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The synthesis of magnetic nanoparticles (MNPs) via the chemical, biological, and physical routes has been reported on along with advantages and attendant limitations. This study focuses on the sensing and emerging theragnostic applications of this category of nanoparticles (NPs) in clinical sciences by unveiling the unique performance of these NPs in the biological sensing of bacteria and nucleotide sequencing. Also, in terms of medicine and clinical science, this review analyzes the emerging theragnostic applications of NPs in drug delivery, bone tissue engineering, deep brain stimulation, therapeutic hyperthermia, tumor detection, magnetic imaging and cell tracking, lymph node visualization, blood purification, and COVID-19 detection. This review presents succinct surface functionalization and unique surface coating techniques to confer less toxicity and biocompatibility during synthesis, which are often identified as limitations in medical applications. This study also indicates that these surface improvement techniques are useful for refining the selective activity of MNPs during their use as sensors and biomarkers. In addition, this study unveils attendant limitations, especially toxicological impacts on biomolecules, and suggests that future research should pay attention to the mitigation of the biotoxicity of MNPs. Thus, this study presents a proficient approach for the synthesis of high-performance MNPs fit for proficient medicine in the detection of microorganisms, better diagnosis, and treatment in medicine.

Abstract Due to the limitations of conventional ultrafiltration/microfiltration-based membrane bioreactors (UF/MF-MBRs) in removing trace organic compounds (TrOCs), the concept of high-retention membrane bioreactors (HR-MBRs) was introduced. Despite the benefits, HR-MBRs still suffer several drawbacks. Therefore, this paper critically reviews the effectiveness and feasibility of the proposed strategies to alleviate fouling, salinity build-up and incomplete biodegradation of TrOCs during wastewater treatment by HR-MBRs. The severity of each challenge is compared amongst the various configurations together with the associated capital and operational expenditure to determine the most cost-effective set-up. Guidance is provided on strategies and/or lessons that could be adopted from well-established processes used at municipal scale. Chemical cleaning as mitigation for fouling degrades membranes leading to poor TrOCs removal, while pre-treatment and membrane surface modification increase operational expenditure (OpEX). However, there are other environmentally-friendly pretreatment and cleaning options which hold great potential for future application. These options such as advanced oxidation processes (AOPs) are critically discussed in this work. Further, in-depth discussion is made on the pros and cons of the various approaches (such as frequent sludge withdrawal, intermittent UF/MF filtration and using organic salts) to alleviate salt build-up. Finally, incomplete biodegradation of rejected TrOCs in the bioreactor transfers problems of toxic pollutants from wastewater treatment to sludge management. Herein mitigation strategies including using stronger biological agents and coupling HR-MBRs with other techniques are debated. Despite the challenges, HR-MBRs are a promising solution for clean water production from TrOCs impaired wastewater. Therefore, more research is needed to improve the performance of HR-MBRs.

The present work demonstrates the performance of hollow fibre membranes fabricated using polyvinyl chloride, polystyrene (EPS) and polydimethylsiloxane (PDMS) coupled with 30% monoethanolamine (MEA) in a gas liquid membrane contactor (GLMC) for the absorption of carbon dioxide. A gas mixture with a composition of (50/50 v/v%) methane (CH4) and (CO2) was used to assess the efficiency of the prepared membranes in the removal of carbon dioxide. Then HFM 3 which showed high CO2 removal was used to separate a mixture of nitrogen (N2)/oxygen(O2)/carbon dioxide (CO2) with a composition of (73/18/9 v/v%), respectively. Four different absorption liquids: 30 % MEA solution, 30 % EDA solution, 30 % MEA – graphene oxide (GO) and 30 % EDA-GO nanofluids were coupled with HFM3 to analyse the efficiency of the different amine liquids in CO2 absorption in GLMC. The 30 % EDA-GO solution showed an increase in the efficiency of CO2 absorption. The nanofluids showed an enhancement factor for CO2 absorption in the nanofluid was 121 % and 117 % for MEA-GO and EDA-GO, respectively. This enhancement was attributed to the hydrodynamic effects and Brownian motion of graphene oxide in the amine liquids. 30 % EDA solution infused with 0.2 mg/ml graphene oxide nanoparticles achieved the highest loading of carbon dioxide 0.25 mol/ cm3.

Abstract Anticorrosion and adsorption behaviour of synthesized carbohydrazide Schiff bases, namely (Z)-N′-(4-hydroxy-3-methoxybenzylidene)-6-methyl-2-oxo-4-phenyl-1,2,3,4-tetrahydropyrimidine-5-carbohydrazide(MBTC) and (Z)-N′-(3,4-dichlorobenzylidene)-6-methyl-2-oxo-4-phenyl-1,2,3,4-tetrahydropyrimidine-5-carbohydrazide (CBTC) was examined for mild steel (MS) in 15% HCl medium. The corrosion inhibition study was performed by using gravimetric, thermodynamic, electrochemical and theoretical studies including density functional theory (DFT), molecular dynamic simulation (MDS) and Monte Carlo simulations (MCS). The outcomes in terms of corrosion inhibition efficiency using electrochemical impedance spectroscopy (EIS) method at 303 K and 150 ppm concentration were 96.75% for MBTC and 95.14% for CBTC. Both inhibitors adsorbed on the MS surface through physical as well as chemical adsorption and followed the Langmuir isotherm. The mixed-type nature of both inhibitors was identified by polarization results. Surface analysis was done using FESEM, EDX, AFM and XPS studies and results showed that a protective layer of inhibitor molecules was developed over the surface of MS. The results of DFT, MCS and MDS are in accordance with experimental results obtained by weight loss and electrochemical methods.

Organic fouling during reverse osmosis (RO) is exacerbated by the presence of calcium up to a limit where extremely high calcium concentration results in lesser fouling due to formation of large organic-calcium aggregates with lower cake resistance. Therefore, this work leveraged on this phenomenon and used calcium chloride as coagulant (at varying concentration) to reduce membrane fouling while enhancing NOM removal. Membrane cleaning efficiency through calcium-EDTA chelation which disintegrates the fouling layers was explored. RO fouling was performed with sodium alginate solutions and lake water. The fouled membranes were soaked in 0.1 ​mM EDTA (1 ​h) and backwashed with water to remove the fouling layer. Alginate fouling was worsened (45–85 ​%) by increase in calcium concentration up to 5 ​mM but lessened at > 5 ​mM calcium concentration (35–15 ​%). Similar observations were made when filtering lake water, except that lesser fouling was observed at calcium concentrations greater than 15 ​mM. Membrane soaking in EDTA enhanced cleaning efficiency leading to over 90 ​% flux recovery for both alginate and late water. However, prolonged membrane exposure to 10 ​mM calcium resulted in slight decline in membrane salt rejection (

Abstract Controlling membrane morphology is crucial to improving the mechanical strength (MS) and hydrophilicity of porous membranes. Here we report on the fabrication of mixed matrix membranes (MMMs) free of macrovoids via non-solvent-induced phase separation (NIPS). Hydrophilic Halloysite nanotubes (HNTs) and poly (ethylene-co-vinyl alcohol) (EVOH) were mixed with Hydrophobic polysulfone (PSF) in the presence of polyethylene glycol (PEG) to fabricate MMMs. The results showed the formation of PSF/EVOH-MMMs with a spongy structure when the content of HNTs varied from 0.06- 0.12 wt.%, owing to the formation of strong hydrogen bonds between PSF, EVOH, PEG, and HNTs, confirmed by molecular dynamics (MD) simulations. The MS of MMMs with 0.12 wt.% HNTs was increased 2.2-fold (up to 6.22 MPa), while the contact angle (CA) was lowest at 47.42 ± 1.9°. In addition, the water permeability increased by a factor of 1.7 up to 419 L m−2 h−1 bar−1. The rejection rates of MMMs (M12) for oil and BSA were >90% and >95%, respectively. While the MMMs had > 90% flux recovery for both oil and BSA. We predict that this study will provide a method for controlling dope thermodynamics, formation dynamics, and morphology of MMMs while maintaining promising properties for improved separation performance.

Zinc oxide nanowires were synthesized and impregnated with trace amounts of palladium ions by adsorption, which was then employed as a heterogeneous catalyst in the Suzuki reaction. To obtain an in-depth understanding of the structure and properties of the ZnO nanowires and the resultant catalyst, different analysis techniques were performed. The as-synthesized catalyst demonstrated exceptional efficiency in promoting the reaction between aryl halides and arylboronic acids, enabling the achievement of biphenyl derivatives in high yields ranging between 82% and 99%. The analysis conducted using transmission electron microscopy demonstrated the formation of palladium nanoparticles during the reaction, confirming their role as the active species driving the catalytic transformation. Further investigation was carried out to examine the effect of the support on the catalytic activity of the catalyst. The results indicated that the morphology and crystallographic structure of zinc oxide had a significant impact on the catalytic activity of the prepared catalyst. The catalytic performance of PdCl2/ZnONWs, where palladium chloride immobilized on ZnO nanowires, was found to be exceptional. The catalyst demonstrated the ability to be recovered and reused up to three times without a noticeable decline in its catalytic activity. Additionally, the loading of palladium species could be reduced to 7.6 mol part per million. Remarkably, the catalyst achieved a total turnover number of 130,000 and a turnover frequency of 0.75 s−1.

In the present protocol, we determined the presence and concentrations of bisphenol A (BPA) spiked in surface water samples using EEM fluorescence spectroscopy in conjunction with modelling using partial least squares (PLS) and parallel factor (PARAFAC). PARAFAC modelling of the EEM fluorescence data obtained from surface water samples contaminated with BPA unraveled four fluorophores including BPA. The best outcomes were obtained for BPA concentration (R2 = 0.996; standard deviation to prediction error’s root mean square ratio (RPD) = 3.41; and a Pearson’s r value of 0.998). With these values of R2 and Pearson’s r, the PLS model showed a strong correlation between the predicted and measured BPA concentrations. The detection and quantification limits of the method were 3.512 and 11.708 micro molar (µM), respectively. In conclusion, BPA can be precisely detected and its concentration in surface water predicted using the PARAFAC and PLS models developed in this study and fluorescence EEM data collected from BPA-contaminated water. It is necessary to spatially relate surface water contamination data with other datasets in order to connect drinking water quality issues with health, environmental restoration, and environmental justice concerns.

In this study, functionalized mesoporous silica was prepared and characterized as a stationary phase using various analytical and solid-state techniques, including a Fourier-transform infrared (FTIR) spectrometer, thermogravimetric analysis, and nitrogen sorption. The results confirmed the successful synthesis of the hybrid stationary phase. The potential of the prepared hybrid mesoporous silica as a solid-phase extraction (SPE) stationary phase for separating and enriching polycyclic aromatic hydrocarbons (PAHs) in both spiked water samples and real water samples was evaluated. The analysis involved extracting the PAHs from the water samples using solid-phase extraction and analyzing the extracts using a two-dimensional gas chromatograph coupled to a time-of-flight mass spectrometer (GC × GC-TOFMS). The synthesized sorbent exhibited outstanding performance in extracting PAHs from both spiked water samples and real water samples. In the spiked water samples, the recoveries of the PAHs ranged from 79.87% to 95.67%, with relative standard deviations (RSDs) ranging from 1.85% to 8.83%. The limits of detection (LOD) for the PAHs were in the range of 0.03 µg/L to 0.04 µg/L, while the limits of quantification (LOQ) ranged from 0.05 µg/L to 3.14 µg/L. Furthermore, all the calibration curves showed linearity, with correlation coefficients (r) above 0.98. Additionally, the results from real water samples indicated that the levels of individual PAH detected ranged from 0.57 to 12.31 µg/L with a total of 44.67 µg/L. These findings demonstrate the effectiveness of the hybrid mesoporous silica as a promising stationary phase for solid-phase extraction and sensitive detection of PAHs in water samples.

Microplastics are discharged into the environment through human activities and are persistent in the environment. With the prevalent use of plastic-based personal protective equipment in the prevention of the spread of the COVID-19 virus, the concentration of microplastics in the environment is envisaged to increase. Potential ecological and health risks emanate from their potential to adsorb and transport toxic chemicals, and ease of absorption into the cells of living organisms and interfering with physiological processes. This review (1) discusses sources and pathways through which microplastics enter the environment, (2) evaluates the fate and behavior of microplastics, (3) discusses microplastics in African aquatic systems, and (4) identifies research gaps and recommends remediation strategies. Importantly, while there is significant microplastics pollution in the aquatic environment, pollution in terrestrial systems are not widely studied. Besides, there is a dearth of information on microplastics in African aquatic systems. The paper recommends that the governments and non-governmental organizations should fund research to address knowledge gaps, which include: (1) the environmental fate of microplastics, (2) conducting toxicological studies under environmentally relevant conditions, (3) investigating toxicity mechanisms to biota, and developing mitigation measures to safeguard human health, and (4) investigating pollutants transported by microplastics. Moreover, regulatory measures, along with the circular economy strategies, may help reduce microplastic pollution.

Exfoliated graphite is a 2D carbon material that has recently received great attention owing to its remarkable analytical merits such as fast electron migration, ease of surface regeneration, high-temperature resistance, ability to withstand high-current density, excellent conductivity, and sensitivity. Due to its excellent analytical signature, an exfoliated graphite electrode has been reportedly used in the construction of sensors and biosensors for various applications. This electrode can be used alone or blended with several nanomaterials/semiconductors for the degradation of various organic pollutants in wastewater. Despite the outstanding results reported in the use of exfoliated graphite electrodes for various analytical applications, very few reports were documented in the literature. Therefore, this review elaborated on the importance of exfoliated graphite electrodes for electrochemical analysis.

We report a simple and cheaper method for the electrochemical detection of Se(IV) using carbon nanodots (CNDTs) prepared from oat. The carbon nanodots were synthesised by a green and facile approach and characterised using scanning electron microscopy, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and Raman spectroscopy. The CNDT was used to fabricate an electrochemical sensor for the quantification of Se(IV) in water. The modification of the glassy carbon electrode (GCE) with carbon nanodots led to an increase in the electroactive surface area of the electrode, which enhances the redox current peak of [Fe(CN)6]3–/4– in comparison to the bare GCE. Using the square wave voltammetry, the detection limit and quantification limit of 0.05 and 0.167 ppb were obtained under the optimised parameters using deposition potential of −200 mV, 0.1 M HNO3 electrolyte, electrodeposition time of 60 s, and pH 1. The results further revealed that the GCE-CNDT was not susceptible to many interfering cations except Cu(II) and Pb(II) and Fe(II). The sensor fabrication involves a one-step electrode modification and was used to detect Se(IV) in a real water sample and the result obtained is in agreement with the inductively coupled plasma technique. Overall, the electrode offers a cheap, fast and sensitive way of detecting selenium in environmental matrices.

Natural materials can provide cost-effective way in the development of various products for specific applications. On the hand, physicochemical properties of composite materials can be enhanced to perform a specific process of interest such as wastewater treatment. Clay materials have been used for many applications including brick making and wastewater treatment. To enhance the properties of natural materials such as clay, multiwalled carbon nanotubes (MWCNTs) were used to enhance the properties of natural clays. Natural clays and MWCNTs composites were characterized to provide insights as a starting point for various applications. There are two sets of data presented in this study: i) raw material, unheated and heated (at 900 °C); ii) natural clay, MWCNTs and natural clay/MWCNTs composites. The chemical composition and phase identification analyzes were carried out using X-ray Fluorescence (XRF) and X-Ray Diffraction (XRD), respectively. A Fourier-transform infrared (FTIR) spectrometer was used to determine the functional groups of the samples. The UV-vis analyzes were carried out to investigate the reflectance percentage of the natural clays and the composites samples. The Thermogravimetric analysis (TGA) analyzes were performed to investigate the weight loss and dehydration process of the samples. The presented data showed that natural clays and natural clays/MWCNTs composites can be used for various applications such as construction industry, for cosmetic usages and for the removal of pollutants in aqueous solutions.

Wastewater treatment plants (WWTPs) in South Africa, like is the case for most WWTPs around the globe albeit capable of removing substantial quantities of microplastics (MPs) and in fact, the treatments become ineffective for those plastic particles less than 100 µm. As a consequence, the receiving water bodies in which the final effluent is discharged becomes highly polluted. The present research is devoted to the analysis of the pervasive MPs in wastewaters of the treatment plant located in the Gauteng Province, South Africa using Pyrolysis – GC-TOF-MS. Based on the results, there were 23 pyrolyzate products with contributions from PVC, PA, PET and PE with abundances of 47.8%, 13.1%, 17.4% and 4.3% respectively. The remaining 17.4% could be attributed as additives in MPs. The SEM images illustrated that the MPs appeared to be inter – wined, fibrous of different thicknesses and lengths. The highly weathered MPs exhibited the rough surface which was noticeably damaged with peeled off layers presumably because of photo-oxidation during the aging process. The vibrational modes of FTIR revealed the presence of the various functional groups in the corresponding polymers of MPs. The thermal studies confirmed the presence of calcium, aluminum and silicon as residues of catalysts or flame retardants or UV stabilizers in MPs or as adsorbates resulting from the surface adsorption from the surroundings. The Py-GC-TOF-MS confirmed the identity of the various fragments related to the MPs monomers

Due to widespread occurrence of lipid lowering drugs such as statins, fibrates and their metabolites in the aquatic environments, there is a worldwide growing concern in their role in water quality and aquatic biota. However, this concern is limited by ability to address their occurrence, distribution, fate and eco-toxicological effects. This study focuses on the quantification of the levels of statins, fibrates and their metabolites in the aquatic environments using Ultra-High Performance Liquid Chromatography coupled to high resolution quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS). The developed UHPLC–QTOF–MS based method was successfully applied to the analysis of statins, fibrates and metabolites in real water samples collected from Daspoort WWWs influent and effluent and Apies River. A series of statin compounds (mevastatin, simvastatin, pravastatin, rosuvastatin, fluvastatin, atorvastatin), fibrates (gemfibrozil, fenofibrate) and the corresponding metabolites (clofibric and fenofibric acids) were detected and quantified in the range of 0.56–19.90 µg/L in both waste and River water samples. In general, the results of the present study are an indication of pollution hazards from wastewater treatment processes and these levels poses a huge risk to the growth and reproduction of aquatic organisms. Thus, regulating the limit levels of statins, fibrates and metabolites in any type of water is paramount as it will provide the vital information on the toxic risks associated with organic pollutants of pharmaceutical origin. Keywords: Aquatic ecosystem, Cholesterol/lipid lowering drugs, UHPLC-QTOF-MS, Eco-toxicological, Spatial distribution

Membrane performance optimization is a critical preparation step that ensures optimum separation and fouling resistance. Several studies have employed additives such as carbon and inorganic nanomaterials to optimize membrane performance. These particles provide excellent results but are rather costly, unstable and toxic to several biological organs. This study demonstrated that performance enhancement can also be achieved through delayed solvent–nonsolvent demixing during phase inversion membrane preparation. The rate of solvent–nonsolvent demixing was delayed by increasing the concentration of the solvent in the coagulation bath. This study employed synthetic and real water samples and several analytical techniques to compare optimized performances and properties of membranes prepared in this study with that of nanoparticle-embedded membranes in the literature. Pure water flux and BSA rejection of the membranes prepared in this study were comparable to those of nanoparticle embedded membranes. This study also shows the influence of delayed solvent–nonsolvent demixing on membrane properties such as morphology, wettability, surface roughness and porosity, thereby showing the suitability of the technique in membrane optimization. Furthermore, fouling studies showed that membranes prepared in this study have high flux recovery when fouled by humic acid feed water (>95%) and above 50% flux recovery with real water samples.

The therapeutic efficiency of doxorubicin (DOX) is dependent on its sufficient accumulation within the nucleus of cancer cells. Taking advantage of the fascinating properties (e.g., multiple dense arrays of hyperbranches and high surface area) of bimetallic nanodendrites as well as the arginine-rich components of protamine sulfate (PS), we herein present a new type of PS-modified Au@PdNDs-based hydrophobic drug carrier in which DOX can effectively bind to the surface of the PS.Au@PdNDs nanocarrier via non-covalent attachment. Chemical characterization of the synthesized PS.Au@PdNDs.DOX showed the successful loading of DOX onto the surface of PS.Au@PdNDs. Darkfield and Hyperspectral imaging analysis of the PS.Au@PdNDs.DOX demonstrated the time-dependent uptake and prolonged accumulation capability for releasing its DOX cargo inside the nucleus. Specifically, data from the 3D-CytoViva fluorescence imaging did not only track the nanocarrier’s distribution but also confirmed its predominant accumulation in the nuclear compartment through clathrin-mediated endocytosis. Cytotoxicity assay showed that the PS.Au@PdNDs.DOX significantly inhibited cancer cell proliferation with maximum DOX release under acidic conditions (pH 4.5 and 5.5) than at normal physiological pH of 7.4. Moreover, the resultant PS.Au@PdNDs-based DOX nanocarrier efficiently improved the induction of apoptosis in MCF-7 cells compared to free DOX and passive targeted platform. In addition, loss of membrane integrity, mitochondria-apoptotic pathway, and internucleosomal DNA contents from cell cycle progression assay provided insights on the mechanism of cell death. Overall, the PS.Au@PdNDs.DOX nanocarrier may be employed for improved subcellular delivery of DOX as well as multimodal visualization in cancer therapy.

Abstract Molecularly imprinted polymers (MIPs) have been widely used for the modification of electrodes because of their native specificity for the intrinsic template molecules. The importance of catecholamines in the neurological and general well‐being of every individual cannot be overemphasized. Disorders associated with the imbalance in catecholamine levels can be diagnosed with electrochemical sensors capable of their determination in the presence of other biological interferents in extracellular fluids. MIPs based sensors have been designed for selective and simultaneous determination of these catecholamines in the past decade. Efforts in this regard and details on the components and preparation of these MIPs were presented in this review.

In this study, Ag and Pd bimetallic nanoparticles were generated in situ in polyethersulfone (PES) dope solutions, and membranes were fabricated through a phase inversion method. The membranes were characterized for various physical and chemical properties using techniques such as FTIR, SEM, AFM, TEM, EDS, and contact angle measurements. The membranes were then evaluated for their efficiency in rejecting EOCs and resistance to protein fouling. TEM micrographs showed uniform distribution of Ag/Pd nanoparticles within the PES matrix, while SEM images showed uniform, fingerlike structures that were not affected by the presence of embedded nanoparticles. The presence of Ag/Pd nanoparticles resulted in rougher membranes. There was an increase in membrane hydrophilicity with increasing nanoparticles loading, which resulted in improved pure water permeability (37–135 Lm2h−1bar−1). The membranes exhibited poor salt rejection (

Population-driven socioeconomic urban expansion, industrialization, and intensified modern agricultural practices are interlinked to environmental challenges culminating in compromised water quality due to pollution by toxic, persistent, and bioaccumulative heavy metal ions, pesticides, nitroaromatics, and other emerging pollutants. Considering the detrimental impact of pollutants on human health and ecosystem, their detection in different media including water is paramount. Notably, electrochemical techniques are more appealing owing to their recognized advantages. This research summarizes and evaluates the most recent advances in the electrochemical sensing of environmental pollutants such as heavy metal ions, pesticides, nitroaromatics, and other distinct emerging contaminants. Besides, the review focuses on the application of electrochemical detection of the selected pollutants through analysis of representative reports in the five years from 2016 to 2020. Therefore, the review is intended to contribute insights and guidelines to contemporary progress in specific electrochemical application practices based on graphene derivatives, toward the aforenamed pollutants. Thus, it focused on sensing methods such as cyclic voltammetry, anodic stripping voltammetry, and electrochemical impedance spectroscopy employing different sensing elements incorporating graphene. Moreover, the review also highlighted graphene synthesis pathways, sensor design strategies, and functionalization. Furthermore, the review showed that there is congruence in the literature that functionalized graphene and its derivatives remain as viable modifiers in electrochemical sensing of pollutants. Nonetheless, the study also appraised the absence of literature reports on electrochemical detection of natural organic matter substances like humic acid and fulvic acid using a graphene-based sensor. In reckoning, current challenges related to graphene synthesis and applicability, envisaged opportunities, and future perspectives are outlined.

This review paper systematically evaluates current progress on the development and performance of photocatalytic nanofiber membranes often used in the removal of micropollutants from water systems. It is demonstrated that nanofiber membranes serve as excellent support materials for photocatalytic nanoparticles, leading to nanofiber membranes with enhanced optical properties, as well as improved recovery, recyclability, and reusability. The tremendous performance of photocatalytic membranes is attributed to the photogenerated reactive oxygen species such as hydroxyl radicals, singlet oxygen, and superoxide anion radicals introduced by catalytic nanoparticles such as TiO2 and ZnO upon light irradiation. Hydroxyl radicals are the most reactive species responsible for most of the photodegradation processes of these unwanted pollutants. The review also demonstrates that self-cleaning and antimicrobial nanofiber membranes are useful in the removal of microbial species in water. These unique materials are also applicable in other fields such as wound dressing since the membrane allows for oxygen flow in wounds to heal while antimicrobial agents protect wounds against infections. It is demonstrated that antimicrobial activities against bacteria and photocatalytic degradation of micropollutants significantly reduce membrane fouling. Therefore, the review demonstrates that electrospun photocatalytic nanofiber membranes with antimicrobial activity form efficient cost-effective multifunctional composite materials for the removal of unwanted species in water and for use in various other applications such as filtration, adsorption and electrocatalysis.

Electrospun cyclodextrin (CD)-based nanofibers with capabilities to remove pollutants from water have been synthesized and characterized. The high-quality nanofibers presented here were synthesized in two simple steps that involved in-situ electrospinning of the nanofibers and all nanocomponents, followed by the reduction of silver (Ag+) and iron (Fe3+) ions to nanoparticles using an environmentally benign process that involved irradiation of the electrospun fibers using a tailor-made UV-equipped furnace at low temperatures. In the previously reported study it was observed that Ag and Fe nanoparticles effectively removed a range of different strains of Gram-negative and Gram-positive bacteria from water. As such, this study focused on improving the thermal and mechanical properties of the nanofibers prepared from polymer blends of β-CDs with cellulose acetate (CA) and small additions (2 wt%) of functionalized multiwalled carbon nanotubes (f-MWCNTs). The electrospinning parameters were varied to determine the optimum conditions for preparation of uniform non-beaded nanofibers. Bead-free and uniform nanofibers were obtained at a polymer concentration of 32% at the ratio of 1:1 β-CDs:CA, syringe injection flow rate of 0.7 mL h−1, 15 cm between the tip of the spinneret and the collector, and a voltage of 16 kV. The addition of f-MWCNTs was found to improve the tensile strength of the nanofibers by twofold, relative to nanofibers with no f-MWCNTs. The thermal degradation of the nanofibers was improved by a magnitude of 50°C. The study has shown that adding small amounts of f-MWCNTs improved the thermal stability and mechanical strength of the CD/CA nanofibers significantly.

Arsenic (As) and selenium (Se) ion imprinted polymers, As-IIPs and Se-IIPs, were synthesized via bulk polymerization. The prepared materials were then characterized using Fourier Transform Infrared (FT-IR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). These characterization methods confirmed the difference between IIPs and non-imprinted polymers (NIP). From the adsorption studies done IIPs did not only show better adsorption than NIPs but also better selectivities as well. As adsorption using As-IIPs (AsAsIIPs) reached a maximum of 482 μg g−1 whilst Se adsorption using Se-IIPs (SeSeIIPs) reached a maximum of 447 μg g−1 after optimization of the sample pH, adsorption time and sample temperature. However these adsorption capacities were increased to 568 μg g−1 and 530 μg g−1 for As and Se respectively when column experiments were done at the same sample temperature and pH. Against Pb, Cd and Hg, As-IIPs and Se-IIPs showed selectivity towards As and Se, respectively.

Herein we present a two-stage phase inversion method for the preparation of nanocomposite membranes for application in ultra-low-pressure reverse osmosis (ULPRO). The membranes containing DA-stabilized xGnP (xGnP-DA-) were then prepared via dry phase inversion at room temperature, varying the drying time, followed by quenching in water. The membranes were characterized for chemical changes utilizing attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The results indicated the presence of new chemical species and thus, the inclusion of xGnP-DA in the polyethersulfone (PES) membrane matrix. Atomic force microscopy (AFM) showed increasing surface roughness (Ra) with increased drying time. Scanning electron microscopy (SEM) revealed the cross-sectional morphology of the membranes. Water uptake, porosity and pore size were observed to decrease due to this new synthetic approach. Salt rejection using simulated seawater (containing Na, K, Ca, and Mg salts) was found to be up to stable at

Imbalance in the levels of monoamine neurotransmitters have manifested in severe health issues. Electrochemical sensors have been designed for their determination, with good sensitivity recorded. Carbon-based quantum dots have proven to be an important component of electrochemical sensors due to their high conductivity, low cytotoxicity and opto-electronic properties. The quest for more sensitive electrodes with cheaper materials led to the development of electrochemical sensors based on carbon-based quantum dots for the detection of neurotransmitters. The importance of monoamine neurotransmitters (NTs) and the good electrocatalytic activity of carbon and graphene quantum dots (CQDs and GQDs) make the review of the efforts made in the design of such sensors for monoamine NTs of huge necessity. The differences and the similarities between these two quantum dots are highlighted prior to a discussion of their application in electrochemical sensors over the last ten years. Compared to other monoamine NTs, dopamine (DA) was the most studied with GQDs and CQD-based electrochemical sensors.

In this study, electrochemical nanosensors were developed from the synthesized metal oxide (MO) nanoparticles by supporting it on a gold electrode (Au). The activity of the developed nanosensor toward the detection of malaria biomarker (β-hematin) was determined and the optimum conditions at which the maximum detection and quantification occurred were established. β-Hematin current response at the sensors was higher when compared with the bare Au electrode and followed the order Au-CuO (C) > Au-CuO (M) > Au-Fe2O3 (M) > Au-Fe2O3 (C) > Au-Al2O3 (M) > Au-Al2O3 (C) > bare Au. The developed sensors were stable with a relatively low current drop (10.61–17.35 %) in the analyte. Au-CuO sensor had the best performance toward the biomarker and quantitatively detected P. berghei in infected mice's serum samples at 3.60–4.8 mM and P. falciparum in human blood serum samples at 0.65–1.35 mM concentration.

Next-generation sequencing provides new insights into the diversity and structure of bacterial communities, as well as the fate of pathogens in wastewater treatment systems. In this study, the bacterial community structure and the presence of pathogenic bacteria in three wastewater treatment plants across Gauteng province in South Africa were studied. The physicochemical results indicated that the quality of wastewater varies considerably from one plant to the others. Proteobacteria, Actinobacteria, Firmicutes, and Chloroflexi were the dominant phyla across the three wastewater treatment plants, while Alphaproteobacteria, Actinobacteria, Bacilli, and Clostridia were the dominant classes. The dominant bacterial functions were highly associated with carbohydrate, energy, and amino acid metabolism. In addition, potential pathogenic bacterial members identified from the influent/effluent samples included Roseomonas, Bacillus, Pseudomonas, Clostridium, Mycobacterium, Methylobacterium, and Aeromonas. The results of linear discriminant analysis (LDA) effect size analysis also confirmed that these bacterial pathogens were significantly abundant in the wastewater treatment systems. Further, the results of this study highlighted that the presence of bacterial pathogens in treated effluent pose a potential contamination risk, transmitted through soil, agriculture, water, or sediments. There is thus a need for continuous monitoring of potential pathogens in wastewater treatment plants (WWTPs) in order to minimize public health risk.

The use of an exfoliated graphite (EG) electrode in the square wave voltammetric detection of bisphenol A (a model phenolic pollutant) in water, whereby the phenolic electrode fouling challenge is mitigated, is described. The oxidation peak of BPA was observed at about 0.45 V in phosphate buffer solution at pH 10. The current response exhibited a linear relationship with the concentration over a range from 1.56 µM–50 µM. The detection limit was calculated to be 0.76 µM. The EG electrode surface was renewed after each measurement with excellent reproducibility. A real sample application was also investigated.

Hollow fibre supported liquid membrane (HFSLM) has been applied in the measurements of distribution constants, KD and lipophilicity (log P) values for the isomeric triterpenic acids, betulinic acid (BA) and oleanolic acid (OA) isolated from indigenous plants. The results have shown that BA had an optimum pH of 3.5 while the optimum sample pH for OA was ranging from 0.5 to 2.5. The log P values obtained for BA and OA were 6.61 and 6.12, respectively. The KD value obtained for BA was 0.29 while that for OA 0.16. The method has advantages of simplicity, use of minimal organic solvents and the ability to selectively extract only one isomer (OA) in the mixture with BA by optimizing pH conditions.

A quick, simple, and environmentally friendly sample preparation method for fatty acids analysis from chemical-grade cellulose was developed employing imidazolium based ionic liquids as solvents. A variety of imidazolium based ionic liquids were screened for their ability to dissolve chemical cellulose at different temperatures. Dissolution of chemical cellulose was observed to be dependent on the ionic liquids’ anions as well as temperature. The effect of ionic liquids on chemical cellulose was examined using FT-IR and TGA techniques, which showed no difference between the original and the regenerated cellulose except for the percentage mass residues in TGA profile which was high for regenerated cellulose, 15% compared to 8% of the original at 600 °C. Fatty acids extracted from cellulose were found to be predominant in the samples from different bleaching stages, with high levels in the oxygen delignification and low levels were observed in hypochlorite bleached samples. The number and levels of the identified fatty acids were observed to decrease with the bleaching sequence. The recoveries obtained using this method ranged from 90 to 107%.

A water soluble azo dye modified β-cyclodextrin polymer 4 was synthesized and used as a chemosensor for the detection of chlorinated phenols, model chlorinated by-products (CBPs) of water treatment for drinking purposes. The characterization of the intermediates and the azo dye modified β-CD polymer was done by UV/Vis Spectrophotometry, FT-IR and 1H-NMR spectroscopies. The chlorophenols were capable of quenching the fluorescence of the polymer. The polymer showed greater sensitivity towards 2,4-dichlorophenol, with a sensitivity factor of 0.35 compared to 0.05 and 0.12 for phenol and 4-chlorophenol, respectively. The stability constants (Ks) of the pollutants were also determined by the Benesi-Hildebrand method to be 2.104 × 103 M−1 for 2,4-dichlorophenol and 1.120 × 102 M−1 for 4-chlorophenol.

Titania nanoparticles were successfully supported on carbon-covered alumina (CCA) supports via the impregnation method to form carbon-covered alumna titania (CCA/TiO2). The CCA supports were synthesised through an equilibrium adsorption of toluene 2,4-diisocyante where the N=C=O irreversibly adsorbs on the alumina and pyrolysis at 700°C affords CCA supports. These CCA/TiO2 nanocatalysts were tested for their photocatalytic activity both under UV and visible light using Rhodamine B as a model pollutant. The reaction rate constant of the CCA/TiO2 was found to be higher than that of unsupported titania and the reaction kinetics were found to follow an apparent first-order rate law. The CCA/TiO2 nanocatalysts had a much larger surface area than the unsupported titania and they exhibited overall higher photodegradation efficiency under both UV and visible light than unsupported TiO2.