Metals In Wastewater Research Articles

Effects of Cu (II) on the Growth of Chlorella vulgaris and Its Removal Efficiency of Pollutants in Synthetic Piggery Digestate.

C. vulgaris has a positive effect on the removal of nutrients from pig farm biogas slurry. However, swine wastewater often contains heavy metal ions, such as Cu (II), which may have impacts on the nutrient removal performance of C. vulgaris. Additionally, the heavy metal ions in wastewater can be adsorbed by microalgae. In this study, the stress effect of Cu (II) on the growth of Chlorella vulgaris, the Cu (II) removal by microalgae, and the effect of different concentrations of Cu (II) on the nutrient removal efficiency of C. vulgaris in biogas slurries were explored. The results showed that the microalgae biomass of microalgae on the sixth day of the experiment was the highest in the treatment with a Cu (II) concentration of 0.5 mg/L, which was 30.1% higher than that of the 2.5 mg/L group. C. vulgaris had higher removal efficiencies of Cu (II) at a Cu (II) concentration of 0.1~1.5 mg/L. The-OH, C=O, -COOH, and C-O groups on the surface of the algal cells play a significant role in the removal of Cu (II). The removal rates of COD, NH3-N, TN, and TP by C. vulgaris at a Cu (II) concentration of 0.5 mg/L were the highest, which were 89.0%, 53.7%, 69.6%, and 47.3%, respectively.

Highly efficient recovery of Zn2+/Cu2+ from water by using hydrotalcite as crystal seeds

The efficient and waste-free recovery of heavy metals is critical for heavy metal wastewater treatment. In this work, we explored how heavy metals can be recovered as valuable chemicals in the presence of crystal seeds. Hydrotalcite (one kind of layered double hydroxides (LDHs)) was used as crystal seeds to recover Zn2+ in the presence of Al3+ from water (i.e., seed-Zn2+-Al3+ system), which was compared with the monometallic heterogeneous system (seed-Zn2+) and direct coprecipitation (Zn2+-Al3+) system. Our results demonstrated that the seed-Zn2+-Al3+ system possessed a recovery rate of 2.6–2.8 times and a recovery kinetic rate of 2.7–5.9 times higher than those of the other two systems. Differing from the latter two systems, hydrotalcite seeds could induce Zn2+ and Al3+ to form ZnAl-LDH in seed-Zn2+-Al3+. Interestingly, the ZnAl-LDH presents a compositional divalent/trivalent cation molar ratio of ca. 3, which is comparable with the value in the hydrotalcite. It was demonstrated that the hydrotalcite seeds could act as a template to significantly induce the formation of ZnAl-LDH complying with the seed's structure and compositional ratio. Similar induction effect of seeds as the Zn2+ system was further verified in Cu2+ systems. This work provides a novel strategy for efficient recovery of heavy metals with product selectivity.

Ion-exchangeable and sorptive reinforced membranes for efficient electrochemical removal of heavy metal ions in wastewater

This study presents the design, characterization, and application of a novel multifunctional membrane specifically developed for an electrochemical system similar to electrodialysis, with the objective of removing low-concentration copper ions from semiconductor wastewater. The membranes were fabricated using the pore-filling method, where porous polytetrafluoroethylene (PTFE) substrates were impregnated with monomer blend solutions containing vinyl phosphonic acid (VPA) and crosslinking agents, such as polyethyleneglycol dimethacrylate (PEGDMA), acrylated thiourea (ATU), and acrylated tannic acid (ATA), with the ladder two synthesized crosslinkers serving roles as sorptive functionality. These pore-filling membranes exhibited excellent mechanical and dimensional stability, rendering them suitable for application in the electrochemical metal ion sorption system. To evaluate the performance of the fabricated membrane, several key parameters were assessed, including ion exchange capacity (IEC), ionic conductivity (∼110.6 mS/cm), and excellent reusability. Batch-type sorption experiments were conducted to investigate the sorption performance at pH 5 and pH 7, and as a result of applying the membranes to the electrochemical sorption removal system, the membranes demonstrated remarkable efficacy, reducing the copper concentration from 1 ppm to 0.01 ppm. Finally, we confirmed the membrane's ability to remove less than 0.01 ppm of copper even in industrial semiconductor wastewater, validating its practical applicability.

Selective metal recovery by mucin: turning gold from wastewater into a peroxymonosulfate-activated catalyst

This study explores mucin's ability to selectively recover gold (Au) from metal wastewater. The Au, in the form of a nanoparticle, was utilized in peroxymonosulfate activation for the degradation of bisphenol A.

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.