查看更多>>摘要：The dairy industry requires membranes with narrow-distributed pore size to separate lactose efficiently as the demand for low-lactose milk is increasing. In this study, ceramic membranes were used to remove lactose from skim milk. Ceramic microfiltration membranes were selected for filtration owing to their high permeation flux and high rejection performance for separating lactose and protein. The operating parameters of the microfiltration processes were systematically discussed and optimized, achieving 99% rejection of the proteins with 100% permeation of lactose, and the permeance was as high as 75 L m~(-2)h~(-1) bar~(-1). A diafiltration model was proposed to optimize the diafiltration process;; moreover, the optimum volume concentration ratio of the pre-concentration process was obtained to minimize the operation time. The diafiltration operation was then optimized to remove lactose from skim milk. The results showed that lactose removal and protein concentration were achieved simultaneously, and low-lactose milk with a lactose concentration of less than 5 g L~(-1) have been prepared. This study serves as a valuable guide for process design and practical operations in the dairy industry.
查看更多>>摘要：Intrinsically inferior electron transfer rate between catalyst and oxidant was considered as a limiting factor to inhibit the catalytic efficiency of peroxymonosulfate (PMS). In this work, the introduction of Mn atoms into iron oxide (Fe2O3) (Mn-Fe2O3) effectively altered the electronic structure of catalyst surface and promoted the adsorption of PMS, which increased the removal rate of Bisphenol A (BPA) by 235 times, with an extensive pH range (3-11). The main active species contained surface active complexes, superoxide radical (O2~), and singlet oxygen ( O2). The reactor unit could operate continuously for 23 days and still maintain a removal rate of more than 95%. In addition, it had good adaptability to actual water bodies and could effectively reduce the toxicity of BPA. This work shed new light on the regulation of the interfacial electron transfer process between catalyst and oxidant.
查看更多>>摘要：As China pledges that its carbon emissions will peak before 2030 and that it will be carbon neutral by 2060, the CO2 capture technology with high efficiency and low energy-consumption was expected in industry. CO2 phase change absorbents, CPCAs, had shown a potential to reduce energy consumption for CO2 capture. Although a lot of CPCAs were reported in the last decade, it still suffered from the lack of theoretical guidance for development. The effect of amine structure, which mainly affects cosolvent effect of amine and salting-out effect of formed salts, on developing CPCAs by means of cosolvent effect was clarified. For cosolvent effect of amine, 12 amines with various carbon chain lengths, isomers and substituents were determined by thermodynamical method and the log P of amine were proposed to characterize the cosolvent effect. The amine with long carbon chain and steric effect showed a high ability to act as a cosolvent to enhance the solubility of 1-butanol in H2O. The salting-out effect of formed salts by reacting amine and CO2 was related to pl<a of amine. The absorbent comprising amine with low log P and high pl<a was prefer to exhibit phase separation behavior, and benefit to develop CPCAs. Based on this guideline, all amines in this study could be developed as CPCAs by adjusting kinds of amine and diluent. Moreover, to explore the absorption-desorption performance of developed CPCAs, DEA/l-butanol/H^O was used as example, the volume ratio, species distributions and CO2 cyclic capacity were measured. When the absorption temperature was 303 K and desorption temperature was 373 K, The maximum CO2 cyclic capacity of CPCA was 2.03 mol CO2 · kg~(-1), which was 34.4% higher than that of 30 wt% DEA/H2Q.
查看更多>>摘要：Titania graphene hybrid nanocomposites (TiO2-FLG) synthesized from graphite and TiO2 precursors, in a simple and sustainable approach via a three-step method, including the mechanochemical treatment of pre-synthesized FLG and TiO2 NPs are effcient has led to the preparation of TiO2-FLG as effcient nano-catalysts for photo-catalytic degradation of a complex mixing of pesticides (isoproturon, pyrimethanil, alachlor and methomyl). The effect of few layer graphene (FLG) loading (0–1.0%) was analyzed to defne the optimal ratio of FLG to TiO2 and compared with the corresponding physical mixtures. X-ray Powder Diffraction (XRD) patterns of all these hybrid photocatalysts have presented the same crystal structure, with anatase as the main crystalline phase and brookite as secondary phase. An interaction between the graphene structure and the TiO2 nanoparticles has been observed from Energy Dispersive X-Ray (EDX), X-ray photoelectron (XPS) and Raman spectroscopy studies, indicating that FLG is mainly deposited on the surface wrapping the TiO2 nanoparticles. The presence of FLG in low concentrations and the mechanochemical activation are the key steps to improve the photocatalytic activity of TiO2 nanoparticles on these hybrid nanocomposites. The TiO2-FLG-0.5% hybrid nanocomposite, with circa 1.9 % content of graphitic carbon in surface, has showed the best photocatalytic performance in the degradation of pesticides. Pesticides were completely removed at 350 min, and around 82 % of total organic carbon (TOC) conversion was achieved at 540 min of irrathation time.
查看更多>>摘要：Microporous materials are highlighted with regard to low-energy and low-carbon adsorptive separation processes, where the interests have evolved simple microporous powders into a structured sorbent platform of fiber sorbent to tackle the technical challenges of large-scale applications. However, the challenge of sorption capacity loss in a limited footprint due to the addition of non-adsorbing binder materials still remained. Polymers of intrinsic microporosity (PIMs) are promising advanced materials for gas separation and capture due to their unique textural properties and processability. This article reports an efficient but straightforward blend of organic and inorganic materials, PIM-1 and zeolite NaY, forming "all-nanoporous" fiber sorbents. The combination of the two nanoporous materials resulted in a structured platform for a sorption-based separation system for volatile organic compounds (VOCs). It is differentiated from other sorption platforms as it presents minimal volumetric sorption loss from the "binder" material by allowing the microporous substrate to work as a VOC sorbent. The "all-nanoporous" fiber sorbent of NaY/PIM-1 shows feasible sorption performance capabilities under both dry and humid conditions while maintaining a minimal pressure drop due to its hierarchical porous structure.
查看更多>>摘要：Various stages of oil production and processing in petroleum industry produce an enormous amount of oilfield produced water (PW). Discharge of this huge amount of PW has an adverse impact on the surrounding environment as it contains different types of toxic and complex organic and inorganic compounds. For a long time, conventional treatment methods have been used to purify PW;; however, these techniques could not meet the environmental regulations especially when the purpose is to reuse water. Therefore, more research efforts are required to select an effective technology that can mitigate the challenges through the best management strategy. In this study, the oilfield PW sources and characteristics, discharge regulations, treatment management, and recent advancements, challenges, and future needs in physical, chemical, thermal, biological, membrane, and hybrid treatment techniques are reviewed. Since the wastewater includes different recalcitrant pollutants, single technologies to date have not been successful enough in rendering it to a reusable form or meeting disposal requirements. Therefore, combined technologies might offer a promising process not only to meet the regulatory criteria but also to provide opportunities to use PW as a non-conventional water source. Furthermore, PW management needs a structured framework and a risk-based approach considering environmental, technical, and economic aspects to choose and design the most efficient strategies).
查看更多>>摘要：Cobalt species often play a crucial role in the sulfate radical ( SO4~) generation during peroxymonosulfate (PMS) activation, but their roles in the formation of non-radical-dominated PMS activation are largely unclear. Here, shell-core hollow Co@NC with exposed two different cobalt species (i.e., Co nanoparticles and Co-Nx site) was prepared and used to activate PMS for tetracycline hydrochloride (TCH) degradation. The experimental results and theoretical calculations showed cobalt species play a crucial role in the 02-dominated TCH degradation in which Co-Nx directly served as active sites to adsorb PMS (PMS) to facilitate PMS decomposition to form SO5", and thereafter evolved into O2 by the rapid self-reaction of SO5~, while Co nanoparticles indirectly promote O2 generation via electron transfer due to their excellent conductivity. With exposed cobalt species and unique structure, Co@NC showed a remarkable catalytic activity for TCH degradation, outperforming the synthesized NC, Co-NC, and commercial C03O4, Fe3O4 and MnO2. Meanwhile, the good stability and reusability, high environmental robustness and universal adaptability of Co@NC were demonstrated. The TCH degradation pathways including aniline ring oxidation, the cleavage of functional groups and ring-opening reactions were also proposed. The improved understanding on the roles of cobalt species in the non-radical-dominated PMS activation may inspire the development of efficient, selective, and robust cobalt-based catalysts.
查看更多>>摘要：Layered double hydroxide (LDH)-based catalysts have been corroborated to be effective for persulfate (PS) activation towards wastewater remethation. However, the effect of vacancies especially the role of cation vacancies in LDH has not been well illustrated. In this study, NiFe-LDH with Ni(II) vacancies (NiFe-LDH-VNi) or Fe(III) vacancies (NiFe-LDH-VFe) were fabricated via defect-engineering to tune catalytic activity on PS activation for tetracycline (TC) degradation. Characterizations of X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy confirmed cation vacancies were successfully implanted in NiFe-LDH catalyst. Experiments demonstrated that cation vacancies enhance the catalytic performance while NiFe-LDH-V_(Ni) exhibited better activation performance since vacancies could facilitate the electron transfer, thereby forming more reactive oxygen species. Meanwhile, theoretical calculations disclosed that the NiFe-LDH with Ni(II) or Fe(III) vacancies possessed larger surface energy, lower Fermi energy and more positive Mulliken atomic charges than bare NiFe-LDH. About 80% of 30 mg · L~(-1) TC could be mineralized through the catalysis of NiFe-LDH-VNi/PS system in 90 min. Furthermore, quenching experiments confirmed that the SO4" and 'OH generated by interface reaction accounted for the TC degradation. ~1O2 and O2~ species were also identified in the presence of oxygen vacancies through nitrogen gas cleaning experiments. Ultimately, a possible mechanism of TC degradation was proposed in NiFe-LDH/PS system with Ni(II) or Fe(III) vacancies. This study provides a possible guideline to discover the appropriate cation vacancies that contribute to the activation process and also provides a strategy to rationally design high-activity catalysts based on defect engineering.
查看更多>>摘要：Single-use polystyrene impose an enormous environmental threat, but their recycling has been proven challenging. Chemical conversion is the most versatile and robust approach to combat polystyrene waste. Carbon materials adsorbent EPMT was prepared from expanded polystyrene waste and applied to recover Eriochrome Black T (EBT) and Congo red (CR) from aqueous solution. EPMT was characterized by different analytical skills and the outcomes were used to analyze the corresponding adsorption interactions. The maximum adsorption capacity of the adsorbent for EBT and CR were 560.25 and 1010.19 mg/g, respectively. Thermodynamic showed the adsorption was subject to an endothermic spontaneous process. In terms of reusability, the performance of adsorbent was kept in a superior state all the time, and the dyes were recovered in better purity. The adsorbent displayed outstanding elimination competence and realized the separation of different dyes when it was used as padding to equip packed column. In brief, converting waste polystyrene to an adsorbent offers potential for water purification and provides a new route for upcycling of polystyrene into value-added materials.
查看更多>>摘要：In order to explore the characteristics of ceramic membranes in the treatment of surface water with high turbidity and high content of organic matters, a pilot-scale test was carried out on the water treatment process composed of pre-zonation, coagulation, sedimentation, and ultrafiltration using flat-sheet ceramic membranes. The water purification effect of the combined process and the influences of different operating parameters on membrane fouling were comprehensively investigated. The results showed that the effluent turbidity of the combined process could be controlled below 0.1 NTU, and the removal rates of CODmid DOC and UV254 in the raw water were 58%, 49%, and 45%, respectively. The membrane fouling rate largely depended on the permeate flux;; when the constant permeate fluxes were set at 80,100,120 and 150 L m~(-2)h~(-1) the rising rates of the transmembrane pressure (TMP) in the early stage were 0.18, 0.42,1.20 and 2.04 kPa/h, respectively. The permeate production period had a relatively small effect on the membrane fouling rate, and the "high-intensity short-time" mode was demonstrated more efficient than the "low-intensity long-time" mode during backwashing. Under the optimized conditions, no chemical cleaning was required by the ceramic membranes during 12 days of continuous operation, with the TMP increasing by only 20 kPa. A series of characterizations suggested that the irreversible membrane fouling was mainly caused by proteins, humic substances and silicates. The chemical cleaning strategy with the combined use of NaClO and acid cleaning agents was recommended for the recovery of membrane performance.
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