Display omitted
•MoP-Mo2C quantum dot heterostructures uniformly distribute on carbon sheet network.•MoP-Mo2C/NPC possesses abundant heterogeneous interfaces and pore structure.•MoP-Mo2C/NPC exhibits ...low overpotentials and ultrahigh stability for HER and OER.
In this work, we constructed MoP-Mo2C quantum dot heterostructures uniformly hosted on a three-dimensional (3D) hierarchically porous thin N,P-doped carbon sheet network (MoP-Mo2C/NPC) by a novel one-pot simultaneous phosphating-carbonization-activation of molybdenum-chelated resin and KOH. Chelate confinement not only prevents the aggregation of MoP/Mo2C quantum dots, but also synchronously produces a carbon sheet network doped with N and P without the requirement for post-atom doping. The prepared MoP-Mo2C/NPC exhibited a large specific surface area, a high electron conductivity, and abundant active sites for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). As a result, MoP-Mo2C/NPC with a low calculated Gibbs free energy for H adsorption exhibited an excellent electrocatalytic activity and an ultrahigh stability for both the HER and OER processes in an alkaline medium. In addition, the assembled MoP-Mo2C/NPC || MoP-Mo2C/NPC alkaline electrolyzer delivered a current density of 10 mA cm−2 at an overpotential of only 1.55 V, and maintained > 95% of the initial current density after 168 h (1 week) of activity, which is superior to that of the state-of-the-art Pt/C || RuO2/C system in the overall water splitting process.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Various montmorillonite (Mt) nanocomposite adsorbents were prepared with Al13 cations, dodecyl trimethyl ammonium chloride (DTAC) or dodecyl amine (DA) and characterized by Fourier transform infrared ...(FTIR) spectroscopy, X-ray diffraction (XRD) and BET surface area and pore size analyses. The adsorption of hexavalent chromium, Cr(VI) onto various Mt nanocomposites as a function of adsorbent dosage, initial Cr(VI) concentration, contact time and solution pH was investigated. The results showed that the obtained nanocomposites had large basal spacing and good porous structure, and the specific surface areas followed the order: OH-Al-Mt>DA-Al-Mt>DTAC-Al-Mt>Na+-Mt>DTAC-Mt>DA-Mt. The removal efficiency of Cr(VI) ions increased with increasing the adsorbent dosage and contact time, but decreased with increasing initial Cr(VI) concentration, as expected. The adsorption of Cr(VI) was highly pH-dependent and the maximum removal efficiency of Cr(VI) was found in the acid environment. The adsorption equilibrium time was 2h and the adsorption kinetic data of Cr(VI) on various adsorbents were well described by the pseudo-second-order kinetics model, which indicated that the adsorption reaction of Cr(VI) ions with the adsorbents was mainly due to chemical adsorption. Both the Langmuir model and Freundlich model fitted the equilibrium data well, which suggested that the Cr(VI) adsorption onto various adsorbents was both as monolayer and on heterogeneous surface conditions. The adsorption results indicated that among all the adsorbents used in this experiment, the dodecyl amine and Al13 cations composited with Mt (DA-Al-Mt) was the most effective for removing Cr(VI) from wastewater.
Display omitted
•Montmorillonite adsorbents were prepared with organic and/or inorganic pillars.•Cr(VI) adsorption by adsorbents was pH-dependent with maximum removal at low pH.•Adsorption equilibrium time was 2h and followed pseudo-second-order kinetics model.•The pseudo-second-order kinetics model indicated chemical adsorption of Cr(VI).
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The prediction of grinding particle size is an effective measure to optimize the grinding process. Cassiterite polymetallic sulfide ore and lead-zinc ore, as the research object in this paper, their ...particle size prediction mechanism are studied based on the drop weight test, batch grinding test, the theory law of media motion in ball mill and population balance model. The results show that particle size distribution of crushing products under different crushing energies and ore particle sizes is obtained by drop weight test, and the crushing parameters A and b are calculated by fitting regression, and then the correlation between t
x
and t
10
obtained in drop weight test is also applicable to the correlation between t
x
and t
10
of grinding products in ball mill medium throwing motion, which can effectively solve the crushing function and the selection function with the help of Matlab, and then establish the grinding population balance prediction model based on the drop weight test and the motion law of ball mill medium. The adaptability and reliability of the prediction model of grinding particle size are verified by batch grinding test.
Full text
Available for:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
In this study, the adsorption capacity of organo-montmorillonites (OMt) modified with cationic surfactants and chelating reagent toward binary-component, heavy metal and organic pollutant, in aqueous ...solution was investigated through batch experiments. The characteristics of the OMt were analyzed by X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), Specific surface area (BET), respectively, confirming that hexadecyl trimethyl ammonium chloride (CTAC), ethylene diamine tetraacetic acid (EDTA) and 1,6-diaminohexane (DA) were successfully introduced into Na
+
-Mt. Comparing with stronger Zn
2+
removal efficiency onto EDTA-Mt and DA-Mt dominated by forming complexes in the binary-component systems, CTAC–EDTA-Mt and CTAC–DA-Mt gained a huge edge in uptaking phenol controlled by layer partition. Factors containing the initial Zn
2+
/phenol concentration and the competitive adsorption where the Zn
2+
, Pb
2+
, Cd
2+
and phenol/Zn
2+
, p-nitrophenol, phenylamine and phenol coexisted in the aqueous solution were shown in the paper. Furthermore, the desorption of Zn
2+
and phenol on the CTAC–DA-Mt was investigated by series experiments under various conditions (with the type of chemical reagents, variable concentration of desorbent and contact time). The results showed HCl solution had higher efficiency on desorbing Zn
2+
over phenol onto the CTAC–DA-Mt. CTAC–EDTA-Mt and CTAC–DA-Mt had potential applications in dealing with the wastewater where heavy metals and organic pollutants coexist.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Bentonite is an important clay for preparation of adsorbents for potential treatment of industrial effluents. However, due to its natural occurrence as fine particles and swelling after moisture ...absorption, bentonite is difficult to be separated from the liquid for regeneration purpose, which limits its application in effluent treatment. In this study, two different bentonite-polypropylene composites were synthesized, i.e., with and without pore-enlarging treatment. They both showed strong ability to resist hydraulic agitation damage with a small breakage rate in water. The obtained results from SEM and XRD characterization revealed that the compounding of bentonite with the polypropylene was a physical process, and the structural characteristics of bentonite particles were maintained in the new products. The granular composite adsorbents were effective in removing Pb2+ in aqueous solution. The suggested pore-enlarging treatment was verified as a successful operation to increase greatly the adsorption rate of contaminants on the granular bentonite composite.
•A novel granular bentonite composite adsorbents were prepared.•The bentonite composite adsorbents can be separated from the liquid easily.•The compounding of bentonite with resin was confined to a physical process.•Pore-enlarging treatment improved the adsorption capacity of the composite.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
As the depletion of zinc sulfide ores becomes more severe, investigations into the recovery of zinc from zinc oxide ores have aroused more interest. In this regard, acid-based hydrometallurgical ...treatment strategies have had great effectiveness. However, they are inadequate for low-grade zinc oxide ores. In this study, we examined the alkaline treatment of gossan for the recovery of oxide ores that bear zinc, such as siderite and limonite. Additionally, of particular note, the effects of a leaching agent, its concentration and time, temperature, liquid-to-solid ratio, as well as the agitation rate on the leaching of zinc from gossan were studied to evaluate the effects of these parameters on the kinetics of zinc dissolution. The results showed that the leaching of zinc is controlled by a single rate-controlling step with an activation energy of 4.458 kJ/mol before 120 min and 5.536 kJ/mol after 120 min, with zinc leaching efficiency less than 50% in all leachings.
Full text
Available for:
CEKLJ, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
With the application of resins in various fields, numerous waste resins that are difficult to treat have been produced. The industrial wastewater containing Cr(VI) has severely polluted soil and ...groundwater environments, thereby endangering human health. Therefore, in this paper, a novel functionalized mesoporous adsorbent PPR-Z was synthesized from waste amidoxime resin for adsorbing Cr(VI). The waste amidoxime resin was first modified with H
3
PO
4
and ZnCl
2
, and subsequently, it was carbonized through slow thermal decomposition. The static adsorption of PPR-Z conforms to the pseudo-second-order kinetic model and Langmuir isotherm, indicating that the Cr(VI) adsorption by PPR-Z is mostly chemical adsorption and exhibits single-layer adsorption. The saturated adsorption capacity of the adsorbent for Cr(VI) could reach 255.86 mg/g. The adsorbent could effectively reduce Cr(VI) to Cr(III) and decrease the toxicity of Cr(VI) during adsorption. PPR-Z exhibited Cr(VI) selectivity in electroplating wastewater. The main mechanisms involved in the Cr(VI) adsorption are the chemical reduction of Cr(VI) into Cr(III) and electrostatic and coordination interactions. Preparation of PPR-Z not only solves the problem of waste resin treatment but also effectively controls Cr(VI) pollution and realizes the concept of “treating waste with waste”.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
To attempt a new approach to improve the grinding of cassiterite–polymetallic sulfide ores while simultaneously reducing cassiterite overgrinding and sulfide undergrinding, this article looked into ...the effects of grinding chemical additives on the distribution of grinding product size. Six chemicals, namely sodium hexametaphosphate, triethanolamine, ferric sulphate, aluminum chloride, polyaluminum chloride and polyacrylamide, were compared in terms of their influence on the grinding product size distribution. The results showed that the six chemicals changed the distribution results with varying orientations and degrees and that the addition of polyacrylamide achieved the most satisfactory effect by decreasing the production of both coarse and fine size fractions and increasing the production of qualified particles. The effect of the molecular weight of polyacrylamide on the grinding was also discussed. The polyacrylamides with molecular weights of about 3 × 106, 5 × 106, 8 × 106 and 12 × 106 could help to produce less of the coarse size fraction and more of the qualified size fraction, but only the polyacrylamides with molecular weights of 3 × 106 and 5 × 106 produced pronounced changes. Moreover, the polyacrylamides could slightly reduce the production of the fine size fraction. Polyacrylamide with a 5 × 106 molecular weight was better than that with a 3 × 106 molecular weight in aiding the grinding of the discussed ore. It was also found that the aid action of the polyacrylamide with a 5 × 106 molecular weight was related to grinding concentration and that a low grinding concentration of less than 70% solid mass was helpful in exerting its aid action. Using polyacrylamide could shorten the grinding time that is needed to achieve the same, or even improved, product size distribution.
Full text
Available for:
CEKLJ, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
During the grinding process, the crushing of minerals mainly depends on the impact action of the grinding medium. Based on the JK drop weight test data of quartz and pyrrhotite and the research ...results of their impact crushing characteristic parameters, this paper calculates the specific crushing energy (Ecs) of mineral samples subjected to impact in a ball mill using the grinding medium motion theory and then calculates the cumulative particle size distribution under screening under any mesh size using the JK drop weight test method. On this basis, the breakage distribution function of mineral samples is calculated, and a selection function is obtained based on grinding experiments. Finally, using Matlab programming and function-fitting mathematical methods, as well as a particle size population balance dynamics simulation of grinding, the particle size distribution characteristics of the grinding products of the two mineral samples in the mill that are only subjected to impact action are calculated. The results show that the selection function of quartz and pyrrhotite decreases overall with the prolongation of the grinding time, and the selection function of the coarse particle size changes more significantly than that of the fine particle size. At the same time, the selection function decreases with the decrease in feed particle size, and the smaller the feed particle size, the lower the probability of impact crushing. The Ecs values of quartz and pyrrhotite at each particle level in the mill are different, and the degree of mineral crushing is closely related to the impact energy, feed particle size, and mineral properties.
To effectively separate and recover Co(II) from the leachate of spent lithium-ion battery cathodes, we investigated solvent extraction with quaternary ammonium salt N263 in the sodium nitrite system. ...NO
2
−
combines with Co(II) to form an anion Co(NO
2
)
3
−
, and it is then extracted by N263. The extraction of Co(II) is related to the concentration of NO
2
−
. The extraction efficiency of Co(II) reaches the maximum of 99.16%, while the extraction efficiencies of Ni(II), Mn(II), and Li(I) are 9.27%–9.80% under the following conditions: 30vol% of N263 and 15vol% of iso-propyl alcohol in sulfonated kerosene, the volume ratio of the aqueous-to-organic phase is 2:1, the extraction time is 30 min, and 1 M sodium nitrite in 0.1 M HNO
3
. The theoretical stages require for the Co(II) extraction are performed in the McCabe—Thiele diagram, and the extraction efficiency of Co(II) reaches more than 99.00% after three-stage counter-current extraction with Co(II) concentration of 2544 mg/L. When the HCl concentration is 1.5 M, the volume ratio of the aqueous-to-organic phase is 1:1, the back-extraction efficiency of Co(II) achieves 91.41%. After five extraction and back-extraction cycles, the Co(II) extraction efficiency can still reach 93.89%. The Co(II) extraction efficiency in the actual leaching solution reaches 100%.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
