Heavy Metal-contaminated Water Research Articles

Adsorption of lead ions from wastewater using electrospun zeolite/MWCNT nanofibers: kinetics, thermodynamics and modeling study.

Heavy metal contamination in water is a serious environmental issue due to the toxicity of metals like lead. This study developed zeolite and multi-walled carbon nanotube (MWCNT) incorporated polyacrylonitrile (PAN) nanofibers via needleless electrospinning and examined their potential for lead ion adsorption from aqueous solutions. The adsorption process was optimized using response surface methodology (RSM) and artificial neural network (ANN) modeling approaches. The adsorbent displayed efficient lead removal of 84.75% under optimum conditions (adsorbent dose (2.21 g), adsorption time (207 min), temperature (48 °C), and initial concentration (62 ppm)). Kinetic studies revealed that the adsorption followed pseudo-first-order kinetics governed by interparticle diffusion. Isotherm analysis indicated Langmuir monolayer adsorption with improved 5.90 mg g-1 capacity compared to pristine PAN nanofibers. Thermodynamic parameters suggested the adsorption was spontaneous and endothermic. This work demonstrates the promise of electrospun zeolite/MWCNT nanofibers as adsorbents for removing lead from wastewater.

EDTA functionalized Mg/Al hydroxides modified biochar for Pb(II) and Cd(II) removal: Adsorption performance and mechanism

This study has successfully synthesized layered double hydroxide (LDH) biochar (E-Mg/Al-LDH BC) with ethylenediaminetetraacetic acid (EDTA) and examined its adsorption capabilities towards Pb(II) and Cd(II). The results demonstrate that the kinetics of heavy metal removal can be well described by the pseudo-second-order model. The intraparticle diffusion model indicates that the controlling steps for Pb(II) and Cd(II) are not uniform. The adsorption isotherm for Cd(II) conforms to the Langmuir model, while for Pb(II), it adheres to the Freundlich model. The distribution coefficient (Kd) shows that Pb has a significantly higher competitive adsorption capacity than Cd(II). Therefore, in comparison to single adsorption, the maximum adsorption capacity of Cd(II) in competitive adsorption decreased by 58.86%, while Pb(II) only decreased by 13.54%. Surface complexation, cation exchange, chemical precipitation, electrostatic interaction, and cation-π bonding are the inherent mechanisms by which E-Mg/Al-LDH BC removes heavy metal ions. E-Mg/Al-LDH BC has the potential to remediate heavy metal-contaminated water, and it also provides insights for the application of modified biochar in the treatment of multi-metal water pollution.

Assessing the Environmental Impact of Heavy Metal Contamination in Water, Sediments, and Aquatic Vegetation of River Yamuna in Delhi

Assessing the Environmental Impact of Heavy Metal Contamination in Water, Sediments, and Aquatic Vegetation of River Yamuna in Delhi

Efficient remediation of heavy metal-contaminated water using a magnetically collectible nanoscale Cu/Fe/rGO primary battery

The removal of highly toxic heavy metal ions is essentially the migration of heavy metal ions from water to materials through adsorption, complexation, exchange, and other forms. However, heavy metals still exist as highly toxic ions on the surface of materials, easily desorbed, and cause secondary pollution. In this study, a novel primary battery of graphene-supported zero-valent copper/iron bimetallic composites (Cu/Fe/rGO) was first prepared with copper as the positive electrode, iron as the negative electrode, and graphene as the "wire". The network-like nanoscale primary battery was fabricated for the reduction and removal of typical highly toxic heavy metal ions (Pb2+) from the water environment. The removal rate of Pb2+ within 20 min was 95.28%. The Pb-immobilized Cu/Fe/rGO primary battery after treatment can be easily separated via a weak magnetic field and maintained an excellent removal rate of Pb2+ during 6 cycles of use. The great potential of Cu/Fe/rGO primary battery in Pb2+ reduction removal was due to its high reduction ability, large surface area, and magnetic separability. This study provides an important foundation for the rapid and stable removal of heavy metals from water, which may have a tremendous application prospect in environmental fields.

Tackling Heavy Metal Pollution: Evaluating Governance Models and Frameworks

Water pollution by heavy metals represents a significant threat to both the environment and public health, with a pronounced risk of stomach cancer and fatalities linked to the consumption of heavy metal-contaminated water. Consequently, the need for effective governance in heavy metal remediation is paramount. Employing a comprehensive review of the existing literature, this study delves into prevalent governance models, including state-centric governance, market governance, network governance, and voluntary governance. The primary objective of this research is to pinpoint the optimal framework for heavy metal remediation and the most efficient governance model. Through an analysis informed by the simplified Multi-Criteria Decision Analysis (MCDA) method, this study presents key findings, offering valuable insights for policymakers, environmental agencies, and industries seeking holistic strategies to combat heavy metal pollution and alleviate its detrimental consequences. These findings significantly contribute to the ongoing global efforts to safeguard the environment, enhance public health, and mitigate the adverse impacts of heavy metal contamination.

Mechanisms of Zn removal from water by amorphous geopolymer: Molecular-level insights from X-ray absorption spectroscopy, isotope fractionation, and surface complexation modeling

Porous geopolymers have attracted widespread attention as promising heavy metal adsorbents that can be synthesized from aluminosilicate solid wastes. However, the precise microstructural evidence for adsorbed heavy metals on geopolymers remains unclear due to the insensitivity of conventional characterization techniques on minerals with amorphous structure and surface disorder. Batch adsorption and column experiments coupled with X-ray absorption spectroscopy (XAS), Zn stable isotope, and surface complexation model (SCM) were employed to reveal the Zn removal mechanisms with coal fly ash porous geopolymer (CFAPG) at a molecular scale. The macroscopic kinetic and isothermal adsorption of Zn on CFAPG were well described by the pseudo-second-order model and Bi_Langmuir equation, respectively, indicating the presence of abundant heterogeneous active sites on the CFAPG surface. Two types of active sites on the CFAPG surface were identified by XAS coupled with Zn isotopes in batch experiments at pH ≤ 6.0: one is pH-dependent and associated with tetrahedral zinc coordination, and the other is pH-insensitive and associated with octahedral zinc coordination; these sites were confirmed by the bidentate SCM as the variable charge site (surface complexation, >S-OH) and the permanent negative charge site (cation exchange, >X–), respectively. Furthermore, the important contribution of surface co-precipitation besides surface complexation and cation exchange to the Zn adsorption on CFAPG was identified by XAS coupled with SCM in a flow-through column experiment at pH >6.0. These investigations provide a systemic understanding of the Zn adsorption mechanisms on CFAPG and an SCM reference for the application and prediction of geopolymers in heavy metal-contaminated water remediations.

Coffee grounds modified zero-valent iron for efficient heavy metal removal

Surface modification is one of the most important approach for improving the reactivity of zero-valent iron. In this study, waste coffee grounds (CG) were chosen to modify zero-valent iron through a mechanochemical method. The synthesized CG-ZVI exhibited a 166 times faster Cr(VI) removal rate. Structural characterization and ATR-FTIR analysis indicated that CG modification endowed ZVI with abundant carboxylic acid groups, and accelerated the adsorption of Cr(VI) via the complexation effect of CG-COOH···HCrO4−. Moreover, the polyphenolic substances from CG-ZVI, as an electron shuttle, accelerated the electron transfer from the iron core to generated surfaced bound Fe2+, resulting in high efficiency of Cr(VI) removal. In addition, CG-ZVI selectively removed Cr(VI) in the presence of anions (Cl−, NO3−, SO42−) and acted as a permeable reactive barrier material for in situ treatment of heavy metal-contaminated water. This work demonstrates that CG modification can function as an excellent candidate for perfecting the reactivity of ZVI. More importantly, it opens up a new way for the utilization of discarded CG.

Water Quality Degradation Due to Heavy Metal Contamination: Health Impacts and Eco-Friendly Approaches for Heavy Metal Remediation.

Water quality depends on its physicochemical and biological parameters. Changes in parameters such as pH, temperature, and essential and non-essential trace metals in water can render it unfit for human use. Moreover, the characteristics of the local environment, geological processes, geochemistry, and hydrological properties of water sources also affect water quality. Generally, groundwater is utilized for drinking purposes all over the globe. The surface is also utilized for human use and industrial purposes. There are several natural and anthropogenic activities responsible for the heavy metal contamination of water. Industrial sources, including coal washery, steel industry, food processing industry, plastic processing, metallic work, leather tanning, etc., are responsible for heavy metal contamination in water. Domestic and agricultural waste is also responsible for hazardous metallic contamination in water. Contaminated water with heavy metal ions like Cr (VI), Cd (II), Pb (II), As (V and III), Hg (II), Ni (II), and Cu (II) is responsible for several health issues in humans, like liver failure, kidney damage, gastric and skin cancer, mental disorders and harmful effects on the reproductive system. Hence, the evaluation of heavy metal contamination in water and its removal is needed. There are several physicochemical methods that are available for the removal of heavy metals from water, but these methods are expensive and generate large amounts of secondary pollutants. Biological methods are considered cost-effective and eco-friendly methods for the remediation of metallic contaminants from water. In this review, we focused on water contamination with toxic heavy metals and their toxicity and eco-friendly bioremediation approaches.

Heavy metal contamination and risk assessment on ecological and public health in a tropical estuarine river

Heavy metals contamination of water is one of the most severe environmental and public health issues. The present study was conducted to assess the levels of lead (Pb), chromium (Cr), cadmium (Cd), arsenic (As), copper (Cu) and zinc (Zn) in surface water of the Pasur River estuary in Bangladesh along with their health risk through the ingestion and dermal exposure. The decreasing order of studied metals was Cr > Pb >Cu > Zn > As > Cd with the mean value of 0.050 > 0.024 > 0.021 > 0.014 > 0.012 > 0.006 mg/L respectively. Pb, Cr, Cd and Zn concentration in water samples exceeded the safe limits of drinking water and thereby not safe for drinking. The multivariate analysis identified the common anthropogenic source and existence of studied metals. Heavy metal pollution index (HPI) and heavy metal evaluation index (HEI) indicated significant contamination of water. The HQ and HI through ingestion and dermal contact were <1 except for the adult, whereas HQ (only for As) and HI value through ingestion was >1 indicating an unacceptable risk of non-carcinogenic effects on public health. Carcinogenic risk through ingestion (CRing) indicated that consumption of water from Pasur River estuary may develop cancer risk of Cd. Therefore, strict rules and regulations must be adopted to reduce water contamination of this tidal river from anthropogenic sources for improving the health of this riverine ecosystem.

An In Vitro Study of the Effects of Temperature and pH on Lead Bioremoval Using Serratia marcescens

Heavy metal contamination of water is a widespread problem in Peru and represents a potential threat to the ecosystem. Bacteria are an ecological alternative to treating these effluents. This research aims to determine the influence of temperature and pH on the lead (Pb) bioremoval in surface water using Serratia marcescens under laboratory conditions. The sample was collected from a stream located in Santiago de Chuco City (Peru). Treatments (T) were carried out by combining pH (5 and 7) and temperature (25, 30, and 35 °C). The bacterial inoculum (S. marcescens) was 3 × 108 CFU/mL, which was constant in all treatments. The lead bioremoval evaluation was performed in an airlift bioreactor and the incubation time was 24 h. The total lead concentration was determined using atomic absorption spectrophotometry. The results show that treatment 6 (temperature: 35 °C, pH: 5, and inoculum: 3 × 108 UFC/mL) showed a better result than the other treatments, with a removal value of 63.94%. Furthermore, the total lead concentration decreased from an initial concentration of 0.268 mg Pb/L to a final value of 0.0964 mg Pb/L. These results are still above the allowed water value (15 µg/L) according to Peruvian standards. On the other hand, temperature and pH influenced lead removal from surface water when S. marcescens was used after a short incubation period (24 h). Although an attempt was made to improve lead bioremoval by varying two parameters, temperature and pH, future research is still needed to investigate the effect of different inoculum concentrations, the use of microbial consortia, and a broader range of physicochemical parameters.

Biochar supported metallo-inorganic nanocomposite: A green approach for decontamination of heavy metals from water.

Heavy metal contamination of water has become a global environmental burden, which has stirred up agitation worldwide. Fabrication of adsorbents utilizing either low cost, environment friendly materials or waste products can be helpful in remediating environmental pollution. The current study evolved around the synthesis of nanocomposites derived from such raw precursors like spent tea waste biochar, hydroxyapatite, and clays. In this context, two nanocomposites, namely manganese ferrite doped hydroxyapatite/kaolinite/biochar (TK-NC) and manganese ferrite doped hydroxyapatite/vermiculite/biochar (TV-NC), were synthesized followed by their employment for decontamination of heavy metals from aqueous media. TK-NC and TV-NC exhibited the crystallite sizes in the range of 2.55-5.94 nm as obtained by Debye Scherrer Equation and Williamsons-Hall equation The fabricated nanocomposites were characterized using FT-IR, SEM-EDX, and powder XRD. Batch adsorption studies were performed, and influence of different adsorption parameters (contact time, reaction temperature, solution pH, adsorbent dose, and initial adsorbate concentration) on metal adsorption was examined. Thermodynamic studies revealed that the adsorption of Cr(VI), Ni(II) and Cu(II) on TK-NC and TV-NC was endothermic (+ΔH°) and indicates disorderness (+ΔS°) at the solid-liquid interface owing to the strong affinity of metal ions with adsorbent. The heavy metal uptake selectivity followed the following decreasing order; Cr(VI) > Cu(II) > Ni(II) by both nanocomposites, with adsorption capacities falling in the range of 204.68-343.05 mg g-1. Several adsorption kinetic and isotherm models were applied to experimentally calculated data, which suggest favorable adsorption of Cr(VI), Ni(II) and Cu(II) by TK-NC and TV-NC from the system while obeying general-order kinetics and R-P adsorption model, conferring the transition in adsorption kinetics order and involvement of multiple adsorption process.

Application of CO2-loaded geopolymer in Zn removal from water: A multi-win strategy for coal fly ash disposal, CO2 emission reduction, and heavy metal-contaminated water treatment

Coal fly ash accumulation, global warming, and heavy metal-contaminated water environments are three primary environmental concerns. Porous geopolymers are economical porous adsorbents that can be produced using coal fly ash as a raw material and employed for heavy metal removal from water. However, residual alkalis on the geopolymer can lead to extreme increases in pH and cause environmental stresses, which limits the large-scale production and application of geopolymers in industries and environments. A green approach to alleviating the high basicity of geopolymers through CO2 exposure is proposed, with CO2 adsorption experiments as well as Zn removal batch and column experiments conducted to evaluate the practicality of the synergistic strategy. CO2 adsorption experiments show the CO2 capture capacity of fresh geopolymer (F@PG) is 0.80 mmol g−1, greater than that of the conventionally washed geopolymer (W@PG, 0.26 mmol g−1), with the pH of the geopolymer decreasing after both washing and CO2 exposure. Batch experiments suggest neither washing nor CO2 exposure cause a significant change in the Zn adsorption capacity of the geopolymer; column experiments show the CO2-exposed geopolymer (C@PG) has a pH < 9.5 and a satisfactory Zn removal performance similar to W@PG, but F@PG with a pH ∼12 results in a conversion of Zn to anionic forms and a decrease in Zn removal efficiency. These results indicate CO2 exposure is a practical method to decrease the pH of geopolymers for applications related to heavy metal-contaminated water treatment and provide a large-scale industrial option for coal fly ash consumption and CO2 emission reduction.

Synthesis of imidazothiazole Schiff base functionalized silica as an adsorbent for efficient and selective removal of Cu(II) from wastewater: a combined experimental and theoretical investigation

Today's world faces a serious problem of heavy metal contamination in water, which can lead to serious health and environmental problems. In this work, an efficient and selective sorbent is synthesized, characterized, and reported to be used for adsorption of Cu(II) from aqueous solution. The obtained hybrid material was systematically characterized by Fourier-transform infrared spectroscopy, scanning electron microscope, and thermogravimetric analysis were confirmed that the imidazothiazole Schiff base was successfully functionalized the silica surface. Parameters influencing adsorption performance such as pH, time, initial concentration, and temperature were studied in the batch method. The results show that the excellent adsorption capacity of the adsorbent for Cu(II) ions was 110.33 mg/g at 30 min and pH = 6. Furthermore, the Cu(II) adsorption process exhibits a pseudo-second-order kinetic model and a Langmuir adsorption isotherm. Thermodynamic studies confirmed that the reaction was spontaneous and endothermic. Moreover, the adsorbent presents the better adsorption selectivity toward Cu(II). The coexisting cations did not show any competing effect on Cu(II) adsorption, and the adsorption performance did not decline appreciably after 5 cycles. The high adsorption efficiency of the sorbent provides potential applications for copper removal from wastewater. Theoretical methods using density functional theory, quantum theory of atoms in molecules (QTAIM), electron localization function (ELF), and localized orbital locator (LOL) confirm the experimentally discovered results. This study suggests that this adsorbent is an attractive material for the selective removal of Cu(II) from wastewater.

Hexavalent chromium bioreduction by chromium-resistant sporulating bacteria isolated from tannery effluent

The main polluting source of heavy metal contamination of water is the leather tanning industry, which uses chrome powder and discharges it into the nearby ecosystem. In this investigation, chromium-resistant bacterial strains were isolated and characterized from tannery effluent. Based on morphological and biochemical characterization, the predominant sporulating Bacillus sp. was isolated and identified as Bacillus subtilis based on 16S rRNA gene sequencing. Chromium degradation by the bacterial strain was evaluated using the flask culture method at three different concentrations (300, 600, and 900 µg/ml) of Cr (VI), and the reduction potential of the isolated bacterium was analyzed by Atomic Absorption Spectrophotometry. A maximum reduction of approximately 78% was found at 24 hrs of incubation at pH 7 and at a constant temperature of 30°C. More than 50% of the Cr(VI) was decreased in 24 hours when the Cr(VI) concentration varied from 300 to 900 g/ml. FTIR analysis showed the involvement of hydroxyl and amine groups in chromium adsorption. As an outcome, this strain could be a promising bioagent for the environmentally friendly elimination of toxic Cr(VI) from polluted environments.

Level of Some Heavy Metal Contamination of Water and Sediments of River Pil-Gani Plateau State Nigeria

Level of Some Heavy Metal Contamination of Water and Sediments of River Pil-Gani Plateau State Nigeria

Analisis Logam Berat pada Air Waduk Tunggu Pampang

Water pollution is the entry or inclusion of living things, substances, energy and or other components into the water by human activities, so that the quality of the water drops to a level that causes the water to not function according to its designation. The Waiting Pampang Reservoir is open and accessible to the general public including fishing activities. The consequences if the water in this reservoir contains heavy metals will also accumulate in marine biota (fish). If these fish are consumed, it will have an impact on human health. This study aims to determine heavy metals in the waiting reservoir water in the city of Makassar. Analysis of the metal content of Hg,Pb,Cu and Cd in the sample using the Atomic Absorption Spectrophotometry (AAS) calibration curve method. Before the samples were analyzed in SSA, sample preparation was carried out using the wet destruction method. The results of the analysis with SSA showed that the heavy metals in the sample had exceeded the threshold set by the 2011 Minister of Health, namely mercury (Hg) of 0.015, lead (Pb) of 0.08, copper (Cu) of 0.05 and cadmium (Cd) of 0. ,05. In conclusion, the water sample of the Waiting Pampang Reservoir has exceeded the maximum limit for heavy metal contamination in water that has been set by the government. It is recommended to add more sampling points to reservoir water.

Evaluation of human health and ecological risk of heavy metals in water, sediment and shellfishes in typical artisanal oil mining areas of Nigeria.

Heavy metal contamination in water and sediment is a serious concern in nations that depend heavily on natural resources such as Nigeria. In most coastal communities around oil mining areas in Nigeria, drinking water quality, staple food, and livelihoods are primarily dependent on ecological systems and marine resources (e.g., fish). Thus, humans and other receptors are exposed to heavy metal risks through ingestion and dermal contact. This research evaluated the potential ecological risks of heavy metals including Cadmium (Cd), Chromium (Cr), Nickel (Ni), and Lead (Pb) in water, sediments, and shellfishes (Callinectes amnicola, Uca tangeri, Tympanotonus fuscatus, Peneaus monodon) along the Opuroama Creek in Niger Delta, Nigeria. The concentrations of heavy metals were measured in three stations using the Atomic Absorption Spectrophotometer and their relative ecological (geo-accumulation index and contamination factor) and human health risk (hazard index and hazard quotient) analysed. The toxicity response indices of the heavy metals indicate that the sediments pose significant ecological risk particularly with Cd. None of the three exposure pathways to heavy metals in the shellfish muscles and age groups pose a non-carcinogenic risk. Total Cancer Risk values for Cd and Cr exceeded the acceptable range (10-6 to 10-4) established by USEPA in children and adults, raising concerns of potential cancer risks following exposure to these metals in the area. This established a significant possibility of heavy metal risks to public health and marine organisms. The study recommends conducting in-depth health analysis and reducing oil spills while providing sustainable livelihoods to the local population.

Fabrication of Aptamer-based Field Effect Transistor Sensors for Detecting Mercury Ions

This study presents an extended gate aptamer-based FET sensor for the detection of mercury ions in water. Heavy metal contamination in water can pose a severe threat to human health, and mercury ions are particularly dangerous as they can accumulate in the human body and cause serious health problems. The sensor provides high selectivity and sensitivity, even in the presence of other heavy metals, and achieves a detection limit of 0.2 ppm using a 500 μm x 500 μm gate sensing area. This cost-effective and efficient method can contribute to the mitigation of environmental pollution and the protection of public health.

Montmorillonite-mediated electron distribution of zirconium phosphate for accelerating remediation of cadmium-contaminated water and soil

Rapid and efficient remediation of heavy metal-contaminated water and soil bodies has been a hot topic in ecological remediation. However, designing and synthesizing green remediation materials with fast kinetics and high adsorption capacity is still challenging. In this study, a novel heavy metal remediation material (Mt@ZrP) has been prepared using montmorillonite to induce the structural rearrangement of zirconium phosphate (ZrP). The results showed that montmorillonite could mediate the external electron distribution of ZrP, thus increasing its O 1 s binding energy. Distinct from the electrostatic adsorption of bare ZrP, Mt.@ZrP with higher orbital binding energy led to an extra adsorption mode with internal spherical coordination. Such characteristics dramatically shortened the adsorption equilibrium time (23 min) and enhanced the adsorption capacity (275.6 mg/g-ZrP) of Mt.@ZrP for Cd removal in comparison to those of bare ZrP (220 min, 196.1 mg/g-ZrP). As for soil remediation, Mt.@ZrP presented a faster Cd removal rate than bare ZrP. The residual fraction increased from 22.03% (control) to 28.47% (Mt@ZrP, 1 wt%) and 37.54% (Mt@ZrP, 3 wt%), which significantly decreased the biological efficacy of Cd in the soil. These findings could provide a novel strategy for the design and synthesis of excellent remediation materials for the rapid and efficient removal of heavy metals in water and soil.

Preparation of Functionalized Palm Kernel Shell Bio-adsorbent for the treatment of heavy metal-contaminated water

Human beings and living creatures are at great risk because of heavy metal contamination in water resulting from industrialization. On the other hand, millions of tons of palm kernel shells (PKS) and other oil palm wastes are produced every year from oil palm downstream industries. In this study, we attempt to consolidate both problems, where the PKS was oxidized with sulfuric acid for the formation of PKS-Sulfo, where the oxygenated and sulfonated functional groups are attached to the activated carbon. The resulting PKS-Sulfo bio-adsorbent was characterized in detail and was used for the treatment of heavy metal-contaminated water. Different adsorption parameters; pH, concentrations of metal ions, contact time, and adsorbent dosage were optimized. It was found that the PKS-Sulfo bio-adsorbent is highly efficient in adsorbing heavy metal ions; Cr6+, Pb2+, Cd2+, and Zn2+ from their aqueous water solutions. The adsorption process was found to follow the pseudo-second-order model and the Langmuir isotherm was better fitted compared to the Freundlich adsorption isotherm for the adsorption process of the heavy metal ions. Furthermore, the adsorption capacities were also determined for all the metal ions were found to be 99% for Cr6+ and Pb2+ and Cd2+ and Zn2+ was found to be 80 % and 70% respectively. This study opens up a new horizon for the preparation of functionalized bio-adsorbents with the potential for numerous applications, especially for water remediation.