Photocatalytic Synthesis of Ammonia from Hollow Coral-Like Graphitic Carbon Nitride/FeOCl Loaded with Fe-1T MoS2 Nanosheets as Cocatalysts.

Photocatalytic ammonia synthesis (PAS) represents an emerging environmentally friendly approach to ammonia production. In this work, we employed Fe doping to modify the cocatalyst 1T MoS2, enhancing the active N2 sites on Fe-1T MoS2 by inducing defects on the surface of 1T MoS2. Afterward, Fe-1T MoS2 was loaded onto a hollow coral-like graphitic carbon nitride (CCN)/FeOCl composite. Under simulated sunlight, the efficiency of 5% Fe-1T MoS2@CCN/FeOCl (Fe-MCN/FeOCl) reached 367.62 µmol g-1 h-1, surpassing 1T MoS2@CCN(MCN) by 3.2 times, CCN by 16.9 times, and g-C3N4 by 32.5 times, where 5% means the doping amount of Fe in 1T MoS2. The good performance of Fe MCN/FeOCl should be attributed to the Fe doping in Fe-MCN/FeOCl which not only increases the separation efficiency of active sites and charge carriers, but also reduces the sample impedance significantly through the heterojunction formed between CCN and FeOCl. This work also presents a method for creating more efficient and stable photocatalysts for ammonia synthesis.

Photocatalytic Synthesis of Ammonia from Pinecone Graphite-Phase Carbon Nitride Loaded with MoS2 Nanosheets as Co-catalysts.

Photocatalytic nitrogen fixation is a promising alternative to the Haber-Bosch process to alleviate the energy and environmental crises. Here, we designed a pinecone-shaped graphite-phase carbon nitride (PCN) catalyst supported with MoS2 nanosheets by a supramolecular self-assembly method. The catalyst shows an excellent photocatalytic nitrogen reduction reaction (PNRR) due to the larger specific surface area and the enhancement of visible light owing to the reduced band gap. Under simulated sunlight, the sample of PCN loaded with 5 wt % MoS2 nanosheets (MS5%/PCN) shows a PNRR efficiency of 279.41 µmol g-1 h-1, which is 14.9 times that of bulk graphite-phase carbon nitride (g-C3N4), 4.6 times that of PCN, and 5.4 times that of MoS2, respectively. The unique pinecone-like structure of MS5%/PCN not only improves the ability of light absorption but also assists in the uniform loading of MoS2 nanosheets. Likewise, the existence of MoS2 nanosheets improves the light absorption ability of the catalyst and reduces the impedance of the catalyst. Furthermore, as a co-catalyst, MoS2 nanosheets can efficiently adsorb nitrogen (N2) and serve as active N2 reduction sites. From the perspective of structural design, this work can offer novel solutions for the creation of effective N2-fixing photocatalysts.

New insight into desorption behavior and mechanism of oil from aged oil-contaminated soil in microemulsion.

The intractable nature of oil-contaminated soil (OS) constitutes the chief limiting factor for its remediation. Herein, the aging effect (i.e., oil-soil interactions and pore-scale effect) was investigated by analyzing the properties of aged OS and further demonstrated by investigating the desorption behavior of the oil from the OS. XPS was performed to detect the chemical environment of N, O, and Al, indicating the coordination adsorption of carbonyl groups (oil) on the soil surface. Alterations in the functional groups of the OS were detected using FT-IR, indicating that the oil-soil interactions were enhanced via wind-thermal aging. SEM and BET were used to analyze the structural morphology and pore-scale of the OS. The analysis revealed that aging promoted the development of the pore-scale effect in the OS. Moreover, the desorption behavior of oil molecules from the aged OS was investigated via desorption thermodynamics and kinetics. The desorption mechanism of the OS was elucidated via intraparticle diffusion kinetics. The desorption process of oil molecules underwent three stages: film diffusion, intraparticle diffusion, and surface desorption. Owing to the aging effect, the latter two stages constituted the major steps for controlling oil desorption. This mechanism provided theoretical guidance to apply microemulsion elution for remedying industrial OS.

Broad Spectral Response Z-Scheme Three-Dimensional Ordered Macroporous Carbon Quantum Dots/TiO2/g-C3N4 Composite for Boosting Photocatalysis.

Photocatalytic degradation technology is one of the effective protocols to solve environmental problems. TiO2 has always been favored for its photostability and low cost. However, the insufficient photocatalytic activity of TiO2 limits its application due to the severe recombination of photogenerated electrons and holes and a narrow light response range. Therefore, 3DTCN, a TiO2/g-C3N4 composite with a three-dimensional ordered macroporous structure was prepared by a colloidal crystal template technique to form a heterojunction for inhibiting the photogenerated electron-hole recombination. On 3DTCN, carbon quantum dots (CQDs) were loaded by impregnation to obtain x % CQDs/3DTCN with a broad spectral response to light. The physical and chemical properties of samples were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution-TEM, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller analysis, photoluminescence spectroscopy, and ultraviolet-visible diffuse reflectance spectroscopy. The photocatalytic activity was evaluated via degrading the rhodamine B (RhB) dye, and the degradation efficiency of 1% CQDs/3DTCN (98%) was found to be much higher than that of 3DTCN (42%) in 80 min under simulated sunlight irradiation. Furthermore, it also possessed excellent durability. Meanwhile, the sample also showed an outstanding photoelectric property. Finally, the proposed mechanism of the composites had been mainly analyzed by density functional theory calculations. This work thus provides an idea to form a 3D structure heterojunction and further improve the photocatalytic activity.

Aged landfill leachate enhances anaerobic digestion of waste activated sludge.

Anaerobic digestion (AD) is considered as a sustainable pathway to recover energy from organic wastes, but the digestive efficiency for waste activated sludge (WAS) is not as expected due to the limitations in WAS hydrolysis. This study proposes an effective strategy to simultaneously treat WAS and landfill leachate, aiming to promote WAS hydrolysis and enhance organics converting to methane. The effects of landfill leachate on the four stages (i.e., solubilization, hydrolysis, acidogenesis, and methanogenesis) of AD of WAS, as well as the effect mechanisms were investigated. Results showed that adding appropriate amounts of landfill leachate could promote the steps of solubilization, hydrolysis and acidogenesis of WAS, but had no-effect on methanogenesis. The hydrolysis and acidogenesis efficiency in the leachate added digesters were 2.0%-8.4% and 35.2%-72.7% higher than the control digester. Mechanism studies indicated that humic acid (HA) contained in the leachate was conducive to the processes of both hydrolysis and acidogenesis, but detrimental to the methanogenesis. Effects of heavy metals (HMs) on AD of WAS was also dose-dependent. Digestive performance was inhibited by excessive HMs but promoted by moderate dosages. Humic acid and metal ions tend to interact to form complexes, and thus relieve their each inhibition effects. It is also found that the stability of sludge flocs was reduced by the leachate through reducing both apparent activation energy (AAE) and median particle size (MPS) of the sludge. Microbial community and diversity results revealed that the relative abundance of microbes responsible for hydrolysis and acidogenesis increased when landfill leachate was present. This research provides a more technically and economically feasible approach to co-treating and co-utilizing WAS and landfill leachate.

Improved Performance of Polysulfone Ultrafiltration Membrane Using TCPP by Post-Modification Method.

Ultrafiltration (UF) membranes have found great application in sewage purification and desalination due to their high permeation flux and high rejection rate for contaminants under low-pressure conditions, but the flux and antifouling ability of UF membranes needs to be improved. Tetrakis (4-carboxyphenyl) porphyrin (TCPP) has good hydrophilicity, and it is protonated under strongly acidic conditions and then forms strong hydrogen bonds with N, O and S, so that the TCPP would be well anchored in the membrane. In this work, NaHCO3 was used to dissolve TCPP and TMC (trimesoyl chloride) was used to produce a strong acid. Then, TCPP was modified in a membrane with a different rejection rate by a method similar to interfacial polymerization. Performance tests of TCPP/polysulfone (PSf) membranes show that for the membrane with a high BSA (bovine serum albumin) rejection, when the ratio of NaHCO3 to TCPP is 16:1 (wt.%), the pure water flux of membrane Z1 16:1 is increased by 34% (from 455 to 614 Lm-2h-1bar-1) while the membrane retention was maintained above 95%. As for the membrane with a low BSA rejection, when the ratio of NaHCO3 to TCPP was 32:1, the rejection of membrane B2 32:1 was found to increase from 81% to 96%. Although the flux of membrane B2 32:1 decreased, it remained at 638 Lm-2h-1bar-1, which is comparable to the reported polymer ultrafiltration membrane. The above dual results are thought to be attributed to the synergistic effect of protonated TCPP and NaHCO3, where the former increases membrane flux and the latter increases the membrane rejection rate. This work provides a way for the application of porphyrin and porphyrin framework materials in membrane separation.

Insight into essential channel effect of pore structures and hydrogen bonds on the solvent extraction of oily sludge.

In this study, solvent extraction experiments were conducted to investigate the channel effect of pore structures and hydrogen bonds by analyzing the desorption behavior of oil components. The highest oil recovery efficiency was 87.9 % under optimum conditions. Pore structure of oily sludge was analyzed by N2 adsorption-desorption analysis and scanning electron microscope (SEM) measurements. Mesopores of sludge inhibited the desorption of oil molecules by analyzing the pore width and cumulative pore volume of residual sludge in desorption process. In addition, saturates and aromatics were easily extracted from sludge, while the desorption rate and desorption efficiency of oily sludge were limited by resins and asphaltenes respectively through component analysis and kinetic analysis. Furthermore, channel effect of pore structures and hydrogen bonds was investigated in the desorption process of oily sludge, which also provided a guidance to selectively extract light components from oily sludge with high efficiency in industry processing.

Product-oriented decomposition of lignocellulose catalyzed by novel polyoxometalates-ionic liquid mixture.

Lignocellulose was oxidatively decomposed in a newly developed polyoxometalates-imidazolium ionic liquid mixture. Aromatic compounds covering acids, esters, ketones, aldehydes, and phenols were selectively produced under various conditions. 4-Hydroxylbenzoic acid was dominatingly yielded under low temperature and high oxidant concentration. Phenolic compounds were mainly generated at high temperature with a selectivity of 45.1% and a yield of 4.3%, higher than those generated in similar polyoxometalates-ionic liquids system. The products distributions and residues of lignocellulose decomposition under various conditions were characterized; the influences of the ionic liquids anions on the polyoxometalates-ionic liquids complex formation, the acidic and redox properties of the catalyst, and the final products were profoundly investigated; and a tentative reacting process was proposed. The ionic liquid could be recycled for five times. This work not only provided a new lignocellulose decomposition strategy to produce aromatic products, but also offered a guidance for product-oriented lignocellulose decomposition.

Bifunctional and recyclable Dawson-type polyoxometalates catalyze oxidative degradation of lignocellulose to selectively produce phthalates.

Acid-redox bifunctional Dawson-type polyoxometalates K6P2W18O62 (P2W18) and K10P2W17O61 (P2W17) were introduced as the new-type catalysts in oxidative decomposition of lignocellulose. The lignin and hemicellulose ingredients of lignocellulose could be decomposed by P2W17 to produce diisobutyl phthalate with the selectivity of 75.67% and other aromatic and aliphatic compounds under mild conditions, evidently differed from other POMs-catalyzed lignocellulose depolymerization in which aromatic ketones and phenols were the main compounds. Diisobutyl phthalate was obtained from the oxidation of Cα-OR and α-OH of the phenyl structure. The catalyst could be recycled for three times without obvious deactivation. This is the first report of lignocellulose decomposition catalyzed by Dawson-type polyoxometalates to selectively produce phthalates.

Co-immobilization of cellulase and lysozyme on amino-functionalized magnetic nanoparticles: An activity-tunable biocatalyst for extraction of lipids from microalgae.

An activity-tunable biocatalyst for Nannochloropsis sp. cell-walls degradation was prepared by co-immobilization of cellulase and lysozyme on the surface of amino-functionalized magnetic nanoparticles (MNPs) employing glutaraldehyde. The competition between cellulase and lysozyme during immobilization was caused by the limited active sites of the MNPs. The maximum recovery of activities (cellulase: 78.9% and lysozyme: 69.6%) were achieved due to synergistic effects during dual-enzyme co-immobilization. The thermal stability in terms of half-life of the co-immobilized enzymes was three times higher than that in free form and had higher catalytic efficiency for hydrolysis of cell walls. Moreover, the co-immobilized enzymes showed greater thermal stability and wider pH tolerance than free enzymes under harsh conditions. Furthermore, the co-immobilized enzymes retained up to 60% of the residual activity after being recycled 6 times. This study provides a feasible approach for the industrialization of enzyme during cell-walls disruption and lipids extraction from Nannochloropsis sp.