Concentrations Of Heavy Metal Ions Research Articles

Batch and column studies for the removal of basic red-46 dye and textile by using magnesium oxide (MgO), strontium titanium trioxide (SrTiO3), cobalt- and iron-doped lanthanum chromium trioxide (Co.Fe.LaCrO3), and cadmium sulfide (CdS)-doped graphene oxide nanocomposites.

Despite efforts to reduce the risk of toxic chemicals, colors, and dyes being released into the environment from urban and industrial areas, there is still cause for concern. Colored water must be filtered and sterilized before it can be used for irrigation. The utilization of metal oxide and nanocomposite materials in wastewater treatment procedures appears to be a viable option for the future. Therefore, different compounds were doped with graphene oxide to identify the best material for dye removal by the adsorption process. According to recent studies, the ideal conditions for graphene oxide-doped magnesium oxide (GO/MgO) are as follows: pH 10 showed the highest adsorption capacity (qe) at 49.4mg/g; an adsorbent dosage of 0.01g/50mL showed 48.3mg/g qe; a shaking time of 30min resulted in 44.2mg/g qe; an initial dye concentration of 100mg/L yielded 53.6mg/g qe; and a temperature of 35°C gave 49.5mg/g qe. For graphene oxide-doped strontium titanate (GO/SrTiO3), the optimum conditions were as follows: pH 10 with 45.8mg/g qe; an adsorbent dose of 0.01g/50mL with 40.5mg/g qe; a shaking time of 30min with 75mg/g qe; and a temperature of 35°C with 44.7mg/g qe. Graphene oxide-doped cobalt and iron-doped lanthanum chromium titanate (GO/Co.Fe.LaCrO3) showed optimum conditions of pH 9 with 34.2mg/g qe; an adsorbent dose of 0.01g/50mL with 27.5mg/g qe; a shaking time of 45min with 33.2mg/g qe; an initial dye concentration of 100mg/L with 37.6mg/g qe; and a temperature of 35°C with 42.5mg/g qe. Graphene oxide-doped cadmium sulfide (GO/CdS) showed the following optimum conditions: pH 8 with 23.1mg/g qe; an adsorbent dose of 0.01g/50mL with 25.5mg/g qe; an initial dye concentration of 75mg/L with 28.3mg/g qe; and a temperature of 35°C with 33.5mg/g qe. The pseudo-first-order model was the best fit only for graphene oxide-doped magnesium oxide (GO/MgO) with an R2 value of 0.966, while the pseudo-second-order adsorption isotherm was the best fit for all four products, with R2 values ranging from 0.991 to 0.998. Additionally, the Langmuir adsorption isotherms provided good results for all four products, with R2 values ranging from 0.957 to 0.985. The Freundlich adsorption kinetics showed satisfactory fit only for graphene oxide-doped magnesium oxide (GO/MgO) and graphene oxide-doped cadmium sulfide (GO/CdS), with R2 values of 0.951 and 0.982, respectively. To examine the characteristics and practicality of the adsorption process, certain thermodynamic variables were calculated. The adsorption capability of the most efficient nanocomposites for the degradation of basic red-46 was significantly affected by various concentrations of heavy metal ions and electrolytes. In dye solutions containing surfactants/detergents, the adsorption efficiency of several effective photocatalysts for basic dyes was significantly reduced. A 0.5M HCl solution was found to be the most effective for desorption. In column investigations, the optimal bed height, flow velocity, and dye intake levels were determined to be 3cm, 1.8mL/min, and 70mg/L, respectively, for maximal adsorption of basic red-46. The adsorption investigation of genuine textile waste products has also been carried out to facilitate the practical deployment of this approach. The methods used in this study were cost-effective, easy to handle, and eco-friendly and involved no hazardous materials in the synthesis, making the resulting materials non-hazardous. All these methods were part of green chemistry.

Manganese metal ion removal from aqueous solution using industrial wastes derived geopolymer

Heavy metal pollutants, highly toxic and invisible, have garnered attention due to bioaccumulation. Increased manganese production from steel industries is expected to lead to harmful concentrations in water, adversely affecting the environment and public health. The sustainable approach of utilizing industrial by-products to synthesize geopolymers for the immobilization of heavy metal ions has gained research interest. The current study aims to verify the feasibility of Paper sludge ash (PSA) in conventional geopolymer (CGP) to immobilize manganese (Mn) heavy metal ions from aqueous solutions. CGP was prepared using Fly ash (FA) as resource material, which was replaced by PSA at a level of 30 %, by weight. The precursors were treated with alkali solutions, namely sodium hydroxide and sodium silicate, incorporating ambient curing. The characterization studies of precursors and CGP were investigated using XRD, XRF, SEM, EDS, FTIR, and Brunauer-Emmett-Teller surface area (BET) analysis techniques to outline the crystal structure, morphology, and pore parameters. Additionally, the experimental investigation comprehensively examined the impact of various pH levels, dosages, contact times, and initial concentrations on the removal efficiency of Mn heavy metal ions. The difference in concentration of Mn heavy metal ions quantified by atomic absorption spectrometry. The Langmuir models effectively explained the removal of Mn ions by CGP due to high fitting coefficients. The highest value of uptake capacity was found to be 28 mg/g at 30 °C with pH value of 4. Therefore, blending industrial wastes improves the potential of decontamination agents in removing heavy metals from wastewater, promoting environmental sustainability.

Green fabrication and efficiency of activated biochar-layered double hydroxide (LDH) nanocomposites against toxic Pink-XFG dye

Removal of dyes has been a matter of great interest for researchers because of health and toxicity issues. In this research work, green biochar was produced using precipitation technique, and by the adsorption process, it was supported on layered double hydroxide (LDH). Biochar/LDH composites were synthesized from Neem, Amaltas, and Keekar stems, eggshells, and Eucalyptus (N, A, K, Egg, and Eu’s biochar/LDH-composite). These composites were employed to remove synthetic dyes from an aqueous solution. Recent studies have identified optimal conditions for LDH-composites under various parameters: pH 9 or 10 with a dosage of 0.05 g/50 mL yields higher adsorption capacities across different LDH composites, ranging from 40.74 to 48.30 mg/g at a reaction time of 90 min using a Pink-XFG dye concentration of 10 ppm, which is favorable. Temperatures of 303–308 K are suitable. Second-order kinetics, along with the Langmuir and Freundlich adsorption isotherms, along with exothermic reactions, presented good-fit results on adsorption kinetics and equilibrium data. The adsorption potential was significantly affected by various concentrations of electrolytes, surfactants, detergents, and heavy metal ions. 0.5 N hydrochloric acid was determined to be the most efficient agent for the process of desorption. These methods are very cost-effective, eco-friendly, and easy to manufacture.

Metal-Organic Framework-Based Materials for Heavy Metal Sensing in Aqueous Media

Industrial development leads to an increasing amount of pollutants including heavy metal ions in surface and subsurface waters. For instance, wastewater from battery manufacturing, paint manufacturing or metal plating, contain heavy metals in high concentrations. The heavy metals are typically non-biodegradable and not-easy to excrete. Their presence within the organisms causes damage and failure of different organs. Consequently, the permissible concentrations of heavy metal ions in drinking water set by the World Health Organization are on a ppb level.In this work, electrode materials based on metal-organic frameworks (MOFs) are prepared and studied for sensing of heavy metals in aqueous media. These involved MOFs in their pristine form, composites of pristine MOFs and conducting polymer polyaniline as well as their carbonized derivatives. Cadmium and lead ions were used as model pollutants. Thorough physico-chemical characterization of the prepared materials was done using scanning electron microscopy, Raman spectroscopy, and dynamic light scattering. Electroanalytical performance was scrutinized using anodic stripping voltammetry and correlated with materials’ structural, morphology and textural properties. Limits of detection and sensitivity were determined upon optimization of the experimental conditions to identify the best material. Moreover, materials proved to be suitable for two heavy metal ions sensing in real river samples. Acknowledgments This work was supported by the Science Fund of the Republic of Serbia, grant number 7750219, Advanced Conducting Polymer-Based Materials for Electrochemical Energy Conversion and Storage, Sensors and Environmental Protection-AdConPolyMat (IDEAS programme).

Terahertz spectroscopy-based rapid detection of exchangeable heavy metal pollution in soil using Scenedesmus obliquus

This study introduces a novel approach for the rapid detection of exchangeable heavy metal pollution in soil, utilizing Scenedesmus obliquus as a bioadsorbent. Terahertz spectroscopy was used to analyze the cell wall proteins and functional groups of S. obliquus following physical adsorption. This analysis enabled the deduction of the types and concentrations of exchangeable heavy metal ions in soil. We established a prediction model for heavy metal concentrations using partial least squares (PLS) regression, achieving optimal detection times: 10 min for Pb2+, 20 min for Ni2+, and 30 min for Co2+. Validation with real surface soil samples demonstrated excellent accuracy rates: 97.8 % for Pb2+, 91.8 % for Ni2+, and 90 % for Co2+. Notably, our method reduces the detection time to 0.5 hours, requires only 5 ml of sample volume, and enhances detection accuracy to 0.1 μg/L.

Enhanced Stability and Detection Range of Microbial Electrochemical Biotoxicity Sensor by Polydopamine Encapsulation.

With the rapid development of modern industry, it is urgently needed to measure the biotoxicity of complex chemicals. Microbial electrochemical biotoxicity sensors are an attractive technology; however, their application is usually limited by their stability and reusability after measurements. Here, we improve their performance by encapsulating the electroactive biofilm with polydopamine (PDA), and we evaluate the improvement by different concentrations of heavy metal ions (Cu2+, Ag+, and Fe3+) in terms of inhibition ratio (IR) and durability. Results indicate that the PDA-encapsulated sensor exhibits a more significant detection concentration than the control group, with a 3-fold increase for Cu2+ and a 1.5-fold increase for Ag+. Moreover, it achieves 15 more continuous toxicity tests than the control group, maintaining high electrochemical activity even after continuous toxicity impacts. Images from a confocal laser scanning microscope reveal that the PDA encapsulation protects the activity of the electroactive biofilm. The study, thus, demonstrates that PDA encapsulation is efficacious in improving the performance of microbial electrochemical biotoxicity sensors, which can extend its application to more complex media.

Electrodes combined with permeable reaction barrier removes Cr (Ⅵ) from low permeability aquifers

Choosing an effective means of dealing with chromium (Cr (VI)) pollution is necessary. Electrokinetic (EK) technology is widely used in low- permeability aquifers. Zero-valent iron/activated carbon (ZVI/AC) can be used as a permeable reactive barrier (PRB) filler for the removal of Cr(Ⅵ) from in low- permeability media. However, the combined effects of these two technologies on aquifers have not been studied extensively. In this study, the ratio of zero-valent iron to activated carbon was determined through a pre-experiment. A series of batch experiment was then conducted to evaluate the effectiveness of electrokinetic (EK) combined with ZVI/AC-PRB on removal of Cr (VI). The ZVI/AC mixture before and after the reaction was analyzed by scanning electron microscopy (SEM), Fourier infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The results of the batch experiment showed that the optimum removal efficiency of Cr (VI) was 90.38 % after 1440 min at a ZVI/AC mass ratio of 1:4. During the experiment, owing to the movement of the acid and base peaks, the pH of the anode region was generally lower than that of the other regions. The current decreased as the concentration of heavy metal ions decreased. The SEM, FTIR, and XPS results show that Cr (Ⅵ) was transformed into Cr(Ⅲ) or adsorbed on the surface under the action of ZVI/AC micro-electrolysis. In the present study, these two technologies were combined to treat Cr (VI)-contaminated aquifers. The experimental results provide a theoretical basis for the field application of the EK-PRB repair technology.

Effective removal of chromium, copper, and nickel heavy metal ions from industrial electroplating wastewater by in situ oxidative adsorption using sodium hypochlorite as oxidant and sodium trititanate nanorod as adsorbent

Sodium hypochlorite and synthesized sodium trititanate nanorods (Na2Ti3O7, 186 × 1270 nm) were used as the oxidant and adsorbents for in situ oxidative adsorption treatment of actual electroplating wastewaters containing Cr(VI) (2.6‒5.2 mg∙L‒1), Cu2+ (2.7‒5.4 mg∙L‒1), and Ni2+ (0.2705‒0.541 mg∙L‒1) ions at pH of 8.8‒9.1 and 20‒60 °C. The as-synthesized sodium trititanate nanorods were characterized by XRD, HRTEM, N2 adsorption/desorption, SEM, EDX, and Zeta potential techniques. The concentrations of heavy metal ions in wastewaters were analyzed by ICP technique. After in situ oxidative adsorption treatment under the concentrations of 25 g∙L‒1 for sodium hypochlorite and 125 mg∙L‒1 for sodium trititanate nanorods at 60 °C for 5 h, the heavy metal ion concentrations could be reduced from initial value of 2.6 to final value of 1.92 mg∙L‒1 for Cr(VI), 3.6 to 0.17 mg∙L‒1 for Cu2+, and from 0.2705 to 0.097 mg∙L‒1 for Ni2+, respectively. Cr(VI), Cu2+, and Ni2+ ions could be effectively removed by the in situ oxidative adsorption method. The in situ oxidative adsorption processes of Cr(VI), Cu2+, and Ni2+ ions are satisfactorily simulated by the pseudo-second order adsorption kinetics and Langmuir adsorption isotherm, respectively. Adsorption thermodynamics analyses reveal that the oxidative adsorption processes of Cr(VI), Cu2+, and Ni2+ ions are spontaneous and endothermic. The oxidation degree of metal-contained complexes influences the values of thermodynamics functions.

Adsorption of heavy metal ions by carbon-based adsorbent using magnetic nitrogen-doped carbon and graphene oxide

ABSTRACT The adsorption of weighty metal particles from contaminated water sources has garnered significant attention due to its critical role in environmental remediation and ensuring safe drinking water. Heavy metal ions can be removed from water using conventional adsorbents such as activated zeolites; however, these materials have low absorption and slow kinetics. To solve these issues, carbon-based adsorbents that exhibit easy synthesis, high porosity, design ability, and stability have been proposed. In this review, a carbon-based adsorbent, named M-NC, and graphene oxide were created for the particular evacuation of weighty metal particles. To increase the potential for Heavy Metals (HM) immobilization, sulfide-modified biochar was created via a process called synchronous carbon layer epitome. A hypothetical physicochemical and thermodynamic examination of the adsorption of weighty metals Zn2+, Cd2+, Ni2+, Ag2+, Pb2+ and Cu2+ on carbon-based adsorbents was done with factual material science fundaments. The biochar with large surface areas is utilized to eliminate weighty metal particles, quite possibly the most significant heavy metal pollutants, from aqueous solutions. The limit of the adsorbent for eliminating weighty metal ions was concentrated on utilizing Langmuir adsorption isotherm under ultrasound-helped conditions. The Mesoporous Silica Nanoparticles (MNCs) can be applied to the Langmuir model and pseudo-second-order kinetics. It is possible to use the Langmuir and second-order kinetic equations to accurately explain the adsorption method. Thermodynamic limitations were also envisioned because sorption is exothermic when it happens spontaneously. A homogeneous measurable physical science adsorption typically was utilized to describe and analyze the experimental heavy metal removal isotherms at 30°C and pH5 utilizing adsorbents produced by pyrolysis of biomasses (broccoli stalks). The experimental results were investigated in terms of Langmuir and pseudo-2nd-order kinetic equations, Freundlich and isotherm models. The outcome of pH, initial heavy metal ion concentration, contact time, and adsorbent dosage regarding the adsorption capacity and removal efficiency of Pb2+ and Cd2+ on the hydrogel was examined. This study contributes to the advancement of information in the ground of environmentally friendly heavy metal removal techniques, specifically focusing on the usage of biomass-based adsorbents. These findings have the potential to address the need for effective solutions in water purification and environmental cleanup efforts.

Heavy metals immobilization of LDH@biochar-containing cementitious materials: Effectiveness and mechanisms

The utilization of tailings for producing solid waste-based concrete can effectively mitigate the environmental consequences stemming from tailings accumulation. However, the presence of high concentrations of heavy metal ions in certain tailings can deleteriously affect the microstructure of the cement matrix. This study investigated the in-situ immobilization performance of Pb2+ and Mn2+ by calcium-aluminum layered double hydroxides (CaAl-LDH) and LDH@biochar blended in cement-based materials. The equilibrium adsorption capacity of CaAl-LDH/LDH@biochar for heavy metals in aqueous solution was assessed by adsorption kinetics, while the effect of pH value on the removal rate of heavy metals was also studied. The workability and mechanical properties of cement mortar are significantly improved with the addition of 4 % LDH@biochar. LDHs@biochar can effectively reduce the deteriorating effects of heavy metal ions on the fundamental properties of cement materials. Compared with CaAl-LDH, the leaching concentrations for Pb2+ and Mn2+ in LDH@biochar at 28 d is decreased by 59 % and 39 %, respectively. The stable adsorption of Pb2+ and Mn2+ by LDH@biochar is attributed to multiple mechanisms, including interlayer anion exchange effect, chemical adsorption of surface functional groups and electrostatic attraction. This study provide valuable insights for enhancing the efficiency of heavy metal immobilization in cement-based materials.

Magnetic heterogenization of supramolecular carbohydrates for the efficient adsorption of heavy metals removal from wastewater

BackgroundAs the high impact of heavy metals hazards for humans and the environment, providing a suitable method to remove heavy metals is of great importance. Recently, magnetic adsorbents have been developed for their ease of separation, high absorption efficiency, and cost-effectiveness has been expanding. On the other hand, hybridism adsorbents composed of a magnetic core and an organic branch amended with different functional groups such as –OH, –NH2, −SH, and –COOH have suitable potentials for heavy metal removals. MethodsIn this, a simple procedure for the preparation of β-cyclodextrin bonded Fe3O4@SiO2 (β-CD-SiO2@Fe3O4) was reported. The morphological, structural, and thermal stability characteristics were investigated by the XRD, SEM, EDS, FT-IR, and TGA-DTA techniques. Next, the potential of β-CD-SiO2@Fe3O4 in the absorption of Cd2+ and Pb2+ ions from wastewaters was investigated. The effect of various parameters such as pH, adsorbent dosage, Pb/Cd concentration, and the temperature was investigated on the absorption of Cd2+ and Pb2+ heavy metal ions. Significant findingsThe maximum adsorption was achieved when pH = 6.5, heavy metal ion concentration (250 mg/L), and adsorbent dosage (0.075 g) at room temperature was used. The adsorption process could be described by kinetic models and the pseudo-second-order model was well-matched. The maximum adsorption capacities of Pb2+ and Cd2+ were obtained at 160 and 159.33 mg/g respectively. The negative value of ΔG indicates the spontaneity of the absorption process. The negative values of ΔH and ΔS show the exothermic nature of the absorption reaction.

Concentration of heavy metal ions from aqueous media under dynamic conditions using a composite sorbent based on chitosan and silica

Objectives. The study set out to investigate the sorption, toxicological, and regeneration properties of a composite sorbent based on chitosan hydrogel and unsuspended silicon dioxide (chitosan–colloidal silica), which manifest themselves under dynamic conditions of purification of aqueous solutions, as a means of removing heavy metal ions.Methods. The total dynamic exchange capacity of a chitosan–colloidal silica composite sorbent was evaluated under dynamic sorption conditions by passing solutions containing Zn(II), Cd(II), Cu(II), and Cr(III) ions having a concentration of 240–251 mg/L through a fixed sorption bed. The method for determining acute toxicity using daphnia (Daphnia magna Straus) is based on the direct calculation of the mortality of daphnia exposed to toxic substances contained in the test aqueous extract in comparison with a reference culture in samples that do not contain toxic substances. The regeneration ability of the sorbent was assessed by counting the number of sorption–desorption cycles using 0.1 M NaOH and 0.1 M NaHCO3 eluents, as well as aqueous solutions of H2O2 (1 and 3%).Results. The effectiveness of the chitosan–colloidal silica composite sorbent in the process of dynamic purification of aqueous media to remove Cu(II), Zn(II), Cd(II), and Cr(III) ions was established. After determining the times of ion breakthrough and saturation of the developed sorbent, its dynamic exchange capacity was calculated by processing the kinetic curves of sorption of heavy metal ions under dynamic conditions. The results of regeneration of the sorbent were presented in the context of the possibility of its reuse. It is shown that the sorbent can withstand up to five sorption–desorption cycles while maintaining a level copper cation extraction above 90%.Conclusions. Analysis of the kinetic curves demonstrated that the driving force behind the removal of heavy metals from aqueous media by means of the obtained sorbent is the external diffusion mass transfer of ions from the mobile phase of the solution. Biotesting of samples showed that the developed chitosan-based sorbent does not have acute toxicity.

. Comparison of sorption properties of zoocompost in relation to Cd2+, Zn2+, Cu2+ ions

The study of relationships between zoocompost containing humic acids and metal ions is of great importance not only for predicting the redistribution of humic compounds and heavy metals in the environment, but also for developing methods for controlling the processes of migration of pollutants in natural environments, creating new materials for protecting the environment and remediating soils contaminated with heavy metal ions. The article compares the sorption capacity of zoocompost cultivated by the Black Lionfly fly, containing humic acids and to Zn2+, Cd2+, Cu2+ ions. It was established that with an increase in the dose of zoocompost, the concentration of heavy metal ions in the solution decreases and the cleaning efficiency reaches 94.6% for Cd2+, 75.2% for Zn2+ and 70.4% for Cu2+. A comparison of the stability constants of complex ions of cadmium, zinc and copper showed that more stable metal-humic acid complexes are formed by Cd2+ and Zn2+, while Cu2+ is characterized by a lower degree of connectivity. The obtained sorption isotherms and values of the sorption capacity of zoocompost for Cd2+ (0.490 mmol/g), Zn2+ (0.225 mmol/g) and Cu2+ (0.145 mmol/g) indicate the specific interaction between the heavy metal ions and functional groups of humic acids included in the composition of zoocompost, and also confirm the theoretical series of stability of chelates Cd < Zn < Cu.

Advancements in Starch‐Based Aerogels and Hydrogels for Treatment of Water Containing Heavy Metals – A Short Review

AbstractRapid industrialization and profligate use of resources in the present era has led to increase in the concentration of toxic heavy metal ions in water bodies and has become a serious environmental concern. Starch hydrogels and aerogels with engineered functionality, porosity, regeneration characteristics, and high surface to volume ratio have rendered them potential candidates for the adsorption of heavy metal ions from wastewater streams. However, grafting, crosslinking, and composting of the starch aerogels and hydrogels to tailor them in response to various stimuli such as ionic strength, pH, and temperature has added an advantage in the treatment of wastewater containing heavy metal ions. This review critically analyses the various synthesis routes for the production of starch‐based aerogels and hydrogels with physico‐chemical characteristics (amylose content, gelatinization temperature, surface area, density, and porosity) and their applicability to adsorb heavy metal (Cd, Cu, Co, Ni, Cr, Pb, Zn, Fe, and Co) ions from wastewater. Future prospects in the development of economical and robust starch‐based aerogels and hydrogels in terms of their stability and reusability have also been discussed.

Nanoconfined polyethyleneimine in mesoporous MCM-41 silica for heavy metal ions removal

Water contamination resulting from the presence of the various coexistent pollutants is an urgent environmental challenge, and effective treatment is demanded to remove the toxic substances. The removal of pollutants by adsorption, as an effective, efficient and economic strategy, has been widely used in water treatment. In this work, PEI@MCM-41 was prepared by infiltrating polyethyleneimine (PEI) into the pores of mesoporous MCM-41, and applied for the removal of heavy metal ions. The adsorption kinetics of Cu2+, Ni2+ and Cd2+ by PEI@MCM-41 were supposed to be pseudo-second-ordered, and the adsorption capacities were as high as 39.30, 33.67 and 21.10 mg·g−1, respectively. The influence of temperature, pH, coexistent salt and heavy metal ions concentration on the adsorption performance was studied. Owing to the nanoconfinement effect and hydrogen bond, PEI remained stable during the adsorption and desorption process, and the adsorption capacity for Cu2+ maintained 84.15 % even after four consecutive adsorption–desorption cycles. This work demonstrates that the potential practical applicability of PEI@MCM-41 as promising adsorbent in the removal of heavy metal ions.

Heavy Metal Detection and Removal by Composite Carbon Quantum Dots/Ionomer Membranes.

The combination of ion exchange membranes with carbon quantum dots (CQDs) is a promising field that could lead to significant advances in water treatment. Composite membranes formed by sulfonated poly(ether ether ketone) (SPEEK) with embedded CQDs were used for the detection and removal of heavy metal ions, such as lead and cadmium, from water. SPEEK is responsible for the capture of heavy metals based on the cation exchange mechanism, while CQDs detect their contamination by exhibiting changes in fluorescence. Water-insoluble "red" carbon quantum dots (rCQDs) were synthesized from p-phenylenediamine so that their photoluminescence was shifted from that of the polymer matrix. CQDs and the composites were characterized by several techniques: FTIR, Raman, UV/VIS, photoluminescence, XPS spectroscopies, and AFM microscopy. The heavy metal ion concentration was analyzed by inductively coupled plasma-optical emission spectroscopy (ICP-OES). The concentration ranges were 10.8-0.1 mM for Pb2+ and 10.0-0.27 mM for Cd2+. SPEEK/rCQDs showed a more pronounced turn-off effect for lead. The composite achieved 100% removal efficiency for lead and cadmium when the concentration was below a half of the ion exchange capacity of SPEEK. The regeneration of membranes in 1 M NaCl was also studied. A second order law was effective to describe the kinetics of the process.

Combined effect of zinc and cadmium ions on nitrification performance during the biological nitrogen removal of simulated livestock breeding wastewater.

Zinc and cadmium ions are usually found in livestock breeding wastewater, and the mixed ions will have an impact on the biological nitrogen removal. Nitrification performance plays an important role in biological nitrogen removal. In order to investigate the combined effect of zinc and cadmium ions on nitrification performance and to reveal the interactions between zinc and cadmium ions, three concentration ratios of zinc and cadmium ions, as well as 18 different concentration gradients were designed with the direct equipartition ray and the dilution factor method. The effect of pollutants on the nitrification performance of biological nitrogen removal was analyzed by the nonlinear regression equation, and the concentration-addition model was conducted to probe into the relationship between the mixed pollutants and the nitrification performance. The results showed that the effect on nitrification performance increased significantly with the increase of reaction duration and pollutant concentration, which indicated that the effects are concentration-dependent and time-dependent. The concentration-addition model suggested that the interactions between zinc and cadmium ions with different concentration ratios were mainly antagonistic, and as the percentage of cadmium ions in the mixtures increased, the antagonism between the mixtures became stronger. This study will provide a relevant theoretical basis for the regulation of the ratios and concentrations of heavy metal ions during the biological treatment of livestock breeding wastewater.

Cancer Incidence Relation to Heavy Metals in Soils of Kyzylorda Region of Kazakhstan.

The purpose of this study was to investigate the relationship of soil pollution factors such as heavy metal ions with the incidence of cancer in the Kyzylorda region of Kazakhstan. Concentrations of heavy metal ions in the soils of different sites of Kyzylorda region, Kazakhstan, were sampled and correlated with incidence of cancer in 2021. Chromium content in the soil exceeded maximum permissible concentration (MPC) in the samples for all sites except Kazaly and Shieli, and the highest excess of 2.8 MPC was found in Terenozek. Content of copper, lead, and cobalt ions was also increased and varied in the range 1.9-15.4, 1.2-4, and 1.2-2.44 MPC, respectively. In addition, lung cancer incidence was statistically significantly correlated with soil concentration to MPC ratio of copper, cobalt, and lead; colorectal cancer was correlated with soil concentration of chromium. Cases of invasive cancer and mutations were recorded Terenozek and Kyzylorda areas. The higher the soil concentration correlate with higher cancer incidence in Kyzylorda region, Kazakhstan.

Mechanistic Coupling of Coagulation-Flocculation, and Machine Learning for Removal of Various Contaminants from Water System

Water is the most precious compound on the earth. Presence of different pollutants in water is a major cause of pollution. Numerous materials and technologies have been used to remove these pollutants from the water supply. Access to safe water for everyone is the prime aim of sustainable development goal six. To do this, numerous materials and technologies have been created. Coagulation-flocculation and adsorption are the prime steps for treatment of wastewater. Coagulation-flocculation is done in tandem to counter the stabilizing force present to disturb the suspended particles' impurities and toxic materials, so as to allow collision of particles and lead to growth of flocs. Acute and chronic illnesses in humans can result from heavy metal ion concentrations that are higher than advised. Adsorption is effectively applied techniques for removal of these heavy metals and rest of the materials present in water. Machine learning helps to analyze the contaminants in water to develop a suitable technique and materials for removal of contaminants from water. The aim of this paper is to couple the coagulation-flocculation, and machine learning techniques together for removal of all contaminants from the water system and explain the mechanism which helps to know the chemical interaction.

The migration process and temperature effect of aqueous solutions contaminated by heavy metal ions in unsaturated silty soils

Adsorption-desorption experiments of three heavy metal ions (i.e., lead, copper, cadmium) in silty soil were carried out at different temperatures, and the microscopic characteristics of silty soil loaded with the three heavy metal ions were analyzed. A one-dimensional soil column was used to discuss the influences of heavy metal ion types and concentrations on the soil moisture distribution and the migration level of different heavy metal ions, especially during the dynamic change process from an unsaturated state to a saturated state. Studies show that the adsorption of heavy metal ions onto silty soil is closely related to the mineral composition and functional groups in silty soil. In addition to physical adsorption, the adsorption of heavy metal ions is closely related to the hydrolysis reaction of mineral components such as kaolinite, calcite, dolomite, plagioclase and quartz. Under constant temperature, the types and concentrations of heavy metal ions play an important role in the moisture migration of unsaturated soil. In the presence of heavy metal ions, the penetration of lead ions is the greatest, followed by copper ions and then cadmium ions. The greater the ion concentration is, the stronger the penetration of heavy metal ions in silty soils.