Removal of cadmium and cobalt from water by Slovak bentonites: efficiency, isotherms, and kinetic study.

Slovak bentonite was used as an effective natural adsorbent for the removal of Cd(II) and Co(II). Characterization of the samples was conducted using X-ray diffraction (XRD), high-resolution scanning electron microscopy with an X-ray energy dispersion spectrometer (SEM-EDS), and infrared spectroscopy (FT-IR). Adsorption experiments were carried out for pure water and artificial seawater, each containing cobalt and cadmium cations within the concentration range of 5-60 mg/L. The highest bentonite adsorption capacities of the tested bentonites were 23.5 (Cd) and 32.2 (Co) mg g-1. The kinetics data revealed that, in addition to chemisorption, intraparticle diffusion contributes to metal removal. The physical and structural properties of bentonites play an important role in adsorption. Bentonite P 135 from the Lieskovec deposit showed the highest efficiency for removing both ions, with removal percentages exceeding 90% and 77.5% for pure water and artificial seawater, respectively. The results indicate the suitability of using Slovak bentonites as an alternative sorbent for both metal extractions. The mechanism of metal ion adsorption on bentonite clay can be understood through surface complexation and ion exchange. The examined bentonite deposits show potential as promising natural sorbents for the removal of cobalt and cadmium cations from polluted waters.

Machine learning approach to evaluate the groundwater quality and human health risk for sustainable drinking and irrigation purposes in South India.

The main purpose of this study was to evaluate the suitability of groundwater for sustainable drinking and irrigation purposes using various indices, such as the nitrate pollution index, agriculture suitability index (ASI), non-carcinogenic human risk assessment (NCHRA), and radial basic function (RBF) model. The novelty of the present study is to develop the ASI model and integrate with RBF model to identify the highly dominating parameter in chemical equilibrium of groundwater. Results showed that >85% of sample locations were suitable for drinking purposes, and the nitrate concentration in groundwater had a negative impact on the overall quality of water. Approximately 12 and 19 sample locations were contaminated owing to the high nitrate concentrations in the study region. The NCHRA study identified that approximately 8.5%, 27.28%, 29.54%, 40.40%, and 28.20% of area was excessively affected during the winter compared to summer season for people 6 to 12 y, 13 to 19 y, 20 to 29 y, 30 to 65 y, and >65 y of age. The RBF model shows that the R2 values for each season were 0.84 and 0.85 during summer and winter, respectively. The north-east and central parts of the study region were found to be more contaminated. The present study identified that, pathway of nitrate contaminant from the agriculture field towards to the sample locations. Overall, parent rock weathering, carbonate ion dissolution, and infiltration of rainwater and leachate from municipal waste dumping yards were the dominant factors influencing the chemical composition of groundwater. The present study achieved the vibrant knowledge about source of contamination, health effect on human body and impact on agriculture uses to develop the cleaner water supply system. The study results will be helpful in enhancing the sustainable action plan for water management in the study area.

Determination and Removal of Selected Pharmaceuticals and Total Organic Carbon from Surface Water by Aluminum Chlorohydrate Coagulant.

In the present research, the removal of Total Organic Carbon (TOC) and erythromycin (ERY), fluoxetine (FLX), amoxicillin (AMO), colistin (COL), ethynylestradiol (EE), and diclofenac (DIC) from surface water by coagulation is studied. The concentration of selected pharmaceuticals in 24 surface water samples originating from some rivers located in Lesser Poland Voivodeship and Silesia Voivodeship, Poland, was determined. The removal of TOC and pharmaceuticals was carried out using the application of Design of Experiments (DOE), Response Surface Methodology (RSM), and by addition of aluminum chlorohydrate (ACH) as a coagulant. The study found that the concentration ranges of ERY, FLX, AMO, COL, EE, and DIC in analyzed water samples were 7.58−412.32, 1.21−72.52, 1.22−68.55, 1.28−32.01, 5.36−45.56, 2.20−182.22 ng/L, respectively. In some cases, concentrations lower than 1 ng/L were determined. In optimal conditions of coagulation process of spiked surface water (pH = 6.5 ± 0.1, ACH dose = 0.35 mL/L, Time = 30 min; R2 = 0.8799, R2adj = 0.7998), the concentration of TOC, ERY, FLX, AMO, COL, EE, and DIC was decreased by 88.7, 36.4, 24.7, 29.0, 25.5, 35.4, 30.4%, respectively. Simultaneously, turbidity, color, Total Suspended Solids (TSS), Chemical Oxygen Demand (COD), Total Nitrogen (Total N), and Ammonium-Nitrogen (N-NH4) were decreased by 96.2%, >98.0%, 97.8%, 70.0%, 88.7%, 37.5%, respectively. These findings suggest that ACH may be an optional reagent to remove studied pharmaceuticals from contaminated water.

Geochemical evaluation and human health risk assessment of nitrate-contaminated groundwater in an industrial area of South India.

The primary goal of this study is to evaluate the groundwater quality and conduct a non-carcinogenic risk assessment of nitrate contamination in an industrialized and high-density region of South India. A total of 40 sampling sites were identified in and around the industrial area, and samples were collected during the pre-monsoon and post-monsoon seasons. Piper and Gibbs' diagram shows that rock-water interaction, lithological characteristics and ion-exchange processes are the primary factors determining groundwater quality. The novel entropy water quality index (EWQI) indicated that 32 and 37.5% of the water in the study area were unsuitable for drinking purposes during both the pre-monsoon and post-monsoon seasons, respectively. Due to landfill leachate and modern agricultural activity, the nitrate concentration in groundwater post-monsoon had increased by 17.11%. The nitrate pollution index (NPI) value of groundwater exceeded the contaminated level by 22.77%. The non-carcinogenic human health risk assessment revealed that 35 and 40% of adult males, 37.5 and 52.5% of adult females and 42.5 and 55% of children during the pre-monsoon and post-monsoon periods were exposed to an increased concentration of nitrate in groundwater. The non-carcinogenic risk level to the exposed population in the study region descends in the following order: children > > females > males. The study suggests that low body weight in children is a direct result of consumption of low-quality water and that adult men and women suffer less severe consequences.

Physicochemical Parameters of Real Wastewater Originating from a Plant Protection Products Factory and Modification of the QuEChERS Method for Determination of Captan.

The aim of this study was the modification and application of the QuEChERS method for the preparation and purification of samples in order to determine the level of captan in real wastewater originating from a plant protection products factory which was characterized by a significant content of organic substances [Chemical Oxygen Demand (COD) = 856 ± 128 mg O2/L and Total Organic Carbon (TOC) = 62 ± 9 mg/L]. The optimization of the method consisted of the selection of solvents used for the extraction of captan from wastewater and also sorbents used to purify the extracts by the dispersion of a solid phase extraction technique (dSPE). Two steps were used: extraction and clean-up. In the extraction step, acetonitrile was replaced by anacetonitrile:acetone mixture. In the clean-up step by the dSPE, five sorbents were tested: Florisil®, aluminum oxide (Al2O3), zirconium oxide (ZrO2), silicon oxide (SiO2) and PSA (primary and secondary amine). Concentrations of captan in wastewater extracts were determined by gas chromatography (GC) combined with electron capture detection (µECD). The best recovery parameters and precision of the method were obtained for samples purified using ZrO2 (recovery 98% and precision expressed as relative standard deviation RSD 8%) and Florisil® (recovery 96%, RSD 9%). Limits of detection (LOD) and quantification (LOQ) for determination of captan in diluted extract of wastewater were 0.003 and 0.01 mg/L, respectively. Matrix effects were in the range of -69% to -44% for samples purified by ZrO2 and Florisil®, respectively. The modified and optimized method was applied for fast and simple determination of captan levels in real industrial wastewater samples, in which the concentration of captan in diluted extract was determined to be 4.0±0.3 mg/L.