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Extraction and recovery of lithium from reserves play a critical role in the sustainable development of energy due to the explosive growth of the lithium‐battery market. However, the low efficiency of extraction and recovery seriously threatens the sustainability of lithium supply. In this contribution, we fabricate a novel mechanically robust fluorine‐rich hydrogel, showing highly efficient Li+ extraction from Li‐containing solutions. The hydrogel was facilely fabricated by simple one‐pot polymerization of supramolecular nanosheets of fluorinated monomers, acrylic acid and a small amount of chemical crosslinkers. The hydrogel exhibits a remarkable lithium adsorption capacity (Qm Li+=122.3 mg g−1) and can be reused. Moreover, it can exclusively extract lithium ions from multiple co‐existing metal ions. Notably, the separation of Li+/Na+ in actual wastewater is achieved with a surprising separation factor of 153.72. The detailed characterizations as well as calculation showed that the specific coordination of Li−F plays a central role for both of the striking recovery capability and selectivity for Li+. Furthermore, an artificial device was constructed, displaying high efficiency of extracting lithium in various complex actual lithium‐containing wastewater. This work provides a new and promising avenue for the efficient extraction and recovery of lithium resource from complex lithium‐containing solutions. [ABSTRACT FROM AUTHOR]

• Cu-MOF is used to recycle Au(S 2 O 3) 2 3− from alkaline leachate for the first time. • The adsorption capacity of 206.19 mg/g is the highest in the adsorption method. • Diphenylamine and copper cluster defects are used as active sites. • Local exotherms of DMF facilitate the recovery of Au(S 2 O 3) 2 3−. • The interaction between Cu-ADA and Au(S 2 O 3) 2 3− was investigated with DFT calculation. Recycling gold from electronic waste is essential for environmental protection and resource sustainability. However, the design of adsorbents for effective recycling of Au(S 2 O 3) 2 3− from alkaline leach solutions is of great challenge and has not been investigated by using MOFs. Herein, we report the design and preparation of a Cu-MOF based on the structural characteristics of Au(S 2 O 3) 2 3−, which is constructed by 4,4′-di carboxy diphenylamine and Cu 2 -paddlewheel. Cu-ADA-53 demonstrates ultra-high adsorption capacity of 206.19 mg g -1, and the gold recovery in actual alkaline leach solutions is more than 99 %. X-ray photoelectron spectroscopy, thermodynamic study, and density functional theory calculations reveal the excellent performance of Cu-ADA-53 for Au(S 2 O 3) 2 3− results from the abundant Lewis base diphenylamine groups and open copper sites. More importantly, different from pore diffusion-promoting adsorption, the axial coordination DMF of Cu 2 -paddlewheel fell off into the water phase and then released heat locally at the adsorption sites. The local exotherms increase the temperature of the adsorption sites, further promoting the adsorption of Au(S 2 O 3) 2 3− by Cu-ADA-53. The local exotherms at adsorption sites provide a novel insight to efficiently recover Au(S 2 O 3) 2 3−. [Display omitted] [ABSTRACT FROM AUTHOR]

It is significant and difficult to selective removal and recovery rare earth elements in wastewater. A novel La(III) imprinted polymer (La-IIP) was synthesized by taking advantage of the strong interaction between Lanthanum and phosphorus combined the adsorption selectively of ion imprinted technology. The adsorption capacity of La-IIP is 62.8 mg g–1 and the selectivity coefficient k La/Cu is 54.57. La-IIP can reach adsorption equilibrium within 0.5 h, the adsorption process was well revealed by the Intra-particle diffusion model. The regeneration properties (desorption rate, extent, and recycle times) of La-IIP were investigated. About 88% of the adsorbed La(III) was desorbed in the first 10 min. The high desorption rate was further confirmed in a fixed-bed column experiment. More significantly, the removal efficiency of the La-IIP remained about 100% after five regeneration cycles. Results of FT-IR, XPS, and DFT calculation indicated that the La(III) adsorption by La-IIP involves the reaction between La and O in the phosphonic group. This study not only demonstrated a high adsorption capacity, acid-stable, quick-desorption, and reusable adsorbent for La(III) recovery, but also developed a more comprehensive strategy for the design and testing of adsorbents with practical application prospects. [Display omitted] • Phosphonic-based ion imprinted was first synthesized for La(III) recovery. • A superior adsorption performance (adsorption capacity, rate, selective) was achieved. • The adsorbent exhibit a high stability in acid and a perfect regeneration capacity. • The adsorption and regeneration mechanism were clarified combined batch experiment, characterization, and theory calculation. [ABSTRACT FROM AUTHOR]

Low-cost and high-selective adsorbents is desirable but challenging for recovering heavy metal ions from actual wastewater. In this work, we developed a novel β-cyclodextrin covalently-crosslinked tannic acid (TA@CD) polymer nanosponge via a simple condensation reaction, and then realized the selective capture of Pb2+ from complex wastewater. TA@CD demonstrated a strong affinity for Pb2+ compared to other coexisting metal ions with a high selective coefficient of 1143 (approximately 188 times higher than that of other polymer, metal-based and bio-based adsorption materials), which can be attributed to the phenolic hydroxyl groups of TA that can effectively bind with Pb2+ to form a relatively stable structure. In the typical adsorption experiments, a high adsorption saturation capacity of 136.8 mg g−1 on Pb2+ at an initial concentration of 200 mg/L (maximum capacity was 116.5 mg/g) and an ultrafast removal efficiency of 81% Pb2+ within 3 min were achieved by TA@CD (adsorption finished within 50 min), due to the abundant exposed TA adsorption sites and the efficient mass transfer rate supported by CD. With the favorable adsorption and regeneration performance, in the dynamic treatment process with a fixed-bed reactor pack of TA@CD nanosponge, the treatment volume of Pb2+-containing simulated wastewater can up to 9860 bed volume (BV) with only 176.5 mL eluent production. This work provides a feasible approach to design economic and directional adsorbents with the potential to selectively recover heavy metal ions from actual wastewater. • A high-selective and low-cost bioadsorbent TA@CD was directionally synthesized. • The phenolic hydroxyl of TA shows a strong affinity to Pb2+ than other metals ions. • The TA@CD possesses an excellent anti-interference ability for Pb2+ recovery. • The TA@CD can treat Pb-containing wastewater with outstanding regenerative ability. [ABSTRACT FROM AUTHOR]

[Display omitted] • F-containing groups tune the electronic microenvironment of adsorption sites. • The adsorption capacity of PCA-Nanofiber for In(III) ions reached 116.3 mg/g. • Effective charge transfer of adsorption sites promotes In(III) ions capturing. Enhancing adsorbent-adsorbate interactions via rational construction of adsorption sites is essential for the capture of the strategic metal indium. Herein, a nanofiber (PCA-Nanofiber) was successfully fabricated for In(III) ions recovery by introducing an electronegative fluorine-containing group to modulate the electronic structure of adsorption sites. Adsorption experiments exhibited that the maximum adsorption of PCA-Nanofiber for In(III) ions (116.3 mg/g) was 3.3 times higher than that of the pre-regulated nanofiber, exceeding most of the reported adsorbents. The PCA-Nanofiber maintained stable performance in five consecutive adsorption–desorption experiments and exhibited excellent selectivity. Furthermore, advanced spectroscopic characterization revealed that the adsorbed complex presented in a six-coordinated octahedral configuration, resembling an anti-triangular prism configuration centered on In(III) ions. The density functional theory demonstrates that the excellent adsorption performance benefits from the electronegative F atoms modulating the electronic microenvironment of the adsorption sites and optimizing the band-gap energy for charge migration, resulting in efficiently driven charge transfer. This work offers ideas for the rational design of adsorption sites in nanofiber from the perspective of regulation of electronic microenvironmental. [ABSTRACT FROM AUTHOR]

Excessive phosphorus (P) enters the water bodies via wastewater discharges or agricultural runoff, triggering serious environmental problems such as eutrophication. In contrast, P as an irreplaceable key resource, presents notable supply-demand contradictions due to ineffective recovery mechanisms. Hence, constructing a system that simultaneously reduce P contaminants and effective recycling has profound theoretical and practical implications. Metal element-based adsorbents, including metal (hydro) oxides, layered double hydroxides (LDHs) and metal-organic frameworks (MOFs), exhibit a significant chaperone effect stemming from strong orbital hybridization between their intrinsic Lewis acid sites and P (Lewis base). This review aims to parse the structure-effect relationship between metal element-based adsorbents and P, and explores how to optimize the P removal properties. Special emphasis is given to the formation of the metal-P chemical bond, which not only depends on the type of metal in the adsorbent but also closely relates to its surface activity and pore structure. Then, we delve into the intrinsic mechanisms behind these adsorbents' remarkable adsorption capacity and precise targeting. Finally, we offer an insightful discussion of the prospects and challenges of metal element-based adsorbents in terms of precise material control, large-scale production, P-directed adsorption and effective utilization. [Display omitted] • Adsorption configurations that enhance the P chaperone effect are summarized. • Structure-effect relationship between metal element-based adsorbents and P are reviewed. • Mechanisms for remarkable adsorption capacity and precise targeting of P are addressed. • Future research efforts to overcome engineering applications barriers are proposed. [ABSTRACT FROM AUTHOR]

• Organo-functionalized SiO 2 were synthesized by a silylation reaction. • Adsorptivity was evaluated on the basis of per functional group. • EDTA exhibited a much better affinity toward heavy metals. • Adsorption sites and configurations were discerned. • Adsorption mechanism was proposed by experimental and theoretical studies. Organo-functionalized SiO 2 nanoparticles are regarded as promising adsorbents for capture of heavy metals. However, actual adsorptivity of a specific functional group onto SiO 2 surface is unclear, thus extending a debate on which type of organic group possesses a better affinity toward heavy metals. Herein, surface functionalization of SiO 2 with different groups (i.e., -EDTA (ethylenediamine triacetic acid), -COOH, -SO 3 H, -SH and -NH 2) were achieved by a facile silylating reaction. Batch experiments indicated that adsorption capacity of SiO 2 was remarkably improved by surface functionalization. Quantitative analysis manifested that one mole of EDTA grafted onto SiO 2 surface can adsorb 1.51 mol of Pb(II) ions, which was 7.7, 17.1, 28.4 and 50.2-fold larger than those of COOH-, SO 3 H-, SH- and NH 2 -functionalized SiO 2 , respectively. This is first time to evaluate adsorptivity of functionalized SiO 2 on the basis of per effective functional group, which may repair deficiency of conventional assessment method that calculated on the basis of per unit mass. Further, adsorption mechanism of these functionalized SiO 2 were identified and uncovered by experimental and theoretical studies. This work not only develops an efficient adsorbent for heavy metal remediation but also provides a valuable insight for evaluation and design of novel SiO 2 -based materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • POP-BPy exhibits excellent stability in extreme water environments. • Selective capture of palladium from aqua regia was achieved by POP-BPy. • Protonation-armed pyridine nitrogen served as active site for Pd capture. • Almost all of Pd in leachate of spent catalysts was recovered by POP-BPy. Due to the hostile environment in which it is recovered, selective separation of palladium from the leachate of spent catalysts containing palladium is of considerable utility but faces substantial obstacles. This work designed and synthesized a bipyridine-based porous organic polymer (POP-BPy) via free radical polymerization. Meanwhile, its adsorption characteristics and the mechanism of adsorption in extreme environments were examined. In hostile conditions, the resultant POP-BPy display exceptional mechanical stability and environmental resistance. Impressively, POP-BPy has an excellent adsorption capacity of Pd(II) (248 mg/g) in harsh environments (aqua regia: AR; half-diluted aqua regia: AR"1 + 1"), and also had superior selectivity and rapid kinetics. The selectivity of POP-BPy for Pd(II) was verified in combination with relevant experiments (β Pd(II)/Pt(II) = 36.19, β Pd(II)/Pt(II) = 23.90). Furthermore, combining density functional theory (DFT) and molecular dynamics (MD) simulations, the mechanism of selectivity of POP-BPy for Pd(II) was revealed from static adsorption sites to dynamic adsorption processes in a holistic manner, which attributed to the strong attraction of protonated pyridine nitrogen to PdCl 4 2- and site suitability. Furthermore, the application of POP-BPy to spent catalyst recovery resulted in up to 100% removal of Pd(II) from the actual leaching solution, and fixed bed column experiments can effectively treat 2688 bed volumes (L) of feed streams (10 mg/L) before reaching the breakthrough point (<1 mg/L). Overall, this work has opened up new avenues for the selective recycling of valuable metals in harsh environments. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electrospun f'ibers with resistant strong acid and oxidation were prepared. • TN-Nanofiber was used to capture Pd(II) ions from extreme systems. • Maximum adsorption capacity of TN-Nanofiber for Pd(II) ions was 348 mg/g at pH = 0. Palladium is not only a precious metal but also is widely used in catalyst production, therefore it is of significance to recover palladium from spent catalysts. In this paper, Nanofiber modified by 2-Thionicotinic acid (TN-Nanofiber) featuring acid- and oxidation-resistant was fabricated through electrospinning and chemical grafting, which can trap efficiently Pd(II) ions from the extremely acidic and oxidizing systems derived from the leaching of spent catalyst. The adsorption kinetic data of Pd(II) ions was well described by the pseudo-second-order model, and the times required to reach equilibrium was 60 min. The Langmuir isotherm model provided better fitting for the Pd(II) ions adsorption, and the maximum uptake capacity of TN-Nanofiber was evaluated as 348.4 mg/g for Pd(II) ions. Furthermore, the column adsorption experiments proved the feasibility of TN-Nanofiber separation of Pd(II) ions from the spent catalyst. Investigation of the adsorption mechanism demonstrated a planar quadrilateral coordination pattern between the Pd(II) ions and the adsorption sites of TN-Nanofiber, which includes one N and one S atom sourced from the adsorption sites and two Cl atoms derived from the original PdCl 4 2−. In summary, TN-Nanofiber may serve as the next generation of emerging adsorbents to recover palladium from the strongly acidic and oxidizing systems due to its excellent performance. [ABSTRACT FROM AUTHOR]

Given the large amount of toxic Cr(VI) wastewater from various industries, it is urgent to take effective treatment measures. Adsorption has been regarded as highly desirable for Cr(VI) removal, but the effectiveness of most adsorbents is significantly dependent on pH value, in which precipitous performance drop and even structural collapse generally occur in strong acidic/alkaline aqueous. Thus, maintaining high adsorption performance and structural integrity over a wide pH range is challenging. To efficiently remove Cr(VI), we designed and prepared of an acid-base resistant metal-organic framework (MOF) Zr-BDPO, by introducing weak acid-base groups (-NH-, -N= and -OH) onto the ligand. Zr-BDPO achieved a maximum adsorption capacity of 555.6 mg · g−1 and retained skeletal structure at pH= 1–11. Interestingly, all these groups can generate conjugate acid-base pairs by means of H+ and OH- in the external solution and then form buffer layer. The removal of Cr(VI) at a broad range of pH values primarily via hydrogen bonds between -NH- and -OH, and the oxoanion species of Cr(VI) is unusual. This strategy that insulating high concentrations of acids and bases and relying on hydrogen bonds to capture Cr(VI) oxoanions provides a new perspective for actual Cr(VI) wastewater treatment. [Display omitted] • A Zr-based metal organic framework with a buffer layer was designed and prepared. • Weak acid-base groups at high or low pH can form conjugate acid-base pairs with itself. • Cr(VI) can be removed over a wide pH range by Zr-BDPO. • The interaction between Zr-BDPO and Cr(VI) was investigated with characterization analysis and DFT calculations. [ABSTRACT FROM AUTHOR]

Supported-adsorbents growing on the substrate in situ are equipped with the advantages of high adsorption capacity, excellent regeneration performance, and adaptability to complex wastewater. However, the effects of substrate on the adsorption properties of supported-adsorbent are rarely considered, which will hinder its development and scale-up applications. In this study, the influences of different substrates (Ti, Mo, W, CC) on the Ag+ adsorption behavior of supported-MoS 2 adsorbents were investigated. The adsorption kinetics, adsorption mechanism, and the renewability of these supported-MoS 2 were compared orderly. As a result, MoS 2 grown on a tungsten substrate (MoS 2 –W) exhibits a remarkable adsorption capacity for Ag+ (1.98 mg cm−2 and 598.80 mg g−1), which is 6.38–33 times more than the other three supported-MoS 2. Moreover, the MoS 2 –W also possesses an ultrahigh distribution coefficient (24.80 mL cm−2) for Ag+, and the selection coefficient can reach 1984. XRD and electrochemical characterization analysis indicated that Ag+ adsorption performance of supported-MoS 2 is positively correlated with the degree of its amorphous structure. Substrate W with the terrific electrical properties which may facilitate the disordered growth of MoS 2 , resulting in more active sites exposed, and endow MoS 2 –W with outstanding Ag+ capture performance. Finally, the supported-MoS 2 retains a high removal efficiency of Ag+ after 5 cycles of adsorption and desorption. This study provides a novel perspective for promoting the practical application of supported-sorbents to recycle heavy metals. [Display omitted] • The substrate effect of supported-adsorbent for removing Ag+ has been studied. • The Ag+ adsorption mechanisms and selectivity of different MoS 2 were compared. • W substrate spurs the electrons transfer and transformed the crystal phase of MoS 2. • Supported-adsorbent showed excellent cycle stability owing to structural advantage. [ABSTRACT FROM AUTHOR]

Specific πδ+–πδ- interaction between –C≡C– with vertical π bond in conjugated microporous polymers and electron-rich Pd center with π 5 8 δ - in PdCl 4 2- is constructed, resulting in highly selective capture of PdCl 4 2- in coexistence systems of heavy metals. It provides a novel design principle for efficient and targeted heavy metal adsorbents in acid wastewater. [Display omitted] • Three kinds of CMPs adsorbents were prepared by S-H coupling reactions. • The –C≡C– groups of CMPs were identifified as the adsorption sites of PdCl 4 2-. • Strong πδ+–πδ- interaction was formed between the –C≡C– and PdCl 4 2-. • CMPs exhibited an excellent PdCl 4 2- selectivity in acid water. The targeted capture of heavy metals from wastewater is urgently necessary in response to strategic demands of sustainable resource utilization, but it is severely hampered by the formation of specific adsorbent-adsorbate interactions. Herein, the conjugated microporous polymer CMP-1 with –C≡C– binding sites is introduced for the adsorption of PdCl 4 2- in acid wastewater. The matched interaction between –C≡C– with vertical π bond and electron-rich Pd center with π 5 8 δ - exhibits exceptional PdCl 4 2- selectivity in competitive systems with coexisting heavy metals. To regulate the electron density of π bond in –C≡C– to further reinforce the πδ+–πδ- interaction, p -FCMP and o -FCMP adsorbents are rationally designed through the substitution of electro-withdrawing F group at different positions. A joint experimental-simulation exploration reveals that the F-induced electron oriented migration in –C≡C– results in the decreased π-electron density, therefore enhancing the binding of PdCl 4 2-. Notably, o -FCMP possesses the maximum positive charge density at –C≡C– binding sites, which greatly promotes the charge transfer between –C≡C– and PdCl 4 2- for stronger bonding interaction, achieving an optimal adsorption capacity of 447.7 mg g−1 as well as enhanced selectivity. This work provides unique insights into the efficiently targeted removal of heavy metals. [ABSTRACT FROM AUTHOR]

• A noticeable dissolution of Mn was observed in adsorption of antimony on MnO 2. • Dissolved amount of Mn depended on antimony adsorption capacity of MnO 2. • Variation of crystalline phases possessed an insignificant effect on Mn release. • Mechanisms of Sb capture and Mn release were unveiled at the atomic scale. Manganese dioxide (MnO 2) exhibits great potential for the uptake of antimony (Sb) from wastewater. Much research has been dedicated to enhancing the capacity of MnO 2 for Sb sequestration. However, the dissolution behavior of Mn has been overlooked, and the underlying relationship between Sb(III) adsorption and Mn dissolution is not clear. In this study, batch experiments evidenced that there was a noticeable dissolution of Mn during the adsorption of Sb(III) on MnO 2. A correlation analysis demonstrated that the amount of Mn dissolved was dependent on the Sb(III) adsorption capacity of MnO 2 , regardless of the crystalline phase of MnO 2. Further experimental and theoretical results (taking α-MnO 2 as an example) unveiled that Mn dissolution involved the following stages. First, Sb(III) adsorbed onto the (3 1 0) crystal plane of α-MnO 2 to form a complex via two Mn-O-Sb bonds, which can be proven by the delicate adsorption configuration and corresponding adsorption energy (E ad) of −4.04 eV. Then, three O atoms from the α-MnO 2 progressively deprived two H atoms from Sb(OH) 3 and one H atom from a water molecule bound to Sb(OH) 3 , respectively. This process was verified by the configuration of the transition state (transition state #3) and the occurrence of electron transfer (i.e., the net charge changed by + 2 e). Finally, the Mn-O bonds of α-MnO 2 were weakened and disrupted, leading to the release of Mn into the aqueous solution. This work advances the fundamental understanding of Sb adsorption onto MnO 2 , which not only promotes a re-evaluation of the utility of MnO 2 for Sb(III) elimination but also provides a theoretical guide for the design of robust MnO 2 -based adsorbents. [ABSTRACT FROM AUTHOR]

Enhancing the performance of adsorbents to the utmost extent is an objective but challenging in applying adsorption technology to wastewater treatment. In this work, novel quaternary ammonium polymers (QAPs) with high density adsorption site (i.e., quaternized N, confirmed by FT-IR results) were designed and prepared for rapid selective removal of Cr(VI) from water. The results of EDS analysis indicated the maximum exposure rate of N on the surface of QAPs was as high as 86.1%, which almost doubled comparing to that of Cr(VI) ions imprinted polymers (Cr(VI)-IIP) (46.2%). Interestingly, the maximum adsorption capacity (211.8 mg/g) and initial adsorption rate (h0 , 66.6 mg/ (g·min)) of QAPs (i.e., 5:1(TRIM)) for Cr(VI) are about 3.6 times and 4.9 times those of Cr(VI)-IIP (63.0 mg/g and 13.5 mg/(g·min)), respectively. Impressively, flow-through adsorption experiments demonstrated 5:1(TRIM) can completely remove 5 mg/L of Cr(VI) within five seconds. Additionally, 5:1(TRIM) exhibited a remarkable selectivity for Cr(VI) adsorption, and high purity (100%) of chromium can be readily obtained. The proposed idea of high exposure effect of the adsorption site can provide a valuable guidance for designing rapid selective adsorbents to remove and reclaim Cr(VI) from wastewater. Schematic Diagram for mechanism of Cr(VI) adsorption on QAPs and correlation between exposure rate of N and Q m. [Display omitted] • QAPs is a kind of adsorbent with high density adsorption sites on its surface. • Adsorption capacity (Q m) of QAPs was positively correlated with exposure rate of N. • QAPs exhibit high capacity, rapid adsorption rate for the Cr(VI) adsorption. • QAPs can achieve high purity chromate recovery due to the high selectivity. • QAPs has a good economic benefit in the recovery of chromate from wastewater. [ABSTRACT FROM AUTHOR]

• DFT calculation is rarely exploited to design an adsorbent. • Adsorption configuration is optimized through DFT calculation. • Adsorption energy and adsorption capacity possess a high correlation coefficient. Trial-and-error method is widely used to seek an efficient adsorbent, although it is time- and money-consuming. Rationally design of functional materials via theoretical calculation is an emerging and appealing strategy in material science. However, exploiting of theoretical calculation for assistance of adsorbent design is rarely to be attempted despite it is usually utilized to explore the adsorption mechanism. In this work, density functional theory (DFT) calculation is exploited to design an adsorbent with high adsorption capacity and selectivity. The well-known palladium ion-imprinted polymer (IIP) was used as a model adsorbent. Then, three types of given adsorption configurations (a-Pd-IIP, b-Pd-IIP and c-Pd-IIP) were optimized. Further, their adsorption energies were calculated by DFT, which were –13.978 eV for b-Pd-IIP, –8.764 eV for a-Pd-IIP and –3.587 eV for c-Pd-IIP, respectively. The correlation coefficient (R 2) between the theoretical adsorption energy and the experimental adsorption capacity reached to as high as 0.985. In addition, the dynamics and selectivity experimental results further consolidated the tendency of the calculation result. All these results demonstrate that the adsorption energy derived from DFT calculations is an important factor in guiding the design of IIPs. [ABSTRACT FROM AUTHOR]