By utilizing polydopamine (PD) nano-thick interlayer as mediator, polyethylenimine (PEI) brushes with abundant amine groups were grafted onto the surface of PD coated graphene oxide (GO) uniformly ...via a Michael-Addition reaction and produced a PEI–PD/GO composite nanosheets. The PEI–PD/GO composite exhibited an improved performance for adsorption of heavy metal ions as compared to PEI-coated GO and pure GO. The adsorption capacities for Cu2+, Cd2+, Pb2+, Hg2+ are up to 87, 106, 197, and 110mg/g, respectively. To further make the GO based composite operable, PEI–PD/RGO aerogel was prepared through hydrothermal and achieved a high surface area up to 373m2/g. Although the adsorption capacity of PEI–PD/RGO aerogel for heavy metal ions decreases a little as compared to PEI–PD/GO composite dispersion (38, 32, 95, 113mg/g corresponding to Cu2+, Cd2+, Pb2+, and Hg2+, respectively), it could be recycled several times in a simple way by releasing adsorbed metal ions, indicating its potential application for cleaning wastewater.
Polyethylenimine (PEI) brushes were grafted onto the surface of graphene oxide (GO) uniformly via a Michael-Addition reaction between the PEI and polydopamine interlayer coated on GO surface. The PEI–PD/GO composite exhibited an improved performance for adsorption of heavy metal ions compared to PEI-coated GO and pure GO Display omitted .
•We prepared polyethylenimine grafted polydopamine-mediated graphene oxide composites.•Introduction of PD layer increases metal ions adsorption capacity.•PEI–PD/RGO aerogel exhibited a superior adsorption performance.•PEI–PD/RGO aerogel can be recycled several times in a simple way.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In recent years, much concern has been addressed over the soil contamination with heavy metals due to rapid industrialization and urbanization. The present study was conducted to investigate ...distribution of potentially hazardous elements (PHEs) (As, Cr, Cu, Ni, Pb and Zn) concentration in soils of Kazipalli, Hyderabad, India. Soil samples from fifty-seven (57) sampling sites were collected from in and around industrial zone and were analysed for their heavy metal contents. Concentrations ranged from 4.4 to 796.3 mg/kg for As, 9.7 to 598.6 mg/kg for Cr, 7.9 to 183.5 mg/kg for Cu, 10.2 to 129.6 mg/kg for Ni, 25.3 to 1830 mg/kg for Pb and 23.8 to 879 mg/kg for Zn. Application of Pearson’s correlation, factor and cluster analysis indicates that heavy metal contamination in soils originates from industrial activities which are of anthropogenic origin. Contamination of soils in the study area was further classified for geoaccumulation index, enrichment factor, contamination factor and contamination degree. The values of pollution index and integrated pollution index indicated that metal pollution levels were in order of As > Pb > Cu > Cr > Zn > Ni. Potential ecological risk indices (PERI, RI) and health risk assessment based on Hazard Quotient, Hazard index and on Average daily doses of individual elements were calculated using exposure parameters for resident population and references from integrated database of USEPA. These results are important for the development of proper management strategies to decrease point and non-point source of pollution by studying different remediation methods.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Natural aging alters the surface physicochemical properties of biochars, which can affect the retention of heavy metals. This work investigated the effect of biochar aging on stabilization of heavy ...metals (Cd and Ni) and soil enzyme activities simulated with laboratory wet–dry (WD) and freeze–thaw (FT) cycling. A wheat straw (WS) biochar and a corn straw (CS) biochar were subjected to 30 WD or FT cycles, and Cd- and Ni-contaminated alkaline soils amended with the two fresh biochars (at 5% w/w) were subjected to 30-day constant moisture incubation and 30 WD or FT cycles. WD and FT aging caused slight reduction in the pH of the biochars, significant increases in their O contents and surface areas, and formation of new carbonate minerals. WS biochar was more effective than CS biochar at reducing the phytoavailable Cd in the soil, with reduction of 12.1%, 14.6%, and 12.9% under constant moisture incubation, WD aging, and FT aging, respectively. Reduction in phytoavailability of Ni by the addition of biochars was observed only under WD aging, by 17.0% and 18.5% in the presence of WS and CS biochars, respectively. Biochar amendment also reduced the distribution of Cd in the acid soluble and reducible fractions in all aging regimes. The addition of biochars decreased catalase activity in almost all aging regimes and invertase activity under FT aging, but increased urease activity under FT aging. Comparison of the enzyme activities in the soils amended with biochars under constant moisture and accelerated aging conditions indicates WD aging significantly decreased the activities of catalase, invertase, and urease in all treatments, while FT aging significantly increased urease activity in all treatments. These findings suggest that biochars can stabilize Cd in alkaline soils under changing environmental conditions, although the activities of some soil enzymes could be negatively impacted.
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•Aging of biochars was simulated with wet–dry (WD) and freeze–thaw (FT) cycling.•Biochar reduced phytoavailable Cd and Ni in alkaline soil under WD and/or FT aging.•Biochar promoted the distribution of Cd into the residual fraction of alkaline soil.•Effect of biochar on enzyme activities varied with enzyme type and aging conditions.•Crop straw biochars hold promise for long-term immobilization of Cd in alkaline soils.
Crop straw biochars stabilized Cd in a historically contaminated alkaline agricultural soil under accelerated aging, and thus hold promise for long-term immobilization of Cd under field conditions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Soil naturally comprises heavy metals but due to the rapid industrialization and anthropogenic events such as uncontrolled use of agrochemicals their concentration is heightened up to a large extent ...across the world. Heavy metals are non-biodegradable and persistent in nature thereby disrupting the environment and causing huge health threats to humans. Exploiting microorganisms for the removal of heavy metal is a promising approach to combat these adverse consequences. The microbial remediation is very crucial to prevent the leaching of heavy metal or mobilization into the ecosystem, as well as to make heavy metal extraction simpler. In this scenario, technological breakthroughs in microbes-based heavy metals have pushed bioremediation as a promising alternative to standard approaches. So, to counteract the deleterious effects of these toxic metals, some microorganisms have evolved different mechanisms of detoxification. This review aims to scrutinize the routes that are responsible for the heavy metal(loid)s contamination of agricultural land, provides a vital assessment of microorganism bioremediation capability. We have summarized various processes of heavy metal bioremediation, such as biosorption, bioleaching, biomineralization, biotransformation, and intracellular accumulation, as well as the use of genetically modified microbes and immobilized microbial cells for heavy metal removal.
In recent years, with the development of the new energy industry, the demand for cobalt as a raw material for power batteries has been increasing. However, China itself has a shortage of cobalt ...resources. Therefore, overcoming poor resource conditions and enhancing the international competitiveness of the cobalt industry have become urgent issues. This paper is based on global trade data on cobalt resources from 2007 to 2020. A panel regression model is constructed from the perspective of trade networks, and Entropy-Topsis is used to construct a comprehensive evaluation index system for the international competitiveness of critical nonferrous metals. This study empirically examines the impact of the trade network characteristics of cobalt resources on international competitiveness, assigns practical significance to trade network characteristic indicators, and analyses the overall competitiveness changes in the global cobalt industry chain and its upstream, midstream, and downstream sectors. The research findings reveal the following key points: (1) In recent years, the competitive focus of the cobalt industry chain in various countries has shifted from upstream and midstream to midstream and downstream, with increasingly fierce trade competition downstream, gradually tilting toward countries such as South Korea, Japan, and China. (2) Cobalt trade competition, which was initially characterized by competition among multiple countries, has gradually become more centralized and stable, with differences in the competitiveness of various countries occurring at different stages of the cobalt industry chain. (3) Network centrality and network heterogeneity both have a significant promoting effect on the international competitiveness of the industry, while network connectivity has a significant inhibitory effect on the improvement of international competitiveness.On this basis, the study also suggests some policy implications. The purpose of the study is to enhance the international competitiveness of China's cobalt industry from a trade perspective and to investigate the developments of cobalt trade between China and the rest of the world.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Cadmium （Cd） contamination has posed an increasing challenge to environmental quality and food security. In recent years, phytoremediation has been particularly scrutinized because it is ...cost-effective and environmentally friendly, especially the use of metal-hyperaccumulating plants to extract or mine heavy metals from polluted soils. Under Cd stress, responses of hyperaccumulator and non-hyperaccumulator plants differ in morphological responses and physiological processes such as photosynthesis and respiration, uptake, transport, and assimilation of minerals and nitrogen, and water uptake and transport, which contribute to their ability to accumulate and detoxify Cd. This review aims to provide a brief overview of the recent progresses in the differential responses of hyperaccumulator and non-accumulator plants to Cd toxicity in terms of growth and physiological processes. Such information might be useful in developing phytoremediation technology for contaminated soils.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Some heavy metals are nutritionally essential elements playing key roles in different physiological and biological processes, like: iron, cobalt, zinc, copper, chromium, molybdenum, selenium and ...manganese, while some others are considered as the potentially toxic elements in high amounts or certain chemical forms. Nowadays, various usage of heavy metals in industry, agriculture, medicine and technology has led to a widespread distribution in nature raising concerns about their effects on human health and environment. Metallic ions may interact with cellular components such as DNA and nuclear proteins leading to apoptosis and carcinogenesis arising from DNA damage and structural changes. As a result, exposure to heavy metals through ingestion, inhalation and dermal contact causes several health problems such as, cardiovascular diseases, neurological and neurobehavioral abnormalities, diabetes, blood abnormalities and various types of cancer. Due to extensive damage caused by heavy metal poisoning on various organs of the body, the investigation and identification of therapeutic methods for poisoning with heavy metals is very important. The most common method for the removal of heavy metals from the body is administration of chemical chelators. Recently, medicinal herbs have attracted the attention of researchers as the potential treatments for the heavy metals poisoning because of their fewer side effects. In the present study, we review the potential of medicinal herbs such as: Allium sativum (garlic), Silybum marianum (milk thistle), Coriandrum sativum (cilantro), Ginkgo biloba (gingko), Curcuma longa (turmeric), phytochelatins, triphala, herbal fibers and Chlorophyta (green algae) to treat heavy metal poisoning.
In this work, we examined the possibility on the application of rice husk as biosorbent for the elimination of heavy metal ions (chromium, lead, and zinc) existing in the aqueous solutions. The ...biosorbent was prepared from rice husk powder and modified with 0.1 N of HCl for creating the functional groups and increase specific surface area. The FT-IR spectra, SEM& EDX studies of rice hulls powder were examined for the pristine adsorbent and after the adsorption of heavy metal ions. The batch adsorption technique was adopted for this work and adsorption parameters were optimized. The maximum efficiency of adsorption is obtained at 6.0 pH, 1 h of contact duration, the rice husk dosage is 2.5 g/L, and temperature of 30°C for 25 mg/L of Cr, Pb & Zn metal ion solutions. The Cr, Pb & Zn metal ions are removed up to 87.12 %, 88.63 % & 99.28 %, respectively, using the rice husk powder. The adsorption process follows the Temkin & D-R isotherm model. Elovich model was fitted against the kinetic data of metal ion adsorption. Based on the experimental observations, the rice husk powder can be considered as a low cost adsorbent for heavy metal ion removal from the industrial effluent.
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•This experimental study provides the details of the production of low cost adsorbent material from rice husk powder.•Adsorptive removal of Cr, Pb & Zn metal ions was investigated by batch mode.•The maximum adsorption efficiency of 87.12% for chromium, 88.63 % for lead and 99.28 % for zinc heavy metal ions was attained.•The maximum amount of desorption was attained by adding 0.2 N of HCl in the adsorbate material.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Elucidating the absorption and translocation of heavy metal(loid)s by common vegetables across different growth environments and stages is crucial for conducting accurate environmental risk ...assessments and for associated control. This study investigated temporal variations in the absorption and translocation capacities of pak choi (Brassica rapa L.) for As, Cd, Cr, Cu, Pb, and Zn in polluted soils during the plant growth cycle under greenhouse and open-field cultivation modes. Results showed high root metal(loid) bioconcentration factors and root-to-shoot translocation factors for Cd (0.25 and 1.44, respectively) and Zn (0.26 and 1.01), but low values for As (0.06 and 0.88) and Pb (0.06 and 0.87). The Cd concentration in the aerial edible parts peaked during the early slow growth period, whereas other heavy metal(loid)s peaked during the later stable maturity period. Root bioconcentration and root-to-shoot translocation factors did not significantly differ between cultivation modes. However, greenhouse cultivation exhibited lower average Cd and Zn concentrations in the edible parts and cumulative uptake amounts of most metal(loid)s than open-field cultivation during the typical harvest period spanning days 60 and 90. Short-term transitioning from open-field to greenhouse cultivation may reduce health risks associated with heavy metal(loid) intake via pak choi consumption. These findings facilitate sustainable agricultural practices and food safety management.
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•Cd concentration in the edible parts of pak choi peaked during the slow growth period.•Other metal(loid)s primarily reached highest levels during the stable maturity period.•Bioconcentration factors and translocation factors: Cd and Zn > As and Pb.•Greenhouse cultivation reduced cumulative uptake of metal(loid)s in mature pak choi.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
An Gram negative strain of
, indigenous to environments contaminated by Cr(VI) and identified by biochemical methods and 16S rRNA gene analysis, reduced chromate by 100%, 98-99% and 92% at ...concentrations in the 10-70, 80-300, and 500 mg/L range, respectively at pH 7 and temperature 37 °C. Increasing concentrations of Cr(VI) in the medium lowered the growth rate but could not be directly correlated with the amount of Cr(VI) reduced. The strain also exhibited multiple resistance to antibiotics and tolerance and resistance to various heavy metals (Ni, Zn and Cu), with the exception of Hg. Hexavalent chromium reduction was mainly associated with the soluble fraction of the cell evaluated with crude cell-free extracts. A protein of molecular weight around 25 kDa was detected on SDS-PAGE gel depending on the concentration of hexavalent chromium in the medium (0, 100 and 500 mg/L). In silico analysis in this contribution, revealed the presence of the chromate reductase gene
in
, evidenced through a fragment of around 468 bp obtained experimentally. High Cr(VI) concentration resistance and high Cr(VI) reducing ability of the strain make it a suitable candidate for bioremediation.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
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