Heavy Metals Research Articles

Sulfur‐Rich Polymers Coatings

AbstractAdvancements in the synthesis of sulfur‐rich materials are driving progress across diverse fields owing to the rich and tunable functionalities of those materials. These materials are typically valued for their electrochemical behaviors, high refractive indices, heavy metal affinity, and ability to form dynamic covalent bonding. As a result, their applications span various industries including electronics, catalysis, lithium‐sulfur batteries, water reclamation, and optoelectronics. Moreover, elemental sulfur, a byproduct of the petroleum industry, is produced abundantly, necessitating the exploration of novel valorization routes for polymers made from this feedstock. The unique combination of properties of sulfur‐rich polymers also makes them an ideal platform for the development of high‐performance functional coatings, offering durability and tailored functionalities for protective coatings, thus enhancing materials lifespan and performances in a variety of environmental conditions. The presence of dynamic covalent bonds in many sulfur‐rich polymers enables the creation of self‐healing coatings, while sulfur itself or the comonomers can contribute to antimicrobial, antifouling, and corrosion‐resistant properties. Furthermore, sulfur‐rich polymers have the potential to be used in the design of icephobic and superhydrophobic coatings. This underscores the versatility of sulfur‐rich polymers as a platform for the creation of advanced coatings with superior properties.

Bioaccumulation of Lead and Mercury in Water, Sediment, and Fish Samples of Baraila Lake, Vaishali, Bihar.

In the current study, a protected subtropical wetland in Bihar (India), Baraila Lake, was investigated for heavy metal (Pb and Hg) status. These metals tend to bioaccumulate in fish, posing a concern to human health. This study reported the concentration of lead and mercury in water, sediment, and fish muscles of Baraila Lake in the year 2022. The samples were collected from pre-monsoon and post-monsoon seasons at four sampling locations, i.e., Loma, Dhulwar, Chakaiya, and Kawai Baraila, and were analyzed in triplicates. Lead concentration in water samples of all four sites of Baraila Lake observed during pre-monsoon and post-monsoon season exceeded the permissible limit for drinking water, while the mercury concentration of all sites was under the permissible limit in both seasons as prescribed by WHO. The extent of elemental pollution was evaluated using the Geo-accumulation index (Igeo), contamination factor (CF), contamination degree (Cd), ecological risk factor (Er), and the potential ecological risk index (Ri). Lead concentration in fish muscles of both seasons exceeded the permissible limit, while the concentration of mercury exceeded in Xenentodon cancila (0.55 ± 0.07µg/g) during the pre-monsoon season. Also, estimated daily intake (EDI), target hazard quotient (THQ), and hazard index (HI) were calculated in different fish muscles to assess potential human health risks. A higher THQ value of 1303 was observed in carnivore fish during the pre-monsoon season.

Functional Hydrogels Promote Vegetable Growth in Cadmium-Contaminated Soil.

Over the years, the concentration of cadmium in soil has increased due to industrialization. Cadmium in the soil enters the human body through plant accumulation, seriously endangering human health. In the current study, two types of hydrogels were successfully synthesized using a free radical polymerization method: an ion-type hydrogel referred to as DMAPAA (N-(3-(Dimethyl amino) propyl) acrylamide)/DMAPAAQ (N,N-Dimethyl amino propyl acrylamide, methyl chloride quaternary) and a non-ion-type hydrogel known as DMAA (N,N-Dimethylacrylamide). In the experiment carried out in this study, the ion-type hydrogel DMAPAA/DMAPAAQ was introduced to cadmium-contaminated soil for vegetable cultivation. The study found that at cadmium levels of 0 and 2 mg/kg in soil, when exposed to a pH 2 solution, cadmium wasn't detected in the filtrate using ICP. As the amount of cadmium increased to 500 mg/kg, hydrogel addition gradually reduced the filtrate cadmium concentration. Notably, the use of the 4% hydrogel resulted in 0 mg/L of cadmium. For the 0% hydrogel, vegetable cadmium absorption was determined to be 0.07 mg/g, contrasting with 0.03 mg/g for the 4% hydrogel. The DMAPAA/DMAPAAQ hydrogel significantly boosts vegetable growth by efficiently absorbing nitrate ions through ion exchange, releasing them for plant uptake. In contrast, the DMAA hydrogel, used as a control, does not enhance plant growth despite its water absorption properties. In summary, the composite hydrogel shows great potential for enhancing vegetable yield and immobilizing heavy metals in soil.

Impact of organic carbon on heavy metals of river sediments and aquatic ecosystems: A review

AbstractOrganic carbon with variable chemical composition sourced primarily from terrestrial and aquatic biogenic input has a significant impact on sediment heavy metal mobility. The present scientific view is unclear in deciphering the role of labile organic carbon in changing sediment heavy metal concentration. The present review critically assesses the impact of various forms of carbon on different geochemically bound heavy metal fractions and their monitoring. It is evident from the review that, the biochemical form of organic carbon (based on degradability and biopolymeric forms), carbon‐geochemical association, and density of organic carbon (light or heavy carbon fractions) plays an important role in determining the bioavailability and toxicity of metals for aquatic organisms. Besides the organic carbon, various sediment conditions that define the behavior of heavy metals include pH, redox condition, sulfide concentration, salinity, temperature, etc. Therefore, it is recommended that carbon relation with heavy metal mobility and stability should be included under long‐term sediment management plans to maintain the sediment quality of the river system.

Evaluation of Selected Heavy Metal Contaminants as Well as Nitrates and Nitrites in the Microgreens of Nigella (Nigella sativa L.), Safflower (Carthamus tinctorius L.), and Camelina (Camelina sativa L.) at Different Stages of Vegetation

Microgreens are a new, rapidly growing group of foodstuffs. The decorative function of these is often accompanied by their use in traditional dishes. As microgreens are eaten at very early stages, when the development of the epidermis is at its minimum, the bioavailability of minerals will be found to be higher in microgreens then in mature vegetables. So, microgreens can be an excellent functional food, especially for mineral-deficient populations, although they can also be a source of contaminants such as heavy metals or nitrates and nitrites. The purpose of this study was to measure the levels of selected heavy metals (i.e., cadmium, arsenic, lead, chromium, aluminium, zinc, copper, cobalt, molybdenum, manganese, vanadium, boron, antimony, thallium, titanium and strontium), as well as nitrates and nitrites, in microgreens at various stage of vegetation, using uncommon oilseed plants like nigella—Nigella sativa L., safflower—Carthamus tinctorius L., and camelina—Camelina sativa L. The examined microgreens of rare oilseed plants may be a source of contaminants and nitrates. The mineral profile of these plants is mainly determined by their genotype. Microgreens’ cultivation involves compliance with safety standards and replicable conditions to guarantee that the highest nutritional value is reached at the lowest possible contaminant level.

Giant Spin-Orbit Torque in Antiferromagnetic-Coupled Pt/[Co/Gd]N Multilayers with Suppressed Spin Dephasing and Robust Thermal Stability.

Manipulating magnetization via power-efficient spin-orbit torque (SOT) has garnered significant attention in the field of spin-based memory and logic devices. However, the damping-like SOT efficiency (ξDL) in heavy metal (HM)/ferromagnetic metal (FM) bilayers is relatively small due to the strong spin dephasing accompanied by additional spin polarization decay. Furthermore, the perpendicular magnetic anisotropy (PMA) originating from the HM/FM interface is constrained by the thickness of FM, which is unfavorable for thermal stability in practical applications. Consequently, it is valuable to develop systems that not only exhibit large ξDL but also balance thermal stability. In this work, we designed antiferromagnetic-coupled [Co/Gd]N multilayers, where staggered Co and Gd magnetic moments effectively suppress the spin dephasing and additional spin polarization decay. The ordered Co-Gd arrangements along the out-of-plane direction provide bulk PMA, endowing Pt/[Co/Gd]N high thermal stability. The SOT of Pt/[Co/Gd]N was systematically studied with N, demonstrating a significantly large ξDL of up to 0.66. The ξDL of Pt/[Co/Gd]N is greater than those of Pt/Co and Pt/ferrimagnetic alloys. This significant enhancement relies on the effective suppression of spin dephasing in [Co/Gd]N. Our work highlights that the antiferromagnetic-coupled [Co/Gd]N multilayer is a promising candidate for low-consumption and high-density spintronic devices.

Graphene-based nanocomposites as scavenger of heavy metal ions from water: a review on synthesis, characterizations and application as adsorbent

Graphene-based nanocomposites as scavenger of heavy metal ions from water: a review on synthesis, characterizations and application as adsorbent

Elucidating the adaptive response and enhanced lipid production of Chlorella minutissima under Cr (VI) stress

The exponential surge in industrialization and urbanization witnessed in recent decades has alarmingly escalated the levels of hazardous pollutants, instigating profound apprehensions regarding environmental safety. In particular, the bioamplification of heavy metals like hexavalent chromium [Cr (VI)] being a prominent example, has not only imposed severe repercussions on human health but has also wrought havoc within the intricate balance of the ecological framework. Rectifying Cr (VI) via bioremediation agents exemplified as microalgae, emerges as an environmentally harmonious strategy. The present study delves into the intricate mechanisms underpinning the adaptive responses of a freshwater microalga, Chlorella minutissima, in the face of Cr (VI) stress. Evidencing exceptional tolerance to Cr (VI) induced stress, this microalga manifested an IC50 value of ~10 ppm while evidencing an astounding removal efficiency of ~89 %. This heightened assimilation of Cr (VI) by the microalgal cells concomitantly accompanied ~1.6 fold rise in total lipid content. The fostered levels of stress metabolites and antioxidant enzymes indicate the activation of defense mechanism to mitigate Cr (VI) induced oxidative damage. Microalgae employ reduction mechanism converting toxic Cr (VI) into the less deleterious Cr (III) where Cr2O3 and CrO (OH) were found to be the prominent species; while Cr (VI) primarily existed as CrO42−. The present study provided a detailed understanding of C. minutissima towards stress tolerance and enhanced lipid production mechanisms incited by chromium exposure.

Comparison of Current Induced Domain Wall Motion Driven by Spin Transfer Torque and by Spin Orbit Torque in Ferrimagnetic GdFeCo Wires

Current-induced domain wall motion (CIDWM) in magnetic wires can be driven by spin transfer torque (STT) originating from transferring angular momentums of spin-polarized conducting electrons to the magnetic DW and can be driven by spin orbit torque (SOT) originating from the spin Hall effect (SHE) in a heavy metal layer and Dzyaloshinsky Moriya (DMI) generated at an interface between a heavy metal layer and a magnetic layer. In this work, we carried out a comparative study of CIDWM driven by STT and by SOT in ferrimagnetic GdFeCo wires with magnetic perpendicular anisotropy based on structures of SiN (10 nm)/GdFeCo (8 nm)/SiN (10 nm) and Pt (5 nm)/GdFeCo (8 nm)/SiN (10 nm). We found that CIDWM driven by SOT exhibited a much lower critical current density (JC), and much higher DW mobility (µDW). Our work might be useful for the realization and the development of low-power and high-speed memory devices.

Application of Cotton Stalk as an Adsorbent for Copper(II) Ions in Sustainable Wastewater Treatment

The capacity of untreated cotton stalk to remove and adsorb Cu2+ ions in synthetic and natural aqueous solutions was evaluated. The influence of three sensitive parameters of the adsorption process—solution pH, adsorbent dosage, and contact time—on the percentage of Cu2+ removal in agricultural wastewater, livestock wastewater, and synthetic samples was studied. Physicochemical and morphological properties were studied using thermogravimetry, Fourier infrared spectrophotometry, and scanning electron microscopy. The elemental composition, proximal composition, zero charge point, and acid–base sites were determined. In addition, kinetic studies were performed, and the adsorption equilibrium was analyzed. The optimum conditions for Cu2+ adsorption were the following: solution pH = 5.5, adsorbent dosage of 0.6 g, and contact time of 60 min. Under these conditions, the percentage of Cu2+ removal in synthetic samples was 66.5% when the initial copper concentration was 50 mg/L. The removal percentage in agricultural and livestock wastewater samples was 87.60% and 85.05%, respectively, when the initial copper concentration was 25 mg/L. The adsorption data are consistent with the Freundlich isotherm model, which achieved a quadratic fit of 0.991 compared to 0.5542 for the Langmuir model. The experimental results indicate that the adsorption adequately fits the pseudo-second-order kinetic model. The results suggest that cotton stalks are a promising adsorbent for the ecological and economical removal of Cu2+ in wastewater. This research, therefore, provides relevant information that contributes to the sustainable management of agricultural waste and instills hope for a reduction in water pollution from heavy metals derived from agricultural activities.

Ecological risk and spatial distribution, sources of heavy metals in typical purple soils, southwest China

The identification and quantification of the ecological risks, sources and distribution of heavy metals in purple soils are essential for regional pollution control and management. In this study, geo-accumulation index (Igeo), enrichment factor (EF), pollution index (PI), potential ecological risk index (RI), principal component analysis (PCA) model and geographical detector (GD) were combined to evaluate the status, ecological risk, and sources of heavy metals (HMs) in soils from a typical purple soil areas of Sichuan province. The results showed that the average contents of As, Cd, Cr, Cu, Hg, Ni, Pb and Zn in purple soil were 7.77, 0.19, 69.5, 27.9, 0.077, 30.9, 26.5 mg/kg and 76.8 mg/kg, and the Igeo, EF and RI of topsoil Hg and Cd in designated area was the highest, and the average contents of Hg and Cd in topsoil were obviously greater than respective soil background value in Sichuan province and purple soil. The hot spots for the spatial distribution of 8 HMs were mainly focused in the southwest and northeast of the designated area, and there were also significant differences for 8 HMs distribution characteristics in the profile soil. Cu comes from both anthropogenic and natural sources, Zn, Ni and Cr mainly come from natural sources, but As, Pb, Hg and Cd mainly derived from human activities. GD results showed that soil texture (X18), altitude (X4), total nitrogen (TN), clay content (X3), sand content (X2) and silt content (X1) had the greatest explanatory power to 8 HMs spatial differentiation.This study provides a reference for understanding the status and influencing factors of HM pollution in typical purple soil, and lays a theoretical foundation for the environmental treatment of purple soil in China.

Potential ecological and human health risk assessments of soil heavy metals in orchards of Antalya province in Türkiye

ABSTRACT Agricultural inputs containing heavy metals are used intensively in Türkiye. However, studies on the assessment of the effects of heavy metals on the environmental and human health risks of agricultural areas in Türkiye are very limited. The aim of this study was to determine the concentrations, sources and potential ecological and human health risks of heavy metals in soils from orchards in Antalya, Türkiye. A total of 127 soil samples were collected and analysed for cadmium (Cd), lead (Pb), nickel (Ni), chromium (Cr), cobalt (Co), iron (Fe), manganese (Mn), copper (Cu) and zinc (Zn). The mean concentrations of total Cd, Pb, Ni, Cr, Co, Fe, Mn, Cu and Zn were found to be 4.54, 64.68, 145.80, 94.00, 23.92, 28264, 763.30, 44.91, and 63.67 mg kg−1, respectively. The mean concentrations of Cd, Co, Ni, Pb, Cu and Mn of soils were higher than the European soil mean values. Enrichment factor (EF) and contamination factor (CF) values of soils indicate serious enrichment for Cd, Pb and Ni. According to the principal component analysis, Cd concentration in the soil from was anthropogenic sources, Ni, Cr and Pb from both anthropogenic and lithogenic origin while other heavy metals from natural sources. Total hazard index (THI) values of heavy metals were <1, suggesting that there were currently absent non-carcinogenic health risks to residents through ingestion, inhalation and dermal contact. Hazard index (HI) indicated that children (3.75) were sensitive 9.4 times more than adults (0.40) to non-carcinogenic risks of heavy metals. The carcinogenic risk values of Cd, Cr, Co and Ni were acceptable range and not expected carcinogenic risks.

PHREEQ C Modelling Tool Application to Determine the Effect of Anions on Speciation of Selected Metals in Water Systems within Kajiado North Constituency in Kenya

Heavy metals and anions in water pose a significant risk to living organisms, including humans, and must therefore be carefully monitored. There are numerous approaches and methods of analysis to choose from. Using the PHREEQ C chemical modeling technique, this study looked at the effect of certain anions on the speciation of selected metals in the water environment of Kajiado North. Twenty-five sampling points were used in the study, which covered five Kajiado North election wards. Samples were taken twice during the dry and rainy seasons, in November 2019 and March 2020. Using standard methods, physicochemical characteristics were analyzed, concentrations of selected heavy metals using the (ICP- OES) 7000 series, and selected anions using a multi parameter photometer, their concentration values compared to the specified maximum contaminant level and speciation analysis done using the Computer-based technique PHREEQ C. The range observed for pH, temperature, electrical conductivity, sulphate, chloride, fluoride, nitrate and carbonates was 7.43- 9.30, 23.0 -28.0oC, 335-1265μS/cm, 4.54-361.41mgL-1, 5.19-184.6 mgL-1, 0.01-2.90 mgL-1, 0.1-8.6 mgL-1, and 3.18-55.19 mgL-1 respectively. The range observed for heavy metals was 0.06-1.08 mgL-1 , 0.00 -0.05082 mgL-1, 0.01-0.02597 mgL-1, 0.01-0.01610 mgL-1, 0.00 -0.0327 mgL-1, 0.00-42.7842 mgL-1, and below detection limit, for Fe, Mn, Cu, Zn, Pb, Mg, and Cd respectively. The findings revealed that Cd, Zn, Cu, Cl-, NO2-, and eElectrical cconductivity concentrations were below the WHO levels. At certain sampling points, however, SO42-, F-, Pb, Fe, and Mn were above WHO limits. In some water systems, traces of SO42-, F-, Cu, Fe, Cd, and Mn were found to pose significant health risks, according to PHREEQ C speciation analysis. Anion concentrations, pH, temperature, and metal concentrations are all important variables in modeling. Metals formed anion complexes and the total abundance of metal species was classified at the highest levels as Fe(OH)3, PbCO3, Zn(CO3)2, Cu(CO3)2, Mn+2, MgF-, and Mg+2. At a water system temperature of 25oC without anions, it was found to have the highest chemical species. CuCO3, CuNO3, and CuOH+ complexes are also formed at low pH. Based on the data for different metal species at different pH values, the bioavailability of metal species definitely depends on pH.

Practical Design of a Breed-and-Burn Lead-Cooled Fast Reactor with Rotational Fuel Shuffling Strategy

The purpose of this study is to demonstrate a practical core design for a lead-cooled, nitride fueled, rotational fuel shuffling breed-and-burn (RFBB) fast reactor. The core design is based on the Westinghouse Lead Fast Reactor (WH-LFR) and uses natural uranium nitride fuel with a sodium bond encased in oxide dispersion-strengthened steel cladding. Simulations confirmed the potential of the reactor to maintain criticality at the equilibrium state, with a reactivity swing of less than 200 pcm at every cycle interval and an average discharge burnup of 235 MWd/kg heavy metals (HM) for a 1050 effective full-power day refueling interval. Power profiles were maintained stable at the equilibrium state, while the cladding of the discharged fuel incurred over 650 displacements per atom over its entire residency in the core. From a nonproliferation perspective, the plutonium vector for the discharge fuel aligns with reactor-grade fuel standards, with over a 70% concentration of 239Pu and over 22% 240Pu, reducing the risk of weaponization. The adopted control rod system has been shown to offer sufficient negative reactivity of over 19 $ to bring the reactor into a subcritical state. Challenges such as the susceptibility of neutron balance to material thickness and neutron leakage have been addressed, emphasizing the necessity for meticulous design improvements. A steady-state thermohydraulic analysis confirmed the heat removal capacity from the hottest channel, ensuring operational safety. This study confirmed the feasibility of the RFBB strategy for a lead-cooled nitride-fueled fast reactor and sets a precedent for future research in enhancing fuel utilization and safety in nuclear reactors.

Adsorption of Cd and Mn from neutral mine effluents using bentonite, zeolite, and stabilized dewatered sludge

This study aimed to investigate the adsorption efficiency of Cd and Mn using natural sorbents—bentonite, zeolite and stabilized digested dewatered waste sludge. The main contributions of the scientific article are in adding to the scientific knowledge of the use of natural and waste sorbents in the removal of heavy metals from neutral mine effluents. Current studies mainly focus on metal removal by sorption using natural sorbents from acid mine drainage. This study investigates sorption in neutral mine drainage. The efficiency of the sorption process was evaluated using the following parameters: efficiency (%) of metal ion removal, Freudlich and Langmuir adsorption isotherm constant. The AES–ICP method (atomic emission spectrometry with inductively coupled plasma) was used for the initial metal analysis of the materials used. The atomic absorption spectrometry (AAS) method was used for the analysis of Cd and Mn in the sorption process. The maximum efficiency of Mn removal by bentonite at the end of the test was approximately 90%. The removal of Mn by zeolite was considerably lower—about 20% compared to the use of sludge—80%. Based on the sorption efficiency, the sludge was suitable for sorption. Much higher levels of Cd sorption were achieved using sludge compared to using natural bentonite and zeolite. The main novelty of the work lies in the sorption of metals using dewatered digested sludge. Previous studies have focused on metal sorption using activated sludge. Most previous studies focused on sorption from acid mine drainage. The novelty of this study is that we focused on the sorption of neutral mine drainages, which are typical for the location we are monitoring.

Genome-wide identification of chalcone synthase (CHS) family members and their expression patterns at the sprouting stage of common bean (Phaseolus vulgaris) under abiotic stress

Secondary metabolites such as flavonoids, produced by plants, could help plants cope with external stress. Flavonoid synthesis is catalyzed by chalcone synthase (CHS). CHS plays a broad role in the growth, development, and physiological activities of plants. However, studies of the CHS gene family in Phaseolus vulgaris are limited. In this study, the HMMER search tool was used to identify 29 CHS members in the reference genome of P. vulgaris. These PvCHS members were divided into 5 subgroups. Notably, subfamilies with close genetic relationships exhibited similarities in motifs and gene structures of PvCHSs. Additionally, analysis of the cis-element indicated the involvement of PvCHSs in response to abiotic stress. Furthermore, quantitative real-time PCR (qRT-PCR) analysis under various abiotic stress conditions revealed that the majority of PvCHSs were associated with the response to salt stress (NaCl), alkaline salt stress (NaHCO3), and heavy metal stress (CdCl2). Particularly, PvCHS01, PvCHS05, PvCHS14, and PvCHS25 were significantly up-regulated under alkaline salt stress. PvCHSs were also correlated with CHS activity and flavonoid content. In addition, exogenous flavonoids were observed to significantly decrease accumulation of ROS in P. vulgaris under alkaline salt stress. This study provides a basis for further analysis of the mechanisms underlying the response of PvCHSs to abiotic stress.

Dealing with elemental toxicities in crops: hot topics and likely solutions

Abstract Background The widespread presence of arsenic (As) and cadmium (Cd) in agricultural soils coupled with a problem of Al phytotoxicity threatens sustainability of agricultural production system as well as natural ecosystems. Scope Understanding the role of membrane transporters responsible for uptake, translocation, and sequestration of above metal(oid)s and the modes of their regulation may be critical to tackle the above issue. In this review, we summarize the current knowledge of membrane transporters mediating As, Cd and Al homeostasis in plants, highlighting unanswered questions and offering potential solutions. Amongst these, the following topics may deserve a special attention in future studies: (1) uncoupling transport of As and inorganic phosphorous in plant roots focusing on PHT1;1 transporters; (2) revealing the modes of their post-translational regulation, especially under hypoxic conditions; (3) better understanding of structure–function relations of various transporters isoforms for Cd, to uncouple transport of toxic Cd metals from that for essential micronutrients such as Fe, Zn or Mn; (4) revealing the role of non-selective cation channels (NSCC) in Cd uptake and revealing mechanisms of their regulation; (5) elucidate the role of various aquaporins in Al3+ uptake in plant roots; (6) understanding the role of slow vacuolar (SV) channels in Al sequestration in plant vacuoles; and (7) revealing the mechanistic basis of long-distant transport of toxic ions, with specific emphasis of phloem transport. Conclusion These multidisciplinary efforts strive to ensure global food safety by mitigating the impact of heavy metal pollution on agriculture and human well-being.

Disposal of spent oil into soils around auto parts markets impacts heavy metal concentrations and poses a potential ecological risk

Disposal of spent oil into soils around auto parts markets impacts heavy metal concentrations and poses a potential ecological risk

Application and mechanism of carbonate material in the treatment of heavy metal pollution: a review.

Among the many heavy metal pollution treatment agents, carbonate materials show strong flexibility and versatility by virtue of their high adsorption capacity for heavy metals and the characteristics of multiple and simple modification methods. It shows good potential for development. This review summarizes the application of carbonate materials in the treatment of heavy metal pollution according to the research of other scholars. It mainly relates to the application of surface-modified, activated, and nano-sized carbonate materials in the treatment of heavy metal pollution in water. Natural carbonate minerals and composite carbonate minerals solidify and stabilize heavy metals in soil. Solidification of heavy metals in hazardous waste solids is by MICP. There are four aspects of calcium carbonate oligomers curing heavy metals in fly ash from waste incineration. The mechanism of treating heavy metals by carbonate in different media was discussed. However, in the complex environment where multiple types of pollutants coexist, questions on how to maintain the efficient processing capacity of carbonate materials and how to use MICP to integrate heavy metal fixation and seepage prevention in solid waste base under complex and changeable natural environment deserve our further consideration. In addition, the use of carbonate materials for the purification of trace radioactive wastewater and the safe treatment of trace radioactive solid waste are also worthy of further exploration.

Removal of Heavy Metal Ions(Fe2+, Mn2+, Cu2+ and Zn2+) on to Activated Carbon Prepared from Kashmiri Walnut Shell (Juglans regia)

Heavy metal pollution poses significant threats to the environment and human health, even at trace concentrations. In this study, activated carbon derived from Kashmiri walnut shell (Juglans regia) was investigated for its potential to adsorb heavy metal ions (Fe2+, Mn2+, Cu2+, and Zn2+). Standard solutions containing heavy metal ions at concentrations ranging from 10 to 50 ppm were prepared for adsorption experiments, i.e., at temperature 25 °C, and adsorbent dosage 1 g using a column mechanism. The activated carbon was first treated with 0.1M HCl and 0.5M ammonia solutions, and then washed with demineralised water. Subsequently, the metal ion solutions were passed through the column individually, and the filtrates were analyzed for heavy metal ion presence. The experimental results demonstrated that walnut shell-derived activated carbon exhibited promising adsorption capacity spanning from 0.36 mg/g for Zn2+, 0.5 mg/g for both Mn2+ and Cu2+ and 0.54 mg/g for Fe2+ thus showing the adsorption trend as Fe2+ &gt; Mn2+ = Cu2+ &gt; Zn2+. This study highlights the potential of using walnut shell-derived activated carbon as an effective and cost-efficient method for mitigating heavy metal pollution in contaminated water sources.