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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]

• 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]