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A new adsorbent with chromium removal function was synthesized by carbon thermal method using iron-containing waste Fenton sludge and carbon-containing solid waste fly ash to treat high pH scoring wastewater generated from industrial processes. The results showed that the adsorbent used T = 273.15 K, pH = 10, t = 1200 min, C 0  = 100 mg/L, had a removal rate of Cr(VI) of more than 80%, and the adsorption capacity could reach 393.79 mg/g. The characterization results show that the synthesized mesoporous nitrogen-doped composite material has a large specific surface area and mesoporous structure, and the surface of the material is rich in oxygen-containing functional groups and active sites. Compared with other studies, the adsorption capacity of the material is larger, which indicates that the removal effect of Cr(VI) in this study is better. The adsorption kinetic results show that the adsorption follows a pseudo second kinetic model, and the adsorption process is a chemisorption involving electron sharing or electron exchange. This experiment designed a simple method to synthesize mesoporous nitrogen-doped composites using industrial solid waste, with raw materials from cheap and easily available industrial solid waste, and solved the dual problems of heavy metals in wastewater and solid waste, providing a new idea for the resource utilization of Fenton sludge while not producing secondary pollution.

Sewage sludge (SS) dewatering is a key step in sludge disposal, which plays an important role in reducing sludge volume, facilitating transportation and subsequent treatment. In this paper, a facile hydrothermal-alkaline treatment for SS was proposed, which can be used for sludge dewatering and humic acid (HA) recycling at the same time. Response surface methodology (RSM) was used to determine the optimal conditions, and a mathematical model was established to accurately predict the changes of sludge water content and the extraction rate of HA. Under the optimal conditions of 170 °C/42 min/0.05 (for hydrothermal temperature, hydrothermal time, and mass ratio of KOH to wet sludge, respectively), the water content decreased to 46.7% and the extraction rate of HA (with a purity of 96.2%) was 89.1%. The improvement of the dewatering performance effectively facilitates the subsequent disposal of the sludge. The hydrothermal-alkaline method not only realizes the efficient dehydration of the sludge, but also obtains HA from the sludge extract. The obtained HA has potential economic value in the fields of agriculture, biological medicine, environment, and the like.

The activity and durability of electrocatalysts are important factors in their practical applications, such as electrocatalytic oxygen evolution reactions （OERs） used in water splitting cells and metal-air batteries. In this study, a novel electrocatalyst, comprising few-layered graphitic carbon （-5 atomic layers） encapsulated heazlewoodite （Ni3S2@C） nanoparticles （NPs）, was designed and synthesized using a one-step solid phase pyrolysis method. In the OER test, the Ni3S2@C catalyst exhibited an overpotential of 298 mV at a current density of 10 mA·cm^-2, a Tafel slope of 51.3 mV·dec^-1, and charge transfer resistance of 22.0 Ω, which were better than those of benchmark RuO2 and most nickel- sulfide-based catalysts previously reported. This improved performance was ascribed to the high electronic conductivity of the graphitic carbon encapsulating layers. Moreover, the encapsulation of graphitic carbon layers provided superb stability without noticeable oxidation or depletion of Ni3S2 NPs within the nanocomposite. Therefore, the strategy introduced in this work can benefit the development of highly stable metal sulfide electrocatalysts for energy conversion and storage applications, without sacrificing electrocatalytic activity.

This paper presents the results of a study of the catalytic hydrogenation of phenanthrene using catalysts based on chrysotile modified with nickel and titanium (chrysotile/NiTi), as well as coal shale. Complex characterization of catalysts in terms of acid, texture and morphological properties was carried out. Pre-reduction in the catalysts has been found to increase the yield of partially and fully hydrogenated products, including tetrahydronaphthalene, trans-decalin and dihydrophenanthrene. Particular attention is paid to the role of coal shale as a donor source of hydrogen in thermolysis conditions. The results of hydrogenation revealed complex mechanisms of phenanthrene transformations, including partial saturation of aromatic rings, desulfurization and the formation of alkyl-substituted compounds. The obtained data emphasize the prospects of using the studied catalysts in the processes of processing heavy and solid hydrocarbon raw materials, which opens up opportunities for creating new technologies for the production of liquid fuel.

This study presents an integrated approach to processing the heavy fraction of coal tar (HFCT) using oil shale (OS) from Shubarkol Komir JSC to simultaneously increase the yield of valuable hydrocarbon fractions and extract rare and dispersed trace elements. The lack of data on the effect of shale on the process and the kinetics of multi-component “tar + shale” systems limits the development of effective technologies. TG/DTG analysis was combined with the Friedman, Ozawa–Flynn–Wall, and Šesták–Berggren methods for the first time to evaluate the role of oil shale (OS). It was shown that the addition of 13% OS provides a sustained reduction in activation energy (~85–86 kJ/mol) and optimal conditions for hydrometallization. At 420 °C, an initial H2 pressure of 4 MPa, and a reaction time of 60 min, the yield of light fractions reaches 62.6%, and the solid residue concentrates Ti, Mo, Ge, and other rare and dispersed elements reach up to 66,000 g/t in total. The possibility of extracting Ge using the Purolite C100 sorbent has also been confirmed. The novelty of the study lies in demonstrating the donor–catalytic effect of shale and the practical prospects of solid residue as a secondary mineral raw materials.

In this paper, WO3·0.33H2O nanorods were prepared through a simple hydrothermal method using p-aminobenzoic acid (PABA) as an auxiliary reagent. X-ray diffraction (XRD) and transmission electron microscopy (TEM) images showed that the products with PABA addition were orthorhombic WO3·0.33H2O, which were mainly composed of nanorods with different crystal planes. The sensing performance of WO3·0.33H2O nanorod bundles prepared by the addition of PABA (100 ppm cyclohexene, Ra/Rg = 50.6) was found to be better than the WO3 synthesized without PABA (100 ppm cyclohexene, Ra/Rg = 1.3) for the detection of cyclohexene. The new synthesis route and sensing characteristics of as-synthesized WO3·0.33H2O nanorods revealed a promising candidate for the preparation of the cost-effective gas sensors.

A facile, cost-effective, non-toxic, and surfactant-free route has been developed to synthesize MoS 2 /carbon (MoS 2 /C) nanocomposites. Potassium humate consists of a wide variety of oxygen-containing functional groups, which is considered as promising candidates for functionalization of graphene. Using potassium humate as carbon source, two-dimensional MoS 2 /C nanosheets with irregular shape were synthesized via a stabilized co-precipitation/calcination process. Electrochemical performance of the samples as an anode of lithium ion battery was measured, demonstrating that the MoS 2 /C nanocomposite calcinated at 700 °C (MoS 2 /C-700) electrode showed outstanding performance with a high discharge capacity of 554.9 mAh g − 1 at a current density of 100 mA g − 1 and the Coulomb efficiency of the sample maintained a high level of approximately 100% after the first 3 cycles. Simultaneously, the MoS 2 /C-700 electrode exhibited good cycling stability and rate performance. The success in synthesizing MoS 2 /C nanocomposites via co-precipitation/calcination route may pave a new way to realize promising anode materials for high-performance lithium ion batteries.

In this work, an efficient nanocatalyst was developed based on nanoadsorbent beads. Herein, carboxymethyl cellulose–copper oxide-cobalt oxide nanocomposite beads (CMC/CuO-Co2O3) crosslinked by using AlCl3 were successfully prepared. The beads were then coated with chitosan (Cs), Cs@CMC/CuO-Co2O3. The prepared beads, CMC/CuO-Co2O3 and Cs@CMC/CuO-Co2O3, were utilized as adsorbents for heavy metal ions (Ni, Fe, Ag and Zn). By using CMC/CuO-Co2O3 and Cs@CMC/CuO-Co2O3, the distribution coefficients (Kd) for Ni, Fe, Ag and Zn were (41.166 and 6173.6 mLg−1), (136.3 and 1500 mLg−1), (20,739.1 and 1941.1 mLg−1) and (86.9 and 2333.3 mLg−1), respectively. Thus, Ni was highly adsorbed by Cs@CMC/CuO-Co2O3 beads. The metal ion adsorbed on the beads were converted into nanoparticles by treating with reducing agent (NaBH4) and named Ni/Cs@CMC/CuO-Co2O3. Further, the prepared nanoparticles-decorated beads (Ni/Cs@CMC/CuO-Co2O3) were utilized as nanocatalysts for the reduction of organic and inorganic pollutants (4-nitophenol, MO, EY dyes and potassium ferricyanide K3[Fe(CN)6]) in the presence of NaBH4. Among all catalysts, Ni/Cs@CMC/CuO-Co2O3 had the highest catalytic activity toward MO, EY and K3[Fe(CN)6], removing up to 98% in 2.0 min, 90 % in 6.0 min and 91% in 6.0 min, respectively. The reduction rate constants of MO, EY, 4-NP and K3[Fe(CN)6] were 1.06 × 10−1, 4.58 × 10−3, 4.26 × 10−3 and 5.1 × 10−3 s−1, respectively. Additionally, the catalytic activity of the Ni/Cs@CMC/CuO-Co2O3 beads was effectively optimized. The stability and recyclability of the beads were tested up to five times for the catalytic reduction of MO, EY and K3[Fe(CN)6]. It was confirmed that the designed nanocomposite beads are ecofriendly and efficient with high strength and stability as catalysts for the reduction of organic and inorganic pollutants.

Pyrolysis of sludge to biochar can not only reduce the sludge volume, toxic organic compound, and pathogens, but also be applied as effective adsorbents. However, the immobilization of heavy metals in the sludge and the properties of the biochar greatly rely on the pyrolysis temperature. In this paper, municipal sludge biochar (SBC) was prepared from 400 to 1000 °C. Pyrolysis immobilized heavy metals in sludge and the potential ecological risk of heavy metals significantly decreased to low level at temperature above 500 °C. At 700 °C, the adsorption capacity of Cd(II) reached a maximum (120.24 mg·g −1 ). The Cd(II) adsorption fitted the Pseudo-second-order model, indicating the existence of chemical adsorption. The adsorption capacity increased along with the initial pH and slowed down after pH reached 5.5. The existence of coexisting cations (Ca 2+ and Na + ) and anions (SO 4 2− and NO 3 − ) displayed different degree of inhibitory action on Cd(II) adsorption. The SEM, XRD, FTIR, and XPS analysis of sludge biochar before and after adsorption revealed that there were CdCO 3 , CdSO 4 , Cd 2 SiO 4 , Cd 3 (PO 4 ) 2 , and Cd 9 (PO 4 ) 6 appearing on the surface of sludge biochar, suggesting that the adsorption of Cd(II) by SBC included co-precipitation, ion exchange, coordination with π electrons, and complexation. It was confirmed that different properties formed by pyrolysis temperature made a difference in adsorption mechanism of sludge biochar.

Environmental pollution has been widely considered by researchers, especially the heavy metals damage to the human and ecological environment is irreversible. Adsorption is an important method to remove heavy metal ions from the environment. In this paper, humic acid (HA) was functionalized by the improved Hummers method, and its adsorption capacity for Pb(II) was studied. The results of scanning electron microscope (SEM), X-ray diffraction (XRD), Roman, and Brunauer-Emmett-Teller (BET) showed that the thickness of irregular particles decreases to a layered structure during the transformation process. In addition, X-ray photoelectron spectroscopic (XPS) and Fourier transform infrared spectra (FT-IR) spectra showed that the surface of oxidized-biochar (OBC) was rich in reactive oxygen species, which was conducive to the formation of coordination bonds with Pb(II). Further adsorption experiments showed that it was a spontaneous monolayer chemisorption. The results of the DFT calculation showed that -COOH had the lowest adsorption energy for Pb(II), and it was easier to form stable chemical bonds than -OH, -C=O, and -C-O-C-. Because those oxygen-containing functional groups not only can promote electrostatic attraction but also are more favorable for forming a covalent bond with Pb(II). This study had guiding significance for the deep modification and application of weathered coal as a heavy metal ion adsorbent or cation exchanger.