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This research delved into the influence of mesoporous silica’s surface charge density on the adsorption of Cu 2+ . The synthesis of mesoporous silica employed the hydrothermal method, with pore size controlled by varying the length of trimethylammonium bromide (C n TAB, 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 Cu 2+ 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 Cu 2+ . More specifically, as the pore size increases within the 3–4.1 nm range, the surface charge density and the adsorption capacity for Cu 2+ also increase. Our findings provide valuable insights into the relationship between the physicochemical properties of mesoporous silica and the adsorption behavior of Cu 2+ , offering potential applications in areas such as environmental remediation and catalysis.

Coal gangue and aluminum ash emerge as quintessential constituents within the ambit of coal-derived solid waste and industrial residue, respectively. Leveraging coal gangue as a primary substrate and aluminum ash as an adjunct aluminum source, molecular sieves can be synthesized through hydrothermal means. By modulating the dosage of aluminum ash, molecular sieves with varying crystalline structures can be obtained. The synthesized LTA-type molecular sieves manifest in two distinct morphologies: regular tetrahedral and stratified spherical stacking, evincing commendable Cu2+ adsorption efficacy. The Cu2+ adsorption phenomenon predominantly transpires via chemisorption, albeit with ancillary manifestations of physical adsorption. The valorization of coal gangue and aluminum ash towards the synthesis of molecular sieves not only underscores the elevation of industrial solid waste towards high-value utility, but also underscores the praxis of waste remediation through upcycling.

In this study, actual piggery wastewater was utilized to cultivate aerobic granular sludge (AGS), which was used to remove conventional and heavy metal pollutants from piggery wastewater. The removal mechanism of Cu 2+ and Zn 2+ by AGS was investigated using adsorption and high-throughput sequencing methods. The results showed that the extracellular polymeric substance (EPS) components and dominant bacterial species in AGS play important roles in the removal of Cu 2+ and Zn 2+ . Both dynamic and static factors influence the abundance of microorganisms, which consequently affect the Zn 2+ adsorption effect of AGS. Microorganisms that are adapted to the presence of heavy metals and possess competitive advantages contribute to the adsorption of Cu 2+ and Zn 2+ by AGS. There are positive and negative correlations within the microbial community after AGS adsorption of Cu 2+ and Zn 2+ . The results of this study are of great significance for promoting the widespread application of AGS technology. Key points •  The removal of Cu 2+ and Zn 2+ mainly depends on the EPS components in AGS •  The biological activity of AGS has a significant impact on the adsorption of Zn 2+ •  Dominant microorganisms play an important role in the adsorption of heavy metals

An amphiphilic HEMA-co-AMPS copolymer was synthesized through microwave-assisted RAFT polymerization using a rapid and energy-efficient approach. Comprehensive characterization confirmed successful copolymer formation, high structural stability, and the presence of abundant negatively charged sulfonate groups. The copolymer exhibited excellent adsorption performance toward Cu 2+ and Cr 6+ ions, achieving maximum capacities of 165 mg g⁻¹ and 115 mg g⁻¹, respectively, within ≤ 3 h. Adsorption followed a pseudo-second-order kinetic model, while equilibrium data were best described by the Langmuir model for Cu 2+ and the Freundlich model for Cr 6+ . Thermodynamic analysis indicated spontaneous adsorption, with Cu 2+ uptake occurring through an endothermic process and Cr 6+ uptake proceeding exothermically. The copolymer retained more than 87% of its initial adsorption capacity after multiple cycles, demonstrating strong reusability. Overall, these findings highlight microwave-assisted RAFT polymerization as an efficient and sustainable strategy for producing high-performance polymeric adsorbents for water treatment applications.

Gel adsorption is an efficient method for the removal of metal ion. In the present study, a functional chitosan gel material (FCG) was synthesized successfully, and its structure was detected by different physicochemical techniques. The as-prepared FCG was stable in acid and alkaline media. The as-prepared material showed excellent adsorption properties for the capture of Cu2+ ion from aqueous solution. The maximum adsorption capacity for the FCG was 76.4 mg/g for Cu2+ ion (293 K). The kinetic adsorption data fits the Langmuir isotherm, and experimental isotherm data follows the pseudo-second-order kinetic model well, suggesting that it is a monolayer and the rate-limiting step is the physical adsorption. The separation factor (RL) for Langmuir and the 1/n value for Freundlich isotherm show that the Cu2+ ion is favorably adsorbed by FCG. The negative values of enthalpy (ΔH°) and Gibbs free energy (ΔG°) indicate that the adsorption process are exothermic and spontaneous in nature. Fourier transform infrared (FTIR) spectroscopy and x-ray photoelectron spectroscopy (XPS) analysis of FCG before and after adsorption further reveal that the mechanism of Cu2+ ion adsorption. Further desorption and reuse experiments show that FCG still retains 96% of the original adsorption following the fifth adsorption–desorption cycle. All these results indicate that FCG is a promising recyclable adsorbent for the removal of Cu2+ ion from aqueous solution.

Developing excellent strategies to optimize the electrochemiluminescence (ECL) performance of C3N4 materials remains a challenge due to the electrode passivation, causing weak and unstable light emission. A strategy of controlling the calcination atmosphere was proposed to improve the ECL performance of C3N4 nanotubes. Interestingly, we found that calcination atmosphere played a key role in specific surface area, pore-size and crystallinity of C3N4 nanotubes. The C3N4 nanotubes prepared in the Air atmosphere (C3N4 NT-Air) possess a larger specific surface area, smaller pore-size and better crystallinity, which is crucial to improve ECL properties. Therefore, more C3N4•− excitons could be produced on C3N4 NT-Air, reacting with the SO4•− during the electrochemical reaction, which can greatly increase the ECL signal. Furthermore, when C3N4 nanotube/K2S2O8 system is proposed as a sensing platform, it offers a high sensitivity, and good selectivity for the detection of Cu2+, with a wide linear range of 0.25 nM~1000 nM and a low detection limit of 0.08 nM.

Background Despite being necessary, copper is a toxic heavy metal that, at high concentrations, harms the life system. The parameters that affect the bioreduction and biosorption of copper are highly copper-resistant bacteria. Results In this work, the ability of the bacterial biomass, isolated from black shale, Wadi Nakheil, Red Sea, Egypt, for Cu 2+ attachment, was investigated. Two Cu 2+ resistance Bacillus species were isolated; Bacillus pumilus OQ931870 and Bacillus subtilis OQ931871. The most tolerant bacterial isolate to Cu 2+ was B. pumilus . Different factors on Cu 2+ biosorption were analyzed to estimate the maximum conditions for Cu biosorption. The q max for Cu 2+ by B. pumilus and B. subtilis determined from the Langmuir adsorption isotherm was 11.876 and 19.88 mg. g −1 , respectively. According to r 2 , the biosorption equilibrium isotherms close-fitting with Langmuir and Freundlich model isotherm. Temkin isotherm fitted better to the equilibrium data of B. pumilus and B. subtilis adsorption. Additionally, the Dubinin-Radushkevich (D-R) isotherm suggested that adsorption mechanism of Cu 2+ is predominately physisorption. Conclusion Therefore, the present work indicated that the biomass of two bacterial strains is an effective adsorbent for Cu 2+ removal from aqueous solutions.

Gold nanoclusters (AuNCs) have been widely investigated because of their unique photoluminescence properties. However, the applications of AuNCs are limited by their poor stability and relatively low fluorescence. In the present work, we developed nanocomposites (L-Cys-AuNCs@ZIF-8) with high fluorescence and stability, which were constructed by encapsulating the water-dispersible L-Cys-AuNCs into a ZIF-8 via Zn2+-triggered growth strategy without high temperature and pressure. The maximum emission wavelength of the L-Cys-AuNCs@ZIF-8 composite was at 868 nm, and the fluorescence intensity of L-Cys-AuNCs@ZIF-8 was nearly nine-fold compared with L-Cys-AuNCs without the ZIF-8 package. The mechanism investigation by fluorescence spectroscopy and X-ray photoelectron spectroscopy showed that L-Cys-AuNCs@ZIF-8 impeded ligand rotation, induced energy dissipation, and diminished the self-quenching effect, attributing to the spatial distribution of L-Cys-AuNCs. Based on the high fluorescence efficiency of L-Cys-AuNCs@ZIF-8, a “signal off” detective platform was proposed with copper ions as a model analyte, achieving a sensitive detection limit of Cu2+ at 16.7 nM. The quenching mechanism was confirmed, showing that the structure of the L-Cys-AuNCs@ZIF-8 nanocomposites was collapsed by the addition of Cu2+. Attributing to the strong adsorption ability between copper ions and pyridyl nitrogen, the as-prepared L-Cys-AuNCs@ZIF-8 was shown to accumulate Cu2+, and the Zn2+ in ZIF-8 was replaced by Cu2+.

Heavy metals (e.g., Cu) in wastewater are attractive resources for diverse applications, and adsorption is a promising route to recovery of heavy metals from wastewater. However, high-performance adsorbents with high adsorption capacity, speed, and stability remain challenging. Herein, chelating fibers were prepared by chemically grafting amine and carboxyl groups onto the polyacrylonitrile fiber surface and used in the wastewater’s adsorption of Cu 2+ . The adsorption behavior of Cu 2+ on the fibers was systematically investigated, and the post-adsorption fibers were comprehensively characterized to uncover the adsorption mechanism. The results show that chelated fiber has a 136.3 mg/g maximum capacity for Cu 2+ adsorption at pH = 5, and the whole adsorption process could reach equilibrium in about 60 min. The adsorption process corresponds to the quasi-secondary kinetic and Langmuir models. The results of adsorption, FTIR, and XPS tests indicate that the synergistic coordination of -COOH and -NH 2 plays a leading role in the rapid capture of Cu 2+ . In addition, introducing hydrophilic groups facilitates the rapid contact and interaction of the fibers with Cu 2+ in the solution. After being used five times, the fiber’s adsorption capacity remains at over 90% of its original level.

The physicochemical properties of ligand-coated nanoparticles make them superior adsorbents for heavy metals from water. In this study, we investigate the adsorption potential of novel polyacrylic-co-maleic-acid-coated magnetite nanoparticles (PAM@MNP) to remove Pb2+ and Cu2+ from an aqueous solution. We argue that modifying the surface of MNP with PAM enhances the physicochemical stability of MNP, improving its ability to remove heavy metals. The adsorption kinetics data show that PAM@MNP attained sorption equilibrium for Pb2+ and Cu2+ after 60 min. The kinetics data are fitted accurately by the pseudo-first-order kinetic model. The calculated Langmuir adsorption capacities are 518.68 mg g−1 and 179.81 mg g−1 for Pb2+ and Cu2+, respectively (2.50 mmol g−1 and 2.82 mmol g−1 for Pb2+ and Cu2+, respectively). The results indicate that PAM@MNP is a very attractive adsorbent for heavy metals and can be applied in water remediation technologies.