Removal Of Copper Ions Research Articles

Remediate and sense: alginate beads empowered by portable electrochemical strips for copper ion removal and detection at environmental sites.

The contamination of environmental sites due to the presence of persistent species represents an important issue to be tackled. In particular, the presence of high levels of metals in soil and surface water is more frequent. One of the metals that sometimes exceeds the permissible limit set by regulatory authorities is copper. For instance, copper-based fungicides are widely used in viticulture. However, copper ions remain in soil and can enter the food chain, posing threats to human health and environmental safety. Although the rapid detection of copper ions using portable sensors is effective in enhancing early warning, it sometimes solves only half of the problem as remediation is not considered. In this paper, we present a novel integrated/portable approach that merges the remediation and sensing of metals by proposing a remediate-and-sense concept. In order to realize this concept, alginate beads were coupled with printed electrochemical strips for on-site copper detection. Within the same architecture, alginate beads were used to remove copper ions from the soil, and printed electrochemical strips were used to evaluate the efficacy of remediation at the point of need. The concept was applied towards soil containing copper ions at the parts per billion level; with few alginate beads and in the absence of additional species, copper ions were quantitatively removed from the matrix; and 3D printing allowed us to combine the printed strips and spheres within a unique tool. The architecture was optimized and the results were compared to inductively coupled plasma-mass spectrometry (ICP-MS) measurements with a recovery percentage of 90%-110%. It should be noted that this novel portable approach may be applied to other pollutants, opening new possibilities for integrated remediation and sensing.

Copper(II) ion removal from aqueous solutions using alginate nanoparticles/ carboxymethyl cellulose/ polyethylene glycol ternary blend: Characterization, isotherm and kinetic studies

This study addresses the critical issue of removing copper(II) ions from water using an eco-friendly approach with natural biomaterials. Alginate, a natural polysaccharide, is employed as the primary adsorption material. The study involves the conversion of alginate into nanoparticles, and a ternary blend is prepared by mixing alginate nanoparticles with carboxymethyl cellulose and polyethylene glycol (AL-NPs/CMC/PEG). The blend's morphological and structural transformations have been comprehensively investigated using techniques such as DLS, FT-IR, XRD, TGA, and SEM. Batch experiments were conducted systematically to investigate crucial parameters, such as contact time (60–300 min), initial copper concentration (62.5 ppm–1000 ppm), solution pH (2–8), and adsorbent dosage (1–5 g). The results obtained are highly encouraging, revealing an impressive 80.9 % efficiency in the removal of copper ions. The acquired experimental data were then subjected to analysis with Langmuir and Freundlich, isotherm, as well as pseudo-first and pseudo-second-order kinetics studies. The outcomes from these isotherm and kinetics models indicated a favorable fit with the Freundlich isotherm, suggesting a strong affinity between the adsorbent and the metal ions. Furthermore, the kinetic studies revealed that the adsorption process closely adheres to pseudo-second-order kinetics, underlining the efficiency and reliability of the adsorption process. From desorption studies, 0.1 M HCl was an extremely effective eluant when compared to HNO3 and EDTA. It could be reused three time with appreciate efficiency. The research underscores the potential for an environmentally sustainable solution to address the persistent environmental challenge posed by copper ion contamination.

Adsorption of Copper Ions from Aqueous Systems Using Moss Peat: Reaction Kinetics and Adsorption Isotherm

The removal of copper ions from aqueous systems using moss peat was investigated. Kinetic experiments were conducted at a constant temperature, pH, and initial copper concentration. The data obtained from the kinetic experiments were analysed and fitted well using the pseudo-second-order model. The data of the isotherm experiment were modelled and fitted well with the Langmuir models. This finding suggests that copper ions are chemically adsorbed on the moss peat and assume monolayer adsorption. The optimum pH for copper ion adsorption by moss peat was investigated over a range of (2-4.5), and it was found that the maximum adsorption capacity of moss peat was achieved at pH 4.5. The results of this study suggest the potential use of moss peat as an effective material for the adsorption of copper ions from aqueous solutions under a range of environmental conditions.

Simultaneous removal of tetracycline and copper ions from wastewater by flow-electrode capacitive deionization

ABSTRACT To effectively solve the problem of tetracycline (TC) and Cu2+ contamination in wastewater, this study innovatively proposed a low-energy flow-electrode capacitive deionization (FCDI) technology to simultaneously remove TC and Cu2+ from wastewater. The removal efficiencies of TC and Cu2+ using FCDI was investigated under various voltages, electrode flow rates, influent flow rates, and electrode liquid concentrations. The results showed that the removal efficiency of TC and Cu2+ was 60.78% and 84.43%, respectively. The energy consumption for TC and Cu2+ removal was only 1.76 and 1.10 kWh kg−1, which was lower than other electrochemical systems. The ion removal performance of the FCDI system remained stable after six cycles of continuous operation. These findings demonstrated the promising potential of FCDI as an innovative technology for the simultaneous removal of TC and Cu2+, presenting a significant prospects for application in the water treatment field.

Removing copper ion from wastewater by surface precipitation using novel hierarchical hydrated magnesium carbonate crystal

It is significant to develop a low-cost, easy-to-separate and efficient adsorbent to remove heavy metals from wastewater. Therefore, the hierarchical hydrated magnesium carbonate (HMC) crystal is prepared. The performances of HMC crystal at different adsorption conditions are studied. The surfaces of HMC crystal before and after Cu2+ adsorption are characterized by XRD, FTIR, XPS, SEM and EDS mapping. The removal efficiency of Cu2+ reaches 99 % under the conditions of an initial concentration of 300 mg/L, HMC dosage of 0.5 g/L, pH value of 4.5 and adsorption time of 180 min. The adsorption kinetic and isotherm can be described by the pseudo-second-order model and Langmuir adsorption model, respectively. The maximum adsorption capacity of Cu2+ is 1406 mg/g. The hierarchical structure provides HMC crystal with sufficient hydroxide ions for Cu2+ surface precipitation and large particle size (40–100 μm) for subsequent solid–liquid separation, presenting a promising application prospect in the future.

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.

Heavy Metal Remediation from Water/Wastewater Using Bioadsorbents - A Review

This paper aims to emphasize heavy metals’ impact on water and its removal mechanism with a focus on adsorption. Furthermore, factors affecting bio adsorption, such as temperature, pH, RPM, and initial heavy metal concentration, have been studied for different heavy metals and bioadsorbents. A comparison of their adsorption capacities and efficiencies has been made. This review reviewed different bioadsorbents for their suitability in removing cadmium, lead, and copper ions from water and wastewater, typically by using adsorption as a methodology. A suitable summary compares various heavy metal removal techniques and their advantages and limitations. For adsorption, the characteristics of bioadsorbents and their activation steps have been consolidated. Furthermore, the effects of operational parameters and adsorption mechanisms have been discussed in the review. Apart from assessing the suitability of bioadsorbent, a novel bioadsorbent has been suggested for copper ions removal. The findings shall be significantly useful in applying bioadsorbent in water/wastewater treatment fields to reduce heavy metal pollution. Thorough and well-planned research in this field can facilitate the creation of sustainable and durable technology for wastewater treatment, addressing the increasing demand for safe and dependable water resources, focusing on making it cost-effective and recyclable.

Linear Polyethyleneimine-Based and Metal Organic Frameworks (DUT-67) Composite Hydrogels as Efficient Sorbents for the Removal of Methyl Orange, Copper Ions, and Penicillin V.

This research explores the integration of DUT-67 metal organic frameworks into polyethyleneimine-based hydrogels to assemble a composite system with enough mechanical strength, pore structure and chemical affinity to work as a sorbent for water remediation. By varying the solvent-to-modulator ratio in a water-based synthesis path, the particle size of DUT-67 was successfully modulated from 1 μm to 200 nm. Once DUT-67 particles were integrated into the polymeric hydrogel, the composite hydrogel exhibited enhanced mechanical properties after the incorporation of the MOF filler. XPS, NMR, TGA, FTIR, and FT Raman studies confirmed the presence and interaction of the DUT-67 particles with the polymeric chains within the hydrogel network. Adsorption studies of methyl orange, copper(II) ions, and penicillin V on the composite hydrogel revealed a rapid adsorption kinetics and monolayer adsorption according to the Langmuir's model. The composite hydrogel demonstrated higher adsorption capacities, as compared to the pristine hydrogel, showcasing a synergistic effect, with maximum adsorption capacities of 473 ± 21 mg L-1, 86 ± 6 mg L-1, and 127 ± 4 mg L-1, for methyl orange, copper(II) ions, and penicillin V, respectively. This study highlights the potential of MOF-based composite hydrogels as efficient adsorbents for environmental pollutants and pharmaceuticals.

Copper (II) ions extraction by poly(N-vinylcaprolactam-mathacrylic acid) microgels for in situ reduction formation of copper nanoparticles to reduce pollutants

It is very important to eliminate organic dyes and most of the toxic transition metal ions from water because they are hazardous substances for livings. Many systems are reported to eliminate organic pollutants or transition metal ions solely from water. A new systematic way has been developed for effectively removal of both metal ions and organic pollutants (nitroarenes and toxic dyes). For this purpose, a spherical poly(N-vinylcaprolactam-co-methacrylic acid) P(NVC-MAAc) microgel system was developed by free radical precipitation polymerization (FRPP) method. The XRD, FTIR, SEM, DLS, and TEM techniques were used for characterization of P(NVC-MAAc) system and then used that system as an adsorbent for removal of copper (II) ions from water under a variety of conditions, including different P(NVC-MAAc) concentrations, pH, copper (II) ions contents, and agitation times. Various adsorption isotherms were applied to evaluate the best fitted adsorption isotherms for extraction of copper (II) ions with P(NVC-MAAc) microgel system. Furthermore, the kinetics of copper (II) ion adsorption on P(NVC-MAAc) were investigated using the pseudo-1st order (P1O), intra-particle diffusion model (InPDM), pseudo-2nd order (P2O), and Elovich model (EM). The loaded copper (II) ions in P(NVC-MAAc) microgel were then in-situ reduced to generate copper nanoparticles (NPs). The resulted [Cu-P(NVC-AAc)] hybrid microgels were used as catalyst to reduce toxic pollutants from water such as 4-nitrophenol (4NiP), 4-nitroaniline (4NiA), chromium (VI) ions (ChVI), rhodamine-B (RhB), methyl orange (MeO), and eyosin-Y (EyY). The values of apparent rate constant (kapp) for 4NiP, 4NiA, ChVI, RhB, MeO and EyY were found 0.725 min−1, 0.587 min−1, 0.097 min−1, 0.821 min−1, 0.860 min−1, and 0.833 min−1 respectively. As a result, a broad range of new organic transformations can be efficiently catalyzed by the Cu-P(NVC-MAAc) system.

Efficient removal of copper ions, zinc ions, and tetracycline in water by functionalized Canadian horseweed hydrothermal carbon: The combination of experiment and DFT calculation

A silicate-hydrothermal carbon composite material (GHC) was prepared by a one-step hydrothermal method using Canadian horseweed as raw material and cheap sodium silicate and magnesium sulfate as modification reagents for the adsorption of copper (Cu2+), zinc (Zn2+), and tetracycline (TC) in water. The results showed that maximum capacities of the adsorption of Cu2+, Zn2+, and TC by GHC are 211.92 mg·g−1, 224.96 mg·g−1, and 358.58 mg·g−1. TC can provide certain active sites for GHC to adsorb Cu2+ or Zn2+ in a binary system. When the concentration of Cu2+ or Zn2+ is low, i.e., <30 mg·L−1, it will promote GHC’s ability to adsorb TC. When the concentration of Cu2+ or Zn2+ is greater than 30 mg·L−1, the adsorption capacity of GHC to TC began to decrease. This may be related to the presence of too many complexes on the surface of GHC. Too many complexes will block the pores on the surface of GHC and reduce the effective adsorption sites of GHC. The different mechanisms for the adsorption of Cu2+ and Zn2+ are different from the adsorption of TC. In this study, 2D-COS and DFT calculations are used to explore these mechanisms. The results show that CO, CO, and CC are involved in the adsorption of Cu2+, Zn2+, and TC, and CO and CO have stronger capacities than CC for Cu2+, Zn2+, and TC. GHC has stable adsorption properties for Cu2+, Zn2+, and TC in different water samples, and has good regeneration performance. Thus, GHC is an economical and efficient adsorbent with good application potential.

Citric acid modified β-cyclodextrin for the synthesis of water-stable and recoverable CD-MOF with enhanced adsorption sites: Efficient removal of Congo red and copper ions from wastewater

Due to the complexity of wastewater pollutants and their adverse effects on human health and the environment, there is an urgent need for the development of a recyclable adsorbent capable of removing both dyes and heavy metals. In this study, citric acid modification β-cyclodextrin metal-organic framework (CA-β-CD-MOF) was synthesized by chemical grafting followed by vapor diffusion methods. The concentration, dosage, and pH of citric acid had a certain impact on the adsorption effect of the adsorbent. The adsorption capacities for the anionic dye Congo red (CR) and copper ions (Cu2+) were as high as 900.9 and 287.4 mg·g−1, respectively. The adsorption process could be well described by the Langmuir isothermal model. The adsorption kinetics of CR and Cu2+ conformed to the pseudo-second-order kinetic model. The adsorption process was a heat absorption and spontaneous process. The combination of density functional theory (DFT) calculations and experimental results proves that electrostatic interaction is the adsorption mechanism of CR. The adsorption of Cu2+ was attributed to the complexation between the carboxyl group on citric acid (CA) and Cu2+. The CA-β-CD-MOF we prepared has good adsorption performance and recyclability and has great potential in removing Congo red and copper ions from wastewater.

Copper Ion Removal Using a Waste-Plastic-Derived Hydrogel Adsorbent Prepared via Microwave-Assisted PET Aminolysis.

Despite the tremendous progress in the development of functional materials from plastic waste to promote its recycling, only a few examples of hydrogel materials from plastic waste were reported. In this study, microwave-assisted depolymerization of waste PET plastic using polyamine was performed to prepare short aminophthalamide oligomers followed by chemically cross-linking into a hydrogel material. Catalyst-free microwave-assisted aminolysis of PET was completed within 30-40 s, demonstrating high efficiency of the depolymerization reaction. Subsequent epoxy cross-linking of the oligomers yielded a hydrogel with a swelling degree of ca. 92.1 times in pure water. The application of the obtained hydrogel for the removal of copper ions (Cu2+) from water was demonstrated. Efficient complexation of NH2 groups of the hydrogel with Cu2+ resulted in high adsorption capacities of the hydrogel material toward Cu2+ removal, which were the highest at neutral pHs and reached ca. 213 mg/g. The proposed type of environmental material is beneficial owing to its waste-derived nature and functionality that can be applied for the high-efficiency removal of a broad scope of known environmental pollutants.

3D-Printed Filters for Efficient Heavy Metal Removal from Water Using PLA@CS/HAP Composites.

Chitosan/Hydroxyapatite composites, enriched with relatively active -NH2 and -OH groups, have emerged as promising adsorbents for heavy metal removal. In this study, we harnessed the potential of CS/HAP composites by developing monolithic PLA@CS/HAP filters utilizing 3D printing and freeze-drying techniques. These filters possess both macroscopic and microscopic porous structures, endowing them with exceptional capabilities for removing heavy metals from water. The adsorption properties of CS/HAP composites were explored by varying the dosage, duration, and initial concentrations of copper ions. The maximum adsorption capacity for Cu2+ was determined to be approximately 119+/-1 mg/g at the natural pH and 298 K. Notably, the monolithic PLA@CS/HAP filters demonstrated remarkable efficiency in the removal of copper ions, with 90% of copper ions effectively removed within a mere 2-h period in a cyclic adsorption experiment. Furthermore, the PLA@CS/HAP filters exhibited a robust dynamic Cu2+ removal capacity (80.8% or even better in less than 35 min) in a dynamic adsorption experiment. Importantly, all materials employed in this study were environmentally friendly. In summary, the PLA@CS/HAP filter offers advantages such as ease of preparation, eco-friendliness, versatility, and broad applicability in diverse wastewater treatment scenarios, thereby presenting a significant potential for practical implementation.

Preparation of Porous Columnar Silicon-Based Sponge and its Application in the Removal of Oil and Copper Ions from Wastewater

Preparation of Porous Columnar Silicon-Based Sponge and its Application in the Removal of Oil and Copper Ions from Wastewater

Adsorptive efficiency of hull-based activated carbon toward copper ions (Cu2+) removal from aqueous solution: Kinetics, modelling and statistical analysis

Activated carbons represent powerful materials for water depollution. In this study, two carbon materials were synthesized by a simple and eco-friendly method using Neem and Hyphaene thebaica biomass waste. The material preparation aimed to reach high surface activity and low cost in order to develop an adsorbent for the removal of harmful substances from water, such as heavy metals. The prepared carbon materials were characterized using various techniques, including Brunauer-Emmett-Teller (BET) specific surface area, thermogravimetric analyses (TGA), inductively coupled plasma-optical emission spectroscopy (ICP-OES) and Fourier transform infrared spectroscopy (FT-IR). The adsorption of Cu (II) ions on activated carbon from Neem (CAN) and Hyphaene thebaica (CAH) hulls was systematically investigated using a batch method by varying several key operational parameters such as contact time, pH, adsorbent dose and the effect of concentration. The results obtained from the study indicated that the maximum uptake capacity was 277 mg/g for CAN and 210 mg/g for CAH at pH 5 after 15 min of equilibrium time in contact with 500 mg/L of initial concentration of copper ions solution. Marczewski-Jaroniec and Sips isotherm models fitted well the experimental data with high R2, adj-R2 and less value or errors analysis for either CAN or CAH. Besides, the kinetic study showed that the adsorption followed a pseudo-first-order model for CAN and a pseudo-second-order for CAH. Thus, this study shows that Neem and Hyphaene thebaica hulls represent a valuable biomass source for the production of activated carbon for heavy metal remediation.

Selective adsorption of tetracycline and copper(II) on ion-imprinted porous alginate microspheres: performance and potential mechanisms.

A novel epichlorohydrin and thiourea grafted porous alginate adsorbent (UA-Ca/IIP) was synthesized using ion-imprinting and direct templating to remove copper ions (Cu(II)) and tetracycline (TC) in aqueous solution. UA-Ca/IIP demonstrated great selectivity for Cu(II) and TC among different coexisting anions (CO32-, PO43- and SO42-), cations (Ca2+, Mg2+ and NH4+), and antibiotics (oxytetracycline and sulfamethoxazole). The adsorption of TC and Cu(II) by UA-Ca/IIP was significantly affected by the pH of the solution, and the quantity of TC and Cu(II) adsorbed reached a maximum at pH 5. A pseudo-second-order model better fitted the kinetic data; the Langmuir model predicted the maximum adsorption quantities 3.527 mmol TC g-1 and 4.478 mmol Cu(II) g-1 at 298 K. Thermodynamic studies indicated that the TC and Cu(II) adsorption was more rapid at a higher temperature. Antagonistic and synergistic adsorption experiments showed that the adsorption capacity of TC would increase significantly with the increase of Cu(II) concentration. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy indicated that along with the influence of pH, electrostatic interaction and complexation were the main mechanisms of TC and Cu(II) adsorption. Regeneration experiments revealed that TC and Cu(II) were removed efficiently and that UA-Ca/IIP was recyclable over the long term. These results show that the modified porous alginate microsphere is a green and recyclable adsorbent, which has good selectivity and high adsorption performance for the removal of TC and Cu(II).

Toxic heavy metal ions removal from wastewater by ion flotation using a nano collector

Industrial wastewater treatment containing heavy metal ions has been a challenge in the ion flotation process development in recent years due to the high collector consumption required to achieve maximum ion removal. To address this issue, a nano collector consisting of functionalized graphene oxide (FGO) was synthesized and applied to increase the removal of heavy metal ions (lead, copper, nickel, cadmium, and zinc) from wastewater. This study evaluated the effect of various critical operating conditions including pH, collector/frother type and concentration, gas type, gas flowrate, and energy input on ion flotation performance to improve the efficiency of the process in this investigation. It was found that using FGO not only increased the ion removal percentage but also decreased collector consumption and water recovery, all of which improved the ion flotation process performance. Under the optimum chemical and hydrodynamic conditions using FGO with much lower concentration than stoichiometry concentration resulted in the maximum removal of lead, copper, nickel, cadmium, and zinc ions with percentages of 97.07, 99.02, 98.38, 95.20, and 98.94, respectively. In optimum condition, water recovery was 8 %. The use of FGO in the ion flotation process for wastewater treatment offered significant benefits, including high adsorption efficiency, low collector consumption, recyclability, and the absence of critical micelle concentration (CMC) and frothing properties.

Diatomite-Trichoderma viride composite microspheres for selective removal of anionic dyes and copper ions

Taking into account that Trichoderma viride dispersion mycelium existed many shortcomings, such as difficult to separate, easy to deactivate, and low adsorption performance, Diatomite-Trichoderma viride (DE-T. viride) composite microspheres were designed and prepared by chemical bonding, and anion dye and copper ion synergistic removal strategies were proposed. The adsorption performance of the composite microspheres on CR and Cu2+ were demonstrated by Zeta potential and Fourier infrared spectroscopy. The adsorption process followed the pseudo-second-order model, involving various mechanisms such as metal chelation, polysaccharide adhesion, hydrogen bonding, and electrostatic interactions. Intraparticle diffusion model identity that adsorption is controlled by multiple steps. Adsorption isotherms of CR and Cu2+ displayed excellent agreement with the Langmuir, Freundlich, and Temkin models. Impressively, DE-T. viride spheres exhibited maximum adsorption capacities of 176.3 and 63.8 mg/g for CR and Cu2+. Moreover, they displayed selective adsorption for anionic dyes, with capacities 8 and 10 times higher than those for cationic and neutral ionic dyes, respectively. T. viride microspheres generates extracellular polymers, which are rich in a variety of functional groups and can adsorb metal ions through chelation and transport, moreover, it adsorbs anions with positive charge. It is worth mentioning that DE-T. viride spheres exhibited ease of separation, stability, and reproducibility even after multiple adsorption-recycling cycles, maintaining an impressive adsorption rate of 80 %. In conclusion, these multifunctional, efficient, and eco-friendly DE-T. viride spheres present promising potential for environmental remediation, particularly in removing contaminants from various environmental matrices. Their outstanding performance, selectivity, and recyclability make them a valuable and sustainable solution for addressing pollution issues and promoting environmental sustainability.

Nanocellulose-based tannin-immobilized biosorbent for efficient copper ion removal

Tannins, which are water-soluble polyhydroxyphenols found in plant structures, offer a sustainable alternative to inorganic products for treating effluents. To overcome their solubility in water, new methods have been developed to immobilize tannin on materials such as nanocellulose, resulting in tannin-based adsorbents. This study investigates the production of different types of tannin-based adsorbents immobilized on nanocellulose nanofibrils using glutaraldehyde as a crosslinking agent. The adsorbents were characterized for their morphology, chemical composition, tannin leaching, thermal stability, and copper adsorption capacity. The main results showed that tannin leaching from the adsorbents in water was greatly reduced with glutaraldehyde. Scanning electron microscopy images showed tannin coating on the surface of nanocellulose nanofibrils due to immobilization. The lyophilized adsorbent was effective in adsorbing Cu (II) within 1 min, with the adsorbed amount increasing gradually until stabilization after 45 min. Overall, this study suggests that tannin immobilized on nanofibrillated cellulose has the potential to offer a sustainable and renewable alternative for effluent treatment.

Efficient removal of copper and silver ions in electroplating wastewater by magnetic-MOF-based hydrogel and a reuse case for photocatalytic application

Direct discharge of electroplating wastewater containing hazardous metal ions such as Cu2+ and Ag + results in environmental pollution. In this study, we rationally prepare a magnetic composite hydrogel consisted of Fe3O4, UiO-66-NH2, chitosan (CTS) and polyethyleneimine (PEI), namely Fe3O4@UiO-66-NH2/CTS-PEI. Thanks to the strong attraction between the amino group and metal cations, the Fe3O4@UiO-66-NH2/CTS-PEI hydrogel shows the maximum adsorption capacities of 321.67 mg g−1 for Cu2+ ions and 226.88 mg g−1 for Ag + ions within 120 min. As real scenario, the Fe3O4@UiO-66-NH2/CTS-PEI hydrogel exhibits excellent removal efficiencies for metallic ions even in the complicated media of actual electroplating wastewater. In addition, we explore the competitive adsorption order of metal cations by using experimental characterization and theoretical calculations. The optimal configuration of CTS-PEI is also discovered with the density functional theory, and the water retention within hydrogel is simulated through molecular dynamics modeling. We find that the Fe3O4@UiO-66-NH2/CTS-PEI hydrogel could be reused and after 5 cycles of adsorption-desorption, removal efficiency could maintain 80%. Finally, the Ag+ accumulated by hydrogel are reduced to generate a photocatalyst for efficient degradation of Rhodamine B. The novel magnetic hydrogel paves a promising path for efficient removal of heavy metal ions in wastewater and further resource utilization as photocatalysts.