Concentrations Of Heavy Metal Ions Research Articles

Curcumin-based ratiometric electrochemical sensing interface for the detection of Cd2+ and Pb2+ in grain products

The conventional electrochemical detection in food samples often suffers from low stability and poor reproducibility. The construction of ratiometric sensor is regarded as an effective means to overcome the issues. Herein, poly-curcumin (p-CCM)-Multi walled carbon nanotubes (MWCNTs)-layered double hydroxides (LDHs) was constructed as a novel rationmetric sensing material for detection of Cd2+ and Pb2+ in grain samples. Under the synergistic effect of MWCNTs and the adsorption capacity of LDHs, the p-CCM/MWCNTs/LDHs can significantly enhance the electrochemical responses of heavy metals. In the differential pulse voltammetry test, the ratio of oxidation peak currents between heavy metal ions and curcumin was directly proportional to the concentration of heavy metal ions. This has formed the basis of a new ratiometric electrochemical sensor for the detection of the levels of Cd2+ and Pb2+ in grain products. Under optimal conditions, the limits of detection for Cd2+ and Pb2+ were found to be 0.61 μg mL−1 and 0.74 μg mL−1, respectively. It is worth mentioning that the method was additionally utilized to detect Cd2+ and Pb2+ in rice and flour samples. The satisfactory recovery outcomes in both samples demonstrated minimal interference of the food matrix with the obtained ratiometric sensor. In this work, a CCM-based ratiometric electrochemical sensor was presented, which could potentially replace the widely used ferrocene-based ratiometric electrochemical sensor, thereby enhancing the exploration of electrode materials for ratiometric electrochemical sensors.

The apple Ca2+/H+ exchanger MdCAX2L-2 functions positively in modulation of Ba2+ tolerance

Calcium is an essential element for plant growth and development, and it plays an important role in the responses of plants to abiotic stress. High concentrations of heavy metal ions in soil significantly affect the yield and quality of crops and pose human health threats when these ions accumulate in edible organs. The Ca2+/H+ exchanger (CAX) family is a class of transporters that mediate the transmembrane transport of both Ca2+ and metal ions, and they are widely involved in regulating plant growth and development and stress responses. Here, we cloned an AtCAX2 ortholog, MdCAX2L-2, from apple. It is constitutively expressed in various apple tissues and significantly induced by Ca2+ and Ba2+ treatments. The MdCAX2L-2 protein is located in the vacuolar membrane in both plant and yeast cells. Overexpression of MdCAX2L-2 enhanced the tolerance of the yeast mutant K667 to high concentrations of Ca2+ and Ba2+. In addition, the role of MdCAX2L-2 in modulating Ba2+ tolerance was identified using MdCAX2L-2-overexpressing transgenic Arabidopsis plants and apple calli. Comparison of growth phenotypes and stress-related physiological indexes under BaCl2 treatment indicated that MdCAX2L-2 could enhance the Ba2+ tolerance of plants by promoting Ba2+ compartmentalization into the vacuoles and eliminating excess ROS. Our results provide insights that will aid future studies examining the function of CAX proteins in regulating stress tolerance in fruit crops, as well as their underlying mechanisms.

Effects of biochar-derived dissolved organic matter on the gut microbiomes and metabolomics in earthworm Eisenia fetida

The ecological risks of biochar-derived dissolved organic matter (DOM) to soil invertebrates at different organismal levels remains limited. This study comprehensively explored the ecological risks of biochar-derived DOM on earthworm gut through assessments of enzyme activity response, histopathology, gut microbiomes, and metabolomics. Results demonstrated that DOM disturbed the digestive enzymes in earthworm, especially for 10% DOM300 groups. The integrated biomarker response v2 (IBRv2) indicated that the perturbation of earthworm digestive enzymes induced by DOM was both time-dependent and dose-dependent. Pathological observations revealed that 10% DOM300 damaged intestinal epithelium and digestive lumen of earthworms. The significant damage and injury to earthworms caused by DOM300 due to its higher concentrations of heavy metal ions and organic substrates (e.g., toluene, hexane, butanamide, and hexanamide) compared to DOM500 and DOM700. Analysis of 16S rRNA from the gut microbiota showed a significant decrease in genera (Verminephrobacter, Bacillus, and Microbacteriaceae) associated with inflammation, disease, and detoxification processes. Furthermore, 10% DOM300 caused the abnormality of metabolites, such as glutamate, fumaric acid, pyruvate, and citric acid, which were involved in energy metabolism, These findings contributed to improve our understanding of the toxic mechanism of biochar DOM from multiple perspectives.

The content of heavy metal ions in ash from waste incinerated in domestic furnaces

The content of heavy metal ions in ash from waste incinerated in domestic furnaces

Investigation on the effect of Cu2+, Mn2+ and Fe3+ on biotreatment of Cr(VI) by Shewanella oneidensis and Bacillus subtilis in bimetallic system

Coexistence of chromium and iron, manganese and copper in industries is common, which may affect the microbial treating efficiency and toxicity to microorganisms, thus restricting the application of microbial treatment technology. In this research, Cu2+ promoted the reduction of Cr(VI) and the fixation of total chromium in bimetallic systems for both Shewanella oneidensis MR-1 and Bacillus subtilis, while Mn2+ and Fe3+ exhibited inhibition effects. Generally, groups with coexisting heavy metal of 0.1 mM were most affected, no matter promotive or inhibitive. Toxicity analysis revealed that high concentration of heavy metal ions led to damage to the cell membranes and reduction of their survival rate. To clarify the optimal condition for microbial treatment, response surface methodology was used to investigate the influencing factors of Cr(VI) reduction by S. oneidensis. The total chromium concentration in the supernatant was correlated with three factors, and the significant order of influence was: culture time > culture temperature > pH.

Synthesis and application of EDTA grafed metal-organic frameworks (MOFs) and graphene composite for the electrochemical detection of lead(II)

ABSTRACTThe rapid and sensitive detection of heavy metal ion concentrations in water holds significant importance for water resource quality control and protection. In this study, we developed a novel electrochemical sensor utilising a composite material consisting of ethylene diamine tetraacetic acid (EDTA) grafted metal-organic frameworks (MOFs NH2-UiO-66) and graphene to detect Pb2+ in water. The NH2-UiO-66 material exhibited a large specific surface area and porous structure, which was advantageous for the pre-enrichment of the heavy meatal ions. EDTA contained abundant – COOH groups, enabling it to chelate metal ions and increase the reaction sites of redox reactions. The introduction of graphene improved the conductivity of the composite, facilitating electron transfer and enhancing the sensitivity of the electrochemical sensor. Under optimal conditions, the linear range for Pb2+ detection was 0.1 μM–50 μM, and the limit of detection was achieved at 0.052 μM. Furthermore, simultaneous detection of Pb2+ and Cd2+ was successfully accomplished. The fabricated sensor also exhibited excellent selectivity, reproducibility and stability.

Biomass derived green carbon dots for sensing applications of effective detection of metallic contaminants in the environment

The rapid consumption of metals and unorganized disposal have led to unprecedented increases in heavy metal ion concentrations in the ecosystem, which disrupts environmental homeostasis and results in agricultural biodiversity loss. Mitigation and remediation plans for heavy metal pollution are largely dependent on the discovery of cost-effective, biocompatible, specific, and robust detectors because conventional methods involve sophisticated electronics and sample preparation procedures. Carbon dots (CDs) have gained significant importance in sensing applications related to environmental sustainability. Fluorescence sensor applications have been enhanced by their distinctive spectral properties and the potential for developing efficient photonic devices. With the recent development of biomass-functionalized carbon dots, a wide spectrum of multivalent and bivalent transition metal ions responsible for water quality degradation can be detected with high efficiency and minimal toxicity. This review explores the various methods of manufacturing carbon dots and the biochemical mechanisms involved in metal detection using green carbon dots for sensing applications involving Cu (II), Fe (III), Hg (II), and Cr (VI) ions in aqueous systems. A detailed discussion of practical challenges and future recommendations is presented to identify feasible design routes.

Recycling of the waste battery: Effect of waste battery on property of asphalt and environmental impact evaluation

A waste battery is a kind of hazardous solid waste, and traditional recycling methods can cause serious environmental pollution. In this paper, a pilot study was conducted to reduce the leaching of heavy metals in waste battery power (WBP) by using the wrapping effect of asphalt and explored the feasibility of adding waste battery as a modifier to asphalt. The main components of WBP are determined through microscopic experiments, and its compatibility with asphalt and microscopic mechanism are analyzed; The influence of WBP on asphalt properties are analyzed through routine tests and mixture tests; The leaching test of toxicity is used to analyze the impact of WBP and WBP modified asphalt on the environment. The experimental results indicate that WBP is mainly composed of MnO2, C, and ZnO; There are many wrinkles and grooves on the surface of WBP, which can effectively adsorb asphalt during the modification process, produce anchoring effect, and have good compatibility with asphalt; The components of waste battery adsorb the aging light components in asphalt through their folds and swelling, so that the proportion of heavy components is relatively increased, improving the property indicators of asphalt; From the perspective of engineering property, WBP modified asphalt mixture has strong resistance to deformation and water damage. The leaching concentration of heavy metal ions from bare WBP in soil seriously exceeded the standard. In contrast, when WBP was added to asphalt, the cumulative leaching concentration of heavy metal ions was significantly reduced due to the wrapping effect of asphalt, and the WBP leaching toxicity was greatly suppressed; The method of recycling waste battery and adding it to asphalt as a modifier can prevent the release of heavy metal ions from waste battery into the environment and reduce the risk of the total environmental harm to soil, groundwater and human health.

FACTORS ON THE BIOSYNTHESIS OF AMYLOLITIC ENZYMES OF STREPTOMYCETE ORIGIN

Modern enzyme biotechnology is a promising and rapidly developing field that requires the latest research on the conditions of enzyme biosynthesis. Optimizing the composition of the nutrient medium depending on the needs of microorganisms and physicochemical factors directly affect the increase in the efficiency of the biosynthesis of amylolytic enzymes, namely the biosynthetic capacity of the strain Streptomyces recifensis var. lyticus 2P-15. Modulation of the biosynthetic activity of strains producing amylolytic enzymes will allow to significantly increase their economic yield. Aim. The purpose of this work is to optimize the biosynthetic capacity of the strain Streptomyces recifensis var. lyticus 2P-15 in terms of the synthesis of amylolytic enzymes and the study of the dynamics of the influence of physical and chemical factors on optimization. Methods. The object of the study is the strain Streptomyces recifensis var. lyticus 2P-15, obtained by three-stage selection of the producer. The simplex method of selecting the composition of the environment was used for the research. The ratio of amylolytic activity to the level of biomass accumulation was taken as the biosynthetic capacity of the strain. A photocolometric method was used to determine amylolytic activity. The level of biomass accumulation was determined by the weight method. Results. It was established that as a result of optimizing the composition of the simplex nutrient medium by the method of mathematical modeling, the biosynthetic capacity increased by 3.63 compared to the control variant. It was also investigated that the optimal concentration of such a component of the nutrient medium as monosodium glutamate С5Н8NO4Na・H2O is 1.5%, which increases the amylolytic activity by 2.63 and increases the accumulation of biomass. Separately, it should be noted the obtained results of the study of the optimal concentrations of heavy metal ions added to the optimized version of the nutrient medium, which allow further research in this aspect to be continued and the use of Co, Mo, Cd ions in the composition of the nutrient medium. With the obtained results, there is an increase in amylolytic activity in the best response by 3.54. The obtained results have theoretical and practical significance for further research in the biotechnology of enzymes. Conclusions. The prospect of further research into the optimization of the biosynthesis of actinomycetes by the simplex method of other aspects of its regulation will be to increase the biosynthetic capacity of the studied strain, which will have a positive effect on the economic output of the production of amylolytic enzyme preparations by obtaining microbial synthesis.

A study on the reduction of heavy metal ions (Cd2+ and Cr3+) in waste water from chemistry laboratory by Pericopsis elata adsorbent

This research was aimed the at preparation and application of Pericopsis elata adsorbent in reducing the concentration of heavy metal ions present in waste water obtained from chemistry laboratory. Atomic Absorption Spectroscopy (AAS) was used to determine the concentration of heavy metal ions (Cd2+ and Cr3+) in laboratory waste water. The concentration of Cd and Cr were 155 and 122 mg/L. At a dosage of 0.25, 0.5 and 0.75 g the concentration ranged from 21.55 25.65 mg/L for Cr and 12.90 14.32 mg/L for Cd. At pH value of 2, 7 and 11, the concentration were 11.30, 20.33 and 39.50 mg/L for Cr and 15.30, 28.20 and 24.80 mg/L for Cd respectively. The concentration of Cr and Cd on adsorption increases with an increase in contact time of the adsorbate. At contact time of 20, 40 and 60, the adsorption concentration were 16.60, 19.30 and 29.40 (mg/L) for Cr and 10.50, 20.40, 48.10 (mg/L) for Cd. The results indicate that as the pH, contact time and temperature increases, the percentage removal of Cr and Cd also increases. As adsorbent dosage increased the percentage removal of Cr and Cd also increased. The result of the morphology showed a porous, rough and irregular surface with crystalline structure which indicated more macro pores for adsorption. It can be deduced that the Pericopsis elata adsorbent provides an external surface of porous and more reactive sites, which enhanced its adsorption capacity.

Comparison of Adsorption Performance of Biochar Derived from Urban Biowaste Materials for Removal of Heavy Metals.

This study investigated the adsorption performance of biochar produced from different types of urban biowaste material viz., sugarcane bagasse (SB), brinjal stem (BS), and citrus peel (CP) for removal of heavy metal ions (Pb, Cu, Cr, and Cd) from aqueous solution. The effects of biowaste material, dosage of biochar, solution pH, and initial concentration of heavy metal ions and isotherm models were performed to understand the possible adsorption mechanisms. The results showed that the biochar derived from BS and SB removes Cu (99.94%), Cr (99.57%), and Cd (99.77%) whereas biochar derived from CP removes Pb (99.59%) and Cu (99.90%) more efficiently from the aqueous solution. Biochar derived from BS showed maximum adsorption capacity for Cu (246.31 mg g-1), Pb (183.15 mg g-1), and Cr (71.89 mg g-1) while the biochar derived from CP showed highest for Cd (15.46 mg g-1). Moreover, biochar derived from BS and SB has more polar functional groups and less hydrophobicity than the biochar derived from CP. This study reveals that solution pH and biochar doses play a major role in removal of heavy metal ions from aqueous solution. The results of Langmuir model fitted well for Pb and Cu while the Freundlich model for Cr and Cd. Our study concludes that the biochar derived from different biowaste materials adsorbs heavy metal ions majorly through surface complexation and precipitation processes. The results of this study will be very useful in selecting the effective urban biowaste material for making biochar for heavy metal removal from the aqueous environment.

Tuning surface wettability of MoS2 to enhance solar‐driven evaporation rates

AbstractMolybdenum disulfide (MoS2), a promising two‐dimensional photothermal material, possesses the capability to convert solar irradiation into thermal energy. This conversion is beneficial for processes like wastewater treatment and seawater desalination. Nevertheless, the influence of the surface chemical properties of MoS2, particularly its wettability, on the evaporation rate of water confined to the surface remains unexplored. In our study, we demonstrate that the wettability degree of MoS2 significantly influences its water evaporation rate performance. Interestingly, this parameter can be simply and accurately modulated by altering the synthesis time of MoS2. We synthesized MoS2 via a simple hydrothermal method at three different durations: 16, 20, and 24 h, at 200°C. Subsequently, we impregnated the resultant MoS2 onto air‐laid paper (ALP), forming a solar‐driven evaporator system. We found that the MoS2 nanosheets synthesized within the shortest duration (MoS2‐16 h) exhibited the highest evaporation rate of 1.77 kg m−2 h−1, along with 92% energy efficiency. MoS2‐16 h resulted in MoS2 rich in defects, featuring the largest surface area and the smallest contact angle. The hydrophilic areas of MoS2‐16 h facilitated the continuous diffusion of water molecules through defect sites, treating them as contact lines. Additionally, the expansive surface area introduced a larger region for light absorption, enhancing water‐solid interactions. The presence of molybdenum oxide on the surface of the nanosheet system also contributed to superior wettability behavior. Notably, all the tested MoS2/ALP systems in this study displayed excellent performance in salt rejection and heavy metal ion concentration reduction.

Removal of heavy metal ions using nano-cellulose prepared from rice husk: validation by differential pulse voltammetry

In this work, Cellulose was extracted from rice husk and chemically modified to produce Nano-Cellulose. It was characterized by FTIR, XRD, SEM/EDS, TEM, BET surface area analyzer, Particle size analyzer and tested for the removal of metal ions i.e. Zn(II), Cd(II), As(III), Pb(II) and Sn(II) from aqueous solution. The removal method was validated by differential pulse voltammetry (DPV). An adsorption experiment was performed to investigate the effects of initial pH, adsorbent dose, contact time and initial concentration of heavy metal ions on the adsorption capacity of nanocellulose. The experimental results revealed that the removal of metal ions on the nanocellulose was a pH-dependent process with the maximum adsorption capacity at the initial solution pH of 5–6. An adsorbent dose of 8mg/mL was sufficient for effective adsorption. In addition, the kinetics and equilibrium data are well described by pseudo-second-order kinetics and the Freundlich adsorption isotherm model at 50 min contact time and 50 mg/L initial concentration. Moreover, the desorption and re-adsorption performance was also studied, and the results revealed that the Nano-cellulose still showed good adsorption performance up to eight cycles of regeneration.

Гальваношламы – источник вторичных материальных ресурсов при получении пигментов-наполнителей для лакокрасочных изделий

Galvanic production occupies one of the first places according to the degree of negative impact on the environment due to the content of heavy metal ions which have toxic, carcinogenic and mutagenic properties. Finding an effective method of recycling and utilization of galvanic sludge will solve the problem of the steady growth of the cost of metals and minimize the negative impact on the environment, which is an important environmental task of great scientific and practical significance. This paper presents the results of studies on the extraction of iron oxide(III) Fe2O3 from ironcontaining galvanic sludge to use it as a filler pigment in the manufacture of paint (red iron oxide). At the initial stage, the original galvanic sludge was dissolved in distilled water to a creamy consistency, and then, sulfuric acid was gradually added until the pH value gradually decreased (pH 6.0–1.5), metal sulfates were obtained. Iron hydroxide(III) Fe(OH)3 was precipitated from filtered sulfate solutions with 40% NaOH alkali solution at pH 1.5–4.1. After preliminary drying at a temperature of ≈ 150 оС, heat treatment was carried out at 600±2 оС for 5–6 h, obtaining iron oxide(III) Fe2O3, which met the requirements of GOST 10503-71 “Oil paints, ready to use. Technical Conditions in terms of particle size, oil capacity, particle density and pH of aqueous extracts. The iron minium paint made on its basis also met the requirements of this GOST on parameters: viscosity, hiding power, drying time, etc. A schematic diagram is proposed for obtaining a filler pigment used for the production of paints and varnishes. The scheme uses a set and layout of equipment widely used in industry (conveyor, batchers, screw feeders, acid and alkali treatment baths, centrifuge, drying and roasting oven).

Changes in the Strength and Leaching Characteristics of Steel Slag-Oil Shale Residue-Based Filling Paste in a Complex Erosive Environment

Our research group prepared a new filling paste consisting of steel slag–oil shale residue and no admixtures. It was used as the research object to explore the combined effect of chloride and dry–wet cycling-driven erosion on the long-term stability of a cemented filling paste made of total solid wastes. Macroscopic experiments and microscopic analyses methods were employed. The influence of solutions with different mass fractions of chloride salts and different cycling periods on the uniaxial compressive strength and toxicity of the steel slag–oil shale residue-based filling paste was studied, and the deterioration mechanisms of the steel slag–oil shale residue-based filling paste under combined erosion from chloride and dry–wet cycling were investigated. The test results showed that in the same cycling conditions, the strength of the steel slag-oil shale residue-based filling paste increased first with the increase in the mass fraction of the chloride solution and then decreased with the increase in the mass fraction of the chloride solution after reaching the peak value; the leached concentrations of heavy metal ions decreased with increasing chloride salt mass fraction. With an increase in the number of dry–wet cycles, the compressive strength of the specimens in the chloride salt solution with a mass fraction of 0 (pure water) first increases and then tends to be stable. The strength of samples in 5% and 10% chloride salt solutions increased first and then decreased with an increase in the number of dry–wet cycles. The leached concentrations of heavy metal ions from the samples in all three solutions first decreased and then stabilized. The prehydration products of the steel slag–oil shale residue-based filling paste were C-S-H gels, AFt and Friedel’s salt, and these increased with increasing chloride salt mass fraction and the number of dry–wet cycles. However, the hydration reactions of the samples in the 0% chloride solution nearly stopped in the later stages of cycling, and the samples in 5% and 10% chloride salt solutions developed local cracks due to the accumulation of hydration products. The results showed that the number of dry–wet cycles and the chloride salt mass fraction affected the strength and leaching characteristics of the steel slag–oil shale residue-based filling paste by changing the type and amount of erosion products. The test results provide a scientific basis for the promotion and application of backfilling pastes made from total solid wastes.

Biomineralization technology for solidification/stabilization of heavy metals in ecosystem: status and perspective

Biomineralization technology offers an eco-friendly and efficient method for stabilizing heavy metals (HMs) in ecosystem. This technology comprises two primary methods: microbially induced carbonate precipitation (MICP) and enzyme-induced carbonate precipitation (EICP). Biomineralization provides a superior alternative to stabilize heavy metals due to its low energy consumption, reduced carbon dioxide emissions, and superior biocompatibility. In the process of biomineralization, heavy metal ions precipitate and co-precipitate with calcium carbonate, forming a solidified and stabilized product. Despite its many advantages, little attention has been paid to the impact of biomineralization on mitigation of ammonia nitrogen of bio-treated polluted water and the strength of contaminated soil, limiting its further applications in ecological environment restoration. This paper summarizes recent advancements in biomineralization for solidifying and stabilizing (S/S) heavy metals in contaminated water and soil. Key factors inhibiting this method’s application include the concentration and combinations of heavy metal ions, the concentration of ammonia nitrogen in polluted water, and the properties of contaminated soil. Finally, this paper offers recommendations on the optimization of further research and experimental design of biomineralization on S/S polluted water and contaminated soil.

Synthesis of Polyvinyl Alcohol/Coal Fly Ash Hybrid Nano-Fiber Membranes for Adsorption of Heavy Metals in Diesel Fuel.

Some studies have shown that the heavy metal emissions (HMEs) emitted from diesel engines can seriously threaten human health. HMEs are mainly related to the content of heavy metal ions in diesel fuel. Therefore, in order to reduce HMEs from diesel engines, a nano-fiber membrane filtration technology for diesel fuel was investigated. Herein, coal fly ash (CFA) from coal-fired power plants combined with polyvinyl alcohol (PVA) was successfully fabricated into nano-fibrous membranes using green electrospinning technology. In order to evaluate the adsorption properties, various hybrid membranes with different mixing ratios (PVA/CFA = 10/0, 10/1, 10/3, 10/5, and 10/7 by weight) were fabricated. The results show that eight metal ions with different concentrations are found in the diesel fuel, including Pb, Cu, Zn, Al, Fe, Cr, Ba, and Ni. All PVA/FA membranes have different adsorption capacities for metal ions, following the order: Cu > Fe > Pb > Al > Zn > Cr > Ba > Ni. In addition, the adsorption capacity of CFA3 (PVA/CFA = 10/3) is the largest. The super lipophilicity of the PVA/FA membranes also provide more adsorption sites for the contact of HMs with the membranes. The above research results provide guidance for development of ultra-fine filters in the future.

The YBR056W-A and Its Ortholog YDR034W-B of S. cerevisiae Belonging to CYSTM Family Participate in Manganese Stress Overcoming

The CYSTM (cysteine-rich transmembrane module) protein family comprises small molecular cysteine-rich tail-anchored membrane proteins found in many eukaryotes. The Saccharomyces cerevisiae strains carrying the CYSTM genes YDRO34W-B and YBR056W-A (MNC1) fused with GFP were used to test the expression of these genes under different stresses. The YBR056W-A (MNC1) and YDR034W-B genes are expressed under stress conditions caused by the toxic concentrations of heavy metal ions, such as manganese, cobalt, nickel, zinc, cuprum, and 2.4-dinitrophenol uncoupler. The expression level of YDR034W-B was higher than that of YBR056W-A under alkali and cadmium stresses. The Ydr034w-b-GFP and Ybr056w-a-GFP proteins differ in the cellular localization: Ydr034w-b-GFP was mainly observed in the plasma membrane and vacuolar membrane, while Ybr056w-a-GFP was observed in the cytoplasm, probably in intracellular membranes. The null-mutants in both genes demonstrated decreased cell concentration and lytic phenotype when cultivated in the presence of excess manganese. This allows for speculations about the involvement of Mnc1 and Ydr034w-b proteins in manganese stress overcoming.

A CNN-Based Method for Heavy-Metal Ion Detection

Data processing is an essential component of heavy-metal ion detection. Most of the research now uses a conventional data-processing approach, which is inefficient and time-consuming. The development of an efficient and accurate automatic measurement method for heavy-metal ions has practical implications. This paper proposes a CNN-based heavy-metal ion detection system, which can automatically, accurately, and efficiently detect the type and concentration of heavy-metal ions. First, we used square-wave voltammetry to collect data from heavy-metal ion solutions. For this purpose, a portable electrochemical constant potential instrument was designed for data acquisition. Next, a dataset of 1200 samples was created after data preprocessing and data expansion. Finally, we designed a CNN-based detection network, called HMID-NET. HMID-NET consists of a backbone and two branch networks that simultaneously detect the type and concentration of the ions in the solution. The results of the assay on 12 sets of solutions with different ionic species and concentrations showed that the proposed HMID-NET algorithm ultimately obtained a classification accuracy of 99.99% and a mean relative error of 8.85% in terms of the concentration.

Green and cost-efficient functionalized clay adsorbent enables one-step ultraefficient removal of Pb(II) at very low and high concentrations

It is always a huge challenge to purify wastewater containing very low or high concentrations of heavy metal ions to drinking water level (World Health Organization (WHO) guidelines) by one-step static or dynamic adsorption with a highly efficient, cost-effective, and environmentally friendly adsorbent. In response to this challenge, a green, low cost and powerful porous silicate/Fe3O4 adsorbent (named MCSiMg49) with ultra-strong purification ability towards the Pb(II) in both low- and high-concentration wastewater was developed using natural abundant, safe, and nontoxic palygorskite-rich clay as the starting material and water as the only solvent. The adsorbent possesses a high specific surface area of 332.41 m2/g (2.81 times that of raw clay), and was proven to be the best one to date that can purify deeply Pb(II) in water. The adsorption capacity of the adsorbent towards Pb(II) reached 499.3 mg/g, and 99.8% of Pb(II) can be removed from 800 mg/L Pb(II) solution after adsorption with 3 g/L of the adsorbent, which is significantly superior to other adsorbents and commercial activated carbon (AC). The adsorption column packed with MCSiMg49 (1 g, upper layer) and clay (1 g, lower layer) can remove completely Pb(II) from natural water (e.g., Yangtze River water or Yellow River water) (concentration: 50 mg/L), and 3000 mL clean drinking water (WHO guidelines) was obtained by a one-step filtration process. The MCSiMg49 adsorbent is easy to use in both dynamic and static adsorption, because it can be quickly recycled from the solution by external magnetic field after use. The adsorption of Pb(II) on the adsorbent was mainly driven by the cooperation of electrostatic attraction, ion exchange, chemical complexation and in situ mineralization of Pb(II).