Heavy Metal Pollution In Water Research Articles

Metabolic Plasticity Endows Mixotrophic Organisms with High Tolerance to Cadmium and Special Potential for Recovering Cadmium-Contaminated Aquatic Environment.

Heavy metal pollution in waters causes serious stress to aquatic ecosystems. Several autotrophs with strong tolerance are extensively used to adsorb heavy metals, but their use may be limited by the specific conditions of polluted waters due to their single nutrition mode. By contrast, mixotrophs possess strong environmental adaptability due to their plastic metabolic modes. However, studies focusing on mixotroph's resistance and its underlying mechanism in response to heavy metals and their bioremediation potentials are currently lacking. In this study, we investigated the population, phytophysiological, and transcriptomic (RNA-Seq) responses of a typical and common mixotrophic organism, Ochromonas, to cadmium exposure and then evaluated their capacity to remove cadmium under mixotrophic condition. Compared with autotrophy, mixotrophic Ochromonas enhanced photosynthetic performances under short-time cadmium exposure and subsequently shifted to stronger resistance with increasing exposure time. Transcriptomic analyses suggested that the genes related to photosynthesis, ATP production, ECM components, and scavenging of reactive oxygen species and damaged organelles were upregulated to boost mixotrophic Ochromonas resistance to cadmium. Consequently, the harm of metal exposure was eventually reduced and cellular stability was maintained. Approximately, 70% of cadmium at 2.4 mg L-1 cadmium was removed by mixotrophic Ochromonas in the end, benefiting from upregulated genes associated with the transport of metal ions. Hence, mixotrophic Ochromonas tolerance to cadmium can be attributed to multiple pathways of energy metabolism and effective transport of metal ions. Collectively, this study advanced a better understanding of the unique mechanism of heavy metal resistance in mixotrophs and their potential use in recovering cadmium-contaminated aquatic ecosystems. IMPORTANCE Mixotrophs widely living in aquatic ecosystems possess unique ecological roles and strong environmental adaptability due to their plastic metabolic modes; however, little is known about their underlying resistance mechanism and bioremediation potential in response to environmental stresses. For the first time, this work investigated how mixotrophs respond to metal pollutants through physiological, population dynamics, and transcriptional regulation, and highlighted the unique underlying mechanism of mixotrophs to resist and remove heavy metal, thereby advancing our understanding of the potentials of mixotrophs in recovering metal-contaminated aquatic environments. These unique properties in mixotrophs are essential for the long-term functional stability of aquatic ecosystems.

Calcium alginate-nZVI-biochar for removal of Pb/Zn/Cd in water: Insights into governing mechanisms and performance

Heavy metals pollution in water caused by the intensification of industrial processes and human activities has attracted worldwide attention. Finding an environmental-friendly and efficient remediation method is in need. In this study, the calcium alginate entrapment and liquid-phase reduction method were used to prepare calcium alginate-nZVI-biochar composite (CANRC), which was firstly used to remove Pb2+, Zn2+, and Cd2+ in water. The effects of pyrolysis temperature, solution pH, and coexisting ions, etc. during adsorption processes were explored. Scanning electron microscope-Energy dispersive spectrometer (SEM-EDS), X-ray diffraction spectroscopy (XRD), and X-ray photoelectron spectroscopy (XPS) were used to characterize the physicochemical properties of CANRC before and after adsorption. Different adsorption models and site energy analysis were used to analyze the possible mechanisms. The results showed that CANRC prepared at 300 °C and a 5 wt% Fe loading ratio had the maximum adsorption capacities with a dosage of 2.5 g/L and pH = 5.0– 6.0. The adsorption process was more in line with the Langmuir isotherm model dominated by monolayer adsorption. The maximum adsorption capacities of Pb2+, Zn2+, and Cd2+ were 247.99, 71.77, and 47.27 mg/g, respectively. Site energy analysis combined with XRD and XPS analysis indicated that surface complexation and precipitation were the main adsorption mechanisms. This study provides an alternative way for the removal of heavy metals from water.

Study on the Combined Behaviour of Montmorillonite and Carbonate Mineralizing Bacteria on Lead Retention and Fixation

Heavy metal pollution management is a global environmental problem that poses a great threat to the ecological environment. Adsorption and biomineralization are considered to be the two most promising heavy metal pollution remediation techniques among the numerous available ones. In this work, a combined heavy metal removal system was constructed employing the adsorption of montmorillonite and the mineralization of carbonate mineralizing bacteria to expand their application potential for controlling heavy metal water pollution. Analysis of changes in pH, CO32− concentration, Pb2+ concentration in the liquid phase, and changes in microscopic morphology, mineral phase, and functional group on sedimentary minerals was done to study the retention and fixation behaviour of montmorillonite and carbonate mineralizing bacteria on Pb2+. The results show that the liquid phase pH may be slightly altered by the ions dissolved in montmorillonite. Based on the conditions of montmorillonite and carbonate mineralizing bacteria functioning separately, the elimination of Pb2+ may reach 35.31% and 45.75%, respectively. However, when montmorillonite is combined with carbonate mineralizing bacteria, which is the heavy metal removal system constructed in this study, montmorillonite can buffer part of the Pb2+ rapidly and reduce its biotoxicity. Subsequently, these buffered Pb2+ are gradually desorbed by carbonate mineralizing bacteria and removed by the effect of mineralized deposition. Results from SEM, FTIR, and XRD indicate that Pb2+ is primarily removed from the liquid phase as rod-shaped PbCO3. It is worth noting that this process is able to significantly increase the removal of Pb2+ up to 90.06%. In addition, the presence of carbonate mineralizing bacteria can increase montmorillonite’s desorption rate to over 81%, greatly enhancing its capacity for reuse. Therefore, our research work contributes to expanding the potential of montmorillonite and carbonate mineralizing bacteria in the treatment of heavy metal-polluted waters.

Application of Herbal Medicine in Cu2+ Removal from Water and Comparison of its Detection Methods

In order to utilize discarded herbal medicine to treat heavy metal pollution in water, various herbal medicines were selected to explore their abilities of metal ions removal. In this experiment, copper ion was used as targeted heavy metal ion and two different treatments of several herbal medicines were compared on the effect of the copper ion removal ability. At the evaluating stage, four metal ion detection methods were employed and analyzed in this herbal medicine Cu2+ removal application. The results showed that directly soaking herbal medicine in the copper aqueous solution was more effective and easier to operate. Iodometry method and EDTA complexometric titration with xylenol orange as indicator were accurate and time-saving in the measurement of copper removal rate. In addition, the EDTA complexometric titration is also applicable in the detection of other metal ions. This experiment provided a basis for the implementation and application of herbal medicine in the deposition of metal ions in polluted water.

Phytoremediation of Wastewater Containing Lead and Manganese Ions Using Algae.

Heavy metal pollution of water from industrial discharge is a major problem worldwide. Thus, the quality of the environment and human health are severely affected. Various conventional technologies have been applied for water treatment, but these can be expensive, especially for industrial water treatment, and may have limited treatment efficiencies. Phytoremediation is a method that is successfully applied to remove metal ions from wastewater. In addition to the high efficiency of the depollution treatment, this method has the advantages of a low cost of the operation and the existence of many plants that can be used. This article presents the results of using algae (Sargassum fusiforme and Enteromorpha prolifera) to treat water containing manganese and lead ions. It was observed that maximum efficiencies for wastewater treatment were obtained when was used the algae Enteromorpha prolifera for a 600 min contact time period. The highest wastewater treatment efficiency obtained using Sargassum fusiforme was 99.46%.

Delamination of multilayer Ti3C2Tx MXene alters its adsorpiton and reduction of heavy metals in water

MXenes are considered as an emerging class of two-dimensional (2D) adsorbent for various environmental applications. In this work, two different morphologies of Ti3C2Tx MXene (multilayer (ML-Ti3C2Tx) and delaminated titanium carbide (DL-Ti3C2Tx)) were prepared through mild in situ HF etching and further delamination. The structural differences between the two were explored with a focus on their effects on the performance and mechanism of removing heavy metals from water. In comparison to ML-Ti3C2Tx, DL-Ti3C2Tx had more oxygen-containing functional groups, higher specific surface area (19.713 vs. 8.243 m2/g), larger pore volume (0.135 vs. 0.040 cm3/g), higher maximum Pb(II) adsorption capacity (77.0 vs. 56.68 mg/g), but lower maximum Cu(II) adsorption capacity (23.08 vs. 55.46 mg/g). Further investigation revealed that the removal of Pb(II) by the MXenes was mainly controlled through electrostatic attraction and surface complexation mechanisms, while Cu(II) was removed mainly through surface reduction by Ti-related groups. Because delamination of ML-Ti3C2Tx increased the surface area and surface functional groups, DL-Ti3C2Tx became a better sorbent for Pb(II) in water. During sonication, however, delamination inevitably led to partial oxidation of Ti3C2Tx nanosheets and thus weakened the reducing ability of DL-Ti3C2Tx for Cu(II) in water. Nevertheless, both ML- and DL-Ti3C2Tx not only exhibited excellent heavy metal adsorption capacity under different solution conditions, but also showed good reusability. Findings of this study indicate that Ti3C2Tx MXenes are promising adsorbents for treating heavy metal pollutants in water.

Biologically-induced synthetic manganese carbonate precipitate (BISMCP) for potential applications in heavy metal removal

Heavy metal pollution of water is a burning issue of today’s world. Among several strategies involved for heavy metal remediation purpose, biomineralization has shown great potential. Of late, research has been focused on developing effective mineral adsorbents with reduced time and cost consumption. In this present paper, the Biologically-Induced Synthetic Manganese Carbonate Precipitate (BISMCP) was produced based on the biologically-induced mineralization method, employing Sporosarcina pasteurii in aqueous solutions containing urea and MnCl2. The prepared adsorbent was characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), SEM-energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD) and BET surface area analyzer. EDX analysis showed the elements in the crystal BISMCP were Mn, C, and O. XRD result of BISMCP determined the crystal structure, which is close to rhodochrosite (MnCO3). Spectral peaks of FTIR at 1641.79 cm−1 confirmed the appearance of CO binding, with strong stretching of CO32− in Amide I. From the six kinds of BISMCP produced, sample MCP-6 has the higher specific surface area by BET analysis at 109.01 m2/g, with pore size at 8.76 nm and higher pore volume at 0.178 cm3/g. These specifications will be suitable as an adsorbent for heavy metal removal by adsorption process. This study presents a preliminary analysis of the possibility of BISMCP for heavy metals adsorption using ICP multi-element standard solution XIII (As, Cr, Cd, Cu, Ni, and Zn). BISMCP formed from 0.1 MnCl2 and 30 ml of bacteria volume (MCP-6) produced a better adsorbent material than others concentrations, with the adsorption efficiency of total As at 98.9%, Cr at 97.0%, Cu at 94.7%, Cd at 88.3%, Zn at 48.6%, and Ni at 29.5%. Future work could be examined its efficiency adsorbing individual heavy metals.

Cadmium accumulation and isotope fractionation in typical protozoa Tetrahymena: A new perspective on remediation of Cd pollution in wastewater

Cadmium (Cd) pollution threatens water safety and human health, which has raised serious public concern. Tetrahymena is a model protozoan, possessing the potential to remediate Cd contaminated water given the rapid expression of thiols. However, the mechanism of Cd accumulation in Tetrahymena has not been well understood, which hinders its application in environmental remediation. This study elucidated the pathway of Cd accumulation in Tetrahymena using Cd isotope fractionation. Our results showed that Tetrahymena preferentially absorb light Cd isotopes, with Δ114/110CdTetrahymena−solution = −0.20 ± 0.02‰ ∼ − 0.29 ± 0.02‰, which implies that the intracellular Cd is probably in the form of Cd−S. The fractionation generated by Cd complexation with thiols is constant (Δ114/110CdTetrahymena−remaining solution ∼ −0.28 ± 0.02‰), which is not affected by the concentrations of Cd in intracellular and culture medium, nor by the physiological changes in cells. Furthermore, the detoxification process of Tetrahymena results in an increase in cellular Cd accumulation from 11.7% to 23.3% with the elevated Cd concentrations in batch Cd stress culture experiments. This study highlights the promising application of Cd isotope fractionation in Tetrahymena for the remediation of heavy metal pollution in water.

The Effect of Cadmium, Copper, and Lead on Brassica juncea in Hydroponic Growth Medium

This study measured the accumulation of cadmium (Cd), lead (Pb), and copper (Cu) in Brassica juncea grown using the hydroponic method in a water environment contaminated with these heavy metals. The accumulated metal content in each part of the plant was monitored after one, three, and six weeks of exposure. The concentrations of Cd, Cu, and Pb in the biomass of B. juncea were determined using atomic absorption spectroscopy. The results showed that heavy metal pollution in water caused heavy metal accumulation in vegetable biomass. Pb tended to accumulate lower vegetable biomass than Cu and Cd. The metal accumulation level in Cu and Cd was in the order of roots > stems > leaves, while with Pb, the concentration accumulated in roots > leaves > stems. The translocation factors of Cu, Cd, and Pb from shoots to stems and shoots to leaves were less than 1.

Fluorescence off–on nanosensor based on MoS2 nanosheets and oligonucleotides for the alternative detection of mercury(II) ions or silver(I) ions

As traditional methods for detection of heavy metal pollution in water involve complex procedures and require expensive equipment, there is a great deal of interest in the development of rapid and simple methods for determining heavy metal ions in water. Here, a nanobiosensor based on molybdenum disulphide (MoS2) nanosheets and fluorophore (FAM) labeled oligonucleotides was proposed, and fluorescence spectroscopy was adopted for detection of Hg2+ or Ag+ ions in aqueous solution. The principle underlying detection by the sensor involves the formation of T-Hg2+-T or C-Ag+-C mismatches by single-stranded DNA (ssDNA) rich in thymine (T) or cytosine (C), thereby forming stable double-stranded DNA (dsDNA) structures. By exploiting the different adsorption capacity of MoS2 nanosheets for ssDNA and dsDNA, when oligonucleotides were in a single chain state, MoS2 nanosheets possessed a strong adsorption capacity for ssDNA, resulting in fluorescence quenching of FAM. After the addition of Hg2+ or Ag+, ssDNA formed double chains structure, the fluorescence recovered due to the weak adsorption capacity of MoS2 nanosheets for dsDNA. Along this line, an “off-on” mode fluorescence nanobiosensor was designed to alternatively detect these two heavy metal ions in water. The sensor showed high sensitivity and excellent selectivity for both Hg2+ and Ag+ ions, with minimum detection limits of 6.8 nM and 8.9 nM, respectively.

Converting wastes to resource: Preparation of NiO@γ-Al2O3 sludge composite from aluminum-containing sludge for cadmium removal from wastewater

Solid sludge waste and heavy metal water pollution have attracted great interest due to the adverse impacts on the ecological environment, which remains a significant challenge to environmental protection. Herein, with the concept of converting wastes to resources, this work presents a general procedure to fabricate NiO@γ-Al2O3 sludge composite derived from aluminum-containing sludge for efficient cadmium removal. During the procedure, the unstable metal compounds were converted into chemically stable metal oxides, and the organic components in sludge are decomposed via high-temperature treatment. Then, the NiO@γ-Al2O3 sludge composite was obtained by in situ growth of NiO nanocrystals using the calcined sludge as raw materials, followed by calcination to form a porous structure. The as-obtained NiO@γ-Al2O3 sludge composite with hierarchical porosity comprises self-assembled NiO nanosheets with sizes ranging from 1 to 3 μm. Compared with raw sludge particles, the specific surface area of NiO@γ-Al2O3 sludge composite is enhanced significantly (116.27 m2/g), revealing that the preparation procedure is favorable for the improvement of the surface properties of the sludge. The cadmium adsorption results showed that the maximum cadmium adsorption capacity of the sludge composite could attain 160.12 mg/g, and cadmium removal efficiency could reach 99.9% with an optimal dose of 1.5 g/L. Meanwhile, the sludge composite showed high adsorption capacity at the neutral pH condition, which was attributed to the exchange of cadmium ions in solution with the surface protons on the adsorbent. Significantly, a simple regeneration operation was used for the desorption of cadmium ions to realize the regeneration of adsorbents, and the regenerated sludge composite can be recyclable for continuous use. This work provides a waste-to-resource strategy for resource utilization of solid waste sludge and presents an adsorbent material with high surface activity for cadmium adsorption, which may inspire the development and application of other solid waste for wastewater treatment.

Study on Adsorption of Ag+ by Waste Tea: Adsorption Kinetics, Thermodynamics, Isotherm Properties

Aims: In order to explore the adsorption effect of tea on heavy metal ions in industrial wastewater, Ag+ is used as the research object in this paper. Background: In recent years, heavy metal pollution in water has seriously affected human health and the stability of the ecological environment. In order to reduce the harmfulness of heavy metals, various countries have issued a variety of control standards for heavy metals in water, but there are still great restrictions in the prevention and control technology and level of heavy metal pollution. Therefore, how to effectively treat heavy metal pollution in water has become a hot topic in the field of water pollution management. Objective: The optimized conditions of the adsorption are obtained. Properties of the thermodynamics, adsorption kinetics, and adsorption isotherm are obtained. Methods: In order to determine the best adsorption conditions for Ag+, the influence of factors such as pH value, initial concentration of Ag+, tea dosage, contact time, and adsorption temperature on the adsorption effect of tea is studied. The thermodynamics, adsorption kinetics, and adsorption isotherm are studied. Results: The results showed that when the temperature is 25°C, the pH of the solution was 3.5, the amount of adsorbent was 2.5 g/L, the initial concentration of Ag+ was 125 μg/L and the contact time was 30min, the adsorption rate was highest, reaching 98.11%. The thermodynamic study of adsorption showed that at room temperature and above (298.15-318.15 K), ΔG° < 0, indicating that the adsorption process can be spontaneous. The value of ΔGo in this study is between -20 and -80 kJ/mol, indicating that this is a physicochemical adsorption process. ΔHo = -80.111 kJ/mol < 0, indicating that the adsorption process of Ag+ is exothermic. ΔSo = -188.977 J/(mol·K) < 0, indicating that the adsorption is a process of entropy reduction. The adsorption kinetics study showed that the adsorption equilibrium capacity of different concentrations had a large gap with the experimental results, and the correlation coefficient was small by fitting the quasi-first-order kinetic equation and combining it with the experimental measurements. When the quasi-second-order kinetic equation was used, the calculated values of the equilibrium adsorption capacity of each concentration were basically close to the experimentally measured values, and the correlation coefficient was large, so the kinetics of the adsorption system of Ag+ by tea conformed to the quasi-second-order kinetic equation. The adsorption isotherm of this adsorption process is accorded with the Freundlich model and belonged to heterogeneous adsorption. Conclusion: Tea is a good adsorbent and has the potential for adsorption of Ag+.

Environmental Risks Due to Heavy Metal Pollution of Water Resulted from Coal Mining Wastes in Korba Chhattisgarh, India

Environmental Risks Due to Heavy Metal Pollution of Water Resulted from Coal Mining Wastes in Korba Chhattisgarh, India

Assessment of heavy metal pollution in water and its effect on Nile tilapia (Oreochromis niloticus) in Mediterranean Lakes: a case study at Mariout Lake

Mariout Lake is one of the Northern Nile-Delta Lakes in Egypt that receives agricultural, industrial and domestic effluents through several drains. The present study aims to evaluate the levels of some heavy metals (HMs) in water and edible parts of Oreochromis niloticus in Mariout Lake, in addition to studying several pollution indices and potential human health risks. The levels of the studied HMs in water were in the order of Fe > Zn > Mn > Pb > Cu > Ni > Cd. However, results of the pollution index, that concerns the effect of individual metal, concluded that Cd and Pb in water had serious pollution effects for aquatic life, while Cu, Fe, Mn, Ni, and Zn had not any pollution effects at different locations in the lake. The indices of the composite effects of all HMs (Metal Index and Heavy Metal Pollution Index) indicated the high pollution of Mariout Lake water, which may cause adverse effects on fish and different aquatic organisms. On the other side, the bioaccumulation factors of HMs in edible parts of O. niloticus were in the order of Zn > Cd > Cu > Ni > Pb > Mn > Fe. Although the target hazard quotient for all metals was less than the non-hazardous limit (THQ < 1), the non-carcinogenic hazard index (HI = 1.24) was classified in the moderate hazard risk level (1 < HI < 10) indicating low potential adverse effects on the exposed population due to consumption of O. niloticus caught from Mariout Lake.

Microbial Biofilms for Environmental Bioremediation of Heavy Metals: a Review.

Heavy metal pollution caused due to various industrial and mining activities poses a serious threat to all forms of life in the environment because of the persistence and toxicity of metal ions. Microbial-mediated bioremediation including microbial biofilms has received significant attention as a sustainable tool for heavy metal removal as it is considered safe, effective, and feasible. The biofilm matrix is dynamic, having microbial cells as major components with constantly changing and evolving microenvironments. This review summarizes the bioremediation potential of bacterial biofilms for different metal ions. The composition and mechanism of biofilm formation along with interspecies communication among biofilm-forming bacteria have been discussed. The interaction of biofilm-associated microbes with heavy metals takes place through a variety of mechanisms. These include biosorption and bioaccumulation in which the microbes interact with the metal ions leading to their conversion from a highly toxic form to a less toxic form. Such interactions are facilitated via the negative charge of the extracellular polymeric substances on the surface of the biofilm with the positive charge of the metal ions and the high cell densities and high concentrations of cell-cell signaling molecules within the biofilm matrix. Furthermore, the impact of the anodic and cathodic redox potentials in a bioelectrochemical system (BES) for the reduction, removal, and recovery of numerous heavy metal species provides an interesting insight into the bacterial biofilm-mediated bioelectroremediation process. The review concludes that biofilm-linked bioremediation is a viable option for the mitigation of heavy metal pollution in water and ecosystem recovery.

New Approach to Modelling the Impact of Heavy Metals on the European Union's Water Resources.

The present research aims to address the highly topical issue of heavy metal water pollution from an integrated European perspective, i.e., to quantify through modelling a general model of water pollution reduction in the EU. The objectives of the study are mainly aimed at identifying effective solutions to reduce heavy metal water pollution and providing supranational decision-makers with public policy directions in the field. The research methods consist of the foundation of working hypotheses based on the study of the literature, the consolidation of official statistical databases in the field, econometric modelling and the conceptualisation of a general model and its testing and validation by statistical methods. The results of the analysis consist of the following marginal contributions: the identification of a general model for combating heavy metal pollution; the calculation of the degree of contribution of regional policies to the general model; and the identification of effective solutions to improve the combating of heavy metal water pollution in Europe. The main conclusion of the analysis shows that significant progress has been achieved at the EU level in the field of combating heavy metal water pollution. However, the level of disparity and poor policy coordination are real vulnerabilities for the EU.

Assessment and Spatiotemporal Variability of Heavy Metals Pollution in Water and Sediments of a Coastal Landscape at the Nile Delta

This study assessed the spatiotemporal variability and pollution grades of heavy metals in water and sediments of Bahr El-Baqar drain, Eastern Nile Delta, Egypt, by integration of geochemical analysis, metal pollution indices, correlation, and multivariate statistical analyses. Twenty samples of water and sediments were collected during 2018 and analyzed for heavy metal concentrations using ICP-OES. Heavy metal contents in the water samples followed the order: Fe &gt; Zn &gt; Al &gt; Pb &gt; Mn &gt; Cu &gt; Ni. The drain sediments were highly contaminated with heavy metals that followed the order: Fe &gt; Al &gt; Mn &gt; V &gt; Zn &gt; Cu &gt; Cr &gt; Ba &gt; Ni &gt; Pb &gt; As. Spatiotemporally, most metals in the drain sediments showed a decreasing trend from upstream (south) to downstream sites (north). Results of principal component analysis (PCA) supported those from the Pearson correlation between investigated heavy metals. In water, Mn, Ni, Pb, Zn, Cu, and Fe showed highly significant correlations. In sediments, Ba, Ni, Zn, Fe, Al, Mn, and V showed strong positive correlations indicating that these metals were derived from similar anthropogenic sources. The calculated metal pollution indices: enrichment factor (EF), contamination factor (CF), pollution load index (PLI), degree of contamination (DC), and index of geo-accumulation (Igeo) indicated high loadings of heavy metals in the drain sediments. EFs revealed low, moderate to significant enrichment, whereas CFs showed low, moderate, and considerable contamination. PLI indicated low, baseline, and progressive contamination, while DC indicated low, moderate, and considerable degree of contamination. Igeo of all investigated metals (except for As; class 1) indicated extremely contaminated sediments (class 7).

Influence of the surface modification of granular-activated carbon synthesized from macauba on heavy metal sorption.

Adsorption on activated carbon is a promising technique for the treatment of low-concentration heavy metal pollutants in water with high efficiency and simple operation. However, commercial-activated carbon is often associated with high costs. Therefore, much attention has been given to activated carbon derived from low-cost agricultural and residual biomass. In this work, adsorption of Zn, Cd, and Pb ions in aqueous solutions was conducted using granular-activated carbon obtained from macauba palm, biomass waste of biofuel production, after surface modification using different methods. The adsorbents were obtained in granular form which facilitates all steps of the use, recovery, and reuse of the material, differently from the powdered-activated carbon normally used. The materials were characterized by using XPS, elemental analysis, N2 sorption (BET method), and zeta potential measurements. Such techniques allowed observation of the functionalization of the carbon surface. The materials presented high adsorption capacities when compared to other works in the literature, with a capacity of approximately 7.69, 8.42, and 1.63mmolg-1 for Zn2+, Cd2+, and Pb2+, respectively. In addition, the materials showed a high capacity to be reused, removing 75% of Pb and 99% of both Cd and Zn after 4 cycles.

The seasonal assessment of heavy metals pollution in water, sediments, and fish of grey mullet, red seabream, and sardine from the Mediterranean coast, Damietta, North Egypt

The current study investigated the deposit of heavy metals, including copper (Cu), zinc (Zn), cadmium (Cd), manganese (Mn), lead (Pb), chromium (Cr), and iron (Fe) in grey mullet (Mugil cephalus), red seabream (Pagrus pagrus), and sardine (Sardinella aruita) over winter and spring seasons 2022 at the Damietta port, a marine port constructed in 1982 on the north coast of Egypt, and the surrounding region. Water, sediment, and fish samples were collected from four sites near Damietta port throughout the spring and winter of 2022 to evaluate the amount of heavy metal in water, sediment, muscles, and fish liver. Heavy metal concentrations significantly differed across organs; however, their levels in liver tissues exceeded those in muscle tissues. It was noted that M. cephalus had the highest concentrations of heavy metals compared with other fish species. Heavy metals accumulation in fish organs was in the following order: Fe > Zn > Mn > Pb >Cu > Ni > Cd > Cr. During winter season, metals levels in water samples were in the following sequence: Fe > Ni > Zn > Cd > Cr > Pb > Cu > Mn, meanwhile in spring season, the order was as follows: Ni > Pb > Fe > Cr > Zn > Cd > Cu > Mn. During the winter time, the order of metals levels in sediment samples was Zn > Fe > Mn > Cu > Pb > Ni > Cd > Cr, but in the springtime, it was Zn > Fe > Mn > Cu > Ni > Pb > Cd > Cr. Finally, the human risk assessment concluded that grey mullet, red seabream, and sardine in Damietta port and neighboring regions are safe for human feeding and that various wastes may be disposed of securely, avoiding the buildup of heavy metals.

Removal of heavy metals from wastewater using synthetic chelating agents

Abstract The issue of heavy metal water pollution is one that concerns everyone. Both plants and humans are negatively impacted by heavy metals. Consequently, the environment and water resources require an efficient heavy metal remediation technique. In this context, a series of compounds were investigated as potential chelating agents for the removal of Cu, Zn, Cd, and Pb cations from water. By solvent extraction, it was shown that the chelating ligands’ affinity for Cu, Zn, Cd, and Pb as indicated by the extraction performance was in the following order: Cu &gt; Zn &gt; Cd &gt; Pb. The size and electrical characteristics of the metal as well as the ligand structure affect how well L1–L6 extracts that metal.