrate under high external bias, which would both weaken the gamma-ray response and cause additional noise. Here, we report the gamma-ray PIN photodiodes made of cascade HLPSCs including both ion-formed and electron-hole-formed electrical junctions that could suppress the ions migration and improve the charges collection. Our photodiodes based on cascade HLPSCs (MAPbBr3/MAPbBr2.5Cl0.5/MAPbCl3) show a wide halide-ion-formed depletion layer of ∼52 µm. The built-in potential along the wide ionic-formed junction ensures a high mobility-lifetime product of 1.1 × 10-2 cm2V-1. As a result, our gamma-ray PIN photodiodes exhibit compelling response to 241Am, 137Cs, and 60Co; the energy resolution can reach 9.4%@59.5keV and 5.9%@662keV, respectively. This work provides a new path toward constructing high-performance gamma-ray detectors based on HLPSCs.

Pathological Role of Oxidative Stress in Aflatoxin-Induced Toxicity in Different Experimental Models and Protective Effect of Phytochemicals: A Review.

Aflatoxin B1 is a secondary metabolite with a potentially devastating effect in causing liver damage in broiler chickens, and this is mainly facilitated through the generation of oxidative stress and malonaldehyde build-up. In the past few years, significant progress has been made in controlling the invasion of aflatoxins. Phytochemicals are some of the commonly used molecules endowed with potential therapeutic effects to ameliorate aflatoxin, by inhibiting the production of reactive oxygen species and enhancing intracellular antioxidant enzymes. Experimental models involving cell cultures and broiler chickens exposed to aflatoxin or contaminated diet have been used to investigate the ameliorative effects of phytochemicals against aflatoxin toxicity. Electronic databases such as PubMed, Science Direct, and Google Scholar were used to identify relevant data sources. The retrieved information reported on the link between aflatoxin B1-included cytotoxicity and the ameliorative potential/role of phytochemicals in chickens. Importantly, retrieved data showed that phytochemicals may potentially protect against aflatoxin B1-induced cytotoxicity by ameliorating oxidative stress and enhancing intracellular antioxidants. Preclinical data indicate that activation of nuclear factor erythroid 2-related factor 2 (Nrf2), together with its downstream antioxidant genes, may be a potential therapeutic mechanism by which phytochemicals neutralize oxidative stress. This highlights the need for more research to determine whether phytochemicals can be considered a useful therapeutic intervention in controlling mycotoxins to improve broiler health and productivity.

Electrochemical detection of selected heavy metals in water: a case study of African experiences.

The safety of water resources throughout the globe has been compromised by various human activities and climate change over the last decades. Consequently, the world is currently confronted with a severe shortage of water supply and a water safety crisis, amidst a growing population. With poor environmental regulations, indiscriminate budding of urban slums, poverty, and a lack of basic knowledge of hygiene and sanitation, the African water supply has been critically threatened by different organic and inorganic contaminants, which results in several health issues. Inorganic pollutants such as heavy metals are particularly of interest because they are mostly stable and non-biodegradable. Therefore, they are not easily removed from water. In different parts of the continent, the concentration of heavy metals in drinking water far exceeds the permissible level recommended by the World Health Organization (WHO). Worse still, this problem is expected to increase with growing population, industrialization, urbanization, and, of course, corruption of government and local officials. Most of the African population is ignorant of the standards of safe water. In addition, the populace lack access to affordable and reliable technologies and tools that could be used in the quantification of these pollutants. This problem is not only applicable to domestic, but also to commercial, communal, and industrial water sources. Hence, a global campaign has been launched to ensure constant assessment of the presence of these metals in the environment and to promote awareness of dangers associated with unsafe exposure to them. Various conventional spectroscopic heavy metal detection techniques have been used with great success across the world. However, such techniques suffer from some obvious setbacks, such as the cost of procurement and professionalism required to operate them, which have limited their applications. This paper, therefore, reviews the condition of African water sources, health implications of exposure to heavy metals, and the approaches explored by various indigenous electrochemists, to provide a fast, affordable, sensitive, selective, and stable electrochemical sensors for the quantification of the most significant heavy metals in our water bodies.

Physico-chemical characteristics and cytotoxicity evaluation of CuO and TiO2 nanoparticles biosynthesized using extracts of Mucuna pruriens utilis seeds.

The green synthesis approach to nanoparticles has been widely received as an alternative to the conventional methods, specifically for applications in areas such as biology, agriculture and medicine, where toxicity is of great concern. In this study, copper oxide (CuO) and titanium oxide (TiO2) nanoparticles (NPs) were synthesized using an aqueous extract of Mucuna pruriens utilis seed. The morphology and structural characterization of the NPs were achieved by using scanning and transmission electron microscopy (SEM and TEM), and X-ray diffraction (XRD) measurement, while the elemental composition was studied using electron diffraction X-ray spectroscopy (EDS). A monoclinic phase of CuO and anatase phases of TiO2 with high crystallinity were confirmed from the diffraction patterns of the XRD. Both TEM and SEM micrographs of the CuO confirmed short rod-shaped nanostructure, while spherical morphologies were obtained for the TiO2 NPs. The EDS study indicated that the composition of the samples conformed with the identified products in the XRD and attest to the purity of the NPs. The nanoparticles exhibited a dose-dependent profile in MTT cytotoxicity assay with some cell specificity. However, the anticancer potential of these NPs was still lower than that of the standard anticancer drug, 5-fluorouracil.

Biogenic Synthesis of CuO, ZnO, and CuO-ZnO Nanoparticles Using Leaf Extracts of Dovyalis caffra and Their Biological Properties.

Biogenic metal oxide nanoparticles (NPs) have emerged as a useful tool in biology due to their biocompatibility properties with most biological systems. In this study, we report the synthesis of copper oxide (CuO), zinc oxide (ZnO) nanoparticles (NPs), and their nanocomposite (CuO-ZnO) prepared using the phytochemical extracts from the leaves of Dovyalis caffra (kei apple). The physicochemical properties of these nanomaterials were established using some characterization techniques including X-ray diffraction analysis (XRD), ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). The XRD result confirmed the presence of a monoclinic CuO (Tenorite), and a hexagonal ZnO (Zincite) nanoparticles phase, which were both confirmed in the CuO-ZnO composite. The electron microscopy of the CuO-ZnO, CuO, and ZnO NPs showed a mixture of nano-scale sizes and spherical/short-rod morphologies, with some agglomeration. In the constituent's analysis (EDX), no unwanted peak was found, which showed the absence of impurities. Antioxidant properties of the nanoparticles was studied, which confirmed that CuO-ZnO nanocomposite exhibited better scavenging potential than the individual metal oxide nanoparticles (CuO, and ZnO), and ascorbic acid with respect to their minimum inhibitory concentration (IC50) values. Similarly, the in vitro anticancer studies using MCF7 breast cancer cell lines indicated a concentration-dependent profile with the CuO-ZnO nanocomposite having the best activity over the respective metal oxides, but slightly lower than the standard 5-Fluorouracil drug.

Plant Extracts Mediated Metal-Based Nanoparticles: Synthesis and Biological Applications.

The vastness of metal-based nanoparticles has continued to arouse much research interest, which has led to the extensive search and discovery of new materials with varying compositions, synthetic methods, and applications. Depending on applications, many synthetic methods have been used to prepare these materials, which have found applications in different areas, including biology. However, the prominent nature of the associated toxicity and environmental concerns involved in most of these conventional methods have limited their continuous usage due to the desire for more clean, reliable, eco-friendly, and biologically appropriate approaches. Plant-mediated synthetic approaches for metal nanoparticles have emerged to circumvent the often-associated disadvantages with the conventional synthetic routes, using bioresources that act as a scaffold by effectively reducing and stabilizing these materials, whilst making them biocompatible for biological cells. This capacity by plants to intrinsically utilize their organic processes to reorganize inorganic metal ions into nanoparticles has thus led to extensive studies into this area of biochemical synthesis and analysis. In this review, we examined the use of several plant extracts as a mediating agent for the synthesis of different metal-based nanoparticles (MNPs). Furthermore, the associated biological properties, which have been suggested to emanate from the influence of the diverse metabolites found in these plants, were also reviewed.

Electrically Modulated Near-Infrared/Visible Light Dual-Mode Perovskite Photodetectors.

Dual-mode photodetectors (PDs) have attracted increasing interest owing to their potential optoelectrical applications. However, the widespread use of PDs is still limited by the high cost of epitaxial semiconductors. In contrast, the solution processability and wide spectral tunability of perovskites have led to the development of various inexpensive and high-performance optoelectronic devices. In this study, we develop a high-performance electronically modulated dual-mode PD with near-infrared (NIR) narrowband and visible light broadband detection based on organic-inorganic hybrid methylammonium lead halide perovskite (MAPbX3; MA = CH3NH3 and X = Cl, Br, and I) single crystals with a pnp configuration. The operating mode of the dual-mode PD can be switched according to voltage bias polarity because the photon absorption region and carrier transport performance are tuned at different bias voltages. The dual-mode PD exhibits a NIR light responsivity of 0.244 A/W and a narrow full width at half-maximum of ∼12 nm at 820 nm at positive voltages and an average visible light responsivity of ∼0.13 A/W at negative voltages. The detectivities of both modes are high (∼1012 Jones), and the linear dynamic range is wide (>100 dB). Our study provides a new method for fabricating multifunctional PDs and can expand their application in integrated imaging systems.

Synthesis, Theoretical Calculation, and Biological Studies of Mono- and Diphenyltin(IV) Complexes of N-Methyl-N-hydroxyethyldithiocarbamate.

In this study, chlorophenyltin(IV) [(C6H5)(Cl)Sn(L)2] and diphenyltin(IV) [(C6H5)2Sn(L)2] of N-methyl-N-hydroxyethyldithiocarbamate were prepared and characterized using various spectroscopic methods (FTIR, 1H, 13C, and 119Sn NMR) and elemental analysis. The FTIR and NMR spectral data, used to establish the structure of the compounds, showed the formation of the complexes via coordination to the two sulfur atoms from the dithiocarbamate ligand and the respective phenyltin(IV) derivatives. This coordination mode was further explored by DFT calculations, which showed that the bonding around the Sn center in [(C6H5)2Sn(L)2] was more asymmetric compared to the bonding around [(C6H5)(Cl)Sn(L)2]. However, the Sn-S bonds in [(C6H5)(Cl)Sn(L)2] were found to be more covalent than those in [(C6H5)2Sn(L)2]. Furthermore, the charge density of the frontier orbitals showed that the Sn atom in the complexes is relatively electrophilic and the Sn atom in [(C6H5)2Sn(L)2] has a lower atomic dipole moment than that of [(C6H5)(Cl)Sn(L)2]. The cytotoxicity and anti-inflammatory study revealed that [(C6H5)2Sn(L)2], with the higher number of phenyl substituents, has a higher potency than [(C6H5)(Cl)Sn(L)2]. The bio-efficacy study of these complexes as cytotoxic and anti-inflammatory agents showed that the complexes possessed moderate to high activity in comparison to the camptothecin and diclofenac in each case. Nevertheless, the diphenyltin(IV) derivative [(C6H5)2Sn(L)2] was found to possess a better activity than its counterpart due to the number of phenyl rings attached to the Sn center.

The Versatility in the Applications of Dithiocarbamates.

Dithiocarbamate ligands have the ability to form stable complexes with transition metals, and this chelating ability has been utilized in numerous applications. The complexes have also been used to synthesize other useful compounds. Here, the up-to-date applications of dithiocarbamate ligands and complexes are extensively discussed. Some of these are their use as enzyme inhibitor and treatment of HIV and other diseases. The application as anticancer, antimicrobial, medical imaging and anti-inflammatory agents is examined. Moreover, the application in the industry as vulcanization accelerator, froth flotation collector, antifouling, coatings, lubricant additives and sensors is discussed. The various ways in which they have been employed in synthesis of other compounds are highlighted. Finally, the agricultural uses and remediation of heavy metals via dithiocarbamate compounds are comprehensively discussed.

Biosynthesis of zinc oxide and silver/zinc oxide nanoparticles from Urginea epigea for antibacterial and antioxidant applications.

Zinc oxide (ZnO) and silver-zinc oxide (Ag/ZnO) nanocomposite were synthesized by a green method using Zn(CH3COO)2 and AgNO3 as precursors for zinc and silver respectively; and Urginea epigea bulb extract as a reducing/capping agent. The nanomaterials were characterized by X-ray diffraction (XRD) analysis, Fourier transform infrared spectrophotometer (FTIR), ultraviolet-visible spectrophotometer, scanning, and transmission electron microscopy (SEM and TEM). Their elemental composition was studied using EDX analysis, while elementary mapping was used to show the distribution of the constituent elements. The powder X-ray diffraction confirmed hexagonal phase ZnO, while the Ag/ZnO nanocomposites identified additional planes due to cubic phase Ag nanoparticles. The absorption spectrum of the nanocomposite indicated a red shifting of the absorption band of the metallic ZnO and a surface plasmon resonance (SPR) band's appearance in the visible region due to the metallic Ag nanoparticles. The analysis from the TEM image showed the particles were of spherical morphology with a mean size of 35 nm (ZnO) and 33.50 nm (Ag/ZnO). The biological activity of the nanoparticles was studied for their antibacterial and antioxidant capacity so as to assess their ability to hinder bacterial growth and capture radical species respectively. The results demonstrated that the modification of ZnO with silver nanoparticles enhanced the antibacterial potency but reduced the antioxidant activity. This biogenic method offers a facile approach to nanoparticles for biological purposes, and the strategy may be extended to other metal oxide and their composites with metallic silver nanoparticles as a more effective approach compared to the physical and chemical routes.

Solvothermal synthesis of pure and Sn-doped Bi2S3 and the evaluation of their photocatalytic activity on the degradation of methylene blue.

BACKGROUND: A large volume of dye molecules finds its way into the environment, accumulates in water bodies, and makes the aquatic system unsafe to human health. Due to the complex nature of these dye materials, most of the conventional techniques are not effective for their removal. Semiconductor photocatalysis has emerged as a promising technique for  the destruction of organic pollutants under UV or visible light irradiation. Among the semiconductors, Bi2S3 is widely employed in photocatalysis due to its non-toxicity and chemical stability. However, one of its problems is the high recombination rate of the charge, and various methods have been employed to enhance the photo-reactivity. One of  these methods is the incorporation of transition elements. RESULTS: Herein, a facile solvothermal method was used to prepare Bi2S3 nanorods and needle- shaped Sn doped Bi2S3, using bismuth(III) tris(N-phenyldithiocarbamate) as a single-source precursor. The prepared nanomaterials were characterized, and used as efficient photocatalyst for the photo enhanced degradation of methylene blue (MB) dye under visible light irradiation. The nanomaterials exhibited very good photocatalytic activity towards the photo degradation of MB, showing a degradation rate of up to 83% and 94% within 150 min for the pristine and Sn doped Bi2S3,  respectively. CONCLUSION: The enhancement in the photocatalytic activity of the Sn doped Bi2S3 was attributed to the suppression in the recombination rate of the electron-hole pairs, due to the formation of new energy level below the CB, that was capable of altering the equilibrium concentration of the carrier. This confirmed that Sn doped Bi2S3 could be utilized as valuable cost-efficient catalysts for eliminating methyl blue from aqueous solutions and also possible candidates in environmental pollution treatment.

Synthesis, computational and biological studies of alkyltin(IV) N-methyl-N-hydroxyethyl dithiocarbamate complexes.

Methyltin(IV) of butyltin(IV)-N-hydroxyethyl dithiocarbamate complexes, represented as [(CH3)2Sn(L(OH))2] and [(C4H9)2Sn(L(OH))2] respectively were synthesized and characterized using spectroscopic techniques (1H, 13C and 119Sn NMR) and elemental analysis. Both infrared and NMR data showed that, the complexes were formed via two sulphur atoms of the dithiocarbamate group. This mode of coordination was further supported by the DFT calculation, which suggested the formation of a distorted octahedral geometry around the tin atom. The complexes were screened for their antioxidant, cytotoxicity and anti-inflammatory properties. Four different assays including DPPH, nitric oxide, reducing power and hydrogen peroxides were used for the antioxidant studies, while an in vitro anti-inflammatory study was done using albumin denaturation assay. The complexes showed good antioxidant activity, especially in the DPPH assay. Butyltin(IV)-N-hydroxyethyl dithiocarbamate showed better cytotoxicity activity compared to methyltin(IV)-N-hydroxyethyl dithiocarbamate in the selected cell lines, which included KMST-6, Caco-2 and A549 cell lines. The anti-inflammatory activities revealed that the two complexes have useful activities better than diclofenac used as control drug.

Microwave-Assisted Synthesis of Bi2S3 and Sb2S3 Nanoparticles and Their Photoelectrochemical Properties.

Bi2S3 and Sb2S3 nanoparticles were prepared by microwave irradiation of single-source precursor complexes in the presence of ethylene glycol as a coordinating solvent. The as-synthesized nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) coupled with energy-dispersive X-ray (EDX), photoluminescence (PL), and UV-vis near-infrared (NIR) spectroscopy. Their electrochemical potential was examined in [Fe(CN)]4-/[Fe(CN)]3- by cyclic and square wave voltammetry (CV and SWV) and electrochemical impedance spectroscopy (EIS). GCEBi2S3 and GCESb2S3 exhibit promising electrochemical performance and a higher specific capacitance of about 700-800 F/g in [Fe(CN)]4-/[Fe(CN)]3. Thin films of Bi2S3 and Sb2S3 were successfully incorporated in the fabrication of solar cell devices. The fabricated device using Bi2S3 (under 100 mW/cm2) showed a power conversion efficiency (PCE) of 0.39%, with a V oc of 0.96 V, a J sc of 0.00228 mA/cm2, and an FF of 44%. In addition, the device exhibits nonlinear current density-voltage characteristics, indicating that Bi2S3 was experiencing a Schottky contact. The Sb2S3-based solar cell device showed no connection in the dark and under illumination. Therefore, no efficiency was recorded for the device using Sb2S3, which indicated the ohmic nature of the film. This might be due to the current leakage caused by poor coverage. The nanoparticles were found to induce similar responses to the conventional semiconductor nanomaterials in relation to photoelectrochemistry. The present study indicates that Bi2S3 and Sb2S3 nanoparticles are promising semiconductor materials for developing optoelectronic and electrochemical devices as the films experience Schottky and Ohmic contacts.

Graphene-Based Composites as Catalysts for the Degradation of Pharmaceuticals.

The incessant release of pharmaceuticals into the aquatic environment continues to be a subject of increasing concern. This is because of the growing demand for potable water sources and the potential health hazards which these pollutants pose to aquatic animals and humans. The inability of conventional water treatment systems to remove these compounds creates the need for new treatment systems in order to deal with these class of compounds. This review focuses on advanced oxidation processes that employ graphene-based composites as catalysts for the degradation of pharmaceuticals. These composites have been identified to possess enhanced catalytic activity due to increased surface area and reduced charge carrier recombination. The techniques employed in synthesizing these composites have been explored and five different advanced oxidation processes-direct degradation process, chemical oxidation process, photocatalysis, electrocatalyis processes and sonocatalytic/sono-photocatalytic processes-have been studied in terms of their enhanced catalytic activity. Finally, a comparative analysis of the processes that employ graphene-based composites was done in terms of process efficiency, reaction rate, mineralization efficiency and time required to achieve 90% degradation.

Green synthesis of copper oxide nanoparticles using extracts of Solanum macrocarpon fruit and their redox responses on SPAu electrode.

In this work, CuO nanoparticles (NPs) were prepared from the aqueous extracts of Solanum macrocarpon fruit by using the conventional heating (CuO(h) NPs) and microwave irradiation (CuO(m) NPs) methods. The synthesized nanoparticles were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The SEM analysis revealed that the CuO NPs from both routes contained essentially smooth surfaces, and displayed some degree of agglomeration. The TEM analysis confirmed some spherical morphology with mean particle sizes of 35.60 ± 6.24 nm and 47.14 ± 6.18 nm for the CuO(h) and CuO(m) NPs respectively. While the CuO(m) NPs possessed a single-phase consistent with the face cantered cubic structure of copper oxide, the CuO(h) NPs showed some extra peaks attributed to Cu2O NPs as secondary phase. Electrochemical studies were conducted in order to evaluate the electrochemical properties of the NPs. The responses of a gold screen-printed electrode surface treated with both NPs showed that their redox behaviours on (Fe(CN)6)3-/4- probe and KCl electrolytes vary significantly. In (Fe(CN)6)3-/4- probe, the SPAuE/CuO(h) showed enhanced electrochemical response relative to the bare, while the SPAuE/CuO(m) showed a lower current response than the bare. However, in the KCl electrolye, the SPAuE/CuO(h) and SPAuE/CuO(m) were highly electroactive and demonstrated peak current magnitude that was about 26.5 and 83.38 times higher than that of the bare. In this KCl medium, the magnitude of the oxidation peak current of Cu2+ for SPAuE/CuO(m) was about 3 times higher than that of SPAuE/CuO(h). The percentage contraction in redox coordinates between the 1st and 10th scans in both electrodes were 3.88 and 19.28% for SPAuE/CuO(h) and SPAuE/CuO(m) respectively. Thus, the choice of green synthesis route could be exploited in different fields where green NPs is desired.

Simultaneous removal of organics and heavy metals from industrial wastewater: A review.

The co-existence of heavy metals and organics in industrial effluents is a prevalent problem. These pollutants usually have dissimilar compositions and properties, making their complete removal very tedious even with the use of conventional methods. In some cases, organics and heavy metals usually exist in a mixed matrix in industrial wastes. This poses harmful health risks to humans, aquatic lives and the entire ecosystem, because majority of these mixed pollutants amass in water in concentrations which are more than the permissible discharge limits in the environment. Therefore, it is necessary to remove these pollutants in order to prevent them from contaminating both the surface and ground water. Although, the removal of organic compounds and heavy metals (such as Hg, Pb, Cd, As and Cr) could be easily achieved individually, however, these pollutants exist together in many industrial effluents and even in surface waters. Hence the complete removal of these pollutants concurrently in a polluted system is the focus of this study. Several technologies have been used for the simultaneous removal of organics and heavy metal pollutants from water, which includes adsorption, ion exchange, photocatalysis, and coagulation. The success of these techniques depends on the water matrices and the choice of water treatment media such as adsorbents, resins, photocatalysts, and coagulants. The advantages and limitations of these technologies together with their respective mathematical modelling is critically examined in this review. Finally, the effect of joint existence of organic pollutants and heavy metals on the removal efficiency were examined in addition to the mathematical models that discusses the mechanisms of their combine elimination.

Photo enhanced degradation of polyfluoroalkyl and perfluoroalkyl substances.

The increase in the presence of highly recalcitrant poly- and per- fluoroalkyl substances (PFAS) in the environment, plant tissues and animals continues to pose serious health concerns. Several treatment methods such as physical, biological and chemical processes have been explored to deal with these compounds. Current trends have shown that the destructive treatment processes, which offer degradation and mineralization of PFASs, are the most desirable process among researchers and policy makers. This article, therefore, reviews the degradation and defluorination processes, their efficiencies and the degradation mechanism of photon-based processes. It shows that high degradation and defluorination efficiency of PFASs could be achieved by photon driven processes such as photolysis, photochemical, photocatalysis and photoreduction. The efficiency of these processes is greatly influenced by the nature of light and the reactive radical generated in the system. The limitation of these processes, however, include the long reaction time required and the use of anoxic reaction conditions, which are not obtainable at ambient conditions.