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Microalgal technology holds great promise for both low C/N wastewater treatment and resource recovery simultaneously. Nevertheless, the advancement of microalgal technology is hindered by its reduced nitrogen removal efficiency in low C/N ratio wastewater. In this work, microalgae and waste oyster shells were combined to achieve a total inorganic nitrogen removal efficiency of 93.85% at a rate of 2.05 mg L−1 h−1 in low C/N wastewater. Notably, over four cycles of oyster shell reuse, the reactor achieved an average 85% ammonia nitrogen removal extent, with a wastewater treatment cost of only $0.092/ton. Moreover, microbial community analysis during the reuse of oyster shells revealed the critical importance of timely replacement in inhibiting the growth of non-functional bacteria (Poterioochromonas_malhamensi). The work demonstrated that the oyster shell - microalgae system provides a time- and cost-saving, environmental approach for the resourceful treatment of harsh low C/N wastewater. [Display omitted] • The removal rate of TIN was 2.05 mg L−1·h−1 in oyster shell - microalgae system. • The average NH 4 +-N removal rate reached 85% when oyster shells were reused. • Replacing oyster shells every 3 cycles prevents non-functional bacteria growth. [ABSTRACT FROM AUTHOR]

Full-component green recovery of As-contained acid wastewater shows great prospect demanding on both urgent resource need and environment protection. In this work, we firstly constructed a three-chamber electrochemical system for full-component recovery of As-Cu acidic wastewater, combining electrochemical redox and electrodialysis techniques to recover metals and acids simultaneously. In which CeO 2 @CC and Cu plate electrode materials were selected and the middle chamber was separated by cation-exchange membrane (CEM) and anion-exchange membrane (AEM). In the anode chamber, 93.84% As(III) was oxidized and adsorbed by the CeO 2 @CC anode within 2 h. Meanwhile, 100% copper was reduced and deposited on the cathode. The pH of the intermediate chamber solution was reduced to 1.2. Besides, economic benefits and carbon emission accounting indicated that the system has better economic and environmental benefits for the full-component recovery of As-Cu strongly acidic wastewater. This work brings a new insight in future wastewater resource recovery and purification. [Display omitted] [ABSTRACT FROM AUTHOR]

Using microalgae for rare earth elements wastewater treatment has been proved to be effective, however, the technology is challenged by the unstable performances caused by the changeable wastewater qualities and natural conditions. In this study, a corrected response surface methodology was first used to provide an optimized operation strategy for the application of wastewater treatment using microalgae, by investigating the effects and interrelations of three main factors including temperature, illumination intensity and microalgae concentration, taking rare earth elements wastewater in Southern Jiangxi as an example. Nine models were obtained using nine types of wastewater. The models were then modified by categorizing wastewaters into two classes (error range <12%) according to their initial ammonia nitrogen concentrations. The optimal conditions for ammonia nitrogen removal in class I and class II wastewater were as follows: temperature of 21.0 and 23.6 °C, illumination intensity of 46.8, 45.3 LX %, microalgae concentration of 1.64 and 1.67 g dry weight/L. The results are confirmed by stable operation of a continuous-flow photobioreactor for more than 122 days. The amount of microalgae required to treat wastewater under natural conditions is 1.5–1.8 g dry weight/L estimated by the corrected model. It implies that nearly 16,710 kg and 46,520 kg of ammonia nitrogen could be removed from two typical wastewaters with optimal microalgae dosage in 2020. The results demonstrated that corrected response surface methodology provides a powerful approach for optimizing the operational conditions for wastewater treatment by microalgae. [Display omitted] • A corrected RSM model for microalgae towards NH 4 +-N removal was first built. • Optimal conditions for REEs wastewater treatment by microalgae were accurately obtained. • Optimized NH 4 +-N removal were predicted from actual REEs watershed wastewater. [ABSTRACT FROM AUTHOR]

Simultaneous recovery and value-added conversion of hazardous heavy metal ions from complex wastewater sources is of great significance yet challenging. Herein, we demonstrate that highly toxic antimonite Sb(III) could be effectively recovered from antimony (Sb) mine flotation wastewater and converted into high-value-added metallic Sb using a novel facile atomic H* enhanced electrochemical reduction avenue coupled with thermal reduction by H 2 gas. The high production of atomic H* generated from the electrochemical cathode with an optimum reduction potential of –1.2 V vs. Ag/AgCl, which is lower than the Sb(III) reduction potential of –1.0 V, might be attributable to the superior Sb recovery capabilities. Furthermore, the metallic Sb concentration at –1.2 V was 14.43 times greater than at –1.0 V due to the strong reductivity of atomic H*. In addition, Sb(III) removal efficiency was found to be as high as 98.52%, with a metallic Sb recovery rate of up to 1.67 mg min–1. The efficiency of Sb(III) recovery was demonstrated throughout a wide pH range, with metallic Sb being the main product, independent of the presence of multiple coexisting ions. Economic analysis also indicated that treating Sb mine flotation wastewater per ton may yield a net profit of $40.09. This research contributes to the advancement of an atomic H* enhanced electrochemical technology for high-valued heavy metal recovery from complex heavy metal-polluted wastewater. [Display omitted] [ABSTRACT FROM AUTHOR]

The tandem type permeable reactive barriers-like reactor recovers Pb(II), As(III) and Zn(II) from the lead–zinc mine wastewater by combining hierarchical partitions and three targeted adsorption mediums. The device exhibits high-efficient removal and selective recovery capabilities for metals, as well as widely applicable to various wastewater inflow conditions. [Display omitted] • A novel combined tandem permeable reactive barriers-like reactor was reported. • Heavy metals in mining wastewater are removed sequentially and high-efficiently. • Each metal can be recycled due to the selective adsorption of the reactor medium. • The combined reactor performs steadily and efficiently under practical conditions. The resource treatment of mine wastewater with low-concentrations heavy metal ions is desirable for the sustainability of the metallurgical industries, but is challenging. In this study, we developed a novel combined tandem type permeable reactive barriers-like (PRBs-like) technology with implanted targeted adsorbents to achieve the selective removal of metals from mining wastewater. In the continuous flow test, the PRBs-like enable the content of lead, arsenate and zinc ions in 790 mL of actual mine effluent to reach below the Chinese pollutant discharge standards for lead and zinc industries (GB2546-2010) within 6 h. The expected ability of the reactor benefits from the outstanding mass transfer of the three adsorbents, tannic acid based polymer (TABP), cerium oxide (CeO 2) and zero-valent iron (ZVI), with capacities of 116.6, 87.5 and 61.8 mg g−1 for lead, arsenic and zinc ions at an equilibration time of 20 min. Noteworthy, TABP features a strong affinity for lead, as well as CeO 2 for arsenate, which is favorable to the aggregation of a single species metal in the corresponding reaction partition. In addition, factors including different flow rates, pH and reaction media distances on the performance of PRBs-like were investigated, demonstrating excellent adaptability of the tandem reactor to the wastewater environment. And long-term experiments showed the high stability and efficiency of the operation of the reactor. The graded combined device and the targeted adsorbent were first integrated in this work to point out a high-efficiency pathway, which can recycle the heavy metals in mine wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electrochemistry-driven adsorption approach was employed to selective capture Pb2+. • A@GO exhibited the enhanced selectivity of Pb2+ capture by applying electric field. • −0.2 V was an optimum potential in the adsorption selectivity operation. • Synergic effect was attributed to electric field and specific sites on TA@GO. Selective recovery of Pb2+ is always a high concern in the industrial application but challenging. Recycling Pb2+ as a sort of resource from contaminated water not only can significantly cut down the resource depletion but also reduce environmental pollution. Herein, a feasible electrochemistry-driven adsorption approach (ECDA) is employed to aid adsorbents for the selective removal of Pb2+ from metal-laden wastewaters. The distribution coefficient (K d) of Pb2+ on the conductive tannic acid-graphene aerogel (TA@GO) is 370.53 mL g−1 at −0.2 V which is 3 times that of the corresponding adsorbent (118.80 mL g−1) without applying a weak electric field. Compared with pure adsorbent, TA@GO achieves an enhanced selectivity coefficient (α) from 1.39 to 4.18 for Pb2+/Cu2+ at −0.2 V. The weak electric field can drive Pb2+ ions migrates rapidly from the bulk solution to the surrounding binding sites (phenolic hydroxyl) of adsorbent forming pre-aggregation, increasing the accessibility and availability of the active sites with target pollutants. And then a strong coordination interaction occurs between Pb2+ and the binding sites on TA. By applying different potentials, the selective properties of TA@GO can be tuned. Moreover, TA@GO shows a high selectivity coefficient of 12.44 for Pb2+/Cu2+ after being improving the electrical conductivity using electro-reduction, which is up to 2.5 times higher than the original TA@GO. We elucidated a new Pb2+ removal mechanism that involves a synergic effect by anchoring additional electric fields on functional adsorbents to improve the selective performance. This study highlights a novel direction for selective Pb2+ recovery by introducing electric fields onto adsorbents in practical application. [ABSTRACT FROM AUTHOR]

Rare earth elements (REEs) are important strategic resources reserved by countries in the 21st century, especially in light of a global supply crisis stemming from the increasing demand for REEs in the high-tech industry. State-of-the-art technologies for the capture and recovery of REEs from wastewater are thus essential for a sustainable future. Algae-based technology is considered one of the most promising methods for recovering REEs for its high efficiency, low cost, and wide applicability. This review begins with a discussion of how the characteristics of algae affect the REEs removal process. A systematic analysis and comparison of the underlying adsorption/absorption mechanisms and factors affecting REEs removal from wastewater by dried/living algae are also presented. Inspired by the differences in these mechanisms, various strategies for improving the removal efficiency of REEs by dried and living algae are developed and summarized. Different recycling and resource utilization technologies are analyzed according to the properties of dried and living algae. Finally, prospects of future studies are proposed to aid future efforts for making algae-based REEs recovery technology a commercial reality. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] Adsorption is a green technology of treating heavy metal-contaminated strong acid wastewaters for the recycling of heavy metal and reuse of strong acid. Herein, three amine polymers (APs) with different alkalinities and electron donating abilities were prepared to investigate the adsorption-reduction processes of Cr(VI). It was found that the removal of Cr(VI) was controlled by the concentration of –NRH+ on the surface of APs at pH > 2, which relies on the alkalinity of APs. However, the high concentration of NRH+ significantly facilitated the adsorption of Cr(VI) on the surface of APs and accelerated the mass transfer between Cr(VI) and APs at strong acid environment (pH ≤ 2). More importantly, the reduction of Cr(VI) was enhanced at pH ≤ 2, due to the high reduction potential of Cr(VI) (E ≥ 0.437). The ratio of reduction to adsorption (α) of Cr(VI) was above 0.70, and the proportion of Cr(III) bonding on Ph-AP excessed 67.6 %. Finally, a proton-enhanced mechanism of Cr(VI) removal was verified by analyzing FTIR and XPS spectra as well as constructing DFT model. This study provides a theoretical basis for the removal of Cr(VI) in the strong acid wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] Copper organic complexes with strong chemical stability and high solubility in water are difficult to eliminate with traditional adsorbents. In this work, a novel amidoxime nanofiber (AO-Nanofiber) with the p-π conjugated structure was fabricated through homogeneous chemical grafting coupled with electrospinning and applied to capture cupric tartrate (Cu-TA) from aqueous solutions. The adsorption capacity of Cu-TA by AO-Nanofiber was 198.4 mg/g at an equilibrium time of 40 min, and the adsorption performance remains basically unchanged after 10 times adsorption–desorption cycles. The capture mechanism of Cu-TA by AO-Nanofiber was jointly validated by experiments and characterization such as Fourier Transform Infrared Spectrometer (FT-IR), X-ray Photoelectron Spectroscopy (XPS), and Density functional theory (DFT) calculations. These results demonstrated that the lone pair of electrons of the N atom from the amino groups and the O atom from hydroxyl groups in the AO-Nanofiber is partially transferred to the 3 d orbital of the Cu(II) ions in Cu-TA, leading to the Jahn-Teller distortion of the Cu-TA and the more stable structure of AO-Nanofiber@Cu-TA was generated. [ABSTRACT FROM AUTHOR]

The discharge of rare earth element (REE) tailings wastewater results in serious ecological deterioration and health risk, due to high ammonia nitrogen, and strong acidity. The low C/N ratio makes it recalcitrant to biodegradation. Recently it has been shown that microalgal technology has a promising potential for the simultaneous harsh wastewater treatment and resource recovery. However, the low nitrogen removal rate and less biomass of microalgae restricted its development. In this work, Chlorococcum sp. was successfully isolated from the rare earth mine effluent. The microalgae was capable of enhancing nitrogen contaminants removal from REEs wastewater due to the carbonate addition, which simulated the activity increase of carbonic anhydrase (CA). The total inorganic nitrogen (TIN) removal rate reached 4.45 mg/L h−1, which compared to other microalgal species, the nitrogen removal rate and biomass yield were 7.8- and 4.9-fold higher, respectively. Notably, high lipid contents (mainly triglycerides, 43.85% of dry weight) and a high biomass yield were obtained. Meanwhile, the microalgae had an excellent settleability attributed to higher extracellular polymeric substance (EPS) formation, leading to easier resource harvest. These results were further confirmed in a continuous-flow photobioreactor with a stable operation for more than 30 days, indicating its potential for application. [Display omitted] • Resourceful treatment of harsh high-nitrogen REEs wastewater is first achieved. • Carbonate activated Chlorococcum sp. microalgae enhances NH 4 +-N and TIN removal. • The microalgae shows an excellent settle ability and biomass yield. • The carbonate activated microalgae photobioreactor is stably operated. [ABSTRACT FROM AUTHOR]

Antimony contamination of tailings from the mining process remain attracted a great amount of concern. In this study, defective UiO-66-X crystal materials are rationally constructed using trifluoroacetic acid and hydrochloric acid as modulators for the removal of Sb(V) from actual tailing sand leachates. XRD and TG characterizations reveal that the number and kind of defects in UiO-66 are influenced by the type of modulators and the addition of trifluoroacetic acid makes UiO-66-TFA contain both cluster and ligand defects. Adsorption experiments show that UiO-66 and UiO-66-HCl achieve 100% removal of Sb(V) at pH 7.5 of the tailing sand leachate, and up to 90% removal of Sb(V) by the three materials at pH 2.5. It is noteworthy that the removal rate of Sb(V) by UiO-66-HCl is still satisfactory even under strongly acidic conditions at pH 0.5, with good potential for practical applications. Four kinetic models are used to fit the adsorption data and the analysis shows that the mechanism of Sb(V) adsorption by three adsorbent is all pseudo-second order and chemisorption acts as an important role in the adsorption process. In addition, the fixed bed adsorption experiments show that the material exhibit good prospects for practical applications. With the help of defect engineering strategy, UiO-66-Xs with structural defects were designed, and the differences in the removal performance of antimony in actual wastewater under different pH conditions were explored, providing new ideas for the removal of antimony in actual wastewater. [Display omitted] • The defective UiO-66 was designed with the help of defect engineering strategy. • The removal performance of Sb(V) by materials under different pH was explored. • The removal performance of Sb (V) varies among the three materials at different pH. • Fixed bed experiments showed that the material exhibited practical application value. [ABSTRACT FROM AUTHOR]

Rare earth element tailings (REEs) wastewater, which has the characteristics of high ammonia nitrogen (NH 4 +-N) and low COD. It can cause eutrophication and biotoxicity in water which is produced in high volumes, requiring treatment before final disposal. Microalgae-Bacteria symbiotic (MBS) system can be applied in REEs wastewater, but its low extent of nitrogen removal and instability limit its application. By adding biodegradable carrier as both carbon source and carrier, the system can be stabilized and the efficiency can be improved. In this work, the extent of NH 4 +-N removal reached 100% within 24 h in a MBS system after adding loofah under optimal conditions, and the removal rate reached 127.6 mg NH 4 +-N·L−1·d−1. In addition, the carbon release from loofah in 3 d reached 408.7 mg/L, which could be used as a carbon source to support denitrification. During 90 d of operation of the MBS system loaded with loofah, the effluent NH 4 +-N was less than 15 mg/L. At phylum level, Proteobacteria were dominant which accounted for 78.2%. Functional gene analysis showed that enhancement of microalgae assimilation was the main factor affecting NH 4 +-N removal. This work expands our understanding of the enhanced role of carbon-based carriers in the denitrification of REEs wastewater. [Display omitted] • The removal rate of NH 4 +-N was 127.6 mg L−1·d−1 in loofah-supported MBS system. • Loofah provides organic carbon for denitrification and maintains a stable pH. • The continuous-flow Microalgae-Bacteria bioreactor achieved 15 m/L effluent NH 4 +-N. • Microalgal nitrogen assimilation contributed to the observed increased NH 4 +-N removal. [ABSTRACT FROM AUTHOR]

Microalgae appear to be a promising and ecologically safe way for nutrients removal from rare earth tailings (REEs) wastewater with CO 2 fixation and added benefits of resource recovery and recycling. In this study, a pilot scale (50 L) co-flocculating microalgae photobioreactor (Ma-PBR) as constructed and operated for 140 days to treat REEs wastewater with low C/N ratio of 0.51–0.56. The removal rate of ammonia nitrogen (NH 4 +-N) reached 88.04% and the effluent residual concentration was as low as 9.91 mg/L that have met the Emission Standards of Pollutants from Rare Earths Industry (GB 26451–2011). Timely supplementation of trace elements was necessary to maintain the activity of microalgae and then prolonged the operation time. The dominant phyla in co-flocculating microalgae was Chlorophyta , the relative abundance of which was higher than 80%. Tetradesmus belonging to Chlorophyceae was the dominant genus with relative abundance of 80.35%. The results provided a practical support for the scaling-up of Ma-PBR to treat REEs wastewater. [Display omitted] • High NH 4 +-N removal of 88.04% was achieved by microalgae in pilot scale. • Reactor operated steadily for 140 days with effluent NH 4 +-N below 10 mg/L. • Timely pH adjustment and trace element addition are two key affect factors. [ABSTRACT FROM AUTHOR]

[Display omitted] • The rare earth wastewater was firstly treated using a microalgae-bacteria system. • The microalgae-bacteria ratio showed positively correlated with NH 4 +-N removal. • High NH 4 +-N removal of 97.46 % was achieved at microalgae/bacteria ratio of 1:3. • Bacteria altered the microbial diversity and promoted functional microalgae growth. Microalgae-bacteria symbiosis system (MBS) appear to be a promising way for treating the rare earth elements (REEs) wastewater due to the natural symbiotic interactions between microalgae and bacteria. Herein, we investigated the effect of different inoculation ratios of microalgae and bacteria including 3:1 (MB_1), 1:1 (MB_2) and 1:3 (MB_3) on NH 4 +-N removal from REEs wastewater and analyzed the corresponding biological mechanism. The NH 4 +-N removal rate with MB_3 reached 17.69 ± 0.45 mg NH 4 +-N/L d−1, which was 2.58 times higher than that in single microalgae system. The results were further verified in continuous feeding photobioreactors and kept stable for 100 days. Metagenomic analysis revealed that the abundance of genes related to microalgae assimilation increased by 14 %-50 % in answer to photosynthesis and NH 4 +-N absorption, while that related to nitrification apparently dropped, indicating that MBS was a sustainable method capable of enhancing NH 4 +-N removal from REEs wastewater. [ABSTRACT FROM AUTHOR]

Low nitrogen (N) removal efficiency limits the potential of microalgae technology for the treatment of high nitrogen and low carbon rare earth tailings (REEs) wastewater. In this study, waste corncob was utilized as a biocarrier immobilizing Chlamydopodium sp. microalgae to realize high-efficient treatment of the REEs wastewater. In only 2.5 d, corncob-immobilized microalgae allowed the residual concentrations of N lower than the emission standards, and ammonia nitrogen (NH 4 +-N) removal rate is 83.3 mg L−1·d−1, total inorganic nitrogen (TIN) removal rate is 86.7 mg L−1·d−1, which was 18.5 times that of the previously-reported microalgae (4.68 mg L−1·d−1). Compared with other microalgae immobilization carriers, corncob possesses the ability to release available carbon sources for microalgae. Composition analysis and sugar verification experiments showed that the main content of TOC released by corncob was monosaccharide, and in a certain range, the removal rate of N was positively correlated with the TOC concentration. The utilization of biomass wastes with dual functions as biological carriers has great potential to improve the performance of microalgae, and is conducive to the development of engineering applications. [Display omitted] • Rapid removal of NH 4 +-N and TIN by microalgae was achieved in REEs wastewater. • The removal efficiency of TIN can reach 100%, and rate can reach 86.7 mg L−1·d−1. • The removal rate of N by corncob-immobilized microalgae reached the highest. • Corncob possess dual functions of biocarrier and available carbon source. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new ion-imprinted polymer that utilizes VTA was prepared for Cr(VI) removal. • The coordination effect and template effect were deep analyzed. • The role of cross-linking agents was investigated and clarified. • The results were successful used to design adsorbents for real wastewater. The template effect is known as the most important feature of ion imprinted polymer (IIP) technology. However, there has been a gap in the theorization of the template effect and apply the template effect to practice. In this work, we propose a method to control the template effect of IIPs by adjusting the ratio of cross-linking. A series of Cr(VI)-IIPs with various contents of the cross-linking agent were synthesized. Based on the qualitative analysis of the coordination selectivity and template effect, the theoretical equation of the template effect generated by the cross-linking agent was established rely on the Scatchard equation. In the Cr(VI) removal process, the contribution of template effect began to surpass the coordination effect when the molar ratio of functional monomer to cross-linking agent was 1/5.46, and the template effect further enhanced with the increase of cross-linking agent content. In the application of actual wastewater treatment, the IIP-1/12 and IIP-1/6 which are designed according to the resulting equation are effective to treat two different types of wastewater. The normalization equations and design concepts proposed in this study theoretically illustrate the role of cross-linking agent in the selectivity of materials. This allows for more flexibility in modulating the template effect of Ion Imprinted Technology for design and application. [ABSTRACT FROM AUTHOR]

Ion imprinted polymers exhibit great potential in ion separation from wastewater. However, the difficulty of ion separation by membrane is proverbial, which severely restricts the application of membrane in metal resource recovery from industrial wastewater. Herein, a rational molecular-level design approaches for membrane fabrication was developed to modify a layer of ion imprinted polymer onto the PVDF membrane. Batch rebind and permeation experiments suggest that specific host-guest binding sites had been fabricated along the membrane pore in ion imprinted membranes (IIM). A higher monomer dose leads to a higher rejection of Cd2+, and the more bind sites in IIM. The binding of IIM to Cd2+ was 1.84 times that of non-ion imprinted membranes (NIM). Permselectivity factors (γ) of IIM are larger than 5.39 in mixture ions solutions. Chemical characterization and density functional theory (DFT) calculation reveal that the Cd2+ recognition sites of functional groups are C−S and C˭S. Cd2+ mass transport in IIM suggest that the imprint effects provide a binding force that would delay Cd2+ to permeate through IIM, so as to selectively separate Cd2+ with other ions. The imprint effects may enlighten a novel molecular-level design approaches for membrane fabrication to enhance the selectivity of ion-ion. [Display omitted] • IIM possesses specific host-guest sites and recognized more Cd2+ than NIM. • The Cd2+ bind ability is ascribed to the coordination of functional monomer. • Structure predetermination of Cd2+ plays a vital role in forming sites. • Delayed permeation of IIM can selective separate Cd2+ from other ions. • DFT calculation expound the delayed permeation mechanism from molecular level. [ABSTRACT FROM AUTHOR]

Here, we show that high permeability and good fouling resistance can save substantial energy and maximize freshwater output for reverse osmosis (RO) desalination of low-salinity wastewater, via both theoretical and experimental demonstrations. First, module-scale modelling revealed that at reasonably low feed salinity, the specific energy consumption (SEC) drops by > 60% when water permeability is increased from 2 to 7 L m−2 hr−1 bar−1. Optimization of different operating parameters was further performed to maximize the energy efficiency and process capacity, and suitable salt rejection to maintain permeate quality was evaluated. Next, we synthesized zwitterionic copolymers of different molecular weight and fabricated hollow fiber membranes with a pure water permeability of 8.6 L m−2 hr−1 bar−1, 98.5% rejection to NaCl, and excellent fouling resistance. 85% water recovery, 56% energy saving and 25% reduction of membrane area were demonstrated for treating membrane bioreactor (MBR) filtrate from a local water reclamation plant. [Display omitted] • Salinity, SEC, permeability and recovery were correlated. • Impact of salt rejection on permeate quality was modeled. • Highly-permeable, anti-fouling membrane was fabricated. • 85% water recovery, 56% energy saving, 25% area reduction were shown. [ABSTRACT FROM AUTHOR]

• An in situ heavy metal removal strategy by MMOGs in actual wastewater was proposed. • In situ method realized full exposure and generation additional of binding sites. • The adsorbed MMOGs can be reutilized for Sb(V) capture. Metal-organic gels (MOGs) as outstanding heavy metals adsorbents suffer the problems of ex situ construction and not being able to reutilize, which restricts the widespread applications. To deal with this challenge, an in situ ultrasound-assisted technology integrated adsorbent fabrication with heavy metals removal in actual wastewater was firstly proposed. Characterizations analyses showed that the multivariate MOGs (MMOGs) was successfully constructed in industrial wastewater and simultaneous obtained a superb removal efficiency of 97.2%, 95.3% and 98.1% for Cu(II), Cd(II) and Cr(III), and the treated wastewater can reach the effluent standard. X-ray photoelectron spectroscopy (XPS) analysis and density functional theory (DFT) calculation indicate that MMOGs obtained the most stable structure owing to the most stable binding energy, mainly attributed to the interaction between Cu(II) and − COOH of gelators that generates additional bonding sites for capturing Cd(II) and Cr(III) during the synthesis of adsorbent. Furthermore, we successfully show the possibility to reuse the adsorbed MMOGs in the oxyanions contaminated water, and it exhibits satisfactory removal capacity for Sb(V) with favorable biodegradability. This study provides a new insight and promising model for actual heavy metal wastewater treatment as well as resource utilization. [ABSTRACT FROM AUTHOR]

• UiO-66-NH 2 -Rd adsorbent with dual coordination sites was designed and synthesized. • UiO-66-NH 2 -Rd exhibited high capacity and outstanding selectivity for Ag(I) capture. • Amide bonds endowed UiO-66-NH 2 -Rd with excellent recyclability and durability. • Specific adsorption site was identified by theoretical and experimental studies. Selective capture and maximum recovery of Ag(I) from wastewater is of great significance for a sustainable future. In this work, novel rhodanine (Rd)-functionalized UiO-66 adsorbents (i.e., UiO-66-Rd and UiO-66-NH 2 -Rd) were designed and synthesized. Different from previously reported UiO-66 derivatives with single metal coordination sites, the as-synthesized UiO-66-Rd and UiO-66-NH 2 -Rd have dual coordination sites, resulting in higher capacity and outstanding selectivity. The maximum capacities of UiO-66-Rd and UiO-66-NH 2 -Rd are 112 and 163 mg·g−1, nearly 5.6 and 8.2 times higher than that of UiO-66, respectively. Impressively, the maximum selectivity coefficient of UiO-66-NH 2 -Rd is approximately 1795 and 1173 folds higher than that of UiO-66 and UiO-66-NH 2. The experimental characterizations and theoretical calculations indicate that the Rd-induced enhancement in the adsorptivity and selectivity are mainly attributed to the dual coordination sites (i.e., C S and C S bonds), which collectively coordinate with Ag(I) in the form of Ag mono-coordinated with S. Compared with the UiO-66-Rd, UiO-66-NH 2 -Rd possesses excellent recyclability and durability due to the vital role of amide bonds generated from NH 2 group in the functionalization of UiO-66 with Rd. Furthermore, UiO-66-NH 2 -Rd can almost completely remove Ag(I) from the actual wastewater with complex matrix, satisfying the national integrated wastewater discharge standard and industrial wastewater emission standard, highlighting a great potential of practical application. [ABSTRACT FROM AUTHOR]