Advanced Adsorption Research Articles

Estimating in situ prepared alkaline soluble flavan as an advanced adsorbent for rare earth elements

Estimating in situ prepared alkaline soluble flavan as an advanced adsorbent for rare earth elements

Utilizing Waste Biomass from Agricultural and Forestry Sustainable Resources: Biomass Conversion to Functional Adsorbent Material for Efficient Removal of Total Phosphate in Practical Water.

The promotion of the utilization of waste agricultural and forestry resources (AFRs) as a means of combating environmental pollution represents an advanced and necessary development approach with the potential to achieve sustainable development. In this work, an advanced adsorbent with a functional Mg-Al bimetallic layer was prepared using waste sawdust biomass (WSD) as a raw material. The layer serves as the primary active component for adsorbing total phosphate from both simulated and real wastewater. The hierarchical structure of the Mg-Al bimetallic hydroxide-modified waste sawdust biomass (MA@WSD) has an abundance of nanosheets on its surface, providing ample binding sites and an enhanced specific surface area of 175.99 m2/g. Under the optimal conditions, the maximum removal efficiency toward phosphate can reach 99.99%. The adsorption of phosphate by MA@WSD follows the pseudo-second order kinetic (PSOK) model, indicating that chemisorption is the rate-determining step. Moreover, the thermodynamic data demonstrate the spontaneous nature of the adsorption process, indicating the favorable characteristics of the developed material. The adsorption mechanism can be summarized as the collaboration of physical adsorption, electrostatic interaction, and chemical adsorption. The results of the regeneration process indicate that MA@WSD exhibits a retention of 50.3% of its initial adsorption performance following the fifth testing cycle, thereby suggesting its potential for comparable reusability. The MA@WSD performs well in adsorbing total phosphate in real river water, and the removal efficiency of MA@WSD is evidently superior to commercial activated carbon, which is at least 70% higher than that of the commercial activated carbon. Besides, the 5-time average removal efficiency toward total phosphate by MA@WSD is 62.9%, evidently higher than the 29.1% of commercially available activated carbon, indicating its potential as an alternative for treating phosphorus-containing wastewater. The research provides theoretical support for harmless treatment, resource utilization, carbon sequestration, and emission reduction of waste biomass.

Dissolved organic matter-mediated adsorption behavior of benzophenones on functionalized covalent triazine frameworks

Adsorption is a highly efficacious technique for the remediation of organic micropollutants (OMPs). However, the presence of dissolved organic matter (DOM) frequently impedes adsorbent process, with insufficient attention given to this influence. This study systematically evaluates the adsorption performance of covalent triazine frameworks (CTFs) functionalized with electron-donating or electron-withdrawing groups for benzophenones (BPs). The adsorption capacities of SO3H-CTF, OH-CTF, and NH2-CTF for BPs were 512.11 μmol/g, 1356.27 μmol/g, and 1421.85 μmol/g, respectively. The adsorption mechanism is predominantly governed by π-π electron donor–acceptor (EDA) interactions, supplemented by hydrogen bonding, particularly in hydroxyl-containing BPs, with electrostatic interactions being relatively negligible. Functionalization with − OH and − NH2 groups increased the electron density in π-conjugated regions, enhancing BPs adsorption capacity, whereas − SO3H modification, due to its electron-withdrawing nature, acted as a π electron acceptor. Importantly, the mediating role of humic acid (HA) in the adsorption process was investigated. The CTF-BPs-HA ternary system can either inhibit/enhance π-π EDA interactions between π-electron donor/acceptor and BPs by adsorbing onto the CTF materials. The HA-mediated system primarily affects the film diffusion stage, with minimal impact on pore diffusion and inner surface adsorption. The oxygenated functional groups in HA slightly enhanced hydrogen bonding within the adsorption system, with negligible influence on electrostatic interactions. In the presence of HA, the overall adsorption capacity of SO3H-CTF decreased by 67.0 %, while that of OH-CTF and NH2-CTF increased by 120.9 % and 55.3 %, respectively. This study elucidates the electronic behavior modifications of functionalized CTFs during BPs adsorption and underscores the significant role of HA in interaction mechanisms, providing theoretical guidance for the design of advanced adsorbents to enhance pollutant removal efficiency.

Exploring the Potential of Beta-Cyclodextrin-Based MIL-101(Cr) for Pharmaceutical Removal from Wastewater: A Combined Density Functional Theory and Molecular Simulations Study.

Pharmaceutical contaminants pose significant risks to ecosystems and human health, necessitating effective removal strategies. This research focuses on developing advanced adsorbents for removing pharmaceutical pollutants from the environment. Metal-organic frameworks (MOFs), specifically MIL-101(Cr) functionalized with biodegradable beta-cyclodextrin (β-CDex), were investigated as potential nanocomposite adsorbents for the removal of ketorolac (KTRK), naproxen (NPXN), and tramadol (TRML). The study employed molecular simulations and density functional theory (DFT) calculations to explore the interactions between the pollutants and adsorbents. Analyses of DFT results, including electrostatic potential, ionization energy, density of states, and molecular orbital analysis, provided insights into the reactivity of pollutants and adsorbents. Additionally, the structural properties of the adsorbents, such as fractional free volume, radius of gyration, and system energies, were thoroughly examined. Molecular dynamics (MD) and Monte Carlo (MC) simulations were used to evaluate the adsorption capacities of MIL-101(Cr) for the target pharmaceutical pollutants. The results demonstrated the superior adsorption performance of the nanocomposite adsorbent, particularly for KTRK, with an adsorption energy of -1934 kcal/mol, compared to the pristine MIL-101(Cr), which had an adsorption energy of -1916 kcal/mol. This enhanced adsorption is attributed to the optimal molecular fit, guest-host solid interactions, and the selective encapsulation capabilities of β-CDex. This research highlights the potential of MOF-based nanocomposites as effective and sustainable solutions for pharmaceutical pollution. By advancing the understanding of molecular interactions through simulations, this study contributes to developing innovative adsorbents for wastewater treatment and the protection of water resources.

Surface engineered waterworks sludge embedded PAN electrospun membrane for efficient and selective removal of phosphate in actual surface water

Advanced adsorbents for selective removal of excessive phosphorus in actual surface water bodies and safe disposal of waterworks sludge are essential due to environmental risks and resource wastes. Herein, a strategy of killing two birds with one stone was proposed to design a La(OH)3/iron-based waterworks sludge/polyacrylonitrile (La(OH)3/IS/PAN) membrane for selective removal of phosphate. In this strategy, nano-La(OH)3 was well-dispersed on IS surface to realize functionalization of IS, and PAN electrospun nanofibers prevented powdered La(OH)3/IS from loss. The membrane showed a maximum adsorption capacity of 19.89 mg/L at 25 °C and remained relatively stable phosphate adsorption capacity under various anions interference. More importantly, after adsorption, the total phosphorus (TP) of the actual surface water from Yudai river was reduced to meet the requirement of the surface water standard of China, Ⅱ (GB 3838–2002). The work provides a novel way to overcome the challenges posed by eutrophication and sludge problems for industrial applications.

UiO-67 Metal–Organic Framework as Advanced Adsorbent for Antiviral Drugs from Water Environment

Metal–organic frameworks (MOFs) have attained significant usage as adsorbents for antiviral medicines in contemporary times. This study focused on synthesizing a UiO-67 metal–organic framework using the hydrothermal method. The synthesized framework was then characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analyses (TGA), and zeta potential measurements. The UiO-67 was then employed for the purpose of assessing the efficiency of various adsorption factors in the removal of antiviral medicines from aqueous solutions, including drugs such as ritonavir (RTV) and lopinavir (LPV), which were extensively used for the treatment of coronavirus (COVID-19) during the pandemic. The variables examined were the quantity of adsorbent used, different pH of the solution, temperature, and contact duration. The experimental findings indicate that the highest level of RTV elimination was 91.2% and of experimental adsorption capacity (qe,exp) was 9.7 mg/g and for LPV this was 85.9%, and (qe,exp) 8.9 mg/g, using 50 mg of UiO-67 at a pH 8, temperature of 298 K, and for 120 min. The impact of contact duration and temperature on the kinetics of adsorption was examined by employing pseudo-first-order and pseudo-second-order kinetic models. The experimental results showed a good match with the pseudo-second-order kinetic model with value of R2 0.99 and the qe,calc was 9.7 RTV and 8.9 mg/g LPV, which is a good match with qe,exp. Also, based on diffusion kinetic studies, the adsorption was confirmed to be catalytic in nature on the surface of the UiO-67 MOFs. A thermodynamic analysis of adsorption was conducted, whereby calculations for the Gibbs free energy change (∆G), enthalpy change (∆H), and entropy change (∆S) were performed. The positive ∆H values confirm the endothermic nature of the adsorption of RTV and LPV by UiO-67. The ΔG values exhibited negativity across all temperatures, suggesting the spontaneous nature of the adsorption process of RTV and LPV by UiO-67 from an aqueous solution. UiO-67 was shown to be highly effective in extracting RTV and LPV from real environmental samples.

In-depth analysis of the removal mechanisms behind neonicotinoid pesticides and bimetal ZIF derived-magnetic carbon

Emerging organic contaminants, such as pesticides, pose significant environmental challenges and necessitate the development of advanced materials and technologies for their efficient removal. This study explored various morphologies of bimetal ZIF-derived magnetic carbon for the removal of three representative neonicotinoid pesticides from water. Among the materials investigated, Co-NP3-1000, carbonized at 1000℃ from Zn/Co-ZIF with a Zn/Co molar ratio of 3:1, demonstrated outstanding adsorption performance, even in the presence of varying water chemistry parameters (e.g., humic acid and particulate matter), and effectively removed neonicotinoid pesticides at low concentrations from diverse actual water samples. Due to its strong magnetic properties, Co-NP3-1000 could be easily separated from solutions and maintained over 70% adsorption efficiency after five consecutive cycles. Moreover, Co-NP3-1000 exhibited high efficiency in removing other neonicotinoid pesticides (i.e., acetamiprid, nitenpyram, and thiamethoxam). Microstructure analysis and density functional theory calculation identified pore filling, hydrogen bonding, and π-π interactions as the primary forces driving NEOs adsorption. Notably, the relative contribution of these interactions was quantitatively assessed across different solution pH levels, and their sequence was elucidated using two-dimensional Fourier transform infrared correlation spectroscopy. This work advances both the design of versatile materials for the removal of emerging organic contaminants and quantitative insights into the interaction mechanisms between advanced adsorbents and these contaminants.

High mixing enhancement for continuous uniformity Li/Al-LDHs in lithium extraction from low grade salt lakes

The enhancement of lithium extraction from low grade salt lake through the development of advanced adsorbents has become a primary focus in current research. A new method was developed in this work for the continuous fabrication of ultra-highly uniform lithium-aluminum layered double hydroxides (H-LDHs), used as lithium adsorbents, through a high mixing reactor. These H-LDHs featured a more consistent particle size distribution, which facilitated an enhanced vibrational density. This not only significantly increased the powder content in granules but also improved lithium adsorption efficiency. Computational fluid dynamics (CFD) modeling showed that the reactor reached peak mixing efficiency with a minimal gap size of 1 mm. The analysis further indicated that a Reynolds number of 75 led to enhanced mixing effects and stronger flow dynamics. Experiments with Qarhan salt lake brine demonstrated that the H-LDHs powders reached a lithium adsorption capacity of up to 7.27 mg/g, while the volumetric adsorption capacity of these H-LDHs granules exceeded that of traditional granules by 1.179 times. Subsequent desorption and cycling experiments verified the material’s enduring lithium adsorption efficacy and structural integrity, underscoring its considerable potential for industrial use.

Zn-MOF-5-Modified biochar derived from KMnO4-activated waste corncob for enhanced adsorption of gaseous ammonia

Ammonia (NH3) is an odor gas pollutant which has serious harm to the environment and human health. The development of advanced adsorbents to remove NH3 is of great significance. Herein, a new adsorbent for NH3 adsorption with high efficiency was prepared by in-situ growth of Zn-MOF-5 on the KMnO4-activated waste corncob-derived porous biochar (KCB). The optimized M0.6K0.1CB-400 sample was obtained by optimizing the mass ratio of KMnO4 to corncob at 0.1, activation temperature at 400 °C, and the dosage ratio of Zn-MOF-5 to porous biochar at 0.6. The M0.6K0.1CB-400 demonstrated an excellent NH3 adsorption capacity of 6.88 mmol/g at 298.15 K and 1 bar, exhibiting a fast adsorption kinetics with 94 % of the equilibrium adsorption capacity reached in just 10 min. The M0.6K0.1CB-400 composite demonstrated good regeneration functionality by maintaining a NH3 removal capacity of 3.44 mmol/g after 6 regeneration cycles. Based on the thermodynamic and kinetic analyses, along with characterization of the chemical composition and physical structure of the NH3-adsorbed samples, the adsorption process of MKCB on NH3 was proven to involve a combination of physical and chemical adsorption. This study introduces a novel method for synthesizing MOF-modified biochar as a highly efficient NH3 adsorbent, offering new insights into the underlying mechanisms of gas purification.

Facile synthesis of poly(tannic acid-1,4-butanediamine) microsphere based on the “self-assembly to polymerization” mechanism and its fast removal feature toward Cr(VI) ions

To remediate toxic Cr(VI) ions in wastewater is a daunting environmental challenge nowadays, thus advanced adsorbents are developed and used to overcome the low removal rate of existing technologies. Herein, poly(tannic acid-1,4-butanediamine) (PTBA) microspheres were synthesized for the purpose of fast removal of Cr(VI) from the aqueous phase. The synthesis was based on the “self-assembly to polymerization” mechanism. The microstructures and chemical characteristics of the fresh and used adsorbents PTBA were characterized systematically by means of TEM, SEM, FT-IR, XPS, TGA and XRD. Effects of pH, contact time, Cr(VI) initial concentration, PTBA dosage, temperature, and the presence of foreign ions on the removal of Cr(VI) had been investigated sequentially. The results indicated that almost 100% of removal efficiency could be achieved in short time intervals, based on the initial concentration of Cr(VI). The spontaneous and endothermic adsorption behavior could be well described by the pseudo-2nd-order (P2O) and Langmuir isotherm models. Finally, the process of partial reduction of Cr(VI) to non-toxic Cr(III) during the adsorption process was explained. Overall, the refined PTBA adsorbent presents a satisfactory behavior to ameliorate the Cr(VI)-pollution elimination means.

MXene Synthesis and Carbon Capture Applications: Mini-Review.

MXenes, a class of two-dimensional transition metal carbides, nitrides, and carbonitrides, have garnered significant attention due to their remarkable potential for energy storage, electrocatalysis, and gas separation applications. The fabrication processes of MXene involve building up the MXene structure from constituent elements and the selective elimination of M-A bonds from the precursor MAX. However, considerable efforts are still required to design and develop efficient MXene-based technologies. This review article aims to briefly analyse the synthesis methods employed for MXene production, ranging from direct synthesis and conventional chemical wet etching approach to the more recent molten salt etching technique. The review highlights the advancements made in achieving precise control over the terminal groups, which is paramount for tailoring the properties of MXenes for specific applications. Furthermore, the potential of MXene-based materials for carbon capture applications, particularly in developing advanced adsorbents, is emphasized. The in-depth examination of MXene synthesis techniques and their implications for carbon capture applications provides a solid foundation for developing and optimizing these promising materials.

Photoinduced synthesis of polymer-coated covalent organic framework microspheres for highly efficient lithium recovery

The increasing demand for lithium-ion batteries has led to a surge in global lithium consumption, calling for efficient extraction and recovery methods. Adsorption-based lithium recovery has gained attention for its simplicity, selectivity, and low energy requirements. However, conventional adsorption materials for lithium-ion (Li+) suffer from low surface area and covered active sites, resulting in slow recovery and inefficient uptake. Herein, we present a facile photoinduced synthesis of crown ether (CE)-based polymer grafted covalent organic framework (COF) microspheres, termed COF-CE, as an efficient lithium adsorbent. The COF-CE hybrid material possesses abundant nanochannels and highly porous surfaces, enabling rapid ion diffusion and enhancing ion accessibility to functional groups with the exclusive selectivity imparted by the grafted CE polymer towards Li+ over other monovalent cations. Notably, COF-CE exhibits exceptional absorption capacity (7.4 mg/g), rapid adsorption rates (k2 = 0.137 g mg−1 min−1) and high selectivity towards Li+, outperforming existing adsorbents. Moreover, COF-CE demonstrates remarkable Li+ regeneration and recycling capabilities, achieving near-unity recovery of lithium during the desorption phase and retaining 97 % of its adsorption capacity after five cycles. These results highlight the potential of COF-CE as an advanced adsorbent for lithium recovery in various applications, including industrial wastewater treatment and environmental remediation efforts.

Ibuprofen removal from water using the IB-COF covalent organic framework

The rising presence of ibuprofen (IBP) in natural water bodies, restricting from its widespread pharmaceutical usage, necessitates effective remediation strategies. This study introduces IB-COF, a novel covalent organic framework synthesized via a solvothermal method, specifically engineered for IBP extraction from aqueous solutions. IB-COF showcases remarkable adsorption performance, achieving equilibrium within 60 min with a capacity of 512 mg/g, outperforming conventional adsorbents. Its adsorption kinetics align with pseudo-second-order and Langmuir models, indicating efficient monolayer adsorption. Significantly, IB-COF exhibits robust recyclability over five cycles. Among the prevalence of IBP contamination, IB-COF demonstrates promise in selectively extracting IBP even in the presence of competing pharmaceuticals. Overall, our findings underscore the potential of IB-COF as an advanced adsorbent for mitigating IBP pollution in water sources, contributing significantly to environmental purification efforts and water pollution mitigation strategies.

Scavenging Radionuclide by Shapeable Porous Materials.

Nuclear energy is a competitive and environmentally friendly low-carbon energy source. It is seen as an important avenue for satisfying energy demands, responding to the energy crisis, and mitigating global climate change. However, much attention has been paid to achieving the effective treatment of radionuclide ions produced in nuclear waste. Initially, advanced adsorbents were mainly available in powder form, which meant that additional purification processes were usually required for separation and recovery in industrial applications. Therefore, to meet the practical requirements of industrial applications, materials need to be molded and processed into forms such as beads, membranes, gels, and resins. Here, we summarize the fabrication of porous materials used for capturing typical radionuclide ions, including UO2 2+, TcO4 -, IO3 -, SeO3 2-, and SeO4 2-.

Record High Iodate Anion Capture by a Redox-Active Cationic Polymer Network.

As a critical radioactive anionic contaminant, traditional adsorbents primarily remove iodate (IO3 -) through ion exchange or hard acid-hard base interactions, but suffer from limited affinity and capacity. Herein, employing the synergistic effect of ion exchange and redox, we successfully synthesized a redox-active cationic polymer network (SCU-CPN-6, [C9H10O2N5 ⋅ Cl]n) by merging guanidino groups with ion-exchange capability and phenolic groups with redox ability via a Schiff base reaction. SCU-CPN-6 exhibits a groundbreaking adsorption capacity of 896 mg/g for IO3 -. The inferior adsorption capacities of polymeric networks containing only redox (~0 mg/g) or ion exchange (232 mg/g) fragments underscore the synergistic "1+1>2" effect of the two mechanisms. Besides, SCU-CPN-6 shows excellent uptake selectivity for IO3 - in the presence of high concentrations of SO4 2-, Cl-, and NO3 -. Meanwhile, a high distribution coefficient indicates its exemplary deep-removal performance for low IO3 - concentration. The synergic strategy not only presents a breakthrough solution for the efficient removal of IO3 - but also establishes a promising avenue for the design of advanced adsorbents for diverse applications.

Record High Iodate Anion Capture by a Redox‐Active Cationic Polymer Network

AbstractAs a critical radioactive anionic contaminant, traditional adsorbents primarily remove iodate (IO3−) through ion exchange or hard acid‐hard base interactions, but suffer from limited affinity and capacity. Herein, employing the synergistic effect of ion exchange and redox, we successfully synthesized a redox‐active cationic polymer network (SCU‐CPN‐6, [C9H10O2N5 ⋅ Cl]n) by merging guanidino groups with ion‐exchange capability and phenolic groups with redox ability via a Schiff base reaction. SCU‐CPN‐6 exhibits a groundbreaking adsorption capacity of 896 mg/g for IO3−. The inferior adsorption capacities of polymeric networks containing only redox (~0 mg/g) or ion exchange (232 mg/g) fragments underscore the synergistic “1+1>2” effect of the two mechanisms. Besides, SCU‐CPN‐6 shows excellent uptake selectivity for IO3− in the presence of high concentrations of SO42−, Cl−, and NO3−. Meanwhile, a high distribution coefficient indicates its exemplary deep‐removal performance for low IO3− concentration. The synergic strategy not only presents a breakthrough solution for the efficient removal of IO3− but also establishes a promising avenue for the design of advanced adsorbents for diverse applications.

In-situ controllable hybridization of CuFeS2-ternary transition metal sulfide with boron carbide nitride toward enhanced antibiotics adsorption

Ternary transition metal sulfide (TTMS) contains numerous metal active sites, rendering promising adsorbents. However, a challenging problem in their further applicability is how to expand the available active surfaces which hindered by aggregation. Here, a novel strategy of engineering hybridization of CuFeS2 with boron carbide nitride (BCN) nanosheets was proposed vis an in-situ facile controlled hydrothermal process. An improved specific surface area of approximate 6.24 times enlargement was achieved for TTMS of CuFeS2 under the uniformly dispersion effect of BCN nanosheets. Meanwhile, the fabrication of nanocomposites CuFeS2-BCN significantly enhanced the adsorption affinities including hydrogen bonding, π-π interactions, metal-complexation and electrostatic interactions, thereby resulting in an amazing elimination capacity of 90.72% which respectively 25% and 368% growth toward pristine CuFeS2 and BCN for antibiotic contaminant of chlortetracycline (CTC). Systematic adsorption studies of adsorption kinetics, isotherms, and thermodynamics revealed that the adsorption process of CuFeS2-BCN-0.1 to CTC was spontaneous and endothermic, and followed the pseudo-second-order kinetics and Langmuir isotherm models. The maximum Langmuir adsorption capacity was super high and up to 1166.31 mg/g, which was superior to the majority of the reported adsorbents. In addition, it is also worth emphasizing that the nanocomposites of CuFeS2-BCN-0.1 possessed satisfactory selectivity, stability and adaptability to many tetracycline antibiotics in multicomponent solution under diverse pH environments. All of these findings presented that the proposed advanced adsorbent of CuFeS2-BCN-0.1 displayed great promising application potential in the treatment of antibiotic contamination wastewater.

Starch-Grafted Polyacrylic Acid Copolymer with Acrylamide: An Advanced Adsorbent for Victoria Green B Dye Removal and Environmental Remediation

A new adsorbent, starch grafted polyacrylic acid copolymer with polyacrylamide (SG@AA-co-AM), was synthesized using free radical polymerization techniques. Proton nuclear magnetic resonance (1H NMR), Fourier-transform infrared spectrophotometry (FTIR), X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), particle size distribution (PSD), and fluorescent electron microscopy (FEM) were employed to elucidate the structure, crystalline nature, thermal stability, and surface morphology of SG@AA-co-AM. SG@AA-co-AM was utilized as an adsorbent for the removal of Victoria green B (VGB) dye from wastewater. SG@AA-co-AM exhibited a removal percentage (% R) of 97.6% towards VGB under optimized conditions: a contact time of 30 min, temperature of 25 °C, adsorbent dose of 20 mg, pH of 8, concentration of dye solution of 20 ppm, and volume of dye solution of 30 mL. The point of zero charge (PZC) for SG@AA-co-AM was determined to be 5.2. Nonlinear pseudo-second-order (PSO) and Langmuir adsorption isotherm models best fitted to the experimental data, with regression coefficients (R2) of 0.95 and 0.99, respectively. The results confirmed the chemi-sorption and monolayer adsorption of VGB onto SG@AA-co-AM. Thermodynamic studies revealed that the adsorption of VGB onto SG@AA-co-AM is endothermic and spontaneous. Furthermore, the regeneration experiment showed a decline of 3.9% after five cycles, confirming the economical and reusable nature of SG@AA-co-AM.

Porous polyvinyl alcohol/polyacrylamide hydrogels loaded with HTO lithium-ion sieves for highly rapid and efficient Li+ extraction

Lithium (Li) reserves in liquid resources are significantly higher than solid lithium ores and can fully meet the growing demand for Li. Lithium-ion sieves (LIS) adsorption of Li from liquid resources is one of the most promising methods. However, conventional polymeric adsorption materials encapsulate most LIS in dense structures, leading to low adsorption capacity and slow adsorption rate. Therefore, HTO-PVA/PAAm hydrogel was synthesized from titanium-type lithium-ion sieves (HTO), acrylamide, and polyvinyl alcohol by free radical polymerization. The HTO-PVA/PAAm hydrogel is characterized by a soft three-dimensional (3D) network, continuously adjustable pore structure, high specific surface area, and excellent hydrophilicity. Accordingly, the HTO-PVA/PAAm owns an excellent Li+ adsorption capacity (22.16 and 31.31 mg·g−1 in pH 7.2 and 12 of LiCl solutions, respectively) among reported advanced adsorbents. 90 % of Li+ is desorbed within 60 min, indicating the efficient and rapid Li+ desorption response of the hydrogel. Meanwhile, this hydrogel still maintains a Li+ adsorption capacity of 90 % after eight adsorption-desorption cycles, during which Ti loss is <0.42 % in each cycle. In this work, HTO-PVA/PAAm hydrogel synthesized by an environmentally friendly and low-cost approach shows great application potential as a new strategy for Li+ adsorption from liquid resources.

Review of emerging technologies for nutrient removal in wastewater treatment

The burgeoning global population and industrial activities have significantly increased the generation of wastewater laden with nutrients, posing severe environmental and public health concerns. Traditional wastewater treatment methods often fall short in effectively removing nutrients like nitrogen and phosphorus, leading to eutrophication of water bodies and endangering aquatic ecosystems. In response, emerging technologies for nutrient removal in wastewater treatment have gained traction in recent years, offering innovative and efficient solutions to mitigate nutrient pollution. This comprehensive review explores the latest advancements in nutrient removal technologies, encompassing biological, physical, and chemical processes. Biological treatment methods, including activated sludge, sequencing batch reactors (SBRs), and membrane bioreactors (MBRs), have been extensively studied and optimized for nutrient removal. Novel biofilm-based systems, such as moving bed biofilm reactors (MBBRs) and integrated fixed-film activated sludge (IFAS), have demonstrated enhanced nutrient removal capabilities and resilience to fluctuations in wastewater composition. Furthermore, the integration of advanced oxidation processes (AOPs) and membrane technologies has revolutionized nutrient removal from wastewater. AOPs, such as ozonation, ultraviolet (UV) irradiation, and photocatalysis, offer effective means to degrade recalcitrant organic pollutants and disrupt nutrient cycles. Membrane-based technologies, including reverse osmosis (RO), nanofiltration (NF), and forward osmosis (FO), enable selective nutrient removal and concentration, thereby producing high-quality effluent suitable for reuse or discharge into sensitive environments. Additionally, the review delves into emerging chemical treatment strategies, such as adsorption, precipitation, and ion exchange, for targeted removal of nutrients from wastewater streams. Advanced adsorbents and nanomaterials exhibit superior adsorption capacities and selectivity for nitrogen and phosphorus compounds, paving the way for cost-effective nutrient recovery and resource recycling. Moreover, the review highlights the importance of process optimization, system integration, and environmental sustainability in the development and deployment of emerging nutrient removal technologies. Life cycle assessments (LCAs) and techno-economic analyses provide valuable insights into the environmental footprint and economic viability of these innovative solutions, guiding decision-makers towards sustainable wastewater management practices. In conclusion, the synthesis of biological, physical, and chemical processes in emerging nutrient removal technologies holds great promise for addressing the challenges of nutrient pollution in wastewater treatment. Future research directions should focus on scalability, energy efficiency, and holistic approaches towards achieving water quality goals and fostering a circular economy.