Journal of Water Chemistry and Technology最新文献

In this study, an iron−manganese double oxide containing wood fiber-based nanomaterial was synthesised for enhanced removal of organic dyes and toxic metals from contaminated water using a modified hydrothermal technique. This adsorbent was formed in situ within the porous structure of wood fibers after a portion of the lignin was removed. Analytical methods, in particular: scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), derivative thermogravimetric (DTG) and energy-dispersive X-ray spectroscopy (EDX) were used to characterise the synthesised nanomaterial. UV-visible spectroscopy and atomic absorption spectroscopy (AAS) were utilised for the investigation of the kinetics of adsorption and adsorption isotherms of organic dye Methylene Blue (MB) and metal pollutant Cr(VI). From the analysis of kinetics data, it is observed that in both cases the adsorption exhibited a superior fit to the pseudo-second-order kinetics model of non-linear form. The Langmuir adsorption isotherm model demonstrated a better fit for the adsorption of MB, displaying a maximum adsorption capacity of approximately 92% over the synthesised material. On the other hand, the Freundlich adsorption isotherm model showed a notably improved fit for Cr(VI) adsorption, displaying very high adsorption capacity. Thus, the specifically designed binary metal oxide was found to be a potential material for applications in environmental remediation initiatives.

The importance of a comprehensive assessment of the quality of surface water environments as sources of drinking water, especially in conditions of global ecological disasters, is shown by the example of pollution by heavy metals (by Cr(III) and Cr(VI), in particular) as ecotoxicants. The solution to this problem is successfully achieved through complex biotesting, which provides an integral assessment of the danger of contaminated water for living organisms, including man. Daphnia magna is used among standardized test organisms to assess the quality of natural waters as sources of drinking water supply. Some aspects of the toxic effect of chromium ions on daphnia have been established: the greatest toxicity effect depends on the degree of chromium oxidation, which corresponds to its MPC for drinking water. Chromium(VI) compounds are characterized by a significantly higher acute toxicity than chromium(III) compounds; and their concentration in aqueous solution, the duration of impact on test organisms, and the presence of complexing ligands (shown by the example of EDTA as an analogue of natural humic acids) also exert a significant effect. The death of Daphnia magna significantly increases with the rise in the concentration and the duration of exposure to chromium ions.

In this study, Fe-carbonised fiber-based textile waste (Fe-CFTW) was synthesised using a green synthesis method from fiber-based textile waste produced in the textile industry, and its usability was investigated through adsorption, Fenton-like oxidation, and UV/persulfate oxidation processes after the pretreatment of textile industry wastewater by coagulation. In the coagulation process, 51.9, 37.7, 89.7, and 63.0% of chemical oxygen demand (COD), total organic carbon (TOC), turbidity, and colour removal, respectively, were achieved at 500 mg/L polyaluminum chloride (PACl) and pH 8. In the adsorption of textile wastewater pretreated by coagulation using Fe-CFTW, the best treatment results obtained were: 53.5, 37.4, and 54.6% of COD, TOC, and colour removal, respectively, at pH 5 and 15 g/L adsorbent. In the Fenton-like oxidation, 67.9, 47.5, and 88.6% removal of COD, TOC, and colour were obtained using 10 g/L Fe-CFTW, respectively. In the UV/persulfate oxidation process, 87.3, 36.5, and 93.4% removal of COD, TOC, and colour were achieved, respectively. As a result, it was shown that fiber-based textile waste, which was generated in large quantities in the textile industry, could be used in the textile wastewater treatment by producing adsorbent or catalyst composites. In this way, a more economical treatment method was provided, and the waste generated in the textile industry is minimised, and could be reused.

The effect of the maximum pyrolysis temperature on the adsorption capacity of biochars obtained from walnut shells (WNS) (Kyiv region, Ukraine) for the removal of synthetic organic compounds (SOCs) from the aqueous phase was studied. The thermolysis of WS samples was performed in an atmosphere with a limited oxygen content at an average furnace heating rate of 15°C and a maximum processing temperature from 340 to 800°C. Initially, the efficiency of the thermal process was estimated by the biochar specific adsorption activity with respect to iodine and Methylene Blue and the product yield and bulk density. The structural and sorption characteristics of the best samples were evaluated by the t-method using the isotherms of adsorption from the aqueous phase of a standardized organic adsorbent and the isotherms of nitrogen adsorption−desorption from the gas phase. The adsorption properties of biochars were determined on three samples carbonized at 410, 650, and 800°C. Phenol, p-chloroaniline (p-CA), and surfactant Triton X-100 (TX-100) were used as adsorbents, for which the isotherms of adsorption from the aqueous phase were measured in a static isothermal process. It was established that the adsorption activity with respect to I₂ for the materials carbonized with WS in the maximum temperature range of 420–800°C increases almost by a parabolic law by 4 times (from 85 to 350 mg/g). The yield of the carbonized product decreases (from 34 to 24%) with an increase in the maximum processing temperature. The best samples of biochar (W800 and W650) showed the adsorption of monoaromatic compounds and nonionic surfactants from dilute aqueous solutions is characterized by rather high energy and value as compared to the nonporous adsorbent. It was established that biochars have a microporous structure with undeveloped mesoporosity. According to the values of structural parameters (surface area, 300–400 m²/g; adsorption volume, less than 0.2 mL/g), new products can be attributed to biochars with initial nanoporosity. To obtain an efficient adsorption material from walnut shells under the studied thermal conditions, it is necessary to perform chemical activation procedures for the precursor.

Water, an indispensable component of our daily lives, plays a pivotal role in sustaining life on Earth. The importance of water extends not only to basic survival but also to various aspects of human activities. However, its quality is increasingly compromised by industrial pollutants, particularly dye effluents from textile industries, which pose significant threats to aquatic ecosystems and public health. Conventional methods for monitoring water quality and measuring dye concentration are often labour-intensive and time-consuming, limiting their applicability for large-scale assessments. To address this challenge, this study investigates the application of artificial neural networks (ANNs) as a predictive tool for evaluating dye degradation in water, thereby supporting real-time monitoring of water quality. Experimental datasets involving three dye types—monoazo, diazo, and polyazo—are utilized, and preprocessing techniques such as Min–Max and Z-score normalization are applied to enhance model training efficiency. The proposed ANN architecture comprises an input layer corresponding to experimental parameters, one or more hidden layers activated by functions such as sigmoid, rectified linear unit (ReLU), and exponential linear Unit (ELU), and an output layer that predicts the percentage of dye degradation. Model training is performed using the backpropagation algorithm. Among the tested configurations, the combination of Min−Max normalization with ReLU activation achieves the highest performance, attaining an R² value of 0.98 in 50 epochs. These findings demonstrate the model’s effectiveness assessment and predicting dye degradation, offering a practical AI-based approach for rapid and scalable water quality assessment, and contributing to more sustainable environmental monitoring solutions.

The structural-sorption and surface properties of activated carbon from apricot pits (KAU) and of its modified sample KAU-Fe obtained by treatment with iron salts are investigated. Modification of KAU leads to an increase in the total specific surface area by 10.0%, in the mesopore surface by 17.8%, in the micropore surface by 17.6%, in the volume of the total pore space by 14.3%, and in the volume of micropores by 19.3%. An increase in the values of cationic and anionic static exchange capacities is noted. Adsorption isotherms of the cationic dye Methylene Blue have been obtained at temperatures of 283, 293, and 313 K. The increase in the adsorption value of Methylene Blue on KAU-Fe relative to the values for unmodified carbon is 40.4% at a temperature of 283 K; 72.4% at a temperature of 293 K; and 54.3% at a temperature of 313 K. The obtained results are described, using the Langmuir, Freundlich, Temkin, BET, and Dubinin−Radushkevich models. It is shown that the adsorption process of Methylene Blue proceeds according to a physical mechanism. Modeling of the kinetics of Methylene Blue adsorption on activated carbons is performed by the pseudo-first order, the pseudo-second order, the Elovich, and the Morris−Weber equations. It is revealed that the adsorption process of Methylene Blue proceeds in a mixed diffusion mode. Negative values of the change in Gibbs free energy indicate the spontaneous adsorption of Methylene Blue by the studied carbon. A positive value of enthalpy testifies to an endothermic course of the adsorption process; and positive entropy indicates that surface changes are related to the interaction of Methylene Blue molecules with active centers of adsorbents.

Groundwater quality assessment is a crucial factor in ensuring sustainable water resources for drinking and irrigation. This study evaluates the hydrochemical characteristics of groundwater from the Sebdou and Hennaya aquifers in northwestern Algeria, using key physicochemical parameters and water quality indices (WQI) such as drinking water quality index (DWQI), the irrigation water quality index (IWQI) and the nitrate pollution index (NPI). The analysis focused on parameters including temperature, pH, electrical conductivity, chloride, sulfate, and nitrate concentrations to determine the suitability of groundwater for human consumption and agricultural use. The results indicate that while the Sebdou aquifer generally provides water of excellent to good quality for drinking purposes, irrigation remains restricted due to elevated salinity levels. Specific points exhibit severe restrictions, whereas others present only moderate limitations. In contrast, the Hennaya aquifer demonstrates poor water quality, with electrical conductivity exceeding the Word Health Organization standards in all sampled locations and nitrate concentrations consistently surpassing the recommended limit of 50 mg L^–1. In both aquifers, the NPI highlights significant nitrate contamination, particularly in the Hennaya region, where pollution levels remain critically high throughout both wet and dry seasons. This high nitrate pollution could be attributed to the discharge of wastewater and the intensive use of fertilizers, especially in the Hennaya region, which is an agriculturally oriented plain. The study underscores the pressing need for sustainable groundwater management strategies to mitigate pollution, regulate nitrate sources. Without proper intervention, continued degradation of water quality may threaten public health and agricultural productivity in the region. These findings provide a scientific basis for policymakers to develop targeted measures that ensure the long-term viability of groundwater resources in northwestern Algeria.

The traditional 5-Br-PADAP (2-(5-bromo-2-pyridylazo)-5-(diethylamino)phenol) spectrophotometric method for determining antimony in water involves the use of highly toxic Sb(III) standards, requires large volumes of chemical reagents, and exhibits low sensitivity. To overcome these drawbacks, this paper couples cloud point extraction (CPE) with complexation colorimetry for the determination of trace antimony in water. This approach enables simultaneous enrichment and high-precision determination of trace pentavalent antimony [Sb(V)]. The effects of various parameters on CPE efficiency were systematically investigated, and the method performance was evaluated in the concentration range of 1–25 μg/L. The results show that under the optimized conditions (4.0 mol/L HCl; 2 mL of 2% Triton X-114; 0.2 mL of 200 mg/L Rhodamine B; extraction temperature 45°C; equilibration time 15 min), the proposed method exhibits good linearity (R² = 0.9978), high precision (relative standard deviation 3.33%), good accuracy (relative error 1.73%), and a low method detection limit (MDL = 0.554 μg/L). When combined with ozone-assisted oxidation pretreatment, this approach can be widely used to determine both total antimony and the distribution of antimony valence states.

Natural organic matter (NOM) negatively affects water purification quality and leads to the formation of disinfection by-products that exhibit carcinogenic, teratogenic, and mutagenic effects. In addition, biodegradable natural organic matter enhances the growth of microorganisms in the distribution network and causes problems with taste and odor. This necessitates the improvement of existing water treatment methods and the search for more efficient technological solutions, one of which is the use of an integrated coagulation−ultrafiltration process. In this study, the optimal conditions of an integrated coagulation−ultrafiltration process using aluminum sulfate as a coagulant for the purification of Dnipro River water were established. It was shown that, at pH of 6.0–6.5 and a coagulant dose of 2 mg_Al/L, the obtained filtrate quality meets the existing regulatory requirements for drinking water. Water quality was evaluated by turbidity, color, residual aluminum concentration, total organic carbon TOC, UV_254, UV₃₆₄, and SUVA parameters. The mechanism of membrane fouling was determined as a gradual transition from the blocking of pores by multiple particles to intermediate filtration with the further formation of a cake layer on the membrane surface. Membrane regeneration was carried out by direct washing with distilled water, which restored the specific permeate flux by 62.0%, and by reverse washing, which improved the obtained result to 89.4%.

Electrocoagulation (EC) is an effective and emerging technique for the treatment of various types of wastewaters due to its unique adaptability, simple design, low cost, and environmental compatibility. This technique uses direct current between the metal electrodes immersed in the wastewater, which leads to the dissolution of electrode plates, releasing metal ions that destabilize and coagulate contaminants for subsequent removal. The performance of EC is influenced by various factors, including electrode material, pH, current density, temperature, and time. Despite its advantages, large-scale industrial application of EC requires further optimization of these key parameters and the development of reliable process models. This manuscript also reviews recent advancements in EC technology, such as EC-biological treatment, EC-chemical coagulation, photovoltaic-EC, and EC-membrane hybrid systems. Owing to its high pollutant removal efficiency, environmental sustainability, ease of operation, and relatively low automation cost, EC shows strong potential as a future wastewater treatment technology.