Functionalized Materials for Environmental Applications

A sustainable alginate-based composite adsorbent was developed by valorizing soy whey wastewater for the efficient removal of copper (II) ions from aqueous solutions. Soy whey wastewater/sodium alginate/cellulose (SWWSAC) beads were fabricated via a controlled slow-release calcium ion cross-linking strategy. This strategy resulted in homogeneous gelation, effective encapsulation of wastewater-derived organics and the formation of a hierarchical mesoporous structure. Compared with pure sodium alginate (SA) and sodium alginate–cellulose (SAC) beads, the SWWSAC beads exhibited a significantly higher specific surface area (3.95 m²/g) and pore volume (0.021 cm³/g), thus having markedly enhanced copper (II) ion adsorption performance. Batch adsorption experiments demonstrate that the adsorption process was strongly dependent on solution pH, adsorbent dosage, contact time and initial metal concentration. Kinetic analysis indicates that the adsorption process followed a pseudo-second-order model, while equilibrium data were well described by the Langmuir isotherm, corresponding to monolayer chemisorption. Based on this isotherm, SWWSAC beads had a theoretical maximum adsorption capacity of 168.3 mg/g (25 °C), 190.8 mg/g (35 °C), and 204.4 mg/g (45 °C). Thermodynamic results reveal that the adsorption was spontaneous and endothermic. FTIR and XPS analyses confirm that copper (II) ion removal was governed by synergistic complexation involving carboxyl, hydroxyl, carbonyl, and protein-derived nitrogen-containing functional groups. Moreover, the SWWSAC beads had a copper (II) ion removal efficiency of (92.4 ± 0.4)% and retained 73.3% of their initial adsorption capacity after six regeneration cycles in actual electroplating wastewater treatment. In this process, the beads exhibited good anti-interference performance against coexisting cations and good structural stability. Therefore, this work demonstrates an effective and low-cost strategy for copper (II) ion removal while providing a value-added route for the sustainable utilization of soy whey wastewater. Full article

Tetracycline antibiotics are increasingly detected in aquatic environments because of their ecological risks and persistence, while conventional wastewater treatment processes are often insufficient for their effective removal from water. Here, we introduce a novel 3D graphene oxide-based nanocomposite that stacks Cu-NPs and amino-functionalized MIL-101(Fe) (denoted by Cu/NH₂-MIL-101(Fe)@GO) to effectively remove tetracycline (TC) and oxytetracycline (OTC) from environmental water samples. XPS, XRD, TEM, SEM, and FTIR analyses were conducted to characterize the structure and surface morphology of the Cu/NH₂-MIL-101(Fe)@GO nanocomposite. Overall, it was confirmed that GO, NH₂-MIL-101(Fe), and Cu-NPs were successfully incorporated, resulting in a porous material with high access to Cu-related sites as well as oxygen- and nitrogen-based functionalities (such as amino-, hydroxy-, and carboxy-groups). This hybrid system facilitates the adsorption by complementary mechanisms like surface complexation/chelation at Cu and Fe centers with the pH-dependent tetracycline species in electrostatic interactions, hydrogen bonding, π–π stacking, and molecule confinement in the metal–organic framework (MOF) pores, and by the synergistic effects at the GO–MOF(Fe)–Cu junction interfaces. The batch adsorption studies showed that the quick and efficient uptake of the two antibiotics at pH 6.5, with removal rates of 99.65–99.83%, was achieved by 15.0 mg of Cu/NH₂-MIL-101(Fe)@GO at an initial concentration of 20 ppm in 40 min at 25 °C. Equilibrium data were found to be well-fitted by the Langmuir isotherm (R² = 0.908–0.909), suggesting monolayer-dominated adsorption with the maximum capacity of 769.8–775.2 mg g⁻¹. The adsorption kinetics was well-described by the pseudo-second order model (R² = 0.9641–0.9749), which agreed with the strong binding between the tetracyclines and active sites of the nanocomposite. The main novelty of this work consists of the design of a single recoverable platform integrating GO-based preconcentration, pore accessibility of NH₂-MIL-101(Fe), and Cu-driven complexation, which led to the strong removal of tetracyclines under a relevant range of water conditions. These findings demonstrate that Cu/NH₂-MIL-101(Fe)@GO could serve as a promising high-efficiency and potentially reusable adsorbent for removing tetracycline from aqueous solution, which provides a more sustainable approach for pharmaceutical wastewater treatment. Full article

Excessive phosphorus discharge from aquaculture effluent significantly contributes to coastal eutrophication, while conventional adsorbents exhibit limited phosphorus removal efficiency in high-salinity, weakly alkaline seawater effluent. This study developed iron/calcium co-modified chlorella biochar (FCBC) through co-impregnation and high-temperature pyrolysis, optimizing the preparation process via the Box–Behnken response surface method. The optimal conditions were identified as an iron concentration of 2.5 mol/L, a calcium concentration of 2.0 mol/L, a pyrolysis temperature of 717 °C, and a duration of 113 min. Under these conditions, FCBC achieved a phosphorus removal rate of 93.23% within 3 h, which was significantly higher than that of the unmodified Chlorella biochar (BC, <8% within the same reaction time). The Fe/Ca co-modification endowed FCBC with a positively charged surface, an increased average pore size of 22.773 nm, and good magnetic responsiveness (saturation magnetization of 6.68 emu·g⁻¹). FCBC demonstrated remarkable adaptability, achieving over 97% phosphorus removal across a pH range of 3 to 11, salinity levels of 5 to 40‰, and phosphorus concentrations of 1 to 15 mg/L. Its adsorption kinetics conformed to pseudo-second-order kinetics (R² = 0.987) and the Freundlich model (R² = 0.971), with efficient phosphorus removal primarily attributed to iron–calcium synergistic effects. FCBC presents significant potential for phosphorus treatment in marine aquaculture effluents. Full article

Arsenic contamination, mainly in the arsenate (As(V)) form, continues to pose a serious threat to groundwater quality worldwide due to its long-term stability and toxicity at very low levels. Herein, we demonstrate, for the first time, a three-dimensional graphene oxide-based nanocomposite composed of Cu nanoparticle-doped, amino-functionalized UiO-66 (Cu/UiO-66-NH₂) anchored on a graphene oxide framework (Cu/UiO-66-NH₂@GO) as a novel and efficient nanosorbent for the rapid removal of As(V) in groundwater-like solutions. The nanocomposite was characterized by SEM and HRTEM to confirm the hybrid structure and by XRD, N₂ adsorption–desorption isotherms, and XPS to investigate crystallinity, porosity, and surface chemistry. The derived material exhibited a highly dispersed morphology and performed rapid arsenate solid-phase extraction to attain equilibration within 10 min and was effective for a wide pH range of 2–11. The best fit for the kinetic profiles was provided by the pseudo-second-order model. Interestingly, the maximum adsorption capacity of 747.9 mg g⁻¹ at pH 6.8 was achieved, demonstrating the benefits of the complementary pairing of dispersive GO sheets and Zr-MOF adsorption domains with Cu-derived active sites. Mechanistically, the enhanced uptake is ascribed to a combination of effects, including electrostatic pre-concentration, ligand exchange, and inner-sphere complexation at metal-oxo nodes; spectroscopic analysis (XPS and FTIR) suggests that the majority of arsenate is immobilized via a strong Zr-O-As bond at coordinatively unsaturated Zr centers, which is in line with t-ZrO₂-like surface domains formed within the nanocomposite. The embedded GO support inhibits further framework interpenetration and enhances active site availability and mass transport, leading to fast and high-capacity arsenate capture in groundwater samples with related conditions. Taken together, this work presents a powerful design concept that integrates unique GO-supported, Cu-modified UiO-66-NH₂ with Zr-O binding motifs to afford high-rate remediation nanocomposites, providing an excellent platform for next-generation arsenate remediation materials. Full article

Current strategies for treating organic dye wastewater are shifting from single-function removal processes and catalytic degradation methods toward more integrated treatment approaches. This study proposes a multifunctional composite integrating adsorption–photodegradation–intelligent recovery for photodegradation and recovery of methylene blue-contaminated wastewater. By optimizing the preparation process to precisely control the pore size and arrangement of the aerogel, a hierarchical porous framework with a high specific surface area is formed, featuring efficient mass transfer and ultra-multiple loading sites. The graphene framework enhances visible-light absorption by optimizing TiO₂ loading, agglomeration behavior and addressing detachable defects through a metal–polyphenol network. After 60 min of illumination, the degradation efficiency exceeds 99.5%, demonstrating superior cycling stability. After 100 cycles, the photocatalytic efficiency remains above 97%, showcasing excellent durability. Furthermore, the in situ polymerized thermoresponsive poly (N-isopropylacrylamide) (PNIPAm) composite exhibits smart responsiveness, enabling reversible temperature-responsive adsorption–desorption behavior within PNIPAm’s LCST range. with an adsorption capacity of 28,000 mg/g at LCST. Heating above LCST desorbs 90.2% of the wastewater, and adsorption stability remains above 98% after 100 thermal cycles, resolving operational challenges in mechanical wastewater recovery. The synergistic integration of an anisotropic porous structure, stable TiO₂ loading, and thermal responsiveness provides an efficient platform for integrated adsorption and recovery. Full article

One-step hydrothermal synthesis of zeolites is a common synthesis technology for zeolites. Las-NaP1 zeolite was synthesized with fly ash (FA) as the silica-alumina source under low-alkalinity conditions for aqueous adsorption. Furthermore, H-NaP1 modified zeolite, a high-efficiency chloride ion (Cl⁻) adsorbent, was fabricated using hollow glass microspheres (HGMs) and FA as a silica-alumina source. The structure of the material was characterized by XRD, SEM, TEM, BET, XPS, FT-IR, Zeta, and other techniques. Effects of the synthesis process and adsorption conditions on the adsorption performance of Cl⁻ and its mechanism were systematically studied. The maximum adsorption capacity of H-NaP1 for Cl⁻ (193.57 mg/g) is 12 times that of Las-NaP1 (15.48 mg/g). The adsorption process conformed to the pseudo-second-order kinetic model and the Freundlich isotherm model. The addition of HGMs effectively inhibited the agglomeration of zeolite particles. This research provided a new idea for the synthesis of efficient dechlorination materials with low alkali and realized the high-value-added utilization of FA. Full article

A carbon-modified attapulgite composite (C-AATP@CTAB) was synthesized via the hydrothermal method using citric acid as the carbon source and cetyltrimethylammonium bromide (CTAB) as a surface modifier for efficient rhodamine B (Rh-B) removal. Carbon modification elevated the composite’s specific surface area (212 m²/g) and negative surface charge (−38.21 mV), significantly enhancing dye adsorption capacity to 666.66 mg/g—nearly double that of unmodified ATP variants (360.4–386.8 mg/g). Kinetic studies confirmed pseudo-second-order adsorption kinetics, attributed to hydrogen bonding and van der Waals interactions between Rh-B and the composite. Under photo-Fenton conditions, C-AATP@CTAB achieved 99.8% Rh-B degradation within 20 min, demonstrating superior catalytic performance in heterogeneous Fenton/photo-Fenton systems. This work establishes a low-cost, high-efficiency adsorbent-catalyst hybrid derived from low-grade attapulgite, offering promising avenues for sustainable wastewater treatment. Full article