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In recent years, conducting polymers are playing a significant role in the field of display devices, transistors, solar cells, sensors, and electrochromic windows due to their outstanding optoelectronic and semiconducting properties due to their conjugated backbone. One potential application that is not as widely explored using these materials is biosensing, where advantage is taken of the porosity that can be generated by the polymerization of a three-dimensional network. There are various approaches for producing conjugated microporous polymers using trifunctional or multifunctional monomers synthesized via chemical or electrochemical methods. In this work, we have used electropolymerization to synthesize conjugated polymer films on a working electrode of flexible indium tin oxide (FITO) using a trifunctional conjugated monomer 1,3,5-tri(furan-2-yl)benzene (TFB). There are several parameters that influence the formation of a porous polymer film, and the most critical ones are substrate conductivity, roughness, method of electropolymerization, and choice of an electrolyte. These porous electropolymerized films were characterized using UV–vis spectroscopy (UV–vis), X-ray photoelectron spectroscopy (XPS), surface profilometry, four-point probe conductivity measurements, and scanning electron microscopy (SEM). The polymer films that were electropolymerized using chronoamperometry rather than repetitive potential cycling demonstrated a more suitable morphology to trap DNA/RNA analytes for biosensing applications.

2D black phosphorus (BP) is one promising electrocatalyst toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) catalysis. The too strong adsorption of oxygen intermediates during OER, while the too weak adsorption of hydrogen intermediate during HER, however, greatly compromise its practical water splitting applications with overpotentials as high as 450 mV for OER and 420 mV for HER to achieve 10 mA cm-2 under alkaline conditions. Herein, by rationally introducing the nanosized iridium (Ir) modifier together with optimized exposing surface toward electrolytes, an efficient Ir-modified BP electrocatalyst with much favorable adsorption energies toward catalytic intermediates possesses an outstanding pH-universal water splitting performance, surpassing the nearly all reported BP-based catalysts and the commercial noble-metal catalysts. The Ir-modified BP catalyst with the optimized exposed surfaces only requires an overall cell voltage of 1.54 and 1.57 V to achieve 10 mA cm-2 in acidic and alkaline electrolysers, respectively. This design uncovers the potential applications of 2D BP in practical electrocatalysis fields via decreasing reaction intermediate adsorption energy barriers and promoting the interfacial electron coupling for heterostructured catalysts, and offers new insights into the surface-dependent activity enhancement mechanism.

Cardiac troponin I (cTnI) is a sensitive biomarker for cardiovascular disease (CVD). Rapid determination of cTnI concentration in blood can greatly reduce the potential of significant heart damage and heart failure. Herein, we demonstrate a new electrochemical immunosensor for selective affinity binding and rapid detection of cTnI in blood plasma by an electrochemical method. A conductive film of “poly 2,5-bis(2-thienyl)3,4-diamine-terthiophene (PDATT)” was deposited onto an Indium Tin Oxide (ITO) electrode using chronoamperometry. Anti-cardiac troponin I antibody was then attached to the two amine (NH2) groups substituted on the central thiophene of terthiophene repeating unit of the polymer chain via amide bond formation. The gaps on the surface of the antibody coated immunosensor were backfilled with bovine serum albumin (BSA) to prevent nonspecific binding of interfering molecules. Differential pulse voltammetry (DPV) was used to determine cTnI upon the formation of cTnI immunocomplex on the sensing surface, appearing a peak at 0.27 V. The response range was 0.01–100 ng mL−1 with limit of quantification down to 0.01 ng mL−1. The developed immunosensor was used to determine cTnI in spiked blood plasma without interference from cardiac troponin T (cTnT). Therefore, this new sensor can be utilised for the detection of cTnI biomarker in pathological laboratories and points of care in less than 15 min.

Metal pollution of stormwater runoff can cause potential toxic impacts on the receiving water environment and human health. Effective pollution mitigation requires accurate stormwater quality modeling. Even though a significant knowledge base exists on the factors influencing metal build-up on urban roads, very limited studies have investigated how metal-particulate interaction influences metal build-up. This study quantitatively assessed the influence of particulate characteristics, together with vehicular traffic and land use, on the build-up of Zn, Cu, Pb, Cr, Ni and Cd on urban roads. The study outcomes revealed that the variability in metal build-up is highly influenced by the variability associated with metal adsorption to particulates. The percentage contribution from particulate properties influencing metal adsorption in the case of150 μm size road dust particles was found to be higher (Zn 44%, Cu 52%, Cr 16%, Ni 27% and Cd 45%) when compared to traffic and land use characteristics (Zn 21%, Cu 13%, Cr and Ni10% and Cd 34%). Similar adsorption behavior was noted for metals associated with150 μm size road dust particles. Among different particulate properties influencing metal adsorption, effective cation exchange capacity showed a strong positive relationship with the build-up of Cd compared to other metals, highlighting the potential role of Cd in stormwater quality as a readily available metal. The build-up of metals such as Cr and Ni are highly influenced by metal oxides of Al, Fe and Mn and clay forming minerals, indicating that Cr and Ni are relatively stable in nature.

The provision of water to meet the needs of an ever increasing urban population is a significant challenge. This is because urban receiving waters are constantly at risk from pollutant inputs via stormwater runoff and wastewater discharge. This research study employed multiple approaches including principal component analysis, Bayesian Networks (BNs) modelling and geospatial analysis to identify patterns in the distributions of nutrients and metals in water and sediments in an urban river and the interactions between the two phases. In both, water and sediments, nutrient concentrations/loads varied in the order of total carbon (TC) total nitrogen (TN) total phosphorus (TP). The river sediments were found to contain the highest crustal metal loads, while in water, the marine-related metals had the highest concentrations. The BNs modelling of pollutant interactions between water and sediment phases indicated that nitrogen is more likely to be transferred from water to sediment than the opposite, while anthropogenic metals are more likely to be transferred from sediments to water. Further, geospatial analysis showed that TN, crustal metals and anthropogenic metal loads in sediments increased from upstream to downstream, while having a decreasing pattern in water. However, marine-related metals in both, water and sediments had increasing concentrations/loads from upstream to downstream. These spatial patterns are attributed to the interactions between water and sediment phases, sediment transport along the river and seawater intrusion in the estuarine area. The study outcomes are expected to contribute to enhancing the knowledge required for developing mitigation strategies to improve urban receiving water quality.

Two-dimensional (2D) bismuth oxide (Bi2O3) heterostructured nanosheets (BOHNs) were first fabricated by a solution-based molecular self-assembly approach. The synthesized BOHNs nanosheets feature mixed α- and β-phases and rich surface/edge-active sites. When utilized as anode materials for rechargeable batteries, dual-phase BOHNs deliver an initial discharge capacity as high as 647.6 mAh g-1 and an increased capacity of over 200 mAh g-1 remained after 260 cycles for lithium-ion batteries (LIBs), and a stable cycling capacity at ∼50 mAh g-1 after 500 cycles for sodium-ion batteries (SIBs). A novel flexible 2D/1D/2D structure is further developed by implanting 2D BOHNs into conductive 1D carbon nanotubes and 2D graphene to form composite (BOHNCG) paper as free-standing anodes for both LIBs and SIBs. The capacity of 2D/1D/2D BOHNCG as a LIB anode reaches 823.5 mAh g-1, corresponding to an enhancement of ∼27%, and remains at >110 mAh g-1 after 80 cycles as a SIB anode with greatly improved cycling stability. This work verifies the promising potential of 2D BOHNs for practical energy-related devices and enriches the current research on emerging 2D nanomaterials.

Product selectivity of alkyne hydroamination over catalytic Au2Co alloy nanoparticles (NPs) can be made switchable by a light-on/light-off process, yielding imine (cross-coupling product of aniline and alkyne) under visible-light irradiation, but 1,4-diphenylbutadiyne in the dark. The low-flux light irradiation concentrates aniline on the catalyst, accelerating the catalytic cross-coupling by several orders of magnitude even at a very low overall aniline concentrations (1.0×10−3 mol L−1). A tentative mechanism is that Au2Co NPs absorb light, generating an intense fringing electromagnetic field and hot electrons. The sharp field-gradient (plasmonic optical force) can selectively enhance adsorption of light-polarizable aniline molecules on the catalyst. The light irradiation thereby alters the aniline/alkyne ratio at the NPs surface, switching product selectivity. This represents a new paradigm to modify a catalysis process by light.

Cobalt oxide nanostructures have been considered as promising electrode materials for various electrochemical applications, especially for batteries, supercapacitors, and electrocatalysis, owing to their unparalleled advantages of high theoretical capacity, highly-active catalytic properties, and outstanding thermal/chemical stability. If hybridized with property-complementary nanomaterials, such as nanocarbon, CNTs, graphene, metal oxides/sulfides and conductive polymers, their electrochemical properties can be further enhanced in terms of specific reversible capacity/capacitance, rate capability, cycling stability, and catalytic activity. In this review, we first give a comprehensive overview on recent progress in both monolithic cobalt oxide nanostructures and their hybrid nanomaterials for batteries, supercapacitors, and electrocatalysis applications. Then, structure-property relationships of the cobalt oxide-based nanomaterials and current challenges in both nanoarchitectures design and their applications in electrochemical energy devices are proposed, and an outlook on future research of this family of materials in electrochemical energy applications are brought forward. This understanding on the relationships of synthesis-nano/microstructure-property-performance of cobalt oxide-based nanomaterials is expected to lay a good foundation for pushing this promising class of materials to the practical application in energy conversion and storage devices and to provide a good reference for the readers in the fields of materials, chemistry, sustainable energy, and nanotechnology.

In this work, we demonstrate the fabrication of disposable and field deployable nanostructured conductive substrates for dual detection by Surface Enhanced Raman Scattering (SERS) and electrochemistry. Using a one-step potentiostatic process, gold nanostructures were electrodeposited on three substrates: bare indium tin oxide (ITO) electrode, ITO coated with plane gold and carbon fibre (CF) covered with ZnO nanowires (ZnO NWs). Their sensitivities were enhanced by incorporating the plane gold layer and ZnO NWs. The intensity of SERS signals produced on the nanostructured ITO substrates with 0.1 μM quinolinethiol were of the order: nanostructured gold-coated ITO > nanostructured bare ITO. The higher SERS signal on the nanostructured gold-coated ITO was attributed to the coupling between the surface plasmon polariton provided by the gold under layer and the surface plasmon resonance of the Au nanostructures. The ZnO NWs on the carbon fibre provided additional surface area for electrodeposition of gold nanostructures at high density. This led to multiple hotspots formation yielding high SERS signal intensity relative to that on a nanostructured bare carbon fibre. The nanostructured substrates, demonstrated good SERS signal reproducibility with relative standard deviation of 5.19%, 3.28% and 4.53% for Au/ITO, Au/Au-ITO and Au/ZnO-CF respectively. To demonstrate the potential application of these substrates and estimate their sensitivities, they were used to detect melamine by SERS at 1 pM (for Au nanostructures on bare ITO), 1 fM (for Au nanostructured gold-coated ITO), and 0.1 nM (for Au nanostructures on ZnO NWs-coated CF) concentrations with LOD of 0.118 pM, 0.189 fM and 57.4 pM respectively. Taking advantage of the conductive properties of gold nanostructured ITOs, electrochemical detection of 0.1 μM melamine (with an LOD of 0.05 μM) was also demonstrated. Hence, these substrates are potentially useful for SERS and electrochemical-based detection of organic toxicants.

A novel 2D-TiO2-2D van der Waals (vdW) heterostructured (BPNs@TiO2@G) hydrogel is developed as a high-performance anode material for lithium ion batteries by coating black phosphorus nanosheets (BPNs) onto porous graphene/TiO2 composite hydrogel (TiO2@G). This unique 2D-TiO2-2D vdW heterostructure not only prevents close restack between 2D nanosheets, but also provides rapid interlayer transfer paths and enhanced interfacial storage, together with some inherited advantages from 2D BPNs and graphene, such as shortened diffusion pathways, improved conductivity, supressed volume changes and lithium dendrite growth over cycling. As a result, BPNs@TiO2@G anode delivers an attractive initial discharge capacity as high as 1336.1 mAh g−1 (at 0.2 A g−1), a superior rate capability (271.1 mAh g−1 at 5.0 A g−1), and a good cycling life (502 mAh g−1 for 180 cycles) under a potential window close to 3.0 V. This study thus opens a new window for designing novel high-performance electrodes for electrochemical energy storage devices.

In order to investigate the transfer and accumulation pathways of heavy metals in cropland ecosystems, an investigation of the geochemical behaviors of heavy metals in soil and rice plants was carried out in the Yangtze River Delta. Soil is one of the biggest reservoirs of heavy metals and affects food safety at the beginning of the food chain. The results of this study demonstrate that heavy metal levels in soil decreased with increasing soil pH, while rice shoots accumulated heavy metals more readily under low soil pH conditions. The non-carcinogenic hazard quotients (HQ) of heavy metals show that health risks for humans were primarily due to Pb and As. Furthermore, cancer risk (Risk) results suggested that ~76% and ~15.7% of cancer risk was caused by Cd and As levels, respectively. Decreasing soil pH enhanced the non-carcinogenic and carcinogenic health risks for the human body. Through exponential change between transfer factor (TFgrain/soil) and soil metals, HQ, a direct monitoring method for rice plants, was built using regression curves. It is proposed that besides condition of soil with high heavy metal concentration, for rice grown with surface soil metals, the safety of the rice product should be monitored when soil metals are under the following levels after harvest: non-carcinogenic risk, As

The fate of metals in stormwater is primarily influenced by the transformation processes that they undergo during build-up on impervious surfaces. These processes result in changes to the bioavaila...

Due to its high analytical sensitivity and field deplorability, surface enhanced Raman spectroscopy (SERS) has emerged as an analytical tool for detecting environmental toxicants in different matrices. Progress has been made towards development of methods for depositing nanostructures onto solid platforms to design SERS substrates. The properties of the solid platforms used for SERS substrates fabrications such as electrical and heat conductivity, malleability and foldability, have significant influence on then design of the nanostructures and are critical for SERS technique. This review takes a look at recent advances in commonly employed conductive solid materials such as indium tin oxide, carbon fiber, silicon wafers, polyaniline fiber and carbon nanotubes as the supporting platforms for fabricating SERS substrates. It also examines their influence on the fabrication method, the morphology of the nanostructures formed as well as the hot spot density on the resultant novel SERS substrates. Real world applications of these substrates for the detection of environmental toxicants over the past decade have been shown. The review indicates that while significant advances have been made on the use of the conductive properties of these support platforms for SERS substrate fabrication, their subsequent application to detect environmental toxicants have not been fully explored.

Diketopyrrolopyrrole (DPP) is one of the most fascinating organic dyes, and has gained significant attention in the organic electronic community in recent times. Due to their outstanding semiconducting properties, DPP-based small molecules and polymers can be used as active semiconductor thin films for various high performance electronic devices. However, although several flanking groups attached to the DPP backbone have been reported in the literature for DPP molecules, there is little study about the effect of fused rings flanked on both sides of the DPP core. Recently our group reported for the first time a naphthalene-flanked DPP as a new DPP family member. In this work, we have performed electropolymerization studies on a newly synthesized naphthalene flanked DPP core with two alkyl chains, hexyl (H-DPPN) and octyl (O-DPPN), as conjugated monomers. Electrochemical studies have been carried out on glassy carbon (GC) and indium tin oxide (ITO) electrodes by using repetitive cyclic voltammetry (CV) as the deposition technique for up to 50 cycles. The concentration of H-DPPN and O-DPPN solution in dichloromethane was found to be a key parameter when optimizing conditions for obtaining an electropolymerised thin film, although other parameters such as the electrolyte, potential range, number of cycles, and the nature of the electrode all play a role in successful thin film formation. The electropolymerized thin films were characterised using UV-Vis spectroscopy, atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photon spectroscopy (XPS) and surface profilometry. We found that each monomer produced different film morphologies on glassy carbon and ITO electrodes. We believe that electropolymerized poly(H-DPPN) and poly(O-DPPN) thin film electrodes could be used for various applications such as studying redox reactions and bio-sensing.

Heteroatom doped-graphene is a potential candidate as an anode material in sodium-ion batteries (SIBs). However, one of the major issues holding back its development is that a complete understanding of the doping effects accounting for the Na-ion storage of heteroatom-doped graphene has remained elusive. In this work, first principles calculations have been conducted to systematically investigate the electronic and geometric effects in various heteroatom-doped graphene. Graphene doping with pyridinic-N, pyrrolic-N, F and B improves the electrochemical Na storage due to the electronic effect which originates from electron deficient sites (i.e. defects or electron deficient atoms). On the other hand, P doping improves the Na storage ability of graphene due to the geometric effect caused by bond length mismatch. In contrast, the introduction of graphitic-N and S into graphene is inefficient for Na storage because of their inability to accept electrons from Na. Interestingly, the diffusion energy barriers obtained for Na on doped graphene are lower than that for the pristine graphene. Furthermore, co-doping strategy is predicted to achieve even better Na storage capacity due to the synergistic effect.

Rivers are viewed as major pathways of microplastic transport from terrestrial areas to marine ecosystems. However, there is paucity of knowledge on the dispersal pattern and transport of microplastics in river sediments. In this study, a three dimensional hydrodynamic and particle transport modelling framework was created to investigate the dispersal and transport processes of microplastic particles commonly present in the environment, namely, polyethylene (PE), polypropylene (PP), polyamide (PA), and polyethylene terephthalate (PET) in river sediments. The study outcomes confirmed that sedimental microplastics with lower density would have higher mobility. PE and PP are likely to be transported for a relatively longer distance, while PA and PET would likely accumulate close to source points. High water flow would transport more microplastics from source points, and high flow velocity in bottom water layer are suggested to facilitate the transport of sedimental microplastics. Considering the limited dispersal and transport, the study outcomes indicated that river sediments would act as a sink for microplastic pollutants instead of being a transport pathway. The patchiness associated with the hotspots of different plastic types is expected to provide valuable information for microplastic source tracking.

Background Dewatering constitutes a major challenge to the production of microalgae, accounting for 20–30% of the product cost. This presents a setback for the applicability of microalgae in the development of several sustainable products. This study presents an investigation into the dynamic dewatering of microalgae in a combined flocculation-filtration process. The effect of process conditions on the performance of 12 flocculants and their mixtures was assessed. Results The mechanism of flocculation via the electrostatic path was dominated by charge neutralization and subsequently followed bridging in a ‘sweep flocculation’ process. Cationic polyacrylamide (CPAM) based flocculants recorded the highest biomass retention with PAM1 and PAM2 attaining 99 and 98% retention with flocculant dosages of 10 and 15 mg/L respectively. Polyvinylamine (PVAM) was also found to improve system stability across the pH range 4–10. Alum was observed to be only effective in charge neutralization, bringing the system close to its isoelectric point (IEP). Chemometric analysis using the multi-criteria decision methods, PROMETHEE and GAIA, was applied to provide a sequential performance ranking based on the net outranking flow (ф) from 207 observations. A graphical exploration of the flocculant performance pattern, grouping the observations into clusters in relation to the decision axis ($$\pi$$ π ), which indicated the weighted resultant of most favorable performance for all criteria was explored. Conclusion CPAM based flocculants and their mixtures demonstrated superior performance due to their viscoelastic behaviour under turbulence. The use of PVAM or alum in mixtures with CPAM reduced the required doses of both flocculants, which will provide beneficial financial impact for largescale microalgae dewatering in a flocculant assisted dynamic filtration process. Chemometric analysis based on the physico-chemical properties of the system provides a time saving assessment of performance across several criteria. The study findings provide an important foundation for flocculant assisted dynamic filtration processes.

A sensitive and recyclable plasmonic nickel foam sensor has been developed for surface-enhanced Raman spectroscopy (SERS). A simple electrochemical method was used to deposit flower-shaped gold nanostructures onto nickel foam substrate. The high packing of the gold nanoflowers onto the nickel foam led to a high enhancement factor (EF) of 1.6 &times, 1011. The new SERS sensor was utilized for the direct determination of the broad-spectrum &beta, lactam carbapenem antibiotic meropenem in human blood plasma down to one pM. The sensor was also used in High Performance Liquid Chromatography (HPLC)-SERS assembly to provide fingerprint identification of meropenem in human blood plasma. Moreover, the SERS measurements were reproducible in aqueous solution and human blood plasma (RSD = 5.5%) and (RSD = 2.86%), respectively at 200 &micro, g/mL (n = 3), and successfully recycled using a simple method, and hence, used for the repeated determination of the drug by SERS. Therefore, the new sensor has a strong potential to be applied for the therapeutic drug monitoring of meropenem at points of care and intensive care units.

Bioavailability is a critical facet of metal toxicity. Although past studies have investigated the individual role of sediment physico-chemical properties in relation to the bioavailability of heavy metals, their collective effects are little-known. Further, limited knowledge exists on the contribution of nutrients to metal bioavailability. In this study, the influence of physico-chemical properties of sediments, including total organic carbon (TOC), total phosphorus (TP), total nitrogen (TN), cation exchange capacity (CEC), specific surface area (SSA), and mineralogical composition to metal bioavailability is reported. The weak-acid extraction method was used to measure Cd, Cr, Cu, Ni, Pb and Zn as the potentially bioavailable fraction in sediments in an urban creek. The results confirmed that Cu has strong selectivity for organic matter (r = 0.814, p

Recombinant human erythropoietin (rHuEPO) is an important hormone drug that is used to treat several medical conditions. It is also frequently abused by athletes as a performance enhancing agent at sporting events. The time window of the rHuEPO in blood is short. Therefore, the rapid detection of rHuEPO use/abuse at points of care and in sports requires a selective analytical method and a sensitive sensor. Herein, we present a highly selective method for the rapid detection of rHuEPO in human blood plasma by a sensitive optical sensor. rHuEPO is selectively extracted from human blood plasma by a target-specific extractor chip and converted into a biothiol by reducing its disulfide bond structure. The formed biothiol reacts with a water soluble (E)-1-((6-methoxybenzo[d]thiazole-2-yl)diazenyl)naphthalene-2,6-diolHg(ii) (BAN-Hg) optical sensor and causes its rapid decomposition. This leads to a rapid change in the sensor color from blue to pink that can be observed by the naked eye. The optical sensor was used to quantify rHuEPO in the concentration range 1 × 10-8 M to 1 × 10-12 M by UV-Vis spectroscopy. For the screening of blood plasma, an EPO-specific extractor chip was synthesized and used to selectively extract the protein from the biological matrix prior to its conversion into biothiol and quantification by the optical sensor. Since many proteins have a disulfide bond structure, the new method has strong potential for their rapid sensitive and selective detection by the BAN-Hg sensor and UV-Vis spectroscopy.

Heteroatom-doping engineering has been verified as an effective strategy to tailor the electronic and chemical properties of materials. The high amount doping of nonmetal atoms to achieve desired performance, however, is always a grand challenge. Herein, a new strategy to achieve ultrahigh-level doping of phosphorus in a 3D graphene skeleton is proposed by sacrificing heterostructured two-dimensional black phosphorus on graphene. Via this approach, the phosphorus-loading in graphene hydrogel reached a record of 4.84 at. %, together with the formation of tunable pores of size 1.7–17.5 nm in graphene. During reaction kinetic analysis, the highly phosphorus-doped 3D graphene hydrogel anode exhibited more favorable capacitive-controlled ion storage behaviors, leading to a specific capacity as high as 1000 mA h g–1 after 1700 cycles, which is superior to the pristine graphene hydrogel electrode. This simple but effective phosphorization offers an effective doping strategy for producing ultrahigh-level phosphorous doping but avoids the usual use of toxic phosphorous precursors. Furthermore, the modulation on the activation process over cycling investigated in this work gives us a new insight into designing stable anodes for carbonaceous electrode materials.

Rivers are regarded as sinks and pathways of plastic pollutants from terrestrial environments to various other aquatic systems such as lakes and oceans. Although extensive research has been conducted in recent years on microplastic pollution in river sediments, knowledge on the relationships between potential influential factors such as catchment characteristics and sediment properties, and microplastics occurrence in river sediments, is still considered an under-researched area. This study evaluated the influence of land use, population, and sediment particle size on the presence of microplastics abundance and types. Based on a Bayesian Network modelling approach to characterise the correlations between influencing factors and microplastics occurrence, it was evident that microplastics type had a positive correlation with different land use types and population. Catchment characteristics were found to play a more important role in influencing microplastics type than microplastics concentration. A statistically significant positive relationship was observed between microplastics concentration and clay particles which suggested that the occurrence of microplastics in sediments can be impacted by the presence of clay particles.

Road dust is a key repository for PAHs and transformed PAH products (TPPs) generated from natural and anthropogenic sources in the urban environment. Eventhough PAHs and TPPs are prone to post-emission photochemical processes, very limited studies exist on the subject for road dust. This knowledge gap is of particular concern since some of the resultant TPPs are notably more carcinogenic than their precursor PAHs. This study evaluated the role of 254 nm ultraviolet (UV) photons on the photochemistry of PAHs and TPPs in road dust. The findings show that UV irradiation had varying effects on the fate of analytes, particularly naphthalene (NAP), phenanthrene (PHE), 7, 12-dimethylbenz(a)anthracene (DMBA), 1-hydroxypyrene (HPY), 1-nitropyrene (1NPY), pyrene (PYR) and 5-nitroacenaphthene (5NAC). Photochemical relationship was identified between PYR, 1NPY and HPY, and DMBA and benzo(a)anthracene. Unlike carbonyl-PAHs, parent PAHs, nitro-PAHs and hydroxy-PAHs can originate from photolysis. Photon irradiation durations of 3, 6 and 7.5 h had the most intense influence on the photolytic process with 7.5 h as optimum. The photochemical rate at optimum irradiation duration shows an increasing trend of NAP PHE1NPY DMBA5NAC HPY with respective estimates of 0.08, 0.11, 0.21, 0.22, 0.43, and 0.59 mg kg

The development, modification and optimization of analytical methods capable of simultaneous extraction and in-cell clean-up of extracts for subsequent determination of parent PAHs and their associated transformed nitro-PAHs (NPAH), carbonyl-PAHs (CPAH) and hydroxy-PAHs (HO-PAH) products (TPPs) is essential for reducing the time and cost of analysis. The aim of this study was to modify and optimize the pressurized fluid extraction (PFE) technique capable of simultaneous extraction and in-cell clean-up of PAHs and TPPs in urban dust standard reference material and road dust for GC-MS analyses. In this study, multivariate data analysis such as factor analysis (FA), and preference ranking organisation method for enrichment evaluation (PROMETHEE) and geometrical analysis for interactive aid (GAIA) were used to assess the performance of the methods. As the key outcome of the study, an optimized selective reaction monitoring (SRM) Triple Quadrupole (TQ) electron ionization (EI)-GC/MS for measuring PAHs and TPPs without derivatization of polar HO-PAHs was developed. The limits of detection (LOD) for parent PAHs, CPAHs, NPAHs and HO-PAHs using Shimadzu TQ were 1.0–5.0 pg, 1.0–5.0 pg, 1.0–50.0 pg, and 1.0–25.0 pg, respectively. The PROMETHEE-GAIA analysis of the results showed that a combination of 3% deactivated silica gel and activated alumina (2:1) as in-cell clean-up material, and sequential PFE extraction (200 °C ASE temperature, 9 min preheat time and 3 times extraction cycle) using 100% hexane followed by hexane/DCM (1:1) is the best condition for analytes extraction from road dust. An optimized, fast and reliable GC/MS method operated solely in electron ionization (EI) mode was developed for measuring all analytes. The outcomes of this study will contribute significantly to future research on PAHs and TPPs, thereby promoting a safe and sustainable environment.

Particle build-up is a key stormwater pollutant process that is typically replicated using a power function with increasing antecedent dry days. Though the use of a power function is recommended by a range of researchers, its applicability is demonstrated primarily for residential roads. Particle build-up process is also subjected to significant variability due to catchment heterogeneity and variability associated with source characteristics such as traffic and land use. Variability in the build-up process and use of stereotypical coefficients can lead to significant model uncertainty. This study evaluates particle build-up characteristics on urban road surfaces using an extensive field investigation program, giving specific priority to industrial and commercial roads. Based on the outcomes, particle build-up process characteristics and respective uncertainties were evaluated and compared for road surfaces in residential, industrial and commercial areas. The study primarily found that both, industrial and commercial land uses generally manifested greater particle build-up loads compared to residential land uses. The study provides estimates for build-up coefficients for a range of land uses, including industrial and commercial with their potential uncertainties in build-up predictions. This provides new knowledge to improve stormwater quality modelling. Aside from land use, the proximity of sites to major road networks was also identified as a critical factor influencing the variability and uncertainty in particle build-up. Variability of the fraction of particles in the

Graphene hydrogel (GH) has attracted increasing attention in energy storage and conversion, pollutant adsorption, catalysis, sensors and tissue engineering applications. However, a good understanding of the structure-property relationship is essential to precisely tune their properties. In this work, a pH assisted hydrothermal process was used to synthesize reduced graphene oxide (rGO) hydrogels with different three-dimensional (3D) porous structures. We systematically investigated the structure-property relationships in the GH, with a focus on the effects of geometrical dimensions of the pore structure. We found that the best mechanical properties were achieved in a compact microstructure consisting of small pores but thick walls. Despite having a lower C/O ratio, the compact structure gave rise to the highest electrical conductivity, attributed to the highly interconnected 3D porous structure providing conductive pathways. On the other hand, the hydrogels prepared under basic conditions exhibited higher C/O ratio but lower mechanical and electrical properties due to the disordered pore structure with large pores and thin walls.

Metals deposited on urban road surfaces and incorporated in stormwater runoff are discharged into receiving waters, influencing their quality and can pose human health risks. Effective design of stormwater treatment measures is closely dependent on the in-depth understanding of stormwater pollutant sources and the associated health risks. The study discussed in this paper has linked the sources of metals in stormwater runoff and the accompanying human health risk to rainfall characteristics. The study outcomes confirmed that the metal contributions to stormwater runoff from the primary sources were in the order of sea salt > soil > traffic. Although traffic contributes a relatively lower percentage to wash-off, the human health risks posed by traffic sourced metals were relatively much higher. This implies that traffic sources should receive particular attention in treating stormwater. These outcomes have the potential to contribute to enhancing effective source control measures in order to safeguard natural waterways from polluted road wash-off.

The adsorption behaviour of metals deposited on road surfaces undergo changes during dry weather periods, with the bioavailability varying compared to the original species, prior to incorporation in stormwater runoff. This study investigated the role of antecedent dry days on the transformation characteristics of Zn, Cu, Pb and Cd attached to different geochemical forms of road dust, in order to predict potential stormwater quality impacts. The study outcomes showed that the exchangeable fraction generally decreased with the increase in antecedent dry days, but the reducible, oxidisable and residual fractions increased. This implies that there is a time-dependent transformation of weakly bound metals in road dust to more persistent chemical forms. The transformation rate of metals was found to be in the order of Pb > Cu > Zn > Cd. Significant changes in metal distribution among the geochemical fractions were observed up to seven dry days, suggesting that during the initial antecedent dry days, the transformations can be relatively more significant. Among the analysed metals, Cd present on road surfaces has a higher potential for being bioavailable during the antecedent dry days.

In this work, we propose a new sensitive, selective and portable surface enhanced Raman spectroscopy (SERS) methodology for the rapid on site detection of Pb(II) pollution in water. The new method utilises aminobenzo-18-crown-6 (AB18C6) as a selective recognition molecule to form a spontaneous complex with Pb(II) ions. The formed AB18C6-Pb(II) complex was rapidly immobilised onto a nanostructured gold substrate via Au-N bond formation and reproducibly screened by SERS using a handheld Raman device. For the SERS measurements, a substrate was fabricated by electrochemical deposition of gold nanostructures onto a flat gold disc, creating multiple hotspots for ultrasensitive SERS measurements. The limit of quantification (LOQ) for Pb(II) ions by the SERS method was 2.20 pM. The limit of detection (LOD) was 0.69 pM which is five orders of magnitude lower than the maximum Pb(II) level of 72 nM allowed by the US Environmental Protection Agency. The high sensitivity of the SERS substrate is attributed to the coupling between the Surface Plasmon Polariton (SPP) of its gold surface, the localised Surface Plasmon Resonance (SPR) of the gold nanostructures and the Raman radiation from the immobilised AB18C6-Pb(II) complex. The new SERS detection method was successfully applied for the selective and rapid screening of Pb(II) ion contamination in water proving its practical application for environmental analysis.

Adsorption of iodate (IO3−) from concentrated solutions by LDH materials has been investigated in laboratory scale batch experiments. Very high iodate (IO3−) uptake (close to 100%) was observed in almost all experiments. Adsorption data was compared to the Langmuir and Freundlich adsorption isotherm models as well as the pseudo first and second order kinetic models. The data from the 3:1 Mg/Al LDH thermally activated to 500 °C was best described by the Freundlich isotherm and the pseudo second order model, suggesting that adsorption was a heterogeneous or multilayer process. HPLC data was used in an attempt to identify any conversion of iodate (IO3−) to iodide (I−) during the adsorption process, however, the residual concentration of iodide (I−) was close to or below the limit of detection of the particular analytical technique. This suggests that little or no conversion happened under experimental conditions.

As one of the most popular beverages around world, factors influencing transfer of heavy metals from soil to tea leaves is crucial to investigate and assess health risk through tea drinking. Parent material (PM), soil and tea samples from Anhui province, typical tea producing area in China were collected in this study. To find out distribution characteristics of heavy metals in tea and soil, and influencing factors for transfer process, variables of plantation factors, soil properties and geological background were taken into account. The results showed that weathering pedogenic process could be the main release source of heavy metals in soil under the acid environment for tea growth. More than 75% of soil Cd, Hg, Pb and Zn exceeded background. However heavy metals in tea samples were below the limits of China, WHO and EU standards. Soil organic matter and redox process influenced the distribution and transfer of As, Pb, Cd and Hg in soil and tea. While geochemical behaviours of Cr, Cu, Ni and Zn were mainly related to soil pH and iron oxides in tea garden. The method of classification and regression trees (CART) showed clones of tea type, bedrock type, soil texture, soil organic and fertilizer application were identified as the main factors influencing transfer factors of heavy metals from soil to tea. The specific types of tea grown in the soil with sandy clay and bedrock of granite/granodiorite and shale should be given more monitoring. The non-carcinogenic hazard quotients (HQ) and cancer risk (Risk) through tea drinking were primarily caused by Pb and Cd respectively. To reduce the potential health risk from tea, application of organic and/or compound fertilizer were thought to be the effective management strategy for tea plantation.

Detailed knowledge of the processes that metals undergo during dry weather periods whilst deposited on urban surfaces and their environmental significance is essential to predict the potential influence of metals on stormwater quality in order to develop appropriate stormwater pollution mitigation measures. However, very limited research has been undertaken in this area. Accordingly, this study investigated the geochemical phase and particle size relationships of seven metals which are commonly associated with urban road dust, using sequential extraction in order to assess their mobility characteristics. Metals in the sequentially extracted fractions of exchangeable, reducible, oxidisable and residual were found to follow a similar trend for different land uses even though they had variable accumulation loads. The high affinity of Cd and Zn for exchangeable reactions in both, bulk and size-fractionated solid samples confirmed their high mobility, while the significant enrichment of Ni and Cr in the stable residual fraction indicated a low risk of mobility. The study results also confirmed the availability of Cu, Pb and Mn in both, stable and mobile fractions. The fine fraction of solids (

In this article, the authors report the adsorption of iodide by Mg/Al LDHs and thermally activated LDH materials in laboratory scale batch experiments. The optimal Mg/Al cation ratio was 3:1while the percentage iodide uptake increased with increasing adsorbent dose up to 1 g/20 mL of solution. The effect of initial iodide concentration was investigated using the Langmuir and Freundlich adsorption isotherm models, while the pseudo second order kinetic model appeared to provide the best fit for the experimental data. High iodide uptake of over 80% could be achieved without completely eliminating dissolved or atmospheric carbonate and leaching of 131I from LDHs did not appear to be a significant problem over the period of 28 days investigated. These results demonstrate that LDHs, which are already commercially available in large quantities, are a technology that shows considerable promise for the removal of radioiodine from aqueous solution.

Highlights - A review of contaminants removed by clay-nZVI composite materials from aqueous solutions is made. - Reaction mechanisms of the materials with contaminants are discussed. - Excellent removal efficiencies of contaminants by composite materials are reported. - The review suggests research needs for future work. Abstract Recent industrialization and urbanization have increased the aqueous concentrations of a wide range of contaminants, which are toxic to human health and the environment. Therefore, remediation of aqueous solutions has turned into an important environmental issue. Over the last decade, growing attention has been paid to clay-supported nanoscale zero-valent iron (nZVI) composite materials as efficient and promising remediation materials in wastewater treatment and groundwater remediation technologies. This paper gives an overview of the clay minerals, zero-valent iron materials, clay-supported nZVI composites, and progress obtained during the remediation of contaminated aqueous solutions utilizing the clay-supported nZVI composites for the removal of heavy metals, nitrate, selenate, dyes, phenolic compounds, chlorinated organic compounds, nitroaromatic compounds and polybrominated diphenyl ethers. Reaction mechanisms and removal efficiencies were studied and evaluated. It was reported that the clay-supported nZVI composites have appreciable removal efficiency for different types of contaminants. This paper also reviews the use of ZVI-clay technology for the remediation of contaminated sites. Concerning clay-supported nZVI composites for future research, some recommendations are proposed and conclusions are drawn.

Highlights - Sofosbuvir metabolite was studied for the first time by Raman spectroscopy. - Cheap and disposable paper substrate was utilized for the determination of PSI-6206 by HPLC-SERS. - The use of disposable substrate eliminated the memory effect problem in the HPLC-SERS. - The SERS LOQ of PSI-6206 was 13 ng L-1 (R2 = 0.959, RSD = 5.23%), 4 orders of magnitude less than HPLC-DAD. - The HPLC-SERS method provided unique structural identification of PSI-6206 similar to HPLC-MS Abstract Sofosbuvir metabolite, 2′-deoxy-2′-fluoro-2′-C-methyluridine (PSI-6206) was studied for the first time by surface enhanced Raman spectroscopy (SERS) using the paper-based SERS substrate. The quantification limit of PSI-6206 by SERS was found to be 13 ng L−1 (R2 value = 0.959, RSD = 5.23%). For the structural and quantitative analysis of PSI-6206 in blood plasma, an interference-free HPLC-SERS method was developed and compared to HPLC-DAD and HPLC–MS methods. The SERS quantification of the drug by the paper substrate was 4 orders of magnitude more sensitive than that by the diode array detector. In addition, the SERS detection provided unique structural identification of the drug in blood plasma, similar to Mass spectroscopy detector. Due to the disposable nature of the SERS substrate, the new method does not suffer from the known “memory effect” which is known to lead to false positive identification in traditional HPLC-SERS methods. Therefore, the presented HPLC-paper SERS platform holds great potential for the sensitive and cost effective determination of drugs and their metabolites in biological fluids.

Sediment samples collected over a 3-year period from Brisbane River, Australia, were analysed for fifteen (15) polycyclic aromatic hydrocarbons (PAHs). The total PAH concentrations varied from 148 to 3079 ng/g with a mean concentration of 849±646 ng/g. The study revealed that PAH input into the river was primarily dominated by pyrogenic sources as evidenced by the predominance of the high molecular weight (HMW) PAHs. Temporal variations of PAHs can be linked to the level of urbanization, with continuous input of combustion related PAHs in the commercial area of the river. Inherent deficiencies in using a single source identification/apportionment approach were overcome by using diagnostic ratios, principal component analysis/absolute principal component scores (PCA/APCS) and positive matrix factorization (PMF). Both PCA/APCS and PMF resolved four (4) identical factors or sources of PAH, namely: gasoline emissions, diesel emissions, biomass burning and natural gas combustion. Diagnostic ratios, PCA/APCS and PMF analysis indicated that vehicular emissions were the principal sources especially within the lower section of the river while biomass burning had moderate contribution. The distribution, temporal trend and source apportionment suggest the containment of industrial-derived sources of PAH in the river. From an ecological point of view, the risk posed by PAHs in the Brisbane River sediment is low. Nevertheless, when the investigated sites were ranked using multi-criteria decision making methods (MCDM) the commercial stratum was the most contaminated. Assessment of potential risks posed by incidental dermal exposure to PAHs revealed some degree of cancer risk, especially to children.

Photochemical smog, characterized by high concentrations of ozone (O3) and fine particles (PM2.5) in the atmosphere, has become one of the top environmental concerns in China. Volatile organic compounds (VOCs), one of the key precursors of O3 and secondary organic aerosol (SOA) (an important component of PM2.5), have a critical influence on atmospheric chemistry and subsequently affect regional and global climate. Thus, VOCs have been extensively studied in many cities and regions in China, especially in the North China Plain, the Yangtze River Delta and the Pearl River Delta regions where photochemical smog pollution has become increasingly worse over recent decades. This paper reviews the main studies conducted in China on the characteristics and sources of VOCs, their relationship with O3 and SOA, and their removal technology. This paper also provides an integrated literature review on the formulation and implementation of effective control strategies of VOCs and photochemical smog, as well as suggestions for future directions of VOCs study in China.

Consumption of crops grown in cadmium-contaminated soils is an important Cd exposure route to humans. The present study utilizes statistical analysis and in vitro digestion experiments to uncover the transfer processes of Cd from soils to the human body through rice consumption. Here, a model was created to predict the levels of bioaccessible Cd in rice grains using phytoavailable Cd quantities in the soil. During the in vitro digestion, a relatively constant ratio between the total and bioaccessible Cd in rice was observed. About 14.89% of Cd in soils was found to be transferred into rice grains and up to 3.19% could be transferred from rice grains to the human body. This model was able to sufficiently predict rice grain cadmium concentrations based on CaCl2 extracted zinc and cadmium concentrations in soils (R2 = 0.862). The bioaccessible Cd concentration in rice grains was also able to be predicted using CaCl2 extracted cadmium from soil (R2 = 0.892). The models established in this study demonstrated that CaCl2 is a suitable indicator of total rice Cd concentrations and bioaccessible rice grain Cd concentrations. The chain model approach proposed in this study can be used for the fast and accurate evaluation of human Cd exposure through rice consumption based on the soil conditions in contaminated regions.

Estuarine environment is complex and receives different contaminants from numerous sources that are persistent, bioaccumulative and toxic. The distribution, source, contamination and ecological risk status of heavy metals in sediment of Brisbane River, Australia were investigated. Sediment samples were analysed for major and minor elements using LA-ICP-MS. Principal component analysis and cluster analysis identified three main sources of metals in the samples: marine sand intrusion, mixed lithogenic and sand intrusion as well as transport related. To overcome inherent deficiencies in using a single index, a range of sediment quality indices, including contamination factor, enrichment factor, index of geo-accumulation, modified degree of contamination, pollution index and modified pollution index were utilised to ascertain the sediment quality. Generally, the sediment is deemed to be "slightly" to "heavily" polluted. A further comparison with the Australian Sediment Quality Guidelines indicated that Ag, Cr, Cu, Ni, Pb and Zn had the potential to rarely cause biological effects while Hg could frequently cause biological effects. Application of potential ecological risk index (RI) revealed that the sediment poses moderate to considerable ecological risk. However, RI could not account for the complex sediment behaviour because it uses a simple contamination factor. Consequently, a modified ecological risk index (MRI) employing enrichment factor is proposed. This provides a more reliable understanding of whole sediment behaviour and classified the ecological risk of the sediment as moderate to very high. The results demonstrate the need for further investigation into heavy metal speciation and bioavailability in the sediment to ascertain the degree of toxicity.

Infliximab (INF) is a chimeric monoclonal immunoglobulin acting against tumor necrosis factor-alpha (TNF-α). The drug is used for the treatment of chronic autoimmune and inflammatory diseases. A target-specific nanomaterial is presented for the extraction of INF from human plasma along with a label-free surface enhanced Raman spectroscopy (SERS) method for its determination using a handheld device. A gold-coated copper oxide chip was functionalized with TNF-α and used to extract the drug from plasma. INF was recovered from the extractor by lowering the pH value to 2.5. The disulfide bond structure of the drug was then reduced and used for its oriented chemisorption onto a gold-coated copper oxide substrate for SERS measurements using the INF-specific band at 936 cm −1. The working range of the SERS method was between 10 −7 and 10 −14 M of reduced INF. The relative standard deviation (RSD), between three different measurements was 4.2% (intra-day) and 7.1% (inter-day). The quantification and detection limits of the assay (LOQ, LOD) were 0.01 pM and 1.4 fM respectively. The SERS detection was cross-validated against ELISA where 99% agreement was found between the two methods. [Figure not available: see fulltext.]

The detection of anti-TNF-α drugs require rapid, selective and sensitive biosensors that can be easily utilised at the point of care. Herein, we demonstrate a new biosensing approach that employs target-specific nanomaterial and label free surface-enhanced Raman spectroscopy (SERS) for the selective extraction and rapid determination of Adalimumab (ADB) in human blood plasma. The new method utilises the tumour necrosis factor (TNF-α) for the fabrication of a target-specific nanomaterial for extraction of ADB. The method also uses the thiol chemistry of the purified antibody drug for its chemisorption onto a gold-coated copper oxide substrate. A handheld Raman spectrophotometer is used for the determination of ADB by label free SERS. The limits of quantification (LOQ) and detection (LOD) of the purified and reduced drug by SERS were 0.10 fM and 0.03 fM respectively. ELISA was used for the cross validation of the SERS quantification of ADB where a 98.8% agreement was found between the two methods. Many proteins have disulfide bonds in their molecular structure. Therefore, the demonstrated biosensing approach can be extended for the rapid screening of other proteins and antibody drugs by developing target-specific extractor nanomaterial and utilizing the disulfide bond structure of the purified biomolecules for their label free SERS detection.

A new benzothiazole azo dye [(E)-1-((6-methoxybenzo[d]thiazole-2-yl)diazenyl)naphthalene-2,6-diol] (also known as “BAN”), has been synthesised and used as a chemosensor for the rapid and selective detection of mercury(II) ions in water. The pink coloured chemosensor turns blue when reacted with mercury(II) ions due to the formation of a 2 : 1 coordination complex. The complex formation causes a bathochromic shift of the chemosensor's UV absorption peak from 540 to 585 nm and turns on a highly selective fluorescence emission at 425 nm. The change in the optical property of BAN upon complexation with mercury(II) was confirmed by ab initio calculations. The new chemosensor was used to quantify mercury(II) ions in water by fluorescence spectroscopy down to 5 × 10−8 M (10 ppb). The limit of detection (LOD) of Hg2+ was 9.45 nM (1.8 ppb) which satisfies the maximum allowable Hg2+ concentration in drinking water that is set by the WHO. The BAN–Hg(II) complex was used for the determination of cysteine (Cys) in aqueous solution by UV-Vis spectroscopy down to 1 × 10−7 M. The thiol-containing amino acid preferentially coordinates the mercury ions of the BAN–Hg(II) complex. This causes dissociation of the blue-coloured complex and the liberation of the pink-coloured BAN dye. The colour change of the BAN–Hg(II) complex from blue to pink was selective to the Cys biothiol while other non-thiol containing amino acids did not cause a colour change. For the in-field application, filter paper strips were loaded with the BAN–Hg(II) complex and used as a disposable sensor for the detection of cysteine (Cys) by the naked eye. Therefore, the BAN chemosensor offers a sensitive, and rapid tool for the detection of mercury(II) in water. In addition, the BAN–Hg(II) complex can be used as a simple and selective chemosensor of the screening of purified biothiols, such cysetine, homocysteine and glutathione in biology research and pharmaceutical/food industries.

Polycyclic aromatic hydrocarbons (PAHs) are prone to post-emission transformation and degradation to yield transformed PAH products (TPPs) that are potentially more hazardous than parent PAHs. This review provides a comprehensive evaluation of the potential environmental processes of PAHs such as sorption, volatilisation, photo- and bio-transformation and degradation on road surfaces, a significant accumulation point of PAHs. The review primarily evaluates key influential factors, toxicity implications, PAHs and TPPs fate and viable options for mitigating environmental and human health impacts. Photolysis was identified as the most significant transformation and degradation process due to the light absorption capacity of most PAHs. Climate conditions, physicochemical properties of road dust (sorbent), PAHs and TPPs and the existence of heavy metals such as Fe (III) are notable underlying factors for photolysis. Available data points to the predominance of carbonyl TPPs than other products such as nitro and hydroxyl TPPs with decreasing concentration trend of 9-fluorenone > 9,10-anthraquinone > benzo[a]fluorenone on road surfaces. The review recommends conducting future investigations targeting the influential factors pertaining to the fate of road deposited PAHs and TPPs. Furthermore, development of cost and time effective modern analytical methods is needed to quantify PAHs and TPPs present in minute quantities of samples. The review also identified that the unavailability of toxicity equivalency factors (TEF) for the most critical TPPs can be addressed using quantitative structure-activity relationship (QSAR) models and bioassays simultaneously. The content of this review is significant to the future work of researchers across various fields including analytical and environmental chemistry, stormwater pollution and toxicology.

Understanding the factors influencing the build-up behaviour of different pollutants accumulated on urban roads is essential for the implementation of effective stormwater pollution mitigation strategies. Even though a significant knowledge base exists on different factors influencing hydrocarbon build-up, there is a dearth of evidence on how physicochemical properties of road dust influence hydrocarbon build-up. Accordingly, this study investigated the relationships between physicochemical properties of road dust and hydrocarbons associated with different particle size fractions of road dust. Hydrocarbons with different sources of origin in all size fractions showed a significant correlation with different soil constituents of road dust, predominantly with organic matter, amorphous matter, clay minerals and clay forming minerals of feldspars. However, the physicochemical properties influencing the hydrocarbon build-up is different among different particle size fractions. The interactions identified between hydrocarbon compounds and different minerals associated with road dust will contribute to the development of effective stormwater pollution mitigation strategies.

The high pollutant loads discharged from cities pose risks to urban waterways, and in turn the estuarine environments, making it challenging to improve urban liveability. Past studies on the behaviour of pollutants in rivers have largely investigated their transport along the waterway, primarily focusing on the movement of water and sediment. However, the current approaches in pollutant transport modelling provide limited insights into how pollutant transfer between water and sediment phases influences their transport from the upstream towards the estuarine environment. This research study firstly identified typical patterns of metal loads along an urban river in a highly populated city in China. The outcomes were then used to conceptualise metal transfer between water and sediment phases. It was noted that physico-chemical characteristics of water and sediments play a key role in metal transfer between the two phases, and the dominant transfer path (sediment to water/water to sediment) is different between different metals, independent of their origin (crustal, anthropogenic or marine-related). Several scenarios were derived from the conceptualisation of metal behaviour. These in turn were then used to develop real-world scenarios of metal transport in rivers based on the field data. The conceptualisation of metal behaviour confirmed that each metal is likely to have a dominant phase of transport (sediment/water), which is influenced by the dominant transfer path of that metal between water and sediments.

Urban road build-up solids contain toxic metals posing potential risks to human health. Management of human health risks arising from these metals is critical in urban areas. This study collected solids build-up data from 16 study sites with various land use and traffic characteristics. Source quantification was conducted using PCA/APCS receptor model. It was found that soil and asphalt wear are the largest contributors (69.43%) to risk and mainly contribute Al, Cr, Mn, Fe, Ni, Zn and Pb to build-up solids. Brake wear is the second largest contributor accounting for 17.20% and contributes Cd and Cu. Tyre wear is the third major contributor (11.38%) and it primarily contributes Ni, Zn and Cr. Mathematical equations were fitted to estimate the risk against daily traffic volume and land use fractions, and the uncertainty analysis highlighted that risk assessment should account for the variability in metal concentrations rather than a point value of concentrations at a given time and space. Based on source quantification and risk assessment, an integrated risk management model was developed to manage human health risks from toxic metals in build-up solids. This risk model provides guidance for urban planning and land use development to mitigate risk arising from urban road deposited solids.

Land use management plays a key role in mitigating urban river pollution. Past research has addressed how primary land uses influence river water and sediment quality, but has given limited attention to the subdivision of primary land uses to a secondary level, limiting the accurate identification of potential sources of pollutants. The current study, using Bayesian Networks, investigated how the hierarchical structure of land use can be employed to accurately characterise the pollution of sediments in two rivers in China and Australia. It was found that the primary land uses are a weak determinant of potential sources of metals, nutrients, and organochlorine pesticides (OCPs). However, secondary land uses provide higher accuracy in determining pollutant sources. The study highlighted that the lack of data to enable the subdivision of land uses can constrain informed decision making for the mitigation of urban water pollution.

Co-precipitation is a common method for the preparation of layered double hydroxides (LDHs) and related materials. This review article is aimed at providing newcomers to the field with some examples of the types of co-precipitation reactions that have been reported previously and to briefly investigate some of the properties of the products of these reactions. Due to the sheer volume of literature on the subject, the authors have had to limit this article to the synthesis of Mg/Al, Zn/Al and Ca/Al LDHs by co-precipitation and directly related methods. LDHs have been synthesised from various reagents including metal salts, oxides and hydroxides. Co-precipitation is also useful for the direct synthesis of LDHs with a wide range of interlayer anions and various bases have been successfully employed to prepare LDHs. Examples of other synthesis techniques including the urea method, hydrothermal synthesis and various mechanochemical methods that are undoubtedly related to co-precipitation have also been included in this review. The effect of post synthesis hydrothermal has also been summarised.

Novel heterogeneous Fenton composite materials were developed by grafting acid precursors and nano zero-valent iron particles on an acid leached diatomite, which can sequentially generate acid and ferrous ions in situ. The results show that the composite materials can potentially solve two of the biggest obstacles, which prevent the conventional Fenton reaction from being widely and practically adopted, namely: the continuous feed of ferrous ions and the maintenance of the optimum acidic pH condition during the reaction. In this study, samples were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Thermogravimetric analysis and micro organic analysis. The novel materials’ degradation capacities for bisphenol A (BPA) were evaluated and optimized. This material can be easily applied to treat wastewater via Fenton-like reaction without changing pH or adding ferrous ions. The relationships between BPA removal efficiency, the amount of grafted organosilane acid precursor and doped nZVI particles on the composite materials were investigated. It is evident from the results that the novel composite materials afford highly effective removal of BPA from water at 250 mg/g. The work thus demonstrates that the novel materials could potentially be utilized for efficient remediation of recalcitrant organic compounds from the environment.

Among urban stormwater pollutants, hydrocarbons are a significant environmental concern due to their toxicity and relatively stable chemical structure. This study focused on the identification of hydrocarbon contributing sources to urban road dust and approaches for the quantification of pollutant loads to enhance the design of source control measures. The study confirmed the validity of the use of mathematical techniques of principal component analysis (PCA) and hierarchical cluster analysis (HCA) for source identification and principal component analysis/absolute principal component scores (PCA/APCS) receptor model for pollutant load quantification. Study outcomes identified non-combusted lubrication oils, non-combusted diesel fuels and tyre and asphalt wear as the three most critical urban hydrocarbon sources. The site specific variabilities of contributions from sources were replicated using three mathematical models. The models employed predictor variables of daily traffic volume (DTV), road surface texture depth (TD), slope of the road section (SLP), effective population (EPOP) and effective impervious fraction (EIF), which can be considered as the five governing parameters of pollutant generation, deposition and redistribution. Models were developed such that they can be applicable in determining hydrocarbon contributions from urban sites enabling effective design of source control measures.