The seasonal variations of dissolved and bioavailable copper (Cu) and zinc (Zn) were studied in two recreational marinas in Sweden and Finland. The time series from the two marinas were characterized by rising concentrations during the spring boat launching, elevated concentrations all through the peak boating season, and decreasing concentrations in autumn when boats were retrieved for winter storage. This pattern shows a clear link between Cu and Zn concentrations and boating activity, with antifouling paints as the principal source. The leaching from antifouling paints was also found to significantly alter the speciation of dissolved Cu and Zn in marina waters, with an increase of the proportion of metals that may be considered bioavailable. This change in speciation, which occurred without any change in dissolved organic carbon (DOC), further increases the environmental risk posed by antifouling paints. In the Swedish marina, dissolved Cu and Zn exceed both Environmental Quality Standards (EQS) and Predicted No Effect Concentrations (PNEC), indicating that the current Swedish risk assessment (RA) of antifouling paints is failing to adequately protect the marine environment. An evaluation of the RA performance showed the underlying cause to be an underestimation of the predicted environmental concentration (PEC) by factors of 2 and 5 for Cu and Zn, respectively. For both metals, the use of inaccurate release rates for the PEC derivation was found to be either mainly (Cu) or partly (Zn) responsible for the underestimation. For Zn, the largest source of error seems to be the use of an inappropriate partitioning coefficient (KD) in the model. To ensure that the use of antifouling coatings does not adversely impact the sensitive Baltic Sea, it is thus recommended that the KD value for Zn is revised and that representative release rates are used in the RA procedure.

Birnessite not only oxidizes arsenite into arsenate but also interacts with organic matter in various ways. However, effects of organic matter on interaction between As and birnessite remain unclear. This study investigated effects of citrate and EDTA (3.12 and 2.05 mM, respectively) on oxidation of As(III) (1.07 mM) and adsorption of As(V) (0.67 mM) on birnessite (5.19 mM as Mn) at near-neutral pH. We found that As(V) adsorption on birnessite was enhanced by citrate and EDTA, which resulted from the increase in active adsorption sites via dissolution of birnessite. In comparison with citrate batches, more As was adsorbed on birnessite in EDTA batches, where dissolved Mn was mainly presented as Mn(III)-EDTA complex. Citrate or EDTA-induced dissolution of birnessite did not decrease the As(III) oxidation rate in the initial stage where As(III) oxidation rate was rapid. Afterwards, As(III) oxidation was conspicuously suppressed in citrate-amended batches, which was mainly attributed to the decrease in adsorption sites by adsorption of citrate/Mn(II)-citrate complex. This suppression was enhanced by the increase in concentrations of dissolved Mn(II). Citrate inhibited As adsorption after As(III) oxidation due to the strong competitive adsorption of citrate/Mn(II)-citrate complex. However, the As(III) oxidation rate was increased in EDTA-amended batches in the late stage, which mainly derived from the increase in the active sites via birnessite dissolution. The strong complexation ability of EDTA led to formation of Mn(III)-EDTA complex. Arsenic adsorption was not affected due to the limited competitive adsorption of the complex on the solid. This work reveals the critical role of low molecular weight organic acids in geochemical behaviors of As and Mn in aqueous environment.

This study reports the results of a comparison made using life cycle assessment (LCA) analysis of the environmental impact of nine different sandwich material models (SMs). The objective is to reveal whether the candidate materials considered for a railway passenger vehicle (conventional or high-speed train) are green/environmentally friendly or not. For this aim, life cycle approach enables to take into account the light weighting gain without disregarding the environmental impact of manufacturing process. These SMs are designed as combinations of existing traditional and candidate materials, such as steel, aluminium, carbon/glass fibre–reinforced plastics (CFRP/GFRP), aluminium honeycomb, and polymer foam core. The environmental performance of these nine different models has been calculated via the LCA analysis with CML-IA v.3.0 impact assessment methodology in a SimaPro 8.5.0. The system boundaries in the LCA analysis include “cradle to grave” process of sandwich composite materials in the railway passenger vehicle. The functional unit was selected as “one product of SM” for each configuration; besides, this panel has a lifetime span of 25 years at 400,000 vehicle-km per year in the vehicle operation. The results show that the use-phase, which dominates the environmental impact of the SMs of the railway passenger vehicle car body, is itself largely affected by electricity generation. In particular, the mass reduction in the models also achieved a reduction in environmental impact over its lifetime, mainly owing to decreased energy consumption. Another important finding regarding the manufacture of certain models (such as CFRP and GFRP) for lightweight design, is that assessment, based solely on mass reduction, may not always have better environmental performance or be reliable due to the manufacturing impact.

Microbial fuel cell (MFC) is a green technology that converts the stored chemical energy of organic matter to electricity; therefore, it can be used for wastewater purification and energy production simultaneously. In this study, three kinds of dairy products, including milk, cheese water, and yogurt water, were mixed with Acid orange 7 (AO7) as the model wastewater and used as the anolyte of an MFC. The capability of the system in energy production and dye removal was also investigated. The FESEM images were used to investigate the biofilms attachment to the anodes. Moreover, the polarization curves, electrochemical impedance spectroscopy, cyclic voltammetry (CV), voltage–time profiles, and coulombic efficiency were used to evaluate the electrochemical activity of the MFCs. Based on the CV results, the biofilm formation significantly improved the electrochemical activity of the electrodes. Maximum power density, voltage, and coulombic efficiency were obtained as 44.05 mW.m⁻², 332.4 mV, and 1.76%, respectively, for cheese water + AO7 anolyte, but the milk + AO7 MFC produced a stable voltage for a long time and its performance was similar to the cheese water + AO7 anolyte. Maximum COD removal and decolorization efficiencies were obtained equal to 84.57 and 92.18% for yogurt water + AO7 and cheese water + AO7 anolytes, respectively.

In recent years, the concentration of aluminium in the Iskar River occasionally exceeds the environmental quality standard (EQS). The river and the Iskar Dam, build on the river, are the main drinking water source of Sofia city (Bulgaria), with population exceeding 1.2 million. The average concentrations of aluminium in the raw water entering the drinking water treatment plants of Sofia city—Bistritza and Pancharevo—in 2018 were 0.148 mg/L and 0.199 mg/L, respectively, which are very close to the limits set in Directive 98/83/EC. This study uses multifactorial analysis, taking into account the influence of the mineral and chemical composition of sediments of the Iskar Dam, the geological conditions at the dam’s catchment area, the relationship between the aluminium concentrations and precipitation in the region and also the relationship between the aluminium concentration and the turbidity at the inlet of the two treatment plants, to determine the origin of aluminium in the raw drinking water of Sofia city. The obtained linear regression models for the aluminium concentration and the turbidity at the inlet are significant (p ≤ 0.001) with coefficients of determination (R²) for DWTP–Bistritza and DWTP–Pancharevo of 0.54 and 0.51, respectively.

In this work was studied the single-component and multi-component abatement of metals in water using a hydrogel based on chitosan. The maximum single-component abatement capacities of cadmium (Cd) and lead (Pb) were 234.84 and 482.83 mg of metal per g of dried hydrogel at pH 6 and 40 °C, according to the Sips isotherm. The value for iron (Fe) was 386.59 mg g⁻¹ at pH 4 and 40 °C, according to the Langmuir isotherm. The best kinetic fits were determined using the pseudo-second-order model, whereas the thermodynamic parameters inferred spontaneous, favorable abatement phenomena. Lower abatement capacities were determined for multi-component studies due to the hydrated ionic radius and electronegativity of the metals. The abatement processes were confirmed by scanning electron microscopy coupled to energy-dispersive X-ray spectroscopy and Fourier-transform infrared spectra, indicating reversible chemical interactions between the hydrogel binding groups and Cd, Pb, and Fe. Such hydrogel proved to be a potential functional biopolymer for the treatment of water and wastewater contaminated by heavy metals. Graphical abstract

We propose to identify the influence of organic acids as well as total proteins in the accumulation and translocation of heavy metals from the rhizosphere to the plant organs of cultivated yellow melon var. Natal throughout the vegetative cycle. Physical and chemical attributes and the concentration of Cu, Zn, and Pb were determined in soil samples. Samples of plant tissue and rhizosphere at 0, 15, 30, 45, and 60 days after transplantation were collected and determined the concentration of heavy metals along with the content of total protein in the tissues and organic acids in the rhizosphere. Subsequently, the transfer factor (TF) and bioconcentration factor (BF) were calculated. Oxalic and citric acids and heavy metal contents were slightly higher in the rhizosphere than those found in the soil. The organic acids and total protein showed correlations with the concentration of heavy metals in different organs of the plant. The protein content in the plant tissues and the contents of oxalic and citric acid released by the plant in the rhizosphere can increase or decrease the absorption, accumulation, and translocation of Cu, Zn, and Pb in the different organs of the yellow melon var. Natal. Even the BF and TF showed values higher than one, being indicative of phytoextraction potential in several stages of the vegetative cycle for Cu and Zn, the yellow melon var. Natal cannot be considered as a hyperaccumulator plant for not meeting all necessary criteria for that purpose.

Metal-modified adsorbent had appreciable adsorption capacity and fast rate toward norfloxacin (NOR), but limited studies focused on the influence of metal species on adsorbents’ performance. In this study, Fe and Cu were chosen to be loaded on mesoporous silicon SBA-15 for absorbing NOR and investigating the key function of metal species. An obvious synergy effect was found between active species and supporter. A high adsorption capacity (44.8 mg g⁻¹ for Fe/SBA-15 and 78.3 mg g⁻¹ for Cu/SBA-15) and short equilibration time (< 2 h) were obtained. NOR adsorptions on two processes were described well by pseudo-second-order kinetics, particle diffusion equation, and Langmuir isotherm. The adsorption processes were spontaneous, but NOR adsorption on Cu/SBA-15 was endothermic while its adsorption on Fe/SBA-15 was exothermic. HA had dual effect on the adsorption efficiency, with a promotion at low HA concentration but an inhibition at high concentration. NOR removal increased first and then decreased with pH ascension from 3 to 9 for both Fe/SBA-15 and Cu/SBA-15, achieving maximum at pH = 7. Comparative characterizations and experiments suggested that NOR adsorption processes were dominated by electrostatic interactions, n-π EDA interactions, hydrogen bonds, and surface complex. The greater n-π EDA and complex efficiency of Cu with NOR resulted in the superior performance of Cu/SBA-15. Graphical abstract

The formation of volatile DBPs and haloacetic acids (HAAs) from algal organic matter (AOM) in different chloramination conditions (i.e., different monochloramine (NH₂Cl) dosages, pH values, and bromide concentrations) was studied. In chloramination of AOM, HAAs were the major DBP species, followed by trihalomethanes (THMs), haloacetonitriles (HANs), and haloketones (HKs). The levels of THMs, HAAs, HKs, and HANs generated in chloramination were 75%, 69%, 68%, and 122% of those in chlorination, respectively. The concentrations of THMs and HAAs both doubled as the NH₂Cl dosage doubled. The proportions of bromodichloromethane and dibromochloromethane in THMs and the proportions of dichloroacetic acid and trichloroacetic acid in HAAs increased with the NH₂Cl dosage. Accelerating the pH value enhanced the formation of THMs, HAAs, and HANs, respectively, and favored the formation of brominated THMs. The HAN species distribution was unaffected by the NH₂Cl dosage and pH. Increasing bromide levels slightly increased the yield of THMs and slightly decreased the yields of HAAs and HKs. The species shift from the chlorinated to the brominated was more significant for THMs and HANs than for HAAs. The THM-BSF and dichloroacetonitrile-BSF values were lower in chloramination than in chlorination. The high pH value and bromide level significantly accelerated the THM-BSFs. The maximum values of THM-BSFs and dichloroacetonitrile-BSF were 0.6 and 0.5.

The aim of this work is the employment of char waste in the synthesis of silicon foams for oil spill remediation and the comparison analysis with carbon nanotubes-filled foams. The foams are obtained by foaming a slurry constituted by a silicone matrix with CNT or char filler (7.7 wt%) in presence of a Sn-based catalyst. All the investigated materials present a foam morphology with an open/closed cell structure. Each foam was tested in three used common oils (kerosene, crude oil, and pump oil). Also, hydrophilic behavior of the foam was investigated. CNT showed a 700% sorption capacity in light oils (almost 7 gₒᵢₗ/gfₒₐₘ in kerosene); on the contrary, char foam evidenced the higher sorption efficiency in heavier oils; in particular, it reaches 130% in pump oil (1.3 gₒᵢₗ/gfₒₐₘ). All the filled foams are reusable. The reuse increases the foam efficiency and decreases the economic and environmental impacts.