Search

Recently, the rational design and development of efficient faradaic deionization electrodes with high theoretical capacitance, natural abundance, and attractive conductivity have shown great promise for outstanding capacitive deionization (CDI)‐based desalination applications. Herein, the construction of novel FeOOH hybrid heterostructures with Na and Cl dopants (e.g., Na‐FeOOH and Cl‐FeOOH) via a robust hydrothermal strategy is reported, and an asymmetric CDI cell (Na‐FeOOH//Cl‐FeOOH) comprising Na‐FeOOH and Cl‐FeOOH working as the cathode and anode, respectively, is assembled. The multiple coupling effects of the specific structural features (e.g., enriched porosity, hierarchical pore alignment, and highly open crystalline framework), enhanced electrochemical conductivity, and optimized ion‐transfer property endow the FeOOH hybrid electrode with improved electrochemical performance. Impressively, the Na‐FeOOH//Cl‐FeOOH cell demonstrates a superior salt adsorption capacity (SACNaCl) of 35.12 mg g−1 in a 500 mg L−1 NaCl solution, a faster removal rate, and remarkable cycling stability. Moreover, the pseudocapacitive removal mechanism from the synergetic contribution of the Na‐FeOOH cathode and Cl‐FeOOH anode account for the significant desalination promotion of the Na‐FeOOH//Cl‐FeOOH cell. [ABSTRACT FROM AUTHOR]

Abstract Recently, the rational design and development of efficient faradaic deionization electrodes with high theoretical capacitance, natural abundance, and attractive conductivity have shown great promise for outstanding capacitive deionization (CDI)‐based desalination applications. Herein, the construction of novel FeOOH hybrid heterostructures with Na and Cl dopants (e.g., Na‐FeOOH and Cl‐FeOOH) via a robust hydrothermal strategy is reported, and an asymmetric CDI cell (Na‐FeOOH//Cl‐FeOOH) comprising Na‐FeOOH and Cl‐FeOOH working as the cathode and anode, respectively, is assembled. The multiple coupling effects of the specific structural features (e.g., enriched porosity, hierarchical pore alignment, and highly open crystalline framework), enhanced electrochemical conductivity, and optimized ion‐transfer property endow the FeOOH hybrid electrode with improved electrochemical performance. Impressively, the Na‐FeOOH//Cl‐FeOOH cell demonstrates a superior salt adsorption capacity (SACNaCl) of 35.12 mg g−1 in a 500 mg L−1 NaCl solution, a faster removal rate, and remarkable cycling stability. Moreover, the pseudocapacitive removal mechanism from the synergetic contribution of the Na‐FeOOH cathode and Cl‐FeOOH anode account for the significant desalination promotion of the Na‐FeOOH//Cl‐FeOOH cell.

Shallow groundwater resources in the lower Kelantan River Basin show anomalously high concentrations of iron and manganese. In some cases, other transition metals and metalloids such as arsenic are also present at elevated levels. Coupled mineral stability and aqueous geochemical models were used to determine the possible sources of iron and manganese in the groundwater. High concentrations of dissolved iron and manganese are related to Na-Cl groundwater types. Geochemical modeling of Fe2+/Fe3+ and S2−/SO42− redox pairs showed that there is a state of redox disequilibrium in the groundwater. Redox conditions control mineral precipitation and dissolution of iron oxy-hydroxides, acid volatile sulphides and subordinate influence from pH fluctuations governs the stability of iron bearing carbonates. Speciation modelling results show the presences of ferric iron complexes and aqueous sulphides, despite supersaturation with respect to hematite, goethite and pyrite. Dissolved manganese in the groundwater possibly originated from the dissolution of amorphous oxide-hydroxides and siderite, having substituted for iron as a minor impurity. The shallow sediments of the Kelantan Basin host high concentrations of iron and manganese bearing minerals that are subject to reductive dissolution during recharge events. Additionally, meteoric recharge is characteristically acidic, destabilizing iron-bearing carbonates phases such as siderite and ankerite. Naturally occurring metal contamination in potable groundwater supplies requires an economical method of remediation to avoid environmental and human health risks. Synthesized magnetic nano-particles created by a one-step method shows effective removal capacity of high iron and manganese concentrations in the groundwater samples at room temperature. The result of this work show that the primary sources of transition metals contamination in potable groundwater is a consequence of natural processes. It is proposed that the nano particulate adsorption method that has recently been developed will provide for an economical method of purification treatment. [ABSTRACT FROM AUTHOR]

The research study was carried out to evaluate trace metals (Pb, Cd, Se, Al, Mn, Cu, Zn, Fe, As, Ni, Cr, and Ag) concentrations in groundwater of Lorong Serai 4, Hulu Langat, Selangor, Malaysia. Additionally, the research study focused on determining non-carcinogenic and carcinogenic health risks, sources of the contaminants, and effective remediation methods. The results show that the concentration levels of Pb, Cd, Se, Al, Cu, Zn, Ni, Cr, and Ag are lower than their corresponding permissible limits, while Fe, Mn, and As concentrations exceed their acceptable limit. The hazard index of the groundwater in the area exceeded the acceptable limit, showing the rate of carcinogenic and non-carcinogenic health effects associated with the water. The findings also indicate that the lifetime cancer risk is high compared to the maximum limits of lifetime cancer risk from the drinking water (10–6 to 10–4). The groundwater geochemical data of the area are used in establishing the source of Fe, Mn, and As metal ions. Evaluation of Fe2+/Fe3+ and S2−/SO42− redox couples and thermodynamic modelling indicates that the groundwater of the area is in redox disequilibrium. The groundwater samples contain aqueous iron sulphate, which is supersaturated, ferrous carbonate and aluminium sulphate that are saturated. The main state of redox disequilibrium is governed by mineral precipitation and dissolution. Aqueous arsenic and manganese are possibly derived from the dissolution of pyrite (arsenopyrite) and amorphous oxide-hydroxides, respectively. The high concentration of iron in the shallow groundwater in the area is primarily the result of silicate rock weathering of ferroan igneous and metamorphic minerals with a minor contribution from the oxidation of iron sulphides. Magnetite coated with graphene oxide (Fe3O4-GO) nanoparticles (NPs) was synthesized and characterized, and the adsorption preliminary experiments were carried out; and the Fe3O4-GO NPs show enhanced removal (Fe > As > Mn) capacity over graphene oxide (GO). [ABSTRACT FROM AUTHOR]

[Display omitted] • FeOOH/Pd/MoS 2 hybrid is constructed via an ingenious interfacial redox avenue. • Excellent desalination capacity and admirable durability is demonstrated. • The hybrid electrode reveals an outstanding heavy metal ion removal capability. • Synergetic pseudocapacitive removal leads to significant capacity promotion. Capacitive deionization (CDI)-based saline water desalination presents an admirable alternative for sustainable freshwater production. However, the lack of robust electrode materials impedes its wide application. Herein, a three-dimension (3D) heterostructured iron oxide-hydroxide-incorporated palladium nanoparticle-anchored molybdenum disulphide (FeOOH/Pd/MoS 2) hybrid constructed by the two-step spontaneous interfacial redox reactions is reported as efficient Faradaic CDI electrode materials for desalination application. The FeOOH/Pd/MoS 2 hybrid electrode delivers a superior desalination capacity of 41.1 mg g−1 in a 500 mg L-1 NaCl solution, along with impressive cycling stability and a high capacitive contribution of 80 % at a rate of 1 mV s−1. The synergetic pseudocapacitive removal process is thoroughly clarified by ex-situ XPS characterizations. Experimental analysis and density functional theory calculations reveal that the bi-component participation of FeOOH and Pd can efficiently tailor the electronic structure of MoS 2 , leading to the reinforcing electronic conductivity toward the promoted Na+ capture feature. Moreover, the hybrid electrode manifests outstanding removal efficiencies up to 91.25 % for diverse heavy metal ions (i.e., Pb2+, Cd2+, Cu2+, Ni2+, and Cr3+), demonstrating its great prospects for low-concentration wastewater purification. This work supplies an ingenious avenue for the rational design of heterostructured MoS 2 Faradaic electrodes for advanced CDI desalination. [ABSTRACT FROM AUTHOR]

• F-FeOOH NRs/rGO hybrids were fabricated by a simple one-step approach. • Strong interfacial coupling exists between F-FeOOH nanorods and rGO sheets. • F-doping and rGO promote the electron/ion transport and structural integrity. • F-FeOOH NRs/rGO hybrids achieve excellent cycling and rate performances. [Display omitted] FeOOH has emerged as an attractive anode material for Li-ion batteries (LIBs) owing to its low cost and high capacity. However, the inferior electronic conductivity and poor structural stability of FeOOH impede its practical applications. To address these issues, novel hybrids of fluorine-doped FeOOH nanorods/reduced graphene oxide (F-FeOOH NRs/rGO) were synthesized via a simple one-step hydrothermal method. F-FeOOH NRs were grown in situ simultaneously with the reduction of graphene oxide, resulting in strong interfacial coupling of F-FeOOH with rGO. Benefitting from the synergetic effect of rGO and F-doping, the optimized F-FeOOH NRs/rGO hybrid presents a stable capacity of 1207.4 mAh g−1 at the 160th cycle at 0.1 A g−1 and a remarkable rate capability of 777.5 mAh g−1 at 2 A g−1. Furthermore, even after 400 cycles at 1 A g−1, a reversible capacity of 701.4 mAh g−1 can still be maintained. With simple synthesis method and excellent Li-storage performance, the F-FeOOH NRs/rGO hybrid is expected to be a prospective material for LIB anode. [ABSTRACT FROM AUTHOR]

Mine tailings are major sources of metals and metalloids in the environment, making the physical and geochemical stabilization of tailings a serious environmental challenge. With a view to facilitate the development of covering vegetation and of decreasing the mobility of Pb in the acid tailings of a former Ag–Pb mine, laboratory microcosm experiments were performed to enable comparison of the effectiveness of several treatments. Tailings were mixed with 5% by weight of ochre, an iron-rich material produced during the treatment of a coal mine water, and with cow manure (0, 0.15, 1 and 2% by weight), either solely or in combination. They were then submitted to weekly watering over 84 days. All treatments raised the pH values from 4 to values between 7 and 8 and induced a strong decrease in the total dissolved Pb concentration in the percolating water (from 13 to 15 mg.L−1 to less than 0.5 mg.L−1). Several processes seemed to be involved in the immobilization of Pb by the amendments: precipitation as hydroxide, sulfate, carbonate and phosphate, and adsorption on iron hydroxides. A transient increase was observed in both Pb mobility and functional microbial diversity with 1% and 2% manure, with a peak after 28 days of incubation. This peak corresponded to an Average Well Color Development (AWCD) in Biolog™ Ecoplates increase from 0.5 to 0.8 with 1% manure and from 0.6 to 1.5 with 2% manure. However, at the end of experiment, Pb immobilization was strengthened by 2% manure and microbial functional biodiversity fell back, with AWCD values of 0.5 and 0.8 for 1% and 2% manure, respectively. Other toxic elements present in the tailings, namely As, Zn and Ba, were not strongly mobilized by the treatments, although cow manure slightly increased the leaching of Ba and As, which maximum concentrations in the leaching water reached 65 μg.L−1 Ba and 9 μg.L−1 As. All amendments improved the growth of ryegrass, which maximum dry biomass ranged from 38 mg/microcosm without amendment to 155 mg/microcosm with 0.15% manure. The results provide key information about the biogeochemical processes driving the mobility of Pb, As, Zn and Ba in acid mine tailings during the first 84 days following their amendment with iron-rich ochre and manure. • Ochre from coal mine water treatment increases pH of acid tailings. • Pb is stabilized and As is not mobilized in tailings by ochre and manure amendment. • Manure induces mobilization of Pb for 35 days then its stabilization. • Microbial functional biodiversity is transiently increased by amendment. • Ochre favors short-term growth of ray-grass on tailings. [ABSTRACT FROM AUTHOR]