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The removal of highly toxic heavy metal ions is essentially the migration of heavy metal ions from water to materials through adsorption, complexation, exchange, and other forms. However, heavy metals still exist as highly toxic ions on the surface of materials, easily desorbed, and cause secondary pollution. In this study, a novel primary battery of graphene-supported zero-valent copper/iron bimetallic composites (Cu/Fe/rGO) was first prepared with copper as the positive electrode, iron as the negative electrode, and graphene as the "wire". The network-like nanoscale primary battery was fabricated for the reduction and removal of typical highly toxic heavy metal ions (Pb2+) from the water environment. The removal rate of Pb2+ within 20 min was 95.28%. The Pb-immobilized Cu/Fe/rGO primary battery after treatment can be easily separated via a weak magnetic field and maintained an excellent removal rate of Pb2+ during 6 cycles of use. The great potential of Cu/Fe/rGO primary battery in Pb2+ reduction removal was due to its high reduction ability, large surface area, and magnetic separability. This study provides an important foundation for the rapid and stable removal of heavy metals from water, which may have a tremendous application prospect in environmental fields. [Display omitted] • A novel primary battery of Cu/Fe/rGO with strong reduction ability is prepared for the first time. • Efficient adsorption and reduction removal of Pb2+ is obtained by Cu/Fe/rGO primary battery. • Pb2+ in soil can also be removed by Cu/Fe/rGO primary battery. • High reduction ability, large surface area and magnetic separability account for Pb2+ efficient removal. [ABSTRACT FROM AUTHOR]

The use of peroxymonosulfate (PMS) activation to eliminate organic contaminants is a promising technology to purify water owing to its strong reactivity. However, because of the existed rate limiting step, the performance of PMS activation was restrained and required external energy consumption. Therefore, a new strategy was proposed to solve this problem by preparing catalysts with abundant electron-rich sites and electron traps to accelerate PMS activation. In this research, a novel MnCeO x -H catalyst with rich surface oxygen vacancies was firstly synthesized to accelerate the transfer of electrons among the catalysts, oxidant and pollutants. The contaminants were rapidly eliminated in the MnCeO x -H/PMS system, while the reaction rate constant of MnCeO x -H/PMS system was 30 times higher than that of CeO 2 /PMS system. The surface oxygen vacancies were able to adsorb and trap PMS, then the free electrons of oxygen vacancies would reduce PMS and produced HO•, 1O 2 and SO 4 •-, while 1O 2 played a major role. The contaminants which acted as electron-donors in this system were adsorbed at Mn, Ce sites, achieving effective conversion recycling of Ce(IV)/Ce(III), Mn(III)/Mn(II) and Mn(IV)/Mn(III). This discovery is believed to inaugurate a novel way for designing powerful electron-rich sites and electron traps to accelerate PMS activation for contaminants degradation. [Display omitted] • Oxygen vacancy-rich MnCeO x -H with abundant electron-rich sites and electron traps was firstly fabricated. • The pollutants were rapidly eliminated in the OVs-rich MnCeO x -H/PMS system. • PMS was trapped by the OVs and reduced by the free electrons to produce HO•, SO 4 •- and 1O 2. • The electrons BPA provided would flow to the OVs and accomplish electron recycle. [ABSTRACT FROM AUTHOR]

A biocompatible and uniquely defined hydroxyapatite (HAP) adsorption membrane with a sandwich structure was developed for the removal of organic micropollutants for the first time. Both the adsorption and membrane technique were used for the removal of organic micropollutants. The hydrophilicity and hydrophobicity of the HAP adsorbent and membrane were tunable by controlling the surface structure of HAP. The adsorption of organic micropollutants on the HAP adsorbent was studied in batch experiments. The adsorption process was fit with the Freundlich model, while the adsorption kinetics followed the pseudo-second-order model. The HAP membrane could remove organic micropollutants effectively by dynamic adsorption in both aqueous and ethanol solutions. The removal efficiencies of organic micropollutants depended on the solution composition, membrane thickness and hydrophilicity, flow rate, and the initial concentration of organic micropollutants. The adsorption capacities of the HAP membrane with a sandwich structure (membrane thickness was 0.3 mm) were 6700, 6510, 6310, 5960, 5490, 5230, 4980 and 4360 L m −2 for 1-naphthyl amine, 2-naphthol, bisphenol S, propranolol hydrochloride, metolachlor, ethinyl oestradiol, 2,4-dichlorophenol and bisphenol A, respectively, when the initial concentration was 3.0 mg L −1 . The biocompatible HAP adsorption membrane can be easily regenerated by methanol and was thus demonstrated to be a novel concept for the removal of organic micropollutants from both aqueous and organic solutions. [ABSTRACT FROM AUTHOR]

A novel graphitic carbon nitride (g-C 3 N 4 ) nanosheet adsorbent with a large surface area, remarkable hydrophilicity and high adsorption capacity, was presented for the removal of cadmium ions (Cd 2+ ) and methylene blue (MB) from aqueous solution. Adsorption measurements were conducted systematically to study the influences of the contact time, initial concentrations of Cd 2+ and MB, temperature, and pH value. The maximum adsorption capacities of g-C 3 N 4 towards Cd 2+ and MB were 94.4 and 42.1 mg g −1 , respectively, at 318.5 K when the initial concentrations of Cd 2+ and MB were 200 and 20 mg L −1 , respectively. The adsorption kinetics fit a pseudo-second-order model. The high adsorption performance of the g-C 3 N 4 adsorbent can be attributed to the multiple adsorption sites on g-C 3 N 4 , including the π-π conjugate interactions and electrostatic attractions with pollutants in water. In addition, it is significant to achieve high adsorption performance of g-C 3 N 4 nanosheets by efficiently exposing the adsorption sites by adjusting the microstructure surface properties and dispersity in solution. [ABSTRACT FROM AUTHOR]

• Recent developments in fluoride removal from water by adsorption are reviewed. • Four technical strategies are proposed for designing of adsorbents. • Transfering the adsorption process to industrial scale is urgently needed. • Fluoride adsorption and desorption in field condition need further investigation. Fluoride contamination in water environment due to natural and artificial activities has been recognized as one of the major problems worldwide. Developing effective and robust technologies for excess fluoride removal from water environment becomes highly important. Among the commonly used treatment technologies applied for fluoride removal, adsorption technique has been explored widely and offers a highly efficient simple and low-cost process for fluoride removal from water. This review reports the recent developments in fluoride removal from water environment by adsorption methods. Studies on fluoride removal from aqueous solutions using various carbon materials are reviewed. It is evident that various adsorbents with high fluoride removal capacity have been developed, however, there is still an urgent need to transfer the removal process to industrial scale. Regeneration studies need to be performed in more extent to recover the adsorbent in field conditions, enhancing the economic feasibility of the process. Based on the review, four technical strategies of adsorption method including nano-surface effect, structural memory effect, anti-competitive adsorption and ionic sieve effect can be proposed. The design of adsorbents through these four strategies can greatly improve the removal efficiency of fluoride in water and provide guidance for the development of new efficient methods for fluoride removal in the future. [ABSTRACT FROM AUTHOR]

• Highly active surface exposed CoFe 2 O 4 catalyst was successfully prepared. • The degradation rate of DC was extremely fast in the first 2 min. • CoFe 2 O 4 /H 2 O 2 system widened pH application limit to the neutral condition. • The prepared CoFe 2 O 4 with high stability can be easily recycled and reused. • Probable transformation pathways of DC degradation were clarified. Heterogeneous Fenton technology is considered to be an effective method to solve the issues of antibiotic pollutants. In this study, a highly active surface exposed CoFe 2 O 4 catalyst was fabricated to activate hydrogen peroxide (H 2 O 2) to degrade aqueous doxycycline (DC). Batch experiments investigated the influence of different factors such as CoFe 2 O 4 dosage, H 2 O 2 dosage, contaminant concentration and pH on DC elimination. Remarkably, the results showed that 1.2 g/L CoFe 2 O 4 with 10 mM H 2 O 2 could quickly remove 92% DC of 20 ppm under neutral pH conditions in 10 min, and after 5 cycles, the removal of DC still remained above 85%. DMPO-X signals captured by EPR illustrated abundant hydroxyl radicals (OH) were produced in the surface CoFe 2 O 4 /H 2 O 2 system swiftly and that was the dominant active oxygen species in the degradation of DC. The valence changes of Co3+/Co2+ and Fe3+/Fe2+ appeared on the surface of CoFe 2 O 4 provided many electrons to participate in the process of activating H 2 O 2. Density functional theory (DFT) calculation was conducted to reveal preferable sites of different atoms on DC for radicals attacking. Combined with LC-MS analysis, two possible degradation pathways were proposed. [ABSTRACT FROM AUTHOR]

Removing heavy metals from aqueous solutions has drawn more and more attentions these years because of their serious global health challenge to human society. To develop an adsorbent with low-cost and high-efficiency for removal of heavy metals (HMs), β-cyclodextrin (β-CD) polymers crosslinked with rigid aromatic groups were prepared and used for lead (Pb), copper (Cu) and cadmium (Cd) removal for the first time. The negatively charged β-CD polymers with large BET surface area were suitable to be used in HMs adsorption. The adsorption process completed in 5 min was well fit by Freundlich isotherm model and pseudo-second-order model. The intraparticle diffusion model was also appropriate to describe the adsorption of Pb, Cu and Cd on β-CD polymer. The maximum of adsorption capacities at 25 °C for Pb, Cu and Cd were 196.42, 164.43 and 136.43 mg/g when the initial concentration was 200 mg/L. The HMs adsorption process on the surface of β-CD polymer was an endothermic and spontaneous process. Both of the electrostatic interaction and distribution of Pb, Cu and Cd species influenced the adsorption process at different pH values. The order of removal efficiencies in multi-component adsorption for the three metal ions were Pb > Cu > Cd. The adsorption mechanisms were H + ions on hydroxyl groups exchanged with heavy metal ions and electrostatic interactions. This study indicated that β-CD polymers could be developed into effective adsorbents for rapid removal of heavy metals. [ABSTRACT FROM AUTHOR]

• A novel magnetic porous carbon coated iron manganese oxides (MnFeO@C) was fabricated. • The carbon film was beneficial to adsorption of bisphenol A and flow of electrons. • BPA was effectively degraded in a broad pH range (3.0–10.0) by MnFeO@C/PMS system. • Over 95% of BPA was degraded in 30 min and exhibited recycle stability. Developing highly-effective catalysts through a facile method for activating peroxymonosulfate (PMS) to degrade recalcitrant pollutants is highly desirable. In this work, porous carbon-coated iron-manganese oxides (MnFeO@C) was facilely synthesized. The porous carbon film on the surface of MnFeO@C was beneficial to adsorption of bisphenol A (BPA) and flow of electrons. The catalytic degradation performance toward BPA was significantly improved with the increase of surface roughness and porosity of MnFeO@C after calcination. In particular, MnFeO@C derived at 300 °C (MnFeO@C-300) exhibited the highest degradation rate benefiting from the existence of Mn 2 O 3. More than 95% BPA could be removed in 30 min by MnFeO@C-300/PMS system and remained efficient in a wide pH range from 3.0 to 10.0, especially in alkaline conditions. The intermediates of BPA degradation were identified and the degradation pathways involved hydroxyl oxidation and benzene ring-opening were proposed based on GC–MS results. The removal rate of BPA can maintain more than 80% following five cycles. Thus, the as-prepared MnFeO@C-300 composites are available to serve as efficient and eco-friendly catalysts for advanced catalytic oxidation of recalcitrant pollutants. [ABSTRACT FROM AUTHOR]

• Novel catalyst CoFe-ONSs were prepared to activate H 2 O 2 for TC degradation. • 83.5% of TC could be removed at neutral conditions by CoFe-ONSs/H 2 O 2 system. • Hydroxyl (OH) radicals were responsible for TC degradation. • Catalytic mechanism was comprehensively discussed. • Intermediate compounds and possible transformation pathways were proved. Ultrathin iron-cobalt oxide nanosheets (CoFe-ONSs) synthesized via a facile one-step routine by using NaBH 4 as the reductant were used for H 2 O 2 activation and tetracycline (TC) elimination. The CoFe-ONSs realized 83.5% removal of TC under the neutral conditions after 50 min with 0.3 g/L catalyst, 20 mM H 2 O 2 and 50 mg/L TC. The effects of catalyst dosage, H 2 O 2 concentration, initial pH, temperature, initial TC concentration, anions and water sources on TC degradation were studied. Hydroxyl (OH) radicals were the main active species in the entire reaction, which was demonstrated by quenching experiments, fluorescence detection and the electron paramagnetic resonance (EPR) technology. Additionally, the redox cycles of FeII/FeIII and CoII/CoIII were participated in OH generation. What's more, the plausible degradation pathways were put forward followed with detected intermediates. The CoFe-ONSs displayed negligible iron ions leaching and held high TC elimination performance even after five trials. Therefore, the CoFe-ONSs may expand the heterogeneous Fenton-like catalysts family and display great potential in eliminating antibiotic contaminants from wastewater. [ABSTRACT FROM AUTHOR]

• UiO-66-NH 2 can effectively remove norfloxacin in water. • UiO-66-NH 2 can remove norfloxacin well in the neutral pH range. • The NH 2 and Zr O bonds play important role for norfloxacin removal. • Various adsorption mechanisms for norfloxacin removal are explored. Antibiotics abuse has been a significant threat to the environment and human health. In this study, we successfully synthesized highly stable amino-functionalized Zr-based metal–organic frameworks (UiO-66-NH 2) and studied the adsorption behaviors of norfloxacin (NOR) in water. The adsorption capacities of UiO-66-NH 2 reached a maximum of 222.5 mg/g for NOR, which were considerably higher than that of most reported adsorbents. Moreover, the equilibrium time (6 h) was less than that of several previously reported adsorbents. Ionic-strength-influenced experiments showed that NaCl and CaCl 2 aqueous solutions could improve the removal efficiency of NOR. The presence of humic acid could barely affect the adsorption amount. At a concentration of 10 mg/L, the highest partition coefficient of 20.9 mg/g/µM was obtained, and the removal rate of NOR was as high as 91.6%, implying that UiO-66-NH 2 offered considerable adsorption performance at a low concentration of NOR. In addition, UiO-66-NH 2 exhibited good regeneration efficiency, thus offering the possibility to remove norfloxacin from sewage. Finally, several credible adsorption mechanisms were proposed. The results will aid us to comprehend the surface interaction between organic micropollutants and UiO-66-NH 2 and prefigure the potential of UiO-66-NH 2 as a novel adsorbent for the removal of NOR. [ABSTRACT FROM AUTHOR]