Journal of Water Chemistry and Technology最新文献

This paper deals with the results of studying the seasonal dynamics of organochlorine pesticides (OCP) in river water with consideration for the physicochemical properties of individual compounds. It is shown that seasonal variability of concentrations for some OCP groups is caused by different mechanisms of physicochemical processes occurring in an aquatic system. It has been established that the content of more hydrophobic and poorly soluble compounds from the dichlorodiphenyl trichloroethane (DDT) group depends predominantly on sorption and photochemical degradation processes, whereas the distribution of less hydrophobic and more soluble hexachlorocyclohexane (HCH) isomers is determined by the equilibrium between the dissolved, sorbed, and gaseous phases. Among all the organochlorine pesticides, particular attention is paid to δ-HCH demonstrating increased mobility and transportability over long distances in a water medium due to its unique physicochemical properties (hydrophobicity constant, distribution coefficient logarithm log K_OW, high solubility in water, moderate volatility, and low Henry constant). The mechanisms of photoisomerization and dechlorination with participation of humic and fulvic acids (humic acids), which may influence on the formation of DDT transformation products, are proposed. The obtained results are of practical importance for environmental risk assessment, OCP migration prediction, and the development of aquatic ecosystem monitoring strategies.

The study reveals the seasonal variation of physicochemical parameters and their functional dynamics on plankton density, diversity, richness, and evenness in Kodiakarai (also known as Point Calimere) wetland Bird Sanctuary. Quantitative samples were collected every month from September 2021 to June 2022 at Kodiakkarai, Bay of Bengal (BOB) coast. Statistical analyses of physicochemical parameters: temperature, salinity, pH, dissolved oxygen, nitrate, nitrite, phosphate, and silicate were performed. The significant variation across seasons as well as the high influence of physicochemical changes of plankton productivity were observed. A total of 40 species: viz. 28 species of Bacillariophyceae, 7 species of Dinophyceae, 2 species of Cyanophyceae and 3 species of Chlorophyceae were recorded in station I; whereas 34 species: viz. 22 species of Bacillariophyceae, 6 species of Dinophyceae, 4 species of Cyanophyceae and 2 species of Chlorophyceae were recorded in station II. In both stations, calanoid was found (40%) dominated, further 32% of Cyclopoida and 28% of Harpacticoida were recorded in station I; whereas 35% of Cyclopoida and 25% of Harpacticoida were recorded in station II. Therefore, a total of 25 and 20 species were recorded during the study period. The statistical analysis of plankton species, including the Shannon−Wiener diversity index, Simpson’s richness index, and Pielou’s evenness index, revealed higher values during the summer season and lower values during the monsoon season. The study found that the productivity of the Kodiakarai wetland contributes on dietary of about a hundred bird species, annually. Among the bird species, a major portion of large wading bird dominance was noted in the Point Calimere Wildlife Sanctuary during the study period.

The study investigates the process of ammonia leaching of copper, zinc, and nickel from solid electroplating sludge. The research determines the kinetics and optimal conditions for copper extraction from the sludge, including ammonia concentration, pH, and solution temperature, and establishes, using copper as an example, the regimes of electroextraction that yield metal of high purity. The results show that equilibrium formation depends only slightly on solution temperature, which characterizes processes with external diffusion kinetics. At an ammonia concentration above 10 wt %, up to 99% of copper salts dissolve, and the copper ion concentration reaches 12 g/dm³. In contrast, the concentrations of nickel and zinc in the sludge remain much lower, and at equilibrium their concentrations reach 1.2 and 2.4 g/dm³, respectively. Copper deposits on the cathode as a dense, compact layer. At a current density of 1.5 A/dm² and a copper concentration in the solution above 5 g/dm³, the current efficiency of copper approaches 100%.

Water pollution poses a significant threat to aquatic ecosystems, requiring effective remediation strategies. This study investigates the use of jowar straw nanobiochar (JNBC) as a bio-adsorbent for camphor removal from water, optimizing its performance using response surface methodology (RSM). JNBC, with a particle size of 71.8 nm and a zeta potential of –46.5 mV, was characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscope (SEM). XRD peak shifts and SEM observations confirmed successful camphor adsorption, with new FTIR peaks appearing post-adsorption. Using central composite design (CCD), optimal conditions for 96% camphor removal were identified: pH 6, initial camphor concentration 60 mg/L, surfactant (Tergitol) concentration 4 mg/L, and contact time 120 min. Experimental results matched the model predictions (desirability value = 0.972). The adsorption data fit well with the Langmuir isotherm model, while the pseudo-second-order kinetic model showed excellent precision. JNBC maintained 74% removal efficiency over six regeneration cycles, demonstrating its potential as a sustainable and effective adsorbent for environmental remediation.

This study evaluates the variability of water quality in the Hirakud dam reservoir by analyzing thirteen key parameters. There exist significant seasonal variations in both reservoir and seepage water. The results indicate that most parameters, including pH, electrical conductivity (EC), and total dissolved solids (TDS), were elevated during the summer months due to factors such as geological composition, evaporation, and anthropogenic inputs from the Ib-Jharsuguda valley. The Langelier saturation index (LSI) indicates that reservoir water was corrosive during winter, spring, and summer, as it was unsaturated with CaCO₃, leading to potential concrete deterioration. Conversely, during the monsoon, CaCO₃ precipitation provided a protective layer, reduces the corrosiveness. The aggressive index (AI) corroborated these findings, showing moderate corrosiveness in winter, spring, and summer, and non-corrosiveness in the monsoon. The Ryznar stability index (RSI) further supported the LSI and AI results, highlighting seasonal stability and corrosivity, with CaCO₃ precipitation observed in the monsoon. Seepage water from the dam’s foundation gallery exhibits higher chloride and sulfate concentrations during summer compared to reservoir water. Elevated pH values indicated increased alkalinity and ongoing leaching from concrete, which may impact concrete integrity and rebar corrosion. Overall, while reservoir water quality meets standards, seepage water poses corrosion risks to concrete structures. Regular monitoring of concrete strength and rebar condition is recommended. Establishing a comprehensive water quality assessment system and extending the study period are essential for understanding long-term impacts and tracking water quality trends.

Microplastics are spread widely in aquatic environments, and it is a growing threat to the ecosystem. It is important to remove microplastics from wastewater, hence successful technology is required. Various techniques are used such as physical, chemical, and biological approaches to remove the microplastics present in the wastewater. One of the techniques is the membrane filtration method to remove the plastic but it creates membrane fouling and replacing a new membrane frequently is expensive. Another method of microplastic removal is biodegradation. However, biological method takes a longer time for degradation and its efficiency is very low. Hence an electrochemical and adsorption method has been adopted to remove the microplastics present in the wastewater. Aluminum–stainless steel (Al–SS) and iron–copper (Fe–Cu) electrodes were used to study the microplastic removal using the electrocoagulation process. The removal percentage was 85.5% for Al–SS and 92.5% for the Fe–Cu electrode. An adsorption technique has also been attempted using magnetic iron oxide as an adsorbent and 96% removal of microplastics was achieved. A quantitative technique has been proposed to measure the microplastic present before and after the treatment process.

Using the mathematical tools of convective filtration theory, the experimental data on the change in the specific capacity of a tubular microfiltration ceramic membrane made of clay mineral in the process of water purification from Al(III) compounds were analyzed. The mechanism and conditions of the formation of a dynamic membrane from Al(III) hydroxo compounds in the studied microfiltration process were established, and its role in improving purification efficiency and ensuring high permeate quality by the content of aluminum compounds was demonstrated. The study was carried out on a model AlCl₃ solution with an Al(ІІІ) concentration of 65 mg/dm³ and pH of 7 at a working pressure of 1.0 MPa. Based on the results of this study, the processing of kinetic data was performed. Using the Darcy and Hagen–Poiseuille equations for constant-pressure filtration, the mechanism of the formation of a dynamic membrane under the above-specified conditions was established. It has been shown that, in the process of water purification from Al(III) on the ceramic membrane, its specific capacity decreases with time due to the precipitation of insoluble hydrolyzed Al(III) forms (hydroxo compounds) onto its surface. It has been established that, in this process, the filtration mechanism is changed from the gradual clogging of pores with several particles to the deposition of a precipitate from Al(III) hydroxo compounds onto the microfilter surface with the formation of a dynamic membrane. To decrease the size of pores and improve the selective properties of the microfiltration ceramic membrane made of clay minerals, its modification via the formation of a dynamic membrane from hydroxo compounds of metals on its surface in the process of water purification from these compounds was proposed.

The waste stockpiling before its incineration often leads to the production of substantial leachate. Climate might affect the leachate production and its treatment. Here, a systematic investigation of leachate quality and the operational status of leachate treatment stations in 9 incineration power plants from subtropical and temperate regions in China was carried out. The results indicated that the average annual leachate production rates of waste incineration power plants in both regions were 17%, with higher production amounts in summer and lower in winter. When compared to subtropical projects, those in temperate zones exhibited greater annual fluctuations in leachate production, poorer raw leachate water quality, and higher treatment loads during the summer. These characteristics posed higher operational management demands for the temperate leachate systems. The “pretreatment + biological treatment + membrane advanced treatment” system is the main technology for leachate treatment in waste incineration power plants. It could be found that the removal rates for chemical oxygen demand (COD), ammonia nitrogen (NH₃–N), and chloride ions (Cl^–) could reach 99.94, 99.88, and 95.70%, respectively. Meanwhile, the treated water met the reuse standards, proving the technology’s high efficiency and stability across different temperature zones. The average annual total operating cost of leachate treatment stations was approximately 50.62 yuan/t. Among the total cost, the electric cost accounted for about 50.95%, making it a key factor in cost reduction and efficiency improvement for leachate treatment systems. This study will provide valuable data and technical support for the efficient and economical leachate treatment in waste incineration power plants.

To investigate the hydrochemical properties, influencing factors, and travertine deposition potential of the Springs and the Secondary Conversion Springs in the Huanglong Scenic Area, 14 surface water samples were gathered from two aquifers. The composition and controlling factors of hydrochemical elements in the region’s surface water were analysed using statistical methods, Pearson correlation, Piper diagrams, Gibbs diagrams, ion ratio analysis, and principal component analysis. The findings are as follows: (1) The dominant hydrochemical classification in the region is ({text{HCO}}_{3}^{ - })–Ca²⁺. (2) The Springs exhibit significant spatial variability in hydrochemical traits, heavily influenced by factors such as temperature, aquifer materials, and terrain. In contrast, the Secondary Conversion Springs are less impacted by these variables. (3) The hydrochemical composition of the Springs and the Secondary Conversion Springs in July and September remained stable over time, primarily influenced by a single factor—water−rock interaction. The hydrochemical profile was mainly governed by the dissolution of carbonate rocks, with minor contributions from halite and gypsum dissolution. (4) The Springs in the study area are characterised by high ({{P}_{{{text{C}}{{{text{O}}}_{{text{2}}}}}}}), high ({text{HCO}}_{3}^{ - }) and high Ca²⁺, concentrations, providing the main sources of calcium and carbon for travertine deposition in the Secondary Conversion Springs, and the deposition capacity of travertine is mainly affected by Ca²⁺, ({text{HCO}}_{3}^{ - }), ({{P}_{{{text{C}}{{{text{O}}}_{{text{2}}}}}}}) and pH.

The present study investigates the degradation of tetracycline (TCH), amoxicillin (AMX), and diclofenac sodium (DCF) under ultraviolet (UV) and visible light conditions using TiO₂ and two composite nanofibers, PAN-MWCNT/TiO₂−NH₂ and PAN-MWCNT/TiO₂, as photocatalysts. The nanofiber catalysts were prepared by the force-spinning method and characterised by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM). Maximum degradation percentage was achieved by optimising various parameters, in particular feed pH (3–11), concentration of feed (50–100 mg/L), and dosing of the catalyst (0.5–1.5 g/L). TiO₂-based nanofiber adjusts the band gap and increase its capability to absorb UV and visible light selectively. The effectiveness of AMX, TCH, and DCF (50 mg/L) degradation was investigated using UV and solar radiation with various photocatalysts (1 g/L) at pH 3 for AMX and DCF and pH 11 for TCH. This study revealed that PAN-MWCNT/TiO₂ was the most efficient catalyst under UV radiation, which showed the maximum degradation percentage of the pollutants, i.e., 97% for AMX, 95% for TCH, and 91% for DCF in 90 min, whereas PAN-MWCNT/TiO₂–NH₂ was highly effective in visible light and resulted in 64% for AMX, 72% for TCH, and 67% for DCF degradation in 6 h. Chemical oxygen demand (COD) analysis was performed before and after the degradation process. 70–80% COD removal efficiencies suggested partial oxidation of the pollutants (AMX/TCH/DCF). To spot the intermediate compounds produced during the degradation process, Liquid chromatography-mass spectrometry (LC-MS) analysis was also performed.