Toxic Heavy Metal Contamination Research Articles

Phytoremediation of contaminated urban soils spiked with heavy metals

Urban environments worldwide face toxic heavy metal pollution originating from industrial discharge, municipal waste disposal, vehicular emissions, and atmospheric deposition. Kazakhstan, experiencing accelerated economic growth and extensive mining activities, contends with widespread heavy metal contamination in its soil-plant-air-water ecosystems. This study explores the potential of hyperaccumulating plants for phytoremediation in urban soils of Kazakhstan contaminated with Pb, Cd, and Co. Twelve plant species, including Korean Mint (Lamiaceae), Ornamental Cabbage (Brassica oleracea), Ageratum (Ageratum houstonianum), Coneflower (Echinacea purpurea), Amaranth (Amaranthus Perfect and Amaranthus Emerald), Fescue (Festuca glauca), Burning Bush (Kochia scoparia), Marigold (Tagetes patula nana), White Cabbage (Brassica-Cavolo cappuccino BIANKO), Tepary Bean (Phaseolus acutifolius), and Rapeseed (Brassica napus), were evaluated for growth and biomass production in urban soils spiked with two maximum permissible addition (MPA) treatments of Pb, Co, and Cd. The selected plants demonstrated varied responses to heavy metal stress, with Marigold (8.4 g shoot biomass/plant), Korean mint (10.5 g shoot biomass/plant), Rapeseed (19.9 g/shoot biomass), and Tepary bean (25.9 g shoot biomass/plant) exhibiting resilience or tolerance to Pb, Co, and Cd stresses. The results highlight the significant potential of these plants for efficient phytoremediation, showcasing their unique abilities to absorb and accumulate specific metals. Marigold, particularly, displayed noteworthy Pb accumulation (40.3 mg/kg biomass), resulting in reduced residual Pb concentrations in the soil (74.7 mg/kg). Conversely, White cabbage and Amaranth showed limited efficiency in Cd extraction, while Rapeseed and Tepary bean emerged as promising candidates for Cd phytoremediation. This study emphasizes the critical role of tailored plant species selection in designing effective phytoremediation strategies for specific metal-contaminated urban sites. A comprehensive understanding of the dynamics of metal accumulation and residual concentrations is crucial for the development of sustainable and efficient environmental remediation approaches. Further research is warranted to explore the long-term effects of different plant species on soil metal concentrations, refining and optimizing phytoremediation methods for urban soils grappling with toxic heavy metal contamination.

The analysis of potentially toxic heavy metal contamination in the Lake Bogoria geothermal springs

Lake Bogoria geothermal system is a natural geological site in Kenya that boasts a habitat for Flamingos which attract tourists, and its water find applications in agriculture and recreation. Accordingly, its geological processes, closed water systems and anthropogenic activities may lead to accumulation of potential toxic metal contamination. The present study focused on the analysis of potentially toxic metals — manganese (Mn), cadmium (Cd), lead (Pb), copper (Cu) and nickel (Ni) using atomic absorption spectrometry (AAS) in geothermal spring water samples after acid digestion method, and evaluated their health risks through dermal and ingestion exposures. Principal component analysis (PCA), enrichment factors (EF) and Pearson correlation coefficient (PCC) were performed to determine the sources and correlation between the metals investigated. Manganese, Cu and Ni recorded mean concentrations (ppm) of 0.19 ± 0.08, 0.02 ± 0.02 and 0.03 ± 0.02, respectively, which were below the permissible World Health Organisation (WHO) limits, whereas Pb (0.06 ± 0.04) and Cd (0.05 ± 0.02) levels were above the threshold standards. PCA revealed that these metals may have originated from geological regimes and surface run-offs. Copper and Cd metals were highly enriched indicating an anthropogenic origin. The Hazard quotients (HQ) of Pb and Cd were >1,\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$>1,$$\\end{document} hence they are potential precursors for non-carcinogenic and carcinogenic risks in both children and adults. The findings of this study showed possible Pb and Cd metal contamination from geothermal waters. Therefore, there is need for remediation, continuous monitoring and assessment of geothermal waters before utilization for recreation, crop production and geothermal energy exploitation to ensure environmental conservation and human safety.

Simple synthesis of flower-like ZnO@Pt composites for dual-mode colorimetric detecting Hg2+ with smartphone and UV–vis

BackgroundMercury is one of the most toxic heavy metal contaminants that can be harmful to human health through the food chain. Recently, the colorimetric detection of heavy metals based on nanozyme catalytic activity has received extensive interest due to the simplicity, signal visibility and suitability for in situ detection. However, the majority of these nanozymes that can be utilized for detecting mercury with high synthesis temperature and complicated synthesis methods, which limited their practical application. ResultsIn this work, flower-like ZnO@Pt composites were simply synthesized at room temperature, the flower-like structure and the high electron mobility of ZnO endow ZnO@Pt with stronger peroxidase-like activity. Consequently, dual-mode (UV–vis and smartphone) colorimetric sensors were designed to detect Hg2+. In UV–vis mode, the Hg2+ concentration linear range was 10–400 nM, and the limit of detection (LOD) was 0.54 nM. In smartphone mode, the Hg2+ concentration linear range was 50–1250 nM, and the LOD was 29.8 nM. A parallel analysis in 3 real water samples was confirmed by ICP-MS, the results showed good correlations (R2 > 0.98), indicating the practical reliability of these sensors. SignificanceThe novel flower-like ZnO@Pt composites with high stability, catalytic activity and Hg2+ response were simply synthesized at room temperature, simplifying the synthesis steps and reducing costs. The sensitivity of the developed colorimetric sensor in UV–vis mode was 3–145 times higher than that of the similar methods. The colorimetric sensor in smartphone mode broadened the detection range and improved the portability of Hg2+ detection. Thus, the dual-mode (UV–vis and smartphone) colorimetric sensors providing new detection modes for rapid monitoring of Hg2+ in environmental water.

Synergistic effect on simultaneous treatment of Cr(VI) and chloramphenicol using a non-thermal plasma technology

Toxic organic and heavy metal contaminants commonly exist in industrial waste stream(s) and treatment is of great challenge. In this study, a dielectric barrier discharge (DBD) non-thermal plasma technology was employed for the simultaneous treatment of two important contaminants, chloramphenicol (CAP) and Cr(VI) in an aqueous solution through redox transformations. More than 70% of CAP and 20% of TOC were degraded in 60 min, while Cr(VI) was completely removed in 10 min. The hydroxyl radicals were the main active species for the degradation. Meanwhile, the consumption of hydroxyl radicals was beneficial to the reduction of Cr(VI). The synergistic effect was investigated between CAP degradation and Cr(VI) reduction. The reduction of Cr(VI) would be enhanced in the presence of CAP with a low concentration and could be inhibited under a high concentration, because part of hydroxyl radicals could be consumed by the low-concentration CAP and the obtained intermediates with a higher kinetic rate. However, CAP with a high concentration could react with such reductive species as eaq− and •H, which could compete with Cr(VI) and inhibit the reduction. In addition, the presence of Cr(VI) enhanced the degradation and mineralization of CAP; the study of obtained intermediates indicated that the presence of Cr(VI) changed the degradation path of CAP as Cr(VI) would react with reductive species, enhance the generation of hydroxyl radicals, and cause more hydroxylation reactions. Moreover, the mechanism for the simultaneous redox transformations of CAP and Cr(VI) was illustrated. This study indicates that the DBD non-thermal plasma technology can be one of better solutions for simultaneous elimination of heavy metal and organic contaminants in aquatic environments.

Carbon composites as an Avante garde material in mitigating dyes and heavy metal pollution

Abstract Depletion of potable water availability is threatening the whole biota, owing to the presence of anthropogenic compounds and hazardous chemicals above the permissible levels. Although many conventional methods exist, the development of innovative technologies is critical for wastewater treatment and recycling. Carbon composites have recently seen widespread use across a variety of industries due to their distinctive and superior properties. These carbon composites are easily integrated into many stages of the treatment process, making them efficient, cost-effective, and environmentally friendly. This chapter discusses the importance and effectiveness of carbon-based composite materials in removing toxic dyes and heavy metal contaminants from the environment. Carbon composites are classified according to their sources, preparation methods, and applications. This chapter also discusses various research perspectives on carbon composites, particularly from an environmental and financial standpoint.

Spatial Trends and Distribution Patterns of Toxic Heavy Metal Contamination in an Urbanized Watershed

Rapid urban growth in developing nations exacerbates pressures on water resources through increased pollution loading if management practices cannot adapt efficiently. This study evaluated industrial effluent impacts on river systems in Nigeria contaminated by discharge from beverage, oil and biscuit manufacturing plants. Physicochemical parameters and heavy metal concentrations were monitored at sites upstream and downstream from waste outfalls during wet and dry seasons. Results demonstrated exceedances of national water quality standards for indicators of organic pollution like biochemical oxygen demand and chemical oxygen demand. Notably, highly toxic heavy metals exceeded World Health Organization limits by over 100 times, posing serious public health concerns through various exposure pathways. Seasonal variations reflected changes in pollution inputs. Spatial trends showed metal levels decreasing with distance, though remaining well above safe levels 100m downstream. A predictive transport model was formulated based on field measurements incorporated into the advection-dispersion equation. Key coefficients for the dispersion rate and velocity/dispersion ratio were quantified, allowing simulation of concentration changes under differing scenarios. Model predictions closely aligned with observed metal distribution patterns. Findings highlight the need for upgraded wastewater treatment and emissions controls to mitigate pollution over-burdening natural assimilative capacity. Continuous monitoring programs should track remediation effectiveness. This study provides insights to help authorities balance rapid industrialization, environmental protection and sustainable development goals through evidence-based regulatory strategies ensuring public health.

Types of Bioremediation and their Applications, in Heavy Metal Detoxification

Heavy metal contamination is the result of various human activities. Increased concentrations of heavy metals are responsible for causing lethal and chronic diseases in humans, affecting the metabolism of plants and causing metal toxicity in the environment. Available conventional techniques for metal detoxification are not found effective and economically feasible. Bioremediation is an ecologically and economically favorable technique that consists of natural biological processes to eliminate toxic heavy metal contaminants. Various microorganisms, fungi and plants can be used for heavy metal detoxification. This paper gives an idea about the concept, types, and principles of bioremediation.

Risk Assessment of Toxic Heavy Metals Concentration of Fish and Drinking Water in Nsukka Metropolis, South East, Nigeria

Background: Toxic Heavy Metals (THMs) threaten food safety and result in human poisonings. It seems to be few studies on THMs contamination in food chain in developing countries. Current investigation determine the concentration and health risk of arsenic (As), cadmium (Cd), lead (Pb), as well as mercury (Hg) in fish and water at Nsukka, Metropolis, Enugu state, Nigeria.
 Methods: Forty eight samples; 24 (catfish and tilapia) fish and 24 (borehole, sachet, and bottled) water were randomly collected from two major markets and districts in Nsukka Metropolis and were evaluated for THMs using Atomic Absorption Spectrophotometer. The Estimated Daily Intake, Target Hazard Quotient, Hazard Index, and Cancer Risk (CR) were assessed as well.
 Results: THMs analaysis showed that As, Cd, and Hg were at 100% and Pb being at 16% in all the fish samples while 12.5% of fish of exceeded the Hg Maximum Permissible Limit (MPL) of 0.050 mg/kg, that not statistically significant (p>0.05).On the other hand, based on the analysis of all water samples, Hg and As were detected at 100% rate, Cd at 58.3% while Pb was not identified. The values above the MPL appeared to be 9 (37.5%), 2 (8.3%), and 3(12.5%) for Hg, As, and Cd, respectively in water while not statistically significant (p>0.05). The mean value of Hg (0.06425 mg/kg) in roasted fish as well as Cd (0.0065 and 0.0105) mg/ml in tap and bottled water respectively surpassed the MPL although not statistically significant (p>0.05). The Estimated Daily Intake of THMs except Cd in fish were proved to be within the Provisional Tolerable Daily Intake in contrast with As and Cd in water. CR is present both in children and adults with CR value >1.
 Conclusion: The finding of THMs in fish and water above the MPL is regarded as potential health risk for the consumers of such contaminated water and fish in the investigation scope.

Potential toxic phthalates and heavy metals contamination in vinegars and human health risk assessment

Phthalate acid esters (PAEs) and heavy metals (HMs) are well-known contaminants due to their toxic effects on human health. Daily food consumption is one of the critical ways of exposure to these contaminants for the human population. In this study, residue profiles and levels for eight phthalate esters and four heavy metals were evaluated in polyethylene terephthalate and glass bottled vinegars from the Turkish market. PAEs and HMs were quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and inductively coupled plasma mass spectrometry (ICP-MS). Packaging polymers were characterized by attenuated total reflection-fourier transform infrared spectroscopy (ATR/FT-IR) spectroscopy. Furthermore, non-carcinogenic health risk assessment was performed based on regular vinegar consumers' daily oral intake rates. Principal component analysis was carried out to evaluate and distinguish between types of vinegar samples. Bottle type, pH, and electrical conductivity values were effective parameters, to some extent, on PAEs and HMs contents of vinegar samples. The concentration ranges were <LOD-22.8 and 0.02–970 µg L−1 PAEs and HMs, respectively. Dimethyl phthalate (DMP) and dibutyl phthalate (DBP) were the most abundant PAEs, while aluminum (Al) was the predominant HMs. Butyl benzyl phthalate (BBP), diisononyl phthalate (DiNP), diisodecyl phthalate (DiDP), di(n-octyl) phthalate (DnOP), and inorganic mercury (iHg) were not detected in any sample. Non-carcinogenic risk assessment associated with vinegar consumption showed that the exposure to PAEs (ranging between 2.82 ×10−6 and 4.07 ×10−4 μg/kg bw day−1) and HMs (ranging between 2.06 ×10−5 and 5.24 ×10−2 μg/kg bw day−1) were well below the permissible limits. The findings showed that the levels of PAEs and HMs exposed through commercial vinegars were not significant enough to pose a health risk among individuals aged 18–65.

X-ray fluorescence analysis of coastal sediments of Tamil Nadu with a statistical approach

X-ray fluorescence spectroscopy is applied to determine the concentration of essential and toxic heavy metals such as silicon (Si), potassium (K), calcium (Ca), titanium (Ti), iron (Fe), copper (Cu), zinc (Zn), nickel (Ni), and lead (Pb) in the sediments of Kovalam coastal area, Tamil Nadu, India. Fe (599280 ppm), an essential heavy metal/mineral shows the highest average concentration, followed by Si (181593 ppm), Ca (130913 ppm), K (99673 ppm), Ti (77620 ppm), Cu (64 ppm), Ni (43 ppm), Pb (20 ppm), and Zn (8 ppm). Heavy metal contamination was assessed using various pollution indicators such as the geo-accumulation index (Igeo), contamination factor (CF), pollution load index (PLI), and enrichment factor (EF). Si, K, Ca, Ti, Fe, Cu, Ni, Pb, and Zn had mean Igeo values of −1.29, 1.54, 1.07, 3.59, 3.19, 0.64, −1.14, −0.22, and −3.70, respectively. Except for Ti (19.36) and Fe (13.87), the average CF value for determined heavy metals was significantly low. The PLI value ranges from 1.47 to 2.46. Heavy metal EF values are greater than 1 in all sampling locations. Multivariate statistical analyses such as Pearson correlation analysis, cluster analysis, and principal component analysis are performed to identify the sources of heavy metals in the studied sediment samples. The findings indicate that anthropogenic sources such as boating and tourism activities have a probable contribution on the enrichment of K, Ca, Ti, Fe, Cu, and Pb in sediments, necessitating more attention in monitoring of toxic heavy metals (such as Pb) contamination in the coastal environment.

Fishing Cat Scats as a Biomonitoring Tool for Toxic Heavy Metal Contamination in Aquatic Ecosystems.

Mangrove forest is one of the productive ecosystems that provide essential habitats for various fauna as breeding and feeding drives. However, heavy metal pollution in the mangrove forest has led to severe health problems for several aquatic species. Biomonitoring of metals using a nondestructive method is an emerging technique. Scats of the fishing cat (Prionailurus viverrinus) were collected from five locations in the Godavari estuary mangrove habitats, Coringa Wildlife Sanctuary, Andhra Pradesh, India, to determine the level of various metals. An opportunistic method was applied to collect scats in the mangrove forest. Six scat samples were collected from each of the sampling sites. The following prey species, such as crabs, fishes, birds, rodents, plants, plastics, and unidentifiable prey matters, were found in the scats. Select metals, such as chromium (Cr), copper (Cu), and lead (Pb) were analyzed from the scats of the fishing cat since they intensively influence the physiology and behavior of top predators. The concentration of Cu in fishing cat scats was higher than the other two metals assessed. Metals showed statistically substantial variation across locations (p < 0.05). According to the current study, heavy metals may significantly threaten the fishing cat in the Coringa Wildlife Sanctuary. The fishing cat is a vulnerable species in accordance with the ICUN categories. Due to pollution and other human pressures, the fishing cat may soon be categorized as a threatened or endangered species; the research advises that authorities should prioritize the protection of the vulnerable species of the fishing cat from the Coringa Wildlife Sanctuary, Andhra Pradesh, India.

Toxic metals and aflatoxins occurrence in smoked-dried fish and their health risks assessment

This study investigated the microbiological and toxic heavy metals contamination in smoked-dried fish, and evaluates their health risk implications. Fifteen widely consumed fish species were sampled randomly, and their aflatoxins, mercury “Hg,” cadmium “Cd” and lead “Pb” concentrations were evaluated though standard guidelines. The results revealed that fish flesh Hg level ranged from 0.085–0.258 mg/kg, Cd concentration ranged from 0.092–0.204 mg/kg, and Pb level varied from 0.173–0.329 mg/kg; the mean toxic metals level in the freshwater fish tissue was lower, when compared to the levels in the saltwater fish (seafood). Regarding toxic metal toxicity, the average Hg, Cd and Pb estimated daily intake values for children and adult were 0.1200 and 1.63 × 10−5 mg/kg bw/day, 2.13 × 10−4 and 7.57 × 10−5 mg/kg bw/day, and 2.48 × 10−4 and 1.24 × 10−4 mg/kg bw/day respectively. Likewise, children targeted hazard quotients (THQ) values were Hg (0.585), Cd (0.151) and Pb (0.071), while adult THQ values were Hg (0.293), Cd (0.076) and Pb (0.035). Children and adult hazard index (HI) values were 0.949 and 0.404 respectively; while Carcinogenic Risk (CR) values indicated that Cd had higher chances of cancer risks when compared to Pb. Additionally, the aflatoxins level in the fish species ranged from 0.564–9.422 ppb, with the seafood having lower aflatoxins level when compared to the freshwater fish species. Aflatoxins estimated daily intakes (EDI) exposure was 4.81 × 10−3 and 2.41 × 10−3 μg/kg bw/day for the children and adults respectively; while the aflatoxins HI value for children was 7.300 × 10−4, and for adults was 7.293 × 10−4. Health risks assessment of heavy metal accumulation in the fish, for both children and adults portrayed insignificant adverse health effects (THQ &lt; 1), through the oral consumption of the fishes. Aflatoxins level detected in the all fishes was within acceptable limits (10 ppb) as approved by the World Health Organization; however, some of the values for freshwater fishes were above the allowable limit (2 ppb) approved by the European Union. Though, the results depicted a very low risk of toxic metals and aflatoxins poisoning, there is the need for proper evaluation of current fish processing and storage methods to prevent human exposure to toxic metals and aflatoxins introduced through smoked-dried fish consumption.

Transcriptome profiling uncovers the lncRNA-mediated regulatory networks associated with tolerance to cadmium stress in barley

Cadmium (Cd) is one of the most harmful and widespread toxic heavy metal contaminants. Long non-coding RNAs (lncRNAs) play vital roles in response to abiotic stress by participating in the gene regulatory network. Here, we performed a transcriptome analysis of lncRNAs in roots of the two contrasting barley genotypes, namely Zhenong8 (ZN, Cd-tolerant) and W6nk2 (Cd-sensitive). In total, 9937 novel lncRNAs were identified, and 5758 lncRNA-target pairs were predicted to be cis-acting and 4159 to be trans-acting. Further comparison of genotypic differences revealed 195 novel lncRNAs as differentially expressed between the two genotypes in response to Cd stress. The miRanda prediction and expression relationship analyses among miRNA, lncRNA, and mRNA revealed that 8 lncRNAs may act as target mimics of miRNAs in barley. Among them, HvGAMYB was predicted to be the target gene of miR319a_1 and miR319b-3p, with LTCONS_00177709 and LTCONS_00185175 acting as endogenous competitors. Barley stripe mosaic virus-induced gene silencing (BSMV-VIGS) of HvGAMYB in ZN8 led to hypersensitivity to Cd stress with significantly increased Cd concentration in both roots and shoots as well as Cd accumulation in shoots. Moreover, silencing HvGAMYB suppressed photosynthesis and antioxidant-related genes but stimulated the production of reactive oxygen species (ROS) after Cd exposure, leading to exacerbated Cd-induced MDA accumulation and cell death. Our findings provide new knowledge and insights into the regulatory functions of lncRNAs in plant Cd tolerance.

Cadmium/lead tolerance of six Dianthus species and detoxification mechanism in Dianthus spiculifolius

Toxic heavy metal contaminants seriously affect plant growth and human health. Reducing the accumulation of toxic metals by phytoremediation is an effective way to solve this environmental problem. Dianthus spiculifolius Schur is an ornamental plant with strong cold and drought tolerance. Because of its fast growth, well-developed root system, and large accumulation of biomass, D. spiculifolius has potential applications as a heavy metal hyperaccumulator. Therefore, the aim of this study was evaluate the ability of D. spiculifolius and other Dianthus species to remediate heavy metals, with an ultimate goal to identify available genetic resources for toxic metal removal. The cadmium (Cd) and lead (Pb) tolerance and accumulation of six Dianthus species were analyzed comparatively in physiological and biochemical experiments. Compared with the other Dianthus species, D. spiculifolius showed higher tolerance to, and greater accumulation of, Cd and Pb. Second-generation transcriptome analysis indicated that glutathione transferase activity was increased and the glutathione metabolism pathway was enriched with genes encoding antioxidant enzymes (DsGST, DsGST3, DsGSTU10, DsGGCT2-1, and DsIDH-2) that were up-regulated under Cd/Pb treatment by RT-qPCR in D. spiculifolius. When expressed in yeast, DsGST, DsGST3, DsGSTU10 and DsIDH-2 enhanced Cd or Pb tolerance. These results indicate that D. spiculifolius has potential applications as a new ornamental hyperaccumulator plant, and that antioxidant enzymes might be involved in regulating Cd/Pb accumulation and detoxification. The findings of this study reveal some novel genetic resources that can be used to breed new plant varieties that tolerate and accumulate heavy metals.

Heavy metals, trace elements, minerals and ascorbic acid content of occasionally consumed eight indigenous fruits in Bangladesh

Herein, a study was carried out to assess the nutritional potential of eight indigenous fruits namely sapodilla, stone apple, bilimbi, amla, litchi, strawberry, tamarind, elephant-apple particularly on the basis of heavy metal, mineral and ascorbic acid content along with the physicochemical properties. Inductively coupled plasma mass spectrometer (ICP-MS) and atomic absorption spectrophotometer (AAS) analysis were performed to determine the essential trace elements and heavy metals in the selected fruits, whereas sodium and potassium content was determined by flame-photometer. Even though the essential trace elements such as zinc, copper, manganese, selenium and cobalt were found in all the examined fruits, sapodilla, stone apple and tamarind were observed as a rich source of selenium and cobalt. The current research demonstrated the presence of toxic heavy metals like arsenic, cadmium, lead, and mercury in elephant-apple, sapodilla, stone apple and tamarind in trace levels which are below the Maximum Residue Limits (MRLs). All the selected eight fruits are found as rich sources of macro-minerals for instance sodium, potassium, calcium, magnesium and phosphorous. Ascorbic acid was estimated by HPLC which ranged from 4.10 to 475.0 mg/100 g of edible portion and the highest amount was found in amla. In summary, these fruits could be potential sources of macro and microminerals and safe from toxic heavy metal contamination. The nutritional data observed in the present study would be played a promising role in dietary recommendation, nutritional education, training, research, and food supplementation.

Synchronous reduction and removal of hexavalent chromium from wastewater by modified magnetic chitosan beads

As one of the highly toxic heavy metal contaminants, hexavalent chromium (Cr(VI)) poses a serious hazard to the environment and public health due to its excellent solubility in aqueous environment. To synchronously reduce and remove Cr(VI) from wastewater efficiently, a class of functionalized magnetic chitosan (CS) beads (MCB-ECH-SH/SO3H) was synthesized with CS as the substrate material and in situ assembling Fe3O4 nanoparticles as the incorporated magnetic material, followed by epichlorohydrin (ECH) cross-linking and l-cysteine grafting. Results showed that Cr(VI) in aqueous solution could be rapidly adsorbed onto MCB-ECH-SH/SO3H via electrostatic attraction, meanwhile -SH groups introduced by l-cysteine grafting could not only significantly facilitate the reduction of Cr(VI) to less toxic trivalent chromium (Cr(III)), but also promote the resultant Cr(III) chelating onto adsorbent due to the proton consumption caused by Cr(VI) reduction, resulting in the synergistic enhancement of Cr(VI) detoxification and total chromium (Cr(Total)) removal. The batch adsorption experiments revealed that the well designed MCB-ECH-SH/SO3H could be applied over a wide pH range (initial pH of 1.0–7.0), and showed much higher remove efficiency (99.6 ± 0.2 %) of Cr(VI) than MCB and MCB-ECH at initial pH 5.0 (60 °C) due to the improvement of stability and reducing capacity. The Cr(Total) sorption behaviors were well according with the pseudo-second-order kinetic and Langmuir models, indicating a single-layer, exothermal, and chemical sorption process, while the maximum Cr(Total) removal capacity of MCB-ECH-SH/SO3H was estimated to be 293.46 mg∙g−1, exceeding most of previously reported related adsorbents. Moreover, MCB-ECH-SH/SO3H could still maintained strong adsorption performance after five cycles and exhibited excellent ability to remove 95 % Cr(VI) within 1 h for low concentration Cr(VI)-containing wastewater. The combination of synchronous reduction and adsorption property, high removal capacity, convenient magnetic separation and good recycling performance makes MCB-ECH-SH/SO3H an ideal candidate for chromium-containing wastewater treatment.

Reline deep eutectic solvent mediated synthesis of lanthanum titanate for heavy metal remediation and photocatalytic degradation

Toxic heavy metal and dye contamination are potential threats that mutilate the essential triad of life; air, water and soil. Despite commercial applicability and importance, the over accumulation of these noxious toxicants has become a disturbing concern. As a result, their remediation has drawn greater fascination leading to the inexplicable quest for a material which can act as both an adsorbent and as a photocatalyst. The present work highlights a novel solid-state technique assisted with reline (Choline chloride: Urea) deep eutectic solvent for the synthesis of lanthanum titanate. The synthesized material was established with physical characterizations like PXRD, FT-IR, UV-DRS, BET, XPS, HR-SEM and TEM techniques. Further, the ruptured petal-like lanthanum titanate was integrated as an adsorbent for the removal of lead (Pb), arsenic (As) and chromium (Cr) heavy metals. The adsorbent presented increased adsorption efficiencies of 96, 74 and 71% towards Pb, As and Cr respectively. Dependence of the degradation efficiency over concentration, pH, contact time and competitive environments were analyzed and inferred. Furthermore, lanthanum titanate was used for the photocatalytic degradation of reactive black (RB5), red (RR198) and yellow (RY145) dyes. The degradation efficiencies were found to be 68.31, 85.2 and 96.8% for RB5, RR198 and RY145 dyes respectively. Variation in concentration and pH of the dye solutions were examined and reaction kinetics was also proposed. In conclusion, the as synthesized lanthanum titanate is assured to play dual roles as a versatile cost-effective adsorbent for the remediation of heavy metals and as a potential candidate for photocatalytic degradation.

Evaluation of potential toxic heavy metal contamination in soil, fly ash, vegetables and grain crops along with associated ecological and health risk assessment of nearby inhabitants of a thermal power station in Jharkhand (India).

The present study aimed to evaluate the potential toxic heavy metal (PTHM) concentrations and associated ecological and health risk of nearby inhabitants (child and adult populations) of the Bokaro thermal power station (BTPS), Jharkhand, India. The fly ash containing PTHMs is released from the thermal power plant and contaminates the soil of the nearby agricultural area, roadside area and residential area. Furthermore, PTHMs cause ecological risk as well as carcinogenic health effects in adults. Inhabitants are exposed to PTHMs through exposure pathways (for instance, direct ingestion, dermal contact and air inhalation), and PTHMs were examined in this study by calculating the estimated daily intake (EDI). The contamination factor (Cf) of Cd exceeded the threshold value throughout the study area, whereas the Cf of Hg was observed higher only in roadside soil (RSS). The geoaccumulation index (Igeo) of Cd was higher in the top soil of agricultural soil (AS) (7.39) and RSS (9.38). The level of PTHMs was monitored slightly higher in the topsoil of RSS. The ecological risk index (Eri) was detected to be the highest in RSS (1628.9). The permissible limit of Cd (0.05mgkg-1) and Pb (0.1mgkg-1) for all sampled vegetables and grain crops was surpassed. The transfer factor (TF) of the studied vegetables and grain crops was in the order of Cd > Cr > Pb > Hg > As. The results of the present study concluded that the hazard quotient (HQ) values for all PTHMs analysed in soil throughout the study area were < 1, which indicates that the child population was within the safe limit. However, the adult population was at a high risk of non-carcinogenic health effects due to increased permissible limits of Cd, Pb and Cr in vegetables and grain crops whereas the target carcinogenic risk (TCR) of Pb and Cr was higher and indicated that there may be a health risk of cancer in adults.

Effects of Toxic Heavy Metal Salts on Oxidative Quality Deterioration in Ground Pork Model during Aerobic Display Storage.

The contamination of toxic heavy metals in meat production and processing can cause the oxidative deterioration of processed meat products. Aside from the possible mechanisms of toxic heavy metals on pro-oxidative reaction, little is known about the potential impacts of toxic heavy metal contamination on meat quality attributes within permitted maximum residual levels. Therefore, the objective of this study was to determine the influence of the intentional contamination of toxic heavy metals on the oxidative deterioration in ground pork models during aerobic display storage. Four types of toxic heavy metal salts (As2O3, CdCl2, K2Cr2O7, and Pb(NO3)2) were mixed with ground pork at two different levels (maximum residue limit and its half level), PVC-wrapped, and displayed in a 4 °C showcase equipped with continuous fluorescent natural white light (1400 l×, color temperature = 6500 K). The contamination of toxic heavy metals significantly decreased the redness of ground pork, and rapidly increased the hue angle. The contamination of Cd and Cr equivalent to maximum residue levels (0.05 and 1.0 mg/kg, respectively) could increase the formation of peroxides, 2-thiobarbituric acid reactive substances, and carbonyls, along with an immediate decrease in total reducing activity. However, there was no difference in protein thiol content between treatments (p > 0.05). These results indicate that contamination of certain toxic heavy metals, particularly Cd and Cr, would accelerate discoloration, lipid oxidation, and carbonyl formation of ground pork during aerobic storage.

Evaluation of a Thermophilic, Psychrostable, and Heavy Metal-Resistant Red Sea Brine Pool Esterase.

Lipolytic enzymes catalyze the hydrolysis and synthesis of ester compounds. They are valuable in the pulp, food, and textile industries. This study aims to comprehensively evaluate the extreme properties of a hormone-sensitive lipase (EstATII-TM) isolated from the Red Sea Atlantis II brine pool. EstATII-TM was cloned, expressed, and its biochemical activities were assessed under different conditions. EstATII-TM catalytic properties and resistance to different metal ions were compared to commercial thermophilic esterases under different temperatures. Phylogenetically, EstATII-TM was assigned to the GDSAG motif subfamily of hormone-sensitive lipase. The optimal enzyme activity was evident at a temperature of 30 °C and pH 7–8. The enzyme retained 84.9% of its activity at 0.5 M NaCl. EstATII-TM maintained 93% to 97% activity at −40 and −20 °C, respectively. EstATII-TM activity was significantly enhanced, up to 10-fold, at temperatures ranging from 45 to 65 °C in the presence of 1 mM Cu2+, Cd2+, Ba2+, Mn2+, and Zn2+. EstATII-TM showed superior catalytic activity and resistance-to/enhancement-by metal ions compared to two commercial thermophilic esterases. The Red Sea Atlantis II brine EstATII-TM is characterized by tolerance to high temperatures, stability to hot and cold conditions, as well as toxic heavy metal contamination, making it an ideal candidate for industrial processes.