Metals In Wastewater Research Articles

Comprehensive Experimental Design for the Preparation of the Magnetic Adsorbent Based on <i>Enteromorpha Prolifera</i> and Its Utilization in the Purification of Heavy Metal Ions Wastewater

Comprehensive Experimental Design for the Preparation of the Magnetic Adsorbent Based on <i>Enteromorpha Prolifera</i> and Its Utilization in the Purification of Heavy Metal Ions Wastewater

Adsorption thermodynamics and kinetics of hydrochloric-acid-modified bentonite for Zn(II) in wastewater

In order to study the Zn(II) adsorption characteristics of hydrochloric-acid-modified bentonite in wastewater, physical characterization of hydrochloric-acid-modified bentonite was carried out, the effects of the initial concentration, reaction time, and temperature on the Zn(II) adsorption were investigated, and the adsorption kinetics and thermodynamic mechanism of the hydrochloric-acid- modified bentonite adsorption of Zn(II) were examined. The results showed that hydrochloric acid modification increased the interlayer spacing of the bentonite, and the structure of the binding between slices became looser. Hydrochloric acid modification altered the hydroxyl groups on the bentonite surface, and the hydrophilicity was enhanced. The Zn(II) adsorption capacities of bentonite and hydrochloric-acid-modified bentonite increased with the increase in the initial Zn(II) concentration, and the adsorption followed the Langmuir and Freundlich equations. The thermodynamic parameters suggested that the adsorption of Zn(II) was an endothermic, spontaneous, and entropy-increasing process. The adsorption basically reached equilibrium within 120 min, and the adsorption followed the quasi-second-order adsorption kinetic equation. The adsorption process was mainly chemical adsorption, and the intra-particle diffusion process was not the only step controlling the adsorption rate. This study provides a theoretical basis for the remediation of toxic metal wastewater and contaminated soil.

危险废物多种重金属废水的预处理工艺研究

危险废物多种重金属废水的预处理工艺研究

An efficient hexavalent chromium scavenger: Polyaniline

Hexavalent chromium ions are a significant type of heavy metal pollutant in water, posing a severe threat to the environment and biological health. Various methods are employed for treating heavy metal wastewater, including traditional, biological, physical, and chemical adsorption, and membrane separation methods. This study focuses on utilizing chemical oxidation polymerization to synthesize polyaniline, followed by structural characterization and performance evaluation. The research shows the material’s exceptional adsorption capacity for Cr(VI) ions under different conditions. The experiments specifically demonstrate a direct relationship between the rate of removal and the proportion of adsorbent utilized in comparison to the Cr(VI) initial concentration. Furthermore, adjusting the pH level during testing shows an increase in the removal rate as the pH decreases, with a peak removal rate of 57.94% at pH 1.02. By aligning with a pseudo-second-order kinetic model, the material demonstrates its potential for efficient and effective removal of Cr(VI) contaminants.

Enhanced microalgal biomass and lipid production with simultaneous effective removal of Cd using algae-bacteria-activated carbon consortium added with organic carbon source

Recently, using microalgae to remediate heavy metal polluted water has been attained a huge attention. However, heavy metals are generally toxic to microalgae and consequently decrease biomass accumulation. To address this issue, the feasibility of adding exogenous glucose, employing algae-bacteria system and algae-bacteria-activated carbon consortium to enhance microalgae growth were evaluated. The result showed that Cd2+ removal efficiency was negatively correlated with microalgal specific growth rate. The exogenous glucose alleviated the heavy metal toxicity to algal cells and thus increased the microalgae growth rate. Among the different treatments, the algae-bacteria-activated carbon combination had the highest biomass concentration (1.15 g L−1) and lipid yield (334.97 mg L−1), which were respectively 3.03 times of biomass (0.38 g L−1) and 4.92 times of lipid yield (68.08 mg L−1) in the single microalgae treatment system. Additionally, this algae-bacteria-activated carbon consortium remained a high Cd2+ removal efficiency (91.61%). In all, the present study developed an approach that had a great potential in simultaneous heavy metal wastewater treatment and microalgal lipid production.

Wood aerogels decorated amino-functionalized MIL-101(Cr) as efficient filter for multistage purification of wastewater

Exploring novel water purifier to efficiently remove heavy metal ions from the wastewater is of vital importance. Inspired by the hierarchical structure of natural wood and the chelation of amino group, a high-efficiency water purifier with ethylenediamine functionalized MIL-101(Cr) octahedrons anchored on the wood aerogel (MIL-101(Cr)-ED/WA) was constructed. Benefiting from the two-pronged approach with the hierarchical structure of the wood aerogel frame for multistage filtration and the –NH2 that capable of chelation with metal ions, the fabricated MIL-101(Cr)-ED/WA exhibits excellent water purification performances, and its adsorption capacity of toxic Pb2+ ions could reach up to 6.46 mmol g−1. Furthermore, it demonstrates superior recyclability without secondary pollution and is also suitable for simultaneous treatment of multiple metal species. In general, this work will broaden the utilization of wood-based structural engineering materials in the treatment of heavy metal wastewater.

Trapping of heavy metal ions from electroplating wastewater with phosphorylated double-shelled hollow spheres

The mesoporous multi-shelled hollow structures are promising for trapping of non-degradable heavy metal ions in wastewater but difficult to synthesize. We successfully demonstrated a simple strategy for the construction of mesopore windows on double-shelled α-Fe2O3 hollow spheres. A step-by-step proof of concept synthesis mechanism has been revealed by using mainly electron microscopy and thermogravimetric analysis. We proved that mesopore windows are indispensable to realize the complete surface coverage of phosphonate ligands on α-Fe2O3 double-shelled hollow spheres. The phosphonic groups inherently coordinated with Ni(II) and Cu(II) ions and formed complexes of high stability. Importantly, owing to the structural merits, the phosphorylated double-shelled hollow spheres selectively removes Ni(II) and Cu(II) at wider sample pH range with a high capacity of 380 mg g−1 and 410 mg g−1, respectively. In addition, no significant decrease in the removal efficiency was observed under high salt matrix. For electroplating industry wastewater, the novel structure performs simultaneous Ni(II) and Cu(II) removal, thus producing effluent of stable quality that meets local discharge regulations.

Engineered Bacillus subtilis Biofilm@Biochar living materials for in-situ sensing and bioremediation of heavy metal ions pollution

The simultaneous sensing and remediation of multiple heavy metal ions in wastewater or soil with microorganisms is currently a significant challenge. In this study, the microorganism Bacillus subtilis was used as a chassis organism to construct two genetic circuits for sensing and adsorbing heavy-metal ions. The engineered biosensor can sense three heavy metal ions (0.1–75 μM of Pb2+ and Cu2+, 0.01–3.5 μM of Hg2+) in situ real-time with high sensitivity. The engineered B. subtilis TasA-metallothionein (TasA-MT) biofilm can specifically adsorb metal ions from the environment, exhibiting remarkable removal efficiencies of 99.5% for Pb2+, 99.9% for Hg2+and 99.5% for Cu2+ in water. Furthermore, this engineered strain (as a biosensor and absorber of Pb2+, Cu2+, and Hg2+) was incubated with biochar to form a hybrid biofilm@biochar (BBC) material that could be applied in the bioremediation of heavy metal ions. The results showed that BBC material not only significantly reduced exchangeable Pb2+ in the soil but also reduced Pb2+ accumulation in maize plants. In addition, it enhanced maize growth and biomass. In conclusion, this study examined the potential applications of biosensors and hybrid living materials constructed using sensing and adsorption circuits in B. subtilis, providing rapid and cost-effective tools for sensing and remediating multiple heavy metal ions (Pb2+, Hg2+, and Cu2+).

Amine-functionalized UiO-66 incorporated electrospun cellulose/chitosan porous nanofibrous membranes for removing copper ions

Cellulose (CE)/chitosan (CS)/amine-functionalized zirconium 1, 4-dicarboxybenzene metal–organic framework (UiO-66-NH2) porous nanofiber membranes were prepared by direct electrospinning and surface in-situ growth and then used to remove copper ions (Cu2+) from polluted water. The micro-morphology, porosity, thermal stability, chemical groups, crystallographic structure, and adsorption performance of CE/CS/UiO-66-NH2 nanofibrous membranes were characterized. The hydrophilicity, thermal stability, and adsorption capacity of the membranes were greatly improved by incorporating UiO-66-NH2. The direct electrospinning CE/CS/UiO-66-NH2 nanofibers displayed the irregular, bumpy shapes and large fiber diameters (768.99–1039.74 nm). They also increased the chemical active sites due to the effective and uniform combination of UiO-66-NH2 with nanofibers. This resulted in a superior adsorption performance than the one with in-situ preparation. The CE/CS/UiO-66-NH2-5 showed the highest adsorption capacity of 121.16 mg g−1 and a removal rate of 90.69 %. The optimal Cu2+ adsorption conditions were obtained at an initial Cu2+ concentration of 100 mg L-1 and in weakly acidic media (pH = 5). The Langmuir model was optimal to describe Cu2+ adsorption of the nanofibrous membranes. The adsorption process involved both physical adsorption with chemical adsorption. This provides a novel strategy to combine metal–organic frameworks with the natural biomasses via electrospinning, which shows a promising application for efficient remediation of heavy metal ions in wastewater.

Research Progress of Treatment Method of Metal Ion in Wastewater

Along with the rapid development of urbanization in China, a series of environmental problems have accompanied, especially industrial effluents containing heavy metals such as lead, cadmium, mercury, etc., which have caused great damage to water, soil and earth, and have caused great harm to human health. In this article, new processes such as adsorption, membrane separation, chemical precipitation, ion exchange, bio-adsorption, and bio-reduction are introduced. The technology has shown excellent results in a variety of working conditions, opening up new ways for the treatment of heavy metal pollution in water. The development of this topic is of great and urgent practical significance for the protection of ecological environment and the promotion of sustainable development in China.

Application of Graphene Technology in the Removal of Heavy Metal Ions in Wastewater

Nowadays, heavy metal pollution has become a serious problem. Toxic heavy metal ions can result in extreme damage to the environment and human society. Under that situation, methods that can remove the heavy metal ions in water have been required. Graphene technology can be widely applied to the removal of heavy metal ions. This article will explain the preparation of graphene oxide and reduced graphene oxide and the efficiency and influence factors of the method applied in water treatment. The method can remove many kinds of mainly occurring toxic heavy metal ions with very high efficiency. Also, large-scale production of graphene oxide can be achieved. The removal of heavy metal ions in water by graphene technology can be a practical method in the water treatment field.

Reductive decomplexation of Cu(II)-complexes from copper wastewater by zero-valent aluminum material

In order to effectively remove the extremely stable Cu(II)-complexes, decomplexation is typically required, with previous efforts focusing on the destruction or substitution of organic ligands. Now, we have a new concept that if starting with Cu(II) group and reducing it directly from the complex state, the reductive decomplexation of Cu(II)-complexes may be attained along with the recovery of Cu(II) to Cu0. In this study, for the first time, we introduced a carbon-modified zero-valent aluminum material (C@mZVAl) for one-step reductive decomplexation of Cu(II)-complexes. It was found that 96.84% Cu-EDTA removal and 91.99% Cu0 recovery could be reached. Furthermore, this efficient reductive decomplexation approach was also applicable to other complexes such as copper pyrophosphate, copper tartrate and copper citrate. SEM-EDS, XPS and XRD showed that Cu0 appeared on the material's surface, providing evidences of successful reduction of complexed Cu(II). Cu-EDTA was firstly adsorbed because of the carbon’s adsorption, and then accepted the electrons released from the powerful reducer zero-valent aluminum to accomplish reductive decomplexation. Furthermore, without any pretreatment, two real industrial copper-plating wastewater containing copper pyrophosphate and Cu-EDTA were treated and the total Cu recovery rates were both achieved up to 98.00%. In conclusion, our innovative approach offers a novel method of decomplexation for the efficient recovery of reusable metal products from complexed metal wastewater through a direct reduction reaction.

Sulfate-reducing bacteria-based bioelectrochemical system for heavy metal wastewater treatment: Mechanisms, operating factors, and future challenges

Heavy metal wastewater (HMW) has resulted in many adverse environmental issues. However, bioelectrochemical system (BES) has been recognized as an effective technology for HMW treatment. This technology generates electricity and removes heavy metals and high concentrations of sulfate. In the sulfate-reducing bacteria-based BES, sulfate-reducing bacteria can anaerobically reduce sulfate to produce sulfide, which reacts with heavy metal ions and forms their corresponding sulfide precipitates, or the heavy metals can be reduced by obtaining electrons at the anode or cathode of the BES. Therefore, this study comprehensively reviews the removal mechanisms of HMW at the anodes and cathodes of the BES. The effects of several key factors, such as electrode materials, biocathode, initial heavy metal concentration, external resistance, and pH, on electricity generation performance and removal efficiency were evaluated. Furthermore, the treatment effects of the microbial fuel cell-microbial electrolytic cell system and the coupled system of BES with plants, artificial wetlands, and electrolytic reactors on HMW and the recovery efficiencies of BES for sulfur and heavy (precious) metals were discussed. Therefore, this review provides a theoretical basis and technical support to broaden the prospects of BES application in HMW remediation.

Synthesis and characterization of pectin-xanthate and their application in heavy metal and lignin enriched paper industry wastewater treatment

ABSTRACT Three grades of pectin xanthates (PX1, PX2, and PX3) have been prepared by the reaction of pectin with carbon disulfide (CS2) in an alkaline medium using NaOH, via the xanthation process. The percentage yield of prepared pectin xanthates has been found to be 87.06%, 90.38%, and 93.80% for PX1, PX2, and PX3, respectively. Prepared pectin xanthates and raw pectin were utilized for heavy metals (Cu(II) and Ni(II)) and lignin enriched paper industry wastewater (LEPIW) treatment. The removal percentage of pectin, PX1, P X2, and PX3 for Cu removal at optimum condition (adsorbent dose: 5.14 g/L, pH: 5 for Cu and 7 for Ni, optimum temperature: 50°C and time: 80 min for Cu(II) and 100 min for Ni(II)) has been found as 85%, 92.33%, 93.5%, and 94.66% and 76.66%, 89.44%, 91.66%, and 93.33%, respectively, for Ni removal. The LEPIW treatment efficacy for pectin, PX1, PX2, and PX3 has been found to be 54%, 77%, 83%, and 86% for the initial COD: 2000 mg/L, pH: 7, optimum temperature: 40°C in 105 min operation time. Adsorption isotherm studies suggest that Langmuir isotherm is most appropriate which indicates adsorption follows chemisorption. The adsorption capacities of PX1, PX2, and PX3 are found as 309.59, 352.11, and 380.22 mg/g for Cu(II) and 299.40, 315.45, and 328.94 mg/g and for Ni(II), respectively, which is very high in comparison with many other recent literature studies.

Ti3C2Tx MXene-derived hydroxyl-rich titanate based hybrid membrane with cellulose as structural regulator for highly-efficient disposition of heavy metal ions

Exploring an efficient and stable adsorbent material for purification of toxic heavy metal ions wastewater is of great significance. However, as a typical heavy metal ions adsorbent, titanate can still improve in material synthesis, adsorption efficiency and the recyclability. Herein, a novel titanate-based adsorbent which composing of Ti3C2Tx MXene-derived hydroxy-rich titanate and cellulose was fabricated for efficient removal of toxic heavy metal ions. Owing to the similar stratified structure, the conversion from Ti3C2Tx MXene to titanate is energy-saving and easy to achieve. In addition, the inherited hydroxy-rich property is beneficial to improve the adsorption efficiency of the derived titanate. Furthermore, the introduction of cellulose as a structural regulator to fabricate the titanate/cellulose membrane could greatly alleviate the problem of difficult recycling of powder adsorbent. Thus, the constructed Ti3C2Tx-derived hydroxy-rich titanate/cellulose membrane adsorbent (M-NTO/CM) exhibits high Cu2+ adsorption capacity of 2.63 mmol g−1 and can reach the adsorption equilibrium in only 5 min. Better yet, there has also been a significant improvement in acid resistance and recyclability of the M-NTO/CM relative to traditional titanate. In short, M-NTO/CM derived from Ti3C2Tx MXene can be used as an advanced membrane for convenient and efficient purification of heavy metal ions from the wastewater.

Chloride ion enhanced oxidant-free in situ degradation of Ni-EDTA by electrochemical process with boron-doped diamond electrodes

Conventional advanced oxidation processes were used to treat heavy metal complexes. However, a considerable amount of oxidants was required to enable effective oxidative degradation, which led to a significant increase of the treatment costs and subsequent difficulties in the sludge disposal. Based on the abundance of anions in heavy metal wastewater, the effects of anions on the in-situ degradation of Ni-EDTA in an oxidant-free electrochemical system with boron-doped diamond (BDD) as the anode were investigated. The presence of Cl- was found to exert a significant effect on improving the degradation process. Moreover, pH had little effect on the removal of nickel (Ni) and Ni-EDTA within a specific pH range (1 < pH < 9). The removal efficiencies of Ni and TOC reached 100 % and 77.45 %, respectively, at pH 2.16 with 0.4 M NaCl electrolyte, 2 mM Ni-EDTA concentration, and a current density of 50 mA/cm2. •OH and Cl• played crucial roles in the removal of Ni-EDTA by disrupting the chelation sites of Ni and EDTA molecules. The released Ni2+ ions could active the H2O2 in-situ generated at the cathode to produce •OH. The formation of the precipitation products such as NiOOH, Ni(OH)2, and NiCO3 in the Cl-/BDD system were conform based on the XRD and XPS analyses, which suggested the possible pathways for the removal of Ni2+ and Ni3+. Finally, the possible degradation pathways of Ni-EDTA were proposed based on the identification of intermediate products using UPLC-MS.

In situ polymerization of three-dimensional polypyrrole aerogel for efficient solar-driven interfacial evaporation and desalination

Solar-driven interfacial evaporation (SIE) and desalination is a promising approach to mitigate the scarcity of freshwater resources. Here, a three-dimensional polypyrrole (3D PPy) aerogel was prepared by in situ polymerization of pyrrole to serve as an independent evaporator. The interconnected pore structure and super-hydrophilicity enabled PPy evaporators with rapid water transport to the top interface (< 5 s). The hydrogen interaction between polymer chains and water molecules induced large amount of intermediate water, thereby reducing the evaporation enthalpy of water in PPy aerogels. As a result, the optimized PPy aerogel attained an evaporation rate of 2.90 kg m−2 h−1 and an energy conversion efficiency of 114% under 1 sun irradiation. Moreover, the generated steam can be accelerated by the convection and an evaporation rate as high as 6.10 kg m−2 h−1 was realized at 2.5 m s−1. The rapid water transport also enabled PPy aerogel with high-efficiency of self-salt-discharge and efficient desalination for 3.5 wt% brine under 2.5 m s−1. In the outdoor SIE experiment, the excellent evaporation performance was achieved at 12:40 (7.04 kg m−2 h−1 under 74.2 mW cm−2 of solar intensity and 2.5 m s−1 of convective flow), and the cumulative evaporation of 41.50 kg m−2 for successive 9 h was obtained. After the evaporation of simulated seawater and heavy metal wastewater, the concentration of collected fresh water could be reduced about 2–3 orders of magnitude. This 3D PPy evaporation platform with high light absorption, porous structure, super-hydrophilic property, effective steam diffusion, and excellent salt resistance provides an effective way to develop advanced solar-driven water treatment technology.

Efficient Hg(Ⅱ) adsorption of polyphenol functionalized Poly(pyrrole methane)s: The role of acid doped ions

A series of doped and dedoped polyphenol functionalized poly(pyrrole methane)s (234HBAs) were designed to investigate the impact of various dopants on mercury adsorption in water. The adsorption performance of dedoped 234HBAs showed no significant difference (ranging from 2961 to 3004 mg·g−1 at 318 K). However, the adsorption capacities of doped 234HBAs for mercury exhibited significant optimization and varied among different dopants (ranging from 3676 to 4103 mg·g−1 at 318 K). In addition to ultra-high adsorption capacity, 234HBAs also exhibited broad working pH range (2–11), fast kinetics (adsorption equilibrium within 10 min), good anti-ion interference and selectivity (Kd > 7.1 × 105 mL·g−1), and excellent regeneration ability (little attenuation of adsorption capacity after 20 cycles). Furthermore, through characterization techniques (FT-IR, XPS) and the density functional theory (DFT) calculation, it was discovered that the presence of doped acid ions enhanced the capture and immobilization of mercury to varying extents besides the robust chelation binding of mercury by the adjacent phenolic hydroxyl groups. Among these ions, oxygen-containing citrate and sulfate exhibited a stronger ability to facilitate the removal of mercury compared with chloride ions. More importantly, this straightforward approach to fabricating functionalized adsorbents for the remediation of mercury-containing wastewater holds significant guiding implications for the treatment of other heavy metal and organic wastewater.

Highly salt-resistant organic-inorganic composite as a solar-driven interfacial evaporator for desalination and electricity generation

The desalination of seawater through solar-driven interfacial evaporation becomes an increasingly important and efficient route to solve the shortage of fresh water. However, this route faces a poor durability during the evaporation because of salt accumulation on the surface of photothermal material and its corrosion. Here, we put forward a novel strategy of constructing the organic-inorganic composite (FeS2-Mo2S3/GF@PDA@STA) as a photothermal material for desalination of seawater and heavy metal ion wastewater to generate clean water. In our work, FeS2-Mo2S3 and polydopamine (PDA) were integrated to achieve photothermal conversion, and then were covered by stearic acid (STA) to attain hydrophobic effect. Next, the hydrophobic photothermal material was further combined with hydrophilic air-laid paper to form a solar-driven evaporation system, which contained photothermal conversion and water supply. Under irradiation of 1 sun, this evaporation system achieved a high evaporation rate of 1.34 kg m−2 h−1 as well as photothermal conversion efficiency of 89 %. This evaporation system also offered an excellent durability at different light intensities, and superstrong salt-resistant ability. Besides, synergistic electricity generation was observed, and achieved a maximum output power of 0.18 W m−2 under 1 sun during the solar-driven interfacial evaporation. In addition, this evaporation displayed an excellent performance for purifying several heavy metal ion solutions such as Cr3+, Ni2+, Cu2+ and Pb2+, in which the ionic contents of the purified water were far lower than drinking water stated by WHO (World Health Organization) standard. This work opened up a novel avenue for desalination of seawater and purification of heavy metal ion wastewater to generate clean water through the organic-inorganic composite by virtue of solar-driven interfacial evaporation.

Photoelectrochemical advanced oxidation processes for simultaneous removal of antibiotics and heavy metal ions in wastewater using 2D-on-2D WS2@CoFe2O4 heteronanostructures

The presence of antibiotics in water poses significant threats to both human health and the environment. Addressing this issue requires the effective treatment of medical wastewater. Photoelectrochemical advanced oxidation processes (PEAOPs) are emerging as promising solutions for wastewater treatment. This process utilizes photocatalysts to convert charge carriers into reactive species such as hydroxyl radicals and superoxide ions, which are essential for degrading pollutants in wastewater. However, limitations in charge carrier separation and transport have hindered the efficiency of photoelectrochemical advanced oxidation processes. To overcome these limitations, we designed WS2@CoFe2O4 heterojunctions, optimizing their energy levels to enhance charge transport and separation. This improvement significantly increased the oxidation of antibiotics such as amoxicillin and azithromycin. Multiple reactions occurred at the WS2@CoFe2O4 heterojunctions during photoelectrochemical advanced oxidation processes, leading to the impressive degradation of up to 99% of antibiotics under visible light irradiation at 0.8 V. Urea and H2O2 acted as oxidation agents within photoelectrochemical advanced oxidation processes, amplifying the generation of hydroxyl radicals and superoxide ions, further enhancing antibiotic oxidation. Moreover, the WS2@CoFe2O4 photoanode efficiently oxidized toxic antibiotics while converting As(III) into the less harmful As(V). Crucially, recyclability tests confirmed the robustness of the WS2@CoFe2O4 photoanode, ensuring its suitability for prolonged use in photoelectrochemical advanced oxidation processes. Integrating WS2@CoFe2O4 photoanodes into water purification systems can enhance efficiency, reduce energy consumption, and improve economic viability. This technology's scalability and its ability to protect ecosystems while conserving water resources make it a promising solution for addressing the critical issue of antibiotic pollution in water environments.