Adsorption Capacity Of Cu Research Articles

Multifunctional carbon nanotube arrays on kapok-derived carbon microtube composites for efficient electromagnetic wave absorption and Cu(II) removal

To cope with different environments of application, electromagnetic wave absorption (EWA) materials with multifunctionality have attracted a wide range of interests. And excessive heavy metal ions in aqueous solutions seriously affect people’s health and pose a major challenge to environmental safety. In this study, carbon microtube/carbon nanotube (CMT/CNT) composites were fabricated via carbonization and chemical vapor deposition (CVD) methods. The CNT wrapped with cobalt nanoparticles were grown in situ on the CMT which derived from kapok fiber. By varying the concentration of cobalt precursors, the EWA and Cu(II) adsorption performances of CMT/CNT can be efficiently tuned. Optimizing the cobalt content to 2 wt% resulted in a minimum reflection loss (RL) of −66.14 dB at a matching thickness of 1.91 mm, with an effective absorption bandwidth (EAB) of 5.35 GHz. The adsorption capacity of Cu(II) by the CMT/CNT composite can reach 102.01 mg/g when the initial Cu(II) concentration is 500 mg/L. This research not only shows great promise for applications in the field of EWA materials but also holds significant potential for heavy metal ion removal and as a catalyst carrier, among other areas.

Efficient removal of low concentrations of copper and lead ions in water using chitosan-condensed tannin composite microspheres

Condensed tannin was solidified onto chitosan microspheres to prepare chitosan-tannin (CT) composite microspheres with a simple preparation method to study its performance in adsorbing copper (Cu2+) and lead ions (Pb2+) in aqueous media. The study investigated the influence of the mass ratio of tannin and chitosan, pH value, adsorption time, and initial concentrations of Cu2+ and Pb2+ on the adsorption capacity of Cu2+ and Pb2+ ions. Additionally, the study examined the adsorption isotherms and kinetics of Cu2+ and Pb2+ on CT composite microspheres. The adsorption process aligns more closely with the fitting results of the Langmuir model. The maximum capacity for saturated monolayer adsorption of CT composite microspheres for Cu2+ and Pb2+ was 37.6 and 52.9 mg/g, respectively. The adsorption process of CT composite microspheres for Cu2+ and Pb2+ was primarily driven by single-layer chemical adsorption. In addition, metal ions adsorbed onto CT composite microspheres can be released by treating them with a dilute solution of strong acid. Furthermore, the CT composite microspheres exhibited impressive removal efficiencies of 82 % and 95 % for Cu2+ and Pb2+ respectively, even at low concentrations of 2 mg/L. The CT composite microspheres have the ability to easily separate the adsorbed Cu2+ and Pb2+ ions.

Isotherm, kinetic, and thermodynamic studies of adsorption of copper (II) and nickel (II) ions using low‐cost treated orange peel from aqueous solutions

AbstractThe aim of this study was to utilize processed orange peel waste (TOP) as an adsorbent to remove Cu(II) and Ni(II) ions from aqueous solutions. As a result of systematic experiments to determine the optimal conditions, it was determined that the most suitable conditions for the effective removal of Cu(II) ions were 400 mg/L initial concentration, 100 min contact time, 0.2 g adsorbent dosage, and a solution pH of 5.92. Similarly, the optimal conditions for the removal of Ni(II) ions were determined by systematic experiments to be 300 mg/L initial concentration, 0.2 g adsorbent dosage, 100 min contact time, and a solution pH of 6.19. The systematic experiments also included further investigation of the surface properties of TOP, and promising results were obtained by tests at three different temperatures (298, 308, and 318 K). The adsorption capacities for Cu(II), Ni(II), and Ni(II) were determined as 72.99, 75.18, and 76.33 mg/g, 42.55, 44.44, and 46.29 mg/g, respectively. Further analysis of the adsorption kinetics revealed that the pseudo‐second‐order model accurately represented the experimental data for both ions. Thermodynamic investigations provided strong evidence that the adsorption process of these noble metal ions on TOP is endothermic and spontaneous. The results of this study emphasize that TOP, with its low cost, easy‐to‐use nature, and high adsorption capacity, can be considered a long‐term solution for environmental remediation and water treatment in sustainable engineering applications.

Binary Biosorption of Cu(II) and Cr(VI) by Naturally Formed Biofilm Matrices

Water pollution poses a significant ecological threat, contributing to the widespread degradation of aquatic ecosystems. Among the pollutants, heavy metals pose severe risks to both organisms and human health, emphasizing the urgent need for effective pollution control technologies. Biosorption presents a promising, cost-effective, and environmentally friendly solution to mitigate heavy metal contamination. Biofilms, consisting of microbial communities, have emerged as potential biosorbents for heavy metals. Since heavy metals can exist as cations and anions concurrently in aquatic environments, understanding their behavior in binary systems is essential for biosorption strategies. This study focuses on the binary biosorption of Cu(II) and Cr(VI), representing cationic and anionic heavy metals. Specific adsorption sites are identified by analyzing adsorption kinetics, isotherms, and IR spectra of biofilms. The results indicate that biofilms, in a binary scenario, demonstrate nearly identical adsorption capacities for Cu(II) and Cr(VI). Moreover, the adsorption process follows the Langmuir adsorption model, emphasizing the potential of biofilms as effective biosorbents for the simultaneous removal of cationic and anionic heavy metals. This study advocates for a sustainable approach to heavy metal remediation through the utilization of biofilms.

Enhanced Removal of Chlorpyrifos, Cu(II), Pb(II), and Iodine from Aqueous Solutions Using Ficus Nitida and Date Palm Biochars

This study explores the adsorption efficiency of biochar derived from palm trees and Ficus nitida for the removal of various contaminants, including Cu(II), Pb(II), iodine, and chlorpyrifos from aqueous solutions. Biochar was prepared using a two-step pyrolysis process for date palm biochar and single-step pyrolysis for Ficus nitida biochar. Characterization techniques such as SEM, EDX, and FTIR revealed a significant surface area and a variety of functional groups in both types of biochar, essential for effective adsorption. The date palm biochar exhibited superior adsorption capacities for Cu(II) and Pb(II) ions, achieving efficiencies up to 99.9% and 100%, respectively, due to its high content of oxygen-containing functional groups that facilitated strong complexation and ion exchange mechanisms. Conversely, Ficus nitida biochar demonstrated a higher adsorption capacity for iodine, reaching 68% adsorption compared to 39.7% for date palm biochar, owing to its greater surface area and microporosity. In the case of chlorpyrifos, Ficus nitida biochar again outperformed date palm biochar, achieving a maximum adsorption efficiency of 87% after 24 h of incubation, compared to 50.8% for date palm biochar. The study also examines the effect of incubation time on adsorption efficiency, showing that the adsorption of chlorpyrifos by date palm biochar increased significantly with time, reaching a maximum of 62.9% after 48 h, with no further improvement beyond 12 h. These results highlight the importance of biochar characteristics, such as surface area, pore structure, and functional groups, in determining adsorption efficiency. The findings suggest that optimizing pyrolysis conditions and surface modifications could further enhance the performance of biochar as a cost-effective and sustainable solution for water purification and environmental remediation.

Interfacial interactions between colloidal polystyrene microplastics and Cu in aqueous solution and saturated porous media: Model fitting and mechanism analysis

Microplastic (MP) and heavy metal pollution have received much attention. Few researches have been carried out on the influence of the interaction between MPs and heavy metals on their transport in saturated porous media, which concerns their fate. Therefore, the interaction mechanisms between colloidal polystyrene microplastics (PSMPs) and Cu were first carried out by applying batch adsorption experiments. Subsequently, the transport and retention of PSMPs and Cu in saturated porous media was explored through column experiments. The interaction process between PSMPs and Cu was further investigated using density functional theory (DFT) calculations. Findings demonstrated that PSMPs had strong adsorption capacity for Cu ((60.07 ± 2.57) mg g−1 at pH 7 and ionic strength 0 M) and the adsorption process was chemically dominated, non-uniform, and endothermic. The O-containing functional groups on PSMP surfaces showed essential roles in Cu adsorption, and the adsorption process mainly contained electrostatic and complexation interactions. In column experiments, Cu could inhibit PSMP transport by the cation bridging effect and changing the electrical properties of glass beads, while PSMPs may facilitate Cu transport through the carrying effect. These findings confirmed that interfacial interactions between MPs and Cu could influence their transport in saturated porous media directly, providing great environmental significance.

Recycling of water treatment plant sludge for copper adsorption from aqueous solutions

Recent studies have explored various adsorbent materials that are low-cost, available in quantity, and effective for heavy metal removal, one of them is the Water Treatment Plant (WTP) sludge. The study aimed to investigate the potential of recycling Water Treatment Plant sludge into an adsorbent for Cu (II) removal. The sludge adsorbent was carbonized by using a furnace at 600°C for 2 hours. This study was conducted in batch. The adsorbent effectiveness was analyzed by varying the dosage, contact time, and activation of the sludge adsorbent on Cu (II) removal. The adsorption isotherm was analyzed using the Langmuir and Ferundlich models, and the kinetic study used pseudo-first-order and pseudo-second-order model. The results showed the removal efficiency of Cu (II) for both activated and non-activated sludge adsorbents reached 98.6–99.9%. The addition of dosage did not affect the increase in Cu (II) adsorption capacity. Activation of the adsorbent increased the adsorption capacity of Cu (II) with the equilibrium time at 60–90 min, shorter than the non-activated adsorbent at 90–120 min. The adsorption isotherm model for both adsorbent types fitted well to the Langmuir model, indicating the adsorption process occurs in a single layer on a homogeneous surface. The adsorption kinetics followed pseudo-second-order with a high correlation coefficient. Water treatment sludge, an industrial by-product, has the potential to be an effective and low-cost adsorbent material for Cu removal.

Biochar modified by ammonium pyrrolidine dithiocarbamate for high selective adsorption of copper in wastewater

Biochar application in wastewater purification is extremely appealing. Although heteropolysaccharides like Gum Seyal biochar (BC GS500) display great surface area and porosity, the adsorption capacity for Cu (II) was relatively low due to the week-binding surface functional groups. In this work, an innovative modification with the chelating agent ammonium pyrrolidine dithiocarbamate (APDC) capable of selectively and effectively adsorbing Cu (II) was conducted. Gum Seyal biochar was grafted with pyrrolidine dithiocarbamate (C5H8NS2–), amine (–NH2), and imine (–NH) groups using APDC based on the “hard and soft acids and bases theory” (HSAB). Batch studies, along with characterization (FITR, XPS, and SEM-EDS), molecular electrostatic potential (MEP) mapping, and density functional theory (DFT) calculations, were implemented to investigate the adsorption performance and mechanism responsible for selectively adsorptive Cu (II) removal. It was found that Cu (II) adsorption by modified biochar occurred endothermically and spontaneously. The adsorption data at pH 5 matched the pseudo-second-order kinetic model and the Langmuir isotherm (211.24 mg/g). DFT calculations show that modified biochar selectively binds Cu (II) superior to common ions such as Mg (II) and Ca (II) through a unique chelating mechanism. Their performance in real electroplating wastewater was investigated, and the production cost was estimated. It was concluded that the modified biochar (BC APDC) could have high applicable potential for Cu (II)-laden wastewater purification.

Copper supported Dowex50WX8 resin utilized for the elimination of ammonia and its sustainable application for the degradation of dyes in wastewater

To obtain high efficient elimination of ammonia (NH4+) from wastewater, Cu(II), Ni(II), and Co(II)) were loaded on Dowex-50WX8 resin (D-H) and studied their removal efficiency towards NH4+ from aqueous solutions. The adsorption capacity of Cu(II)-loaded on D-H (D-Cu2+) towards NH4+ (qe = 95.58 mg/g) was the highest one compared with that of D-Ni2+ (qe = 57.29 mg/g) and D-Co2+ (qe = 43.43 mg/g). Detailed studies focused on the removal of NH4+ utilizing D-Cu2+ were accomplished under various experimental conditions. The pseudo-second-order kinetic model fitted well the adsorption data of NH4+ on D-Cu2+. The non-linear Langmuir model was the best model for the adsorption process, producing a maximum equilibrium adsorption capacity (qmax = 280.9 mg/g) at pH = 8.4, and 303 K in less than 20 min. The adsorption of NH4+ onto D-Cu2+ was an exothermic and spontaneous process. In a sustainable step, the resulting D-Cu(II)-ammine composite from the NH4+ adsorption process displayed excellent catalytic activity for the degradation of aniline blue (AB) and methyl violet 2B (MV 2B) dyes utilizing H2O2 as an eco-friendly oxidant.

Polydopamine nanoparticles reinforced injectable hydrogels for the efficient adsorption and catalysis in the wastewater treatment

By in situ generation of hydrazone bonds, a composite hydrogel that combines poly(N-isopropylacrylamide) and carboxymethyl cellulose and is reinforced with PDA nanoparticles was successfully prepared for injectable use, and was employed to treat metal ions in aqueous solutions. The composite hydrogels presented desirable compressive strength and anti-fatigue performance. The adsorption capacities of Cu2+, Pb2+ and Cd2+ reached high values of 193.8, 168.8 and 112.6 mg/g, respectively, in a single-ion adsorption system, due to the plentiful adsorptive sites on the hydrogels. The adsorption kinetics followed the Pseudo-second-order model, while the adsorption isotherm adhered to the Langmuir model. Besides, the hydrogels showed slightly higher selectivity for Cu2+ in an adsorption system involving multiple ions, and exhibited good reusability, enabling it to be employed repeatedly as a recyclable adsorbent. The analysis of the mechanism indicated that ion exchange, electrostatic interaction, chemical adsorption and coordination effect might occurred between metal ions and functional groups in hydrogel matrix and PDA nanopartiles. Moreover, the Cu2+-adsorbed hydrogels could act as a scaffold for the on-site generation of Cu nanoparticles. With the Cu nanoparticles, the hydrogels showed catalytic activity of ∼ 80 % conversion of 4-nitrophenol (1 mmol) to 4-aminophenol in 30 min, validating the dual functional properties for both adsorption and catalytic purposes in the treatment of wastewater.

Properties of Biochar Prepared by Solar Pyrolysis and Its Adsorption of Cu<sup>2+</sup> in Water

This study investigates the potential of biochar produced via a solar pyrolysis system and its effectiveness in removing copper (Cu<sup>2+</sup>) ions from water, presenting a sustainable and energy-efficient method for biochar production and biomass recycling. Two common agricultural and livestock wastes, corn straw and cow dung, were used as raw materials to produce biochar. These materials underwent solar pyrolysis under limited oxygen conditions to produce biochar, which was then compared to biochar produced via traditional pyrolysis. The comparison involved elemental analyses, infrared spectroscopy, scanning electron microscopy, and specific surface area and pore size analysis to highlight differences in their physical and chemical properties. Adsorption experiments were conducted to evaluate the adsorptive capacity of biochar for copper ions (Cu<sup>2+</sup>) from water, determining the optimal pH conditions and underlying adsorption mechanisms. The findings reveal that biochar produced through solar pyrolysis exhibits similar properties and Cu<sup>2+</sup> adsorption capacities to those prepared by traditional methods. Specifically, cow dung biochar demonstrated a higher adsorption capacity for Cu<sup>2+</sup> compared to corn straw biochar. The Cu<sup>2+</sup> adsorption by corn straw biochar followed the Langmuir isothermal adsorption model and pseudo-second-order kinetic equation, whereas cow dung biochar conformed to the Freundlich isothermal adsorption model and pseudo-second-order kinetic equation. By demonstrating the comparable efficacy of solar pyrolysis biochar in heavy metal adsorption, this study highlights its potential for sustainable environmental remediation and biomass utilization.

Synthesis of amidoxime adsorbent prepared by radiation grafting on upcycled low-density polyethylene sheet for removal of heavy metals from wastewater

The issue of discharging waste, especially heavy metals from industrial activities into the environment, not only adversely impacts environmental quality but also has impacts on communities and human health. Removal and reduction of heavy metal contamination in rivers and wastewater are, therefore, critical initiatives that require significant attention. This work studied the removal of heavy metals, including Zn(II), Cu(II), As(III), and Pb(II) by utilizing an upcycled amidoxime low-density polyethylene sheet (AO-sheet). The synthesized AO-sheet was analyzed for various physical properties, including scanning electron microscope, energy-dispersive x-ray spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. For the batch adsorption experiment, parameters affecting adsorption capacity were studied: initial concentration, submerging time, and pH. Adsorption isotherms were also studied. The results of the heavy metal adsorption study showed that the initial concentration was the most significant parameter; the higher the initial concentration, the greater the adsorption capacity. The adsorption capacity of Zn(II) and Pb(II) increased with submersion time, which achieved 21.07 and 0.855 mg/g-adsorbent, respectively, after four weeks of submersion under the highest initial concentration studied. The adsorption capacity of Cu(II) was 7.98 mg/g-adsorbent after two weeks of optimal adsorption duration under the highest initial concentration studied. The adsorption capacity of As(II) was 1.07 mg/g-adsorbent after one week of optimal submersion time under the highest initial concentration studied. Moreover, the appropriate pH range for effective adsorption of Zn(II), Cu(II), and Pb(II) was identified as 8–9, while for As(III), it was 6–8, with an adsorption duration of 0.43 weeks (3 days). From the Langmuir isotherm, it was found that the adsorption of this work was characterized by monolayer adsorption. The results demonstrate that the AO-sheet can be effectively used to remove heavy metals from wastewater. Its potential for reusability was up to 8 cycles, with the Zn(II) adsorption capacity being reduced to about 20.37%.

Kenaf Biochar as an Eco‐Friendly Adsorbent for Removal of Cu(II) and Pb(II): Optimal Temperature, Adsorption Models, and Efficiency Evaluation

ABSTRACTThis study examined the adsorption capacities of biochars derived from kenaf (KF‐BCs) for the removal of heavy metals such as Cu(II) and Pb(II). The thermal decomposition temperature (300–750°C) significantly influenced the morphology and composition of KF‐BCs, enhancing their surface area, pore structure, and alkalinity. Among them, kenaf pyrolyzed at 750°C (KF‐750) was the most effective in removing Cu(II) and Pb(II), as validated by kinetic, equilibrium, and isotherm model analyses. Adsorption kinetics revealed that equilibrium was attained after 24 h, with chemisorption governing the process rate. Equilibrium adsorption conformed to the Langmuir and Freundlich models for Cu(II) and Pb(II), respectively. KF‐750 exhibited midrange adsorption capacities for Cu(II) and Pb(II) (23.47 ± 0.3 mg/g and 50.07 ± 0.9 mg/g, respectively), compared with the literature. The thermodynamic assessment revealed an endothermic process with positive ∆H0, indicating that higher temperatures favor metal adsorption. At low pH, adsorption decreased due to electrostatic repulsion, particularly affecting Cu(II). More than 99.8% of Cu(II) and Pb(II) were removed with a 5.00 g/L KF‐750 dose. The cation effect order on KF‐750 was Ca2+ > Mg2+ > Na+ > K+. Overall, KF‐750 demonstrates promising potential as an adsorbent for the efficient heavy metal removal from aqueous solutions, presenting a viable option for environmental remediation.

MOF-525 and Fe-loaded MOF-525 for the selective adsorption removal of Cu(Ⅱ) and Cr(VI)

Two Zr-MOFs (including MOF-525 and MOF-525(Fe)) are synthesized and used to evaluate the adsorption performances for Cu(Ⅱ) and Cr(VI). Batch experiments demonstrate MOF-525 exhibits excellent adsorption removal for Cu(Ⅱ) and MOF-525(Fe) shows excellent adsorption removal for Cr(VI). The isotherms characteristic results indicate MOF-525 is micropores and conformed to type I, while MOF-525(Fe) is mesopores and conformed to type Ⅳ. The removal efficiency of Cu(Ⅱ) by MOF-525 is sharply increased from 26.1 % to 99.7 % and that of Cr(VI) by MOF-525(Fe) is decreased slightly from 99.6 % to 95.5 % as the pH increased from 3.0 to 8.0; besides, the adsorption capacity of Cu(Ⅱ) is enhanced in the presence of Cl− or PO43−, but that of Cr(VI) is significantly decreased. The adsorption processes of both MOF-525 for Cu(II) and MOF-525(Fe) for Cr(VI) are fitted better to the pseudo-second-order kinetic model and Langmuir model, indicating they are mainly monolayer chemisorption. In addition, adsorption thermodynamics results demonstrate the adsorption processes are endothermic and spontaneous physisorption. The adsorption mechanisms investigations further revealing that the electrostatic interaction, reducing action, and coordination interaction are involved in the adsorption removal of Cu(II) and Cr(VI); moreover, the surface precipitation is existed in the adsorption of Cu(II) and the hydrogen bonding is found in that of Cr(VI).

Engineering Bis-Pyridine N-Functionalized Cellulose Aerogel for Efficient Extraction of Cu2+ from High-Acidity Wastewaters: Coupling Molecular Scale Interpretation with Experiment.

In order to address the issue of protonation of functional groups and structural instability on the surface of aerogel due to strong acidic wastewater, a three-dimensional bis-pyridine N cellulose aerogel [PEIPD/carboxymethyl cellulose (CMC)] with protonation resistance was prepared in this paper by grafting pyridine onto polyethylenimine. The adsorption capacity for Cu2+ of the as-prepared aerogel is as high as 1.64 mmol/g (pH 5) and is maintained well in high-acidity solutions (1.15 mmol/g at pH = 2). It reveals high selectivity, splendid anti-interference ability, and also reliable on the recycle performance. Through the zeta potential tests, this adsorbent reveals a rather low zero charge point (pHpzc = 2.2). The adsorption of Cu2+ on the adsorbent is consistent with the pseudo-second-order kinetic model and the Langmuir model, suggesting that the adsorption process is dominated by chemisorption in a monolayer. The characterizations by Fourier transform infrared spectrometry and X-ray photoelectron spectroscopy proved pyridine N as responsible binding sites, based on which two possible mechanisms are proposed, including chelation and cation-π interaction. Density functional theory calculations are further used to precisely investigate the pathway. By comparing the binding energies, molecular electrostatic potentials, electron densities, and differential charge densities, the bis-pyridine N functional group is finally determined to be of much higher affinity to Cu2+ following chelation reaction as designated. By integrating bis-pyridine N with the CMC and understanding their crucial roles, this will provide significant insights into the rational design of aerogel adsorbents to enhance the recovery of Cu from strongly acidic wastewaters.

Fabrication of Sustainable Sodium Alginate/Polyethyleneimine/Polyvinyl Alcohol Multilayer Composite Electrospun Nanofiber Membrane for Efficient Cu2+ Removal

In pursuit of sustainable solutions for water pollution mitigation, we have successfully employed electrospinning technology to fabricate a multilayered sodium alginate (SA)/polyethyleneimine (PEI)/polyvinyl alcohol (PVA) nanocomposite fiber membrane, with a focus on enhancing its adsorption capacity for Cu2+ ions in wastewater. Our research underscores the potential of this novel membrane, characterized by its small diameter, high uniformity, and expansive surface area, in effectively filtering heavy metal ions. By optimizing critical electrospinning parameters such as a voltage of 19.5 KV, a collector distance of 8 cm, a specific mass ratio of SA:PEI: PVA (1:2:6), and an injection rate of 8 μL/min, we achieved a nanofiber membrane with an average diameter of 112.5 nm, exhibiting exceptional morphological characteristics and high efficiency. Notably, the membrane exhibited an adsorption capacity of over 85% for Cu2+ during initial testing, maintaining over 80% efficiency throughout four consecutive filtration cycles. This work not only advances the field of nanocomposite membranes for water purification but also contributes significantly to the broader goal of achieving environmental sustainability by mitigating the impact of heavy metal contamination in water bodies.

Efficiency and mechanism of modified carbon nitride for the co-adsorption of copper and tetracycline from water

The escalating contamination of heavy metal ions and antibiotics in the aqueous environment underscores the necessity of developing efficient treatment technologies for their concurrent removal. In this work, a phosphate-modified g-C3N4(PCN) by assembling phytic acid with graphitized carbon nitride was prepared through a hydrothermal reaction. The characterization results reveal that PCN exhibits increased porosity, an enhanced specific surface area, and larger pore volume in comparison to pristine CN. At pH 5.0 and 25 °C, PCN demonstrates remarkable adsorption capacities for Cu (II) (q = 172.3 mg g−1) and tetracycline (TC) (q = 63.1 mg g−1) in a single system, respectively, which correspondingly surpasses those of CN by 7 and 8 times. In systems where Cu (II) and TC coexist, Cu (II) enhances the TC removal rate by acting as a bridge. As Cu(II) concentration increases, TC adsorption efficiency significantly improves. Although common ions in solution influence PCN adsorption, it maintains high efficiency for TC and Cu(II) across various water matrices and in the presence of natural organic matter. Detailed characterization and computational chemical analysis reveal that the enhanced adsorption capacity of PCN is due to increased porosity and the presence of additional functional groups. Surface complexation and adsorption bridging are identified as the key mechanisms for effective Cu(II) and TC adsorption. Additionally, recycling experiments validate its reusability, thereby offering a novel avenue for the removal and recovery of TC and Cu(II) from wastewater.

Nanoconfined polyethyleneimine in mesoporous MCM-41 silica for heavy metal ions removal

Water contamination resulting from the presence of the various coexistent pollutants is an urgent environmental challenge, and effective treatment is demanded to remove the toxic substances. The removal of pollutants by adsorption, as an effective, efficient and economic strategy, has been widely used in water treatment. In this work, PEI@MCM-41 was prepared by infiltrating polyethyleneimine (PEI) into the pores of mesoporous MCM-41, and applied for the removal of heavy metal ions. The adsorption kinetics of Cu2+, Ni2+ and Cd2+ by PEI@MCM-41 were supposed to be pseudo-second-ordered, and the adsorption capacities were as high as 39.30, 33.67 and 21.10 mg·g−1, respectively. The influence of temperature, pH, coexistent salt and heavy metal ions concentration on the adsorption performance was studied. Owing to the nanoconfinement effect and hydrogen bond, PEI remained stable during the adsorption and desorption process, and the adsorption capacity for Cu2+ maintained 84.15 % even after four consecutive adsorption–desorption cycles. This work demonstrates that the potential practical applicability of PEI@MCM-41 as promising adsorbent in the removal of heavy metal ions.

Understanding the relationship between pore size, surface charge density, and Cu2+ adsorption in mesoporous silica

This research delved into the influence of mesoporous silica’s surface charge density on the adsorption of Cu2+. The synthesis of mesoporous silica employed the hydrothermal method, with pore size controlled by varying the length of trimethylammonium bromide (CnTAB, n = 12, 14, 16) chains. Gas adsorption techniques and transmission electron microscopy characterized the mesoporous silica structure. Surface charge densities of the mesoporous silica were determined through potentiometric titration, while surface hydroxyl densities were assessed using the thermogravimetric method. Subsequently, batch adsorption experiments were conducted to study the adsorption of Cu2+ in mesoporous silica, and the process was comprehensively analyzed using Atomic absorption spectrometry (AAS), Fourier transform infrared (FTIR), and L3 edge X-ray absorption near edge structure (XANES). The research findings suggest a positive correlation between the pore size of mesoporous silica, its surface charge density, and the adsorption capacity for Cu2+. More specifically, as the pore size increases within the 3–4.1 nm range, the surface charge density and the adsorption capacity for Cu2+ also increase. Our findings provide valuable insights into the relationship between the physicochemical properties of mesoporous silica and the adsorption behavior of Cu2+, offering potential applications in areas such as environmental remediation and catalysis.

Effect of Photoaging on Adsorption of Cu(Ⅱ) by Polystyrene Microplastics with Different Particle Sizes

In order to evaluate the effect of aging and particle size on the adsorption of heavy metals by microplastics, the adsorption behavior of Cu(Ⅱ) by three different particle sizes of polystyrene (PS; 1, 50, and 100 μm) under UV irradiation was systematically studied. The results demonstrated that UV aging significantly changed the surface morphology and physicochemical properties of PS, and 1 μm PS had the strongest aging degree. The adsorption kinetics of PS on Cu(Ⅱ) conformed to the pseudo-second-order kinetic model, and the Freundlich model was more suitable for the experimental data of isothermal adsorption of Cu(Ⅱ) by PS. These results indicated that the adsorption of Cu(Ⅱ) by PS occurred on the non-uniform surface of PS, and the adsorption behavior was multilayer adsorption. Parameter "n" of the Freundlich model was less than 1, indicating that the adsorption behavior of PS on Cu(Ⅱ) was a higher intensity physical adsorption behavior. The order of theoretical maximum adsorption capacity of different particle sizes PS for Cu(Ⅱ) was as follows:1 μm > 50 μm > 100 μm, indicating that the size of PS was an important influence factor for the adsorption capacity of PS to pollutants. For the same particle size PS, aging enhanced its adsorption capacity for Cu(Ⅱ). The results on the adsorption of Cu(Ⅱ) by PS under different environmental conditions indicated that the adsorption capacity of PS for Cu (II) increased with the increase in pH, whereas an increase in salinity had the opposite effect. Surface complexation and electrical adsorption were the main mechanisms of adsorption of Cu(Ⅱ) by PS. This study provides an important scientific basis for understanding the adsorption behavior of microplastics to heavy metals in the environment.