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Mechanism of ethanol/water reverse separation through a functional graphene membrane: a molecular simulation

《化学科学与工程前沿(英文)》 2023年 第17卷 第3期   页码 347-357 doi: 10.1007/s11705-022-2246-z

摘要: Reverse-selective membranes have attracted considerable interest for bioethanol production. However, to date, the reverse-separation performance of ethanol/water is poor and the separation mechanism is unclear. Graphene-based membranes with tunable apertures and functional groups have shown substantial potential for use in molecular separation. Using molecular dynamics simulations, for the first time, we reveal two-way selectivity in ethanol/water separation through functional graphene membranes. Pristine graphene (PG) exhibits reverse-selective behavior with higher ethanol fluxes than water, resulting from the preferential adsorption for ethanol. Color flow mappings show that this ethanol-permselective process is initiated by the presence of ethanol-enriched and water-barren pores; this has not been reported in previous studies. In contrast, water molecules are preferred for hydroxylated graphene membranes because of the synergistic effects of molecular sieving and functional-group attraction. A simulation of the operando condition shows that the PG membrane with an aperture size of 3.8 Å achieves good separation performance, with an ethanol/water separation factor of 34 and a flux value of 69.3 kg∙m‒2∙h‒1∙bar‒1. This study provides new insights into the reverse-selective mechanism of porous graphene membranes and a new avenue for efficient biofuel production.

关键词: reverse separation     graphene membrane     ethanol/water separation     molecular simulation    

Effects of baffles on separation of aqueous ethanol solution with hollow fibers

Zhihong YANG, Guoliang ZHANG, Lan LIN, Danping REN, Qin MENG, Hongzi ZHANG

《化学科学与工程前沿(英文)》 2009年 第3卷 第1期   页码 68-72 doi: 10.1007/s11705-009-0130-8

摘要: The effects of baffles on the operation and mass-transfer characteristics in novel hollow fiber membrane contactor used in distillation were investigated. Hollow fiber membranes, coated with a 7 μm polydimethyl-siloxane, were operated as structural packing in the separation of ethanol-water solutions. The parallel flow mode was chosen for separation due to the stronger driving force of the concentration difference, in which liquid flows through the lumens of the fibers and vapor flows countercurrent-wise outside the fibers. Two baffles were installed on the shell side of the membrane contactors to enhance separation, which had a round shape with a semi-lunar hole. The results show that both baffled and unbaffled membrane contactors gave better, more productive separations than traditional packing in distillation, such as the excellent Sulzer Gauze BX structured packing. The baffled membrane contactors performed better than unbaffled ones, especially at high vapor velocities. The minimal HTU of membrane contactor with baffles could reach as low as 4.5 cm, and almost all the contactors could work well above the limit where flooding normally occurs in conventional cases. Theoretical analysis predicted that baffles helped membrane module to obtain a higher mass-transfer coefficient and a smaller mass-transfer resistance. Finally, theoretical mass-transfer coefficient and experimental value were compared as well as the contribution of each individual mass-transfer coefficients among liquid, gas and membrane.

关键词: hollow fiber     membrane contactor     baffle     mass-transfer     ethanol-water    

Theoretical study on Janus graphene oxide membrane for water transport

Quan Liu, Mingqiang Chen, Yangyang Mao, Gongping Liu

《化学科学与工程前沿(英文)》 2021年 第15卷 第4期   页码 913-921 doi: 10.1007/s11705-020-1954-5

摘要: Graphene oxide (GO) membranes have received considerable attention owing to their outstanding water-permeation properties; however, the effect of the membrane’s microstructures (such as the distribution of oxidized and pristine regions) on the transport mechanism remains unclear. In this study, we performed molecular simulations to explore the permeation of a water–ethanol mixture using a new type of Janus GO membranes with different orientations of oxidized and pristine surfaces. The results indicate that the oxidized upper surface endows the GO membrane with considerable water-capture capability and the in-built oxidized interlayer promotes the effective vertical diffusion of water molecules. Consequently, using the optimized Janus GO membrane, infinite water selectivity and outstanding water flux (~40.9 kg⋅m ⋅h ) were achieved. This study contributes to explaining the role of oxidized regions in water permeation via GO membranes and suggests that Janus GO membranes could be used as potential candidates for water–ethanol separation.

关键词: graphene oxide membrane     molecular dynamics simulation     water permeation     water-ethanol separation     oxidized and pristine regions    

Investigation of bubble diameter and flow regime between water and dilute aqueous ethanol solutions in

Baharak SAJJADI, Mostafa Keshavarz MORAVEJI, Reza DAVARNEJAD

《化学科学与工程前沿(英文)》 2011年 第5卷 第2期   页码 194-202 doi: 10.1007/s11705-010-1019-2

摘要: In this study, the effect of ethanol addition into pure water and its concentration on bubble diameter, gas hold-up and flow regimes were investigated in an airlift reactor. Air and water with ethanol (concentration ranging from 0%–1%, v/v) were as dispersed and continuous phases, respectively. Superficial gas velocity was considered as an effective parameter. Bubble size distribution was measured by photography and picture analysis at various concentrations of ethanol and various velocities of gas. Alcohol concentration enhancement caused bubble diameter to decrease. Furthermore, the bubbles diameter in pure water was nearly 4 times higher than that of ethanol with concentration of 1% (v/v) and also was 3.4 times higher than that of ethanol with concentration of 0.25% (v/v) at the highest aeration gas velocity inlet. For ethanol solutions in lower superficial gas velocity, a homogenous flow regime was observed. This trend continued to inlet gas velocity of about 0.4 cm/s. The transition flow regime occurred after this datum although in pure water, a homogenous flow regime was observed up to a superficial gas velocity of 0.7 cm/s. The gas hold-up in dilute ethanol solutions were more than (around 2 times) that of pure water and increased with increasing concentration of ethanol in those solutions.

关键词: airlift rector     bubble diameter     gas hold-up     flow regime     ethanol    

Highly hydrophobic oil−water separation membrane: reutilization of waste reverse osmosis membrane

《化学科学与工程前沿(英文)》 2023年 第17卷 第10期   页码 1606-1615 doi: 10.1007/s11705-022-2200-0

摘要: The increasing applications of seawater desalination technology have led to the wide usage of polyamide reverse osmosis membranes, resulting in a large number of wasted reverse osmosis membranes. In this work, the base nonwoven layer of the wasted reverse osmosis membrane was successfully modified into the hydrophobic membrane via surface deposition strategy including TiO2 and 1H,1H,2H,2H-perfluorooctyltrichlorosilane (PFOTS), respectively. Various techniques were applied to characterize the obtained membranes, which were then used to separate the oil–water system. The optimally modified membrane displayed good hydrophobicity with a contact angle of 135.2° ± 0.3°, and its oil–water separation performance was as high as 97.8%. After 20 recycle tests, the oil–water separation performance remained more than 96%, which was attributed to the film adhesion of the anchored TiO2 and PFOTS layer on the surface. This work might provide a new avenue for recycling the wasted reverse osmosis membrane used in oily wastewater purification.

关键词: oil–water separation     wasted reverse osmosis membrane     hydrophobic modification    

Bioinspired and biomimetic membranes for water purification and chemical separation: A review

《环境科学与工程前沿(英文)》 2021年 第15卷 第6期 doi: 10.1007/s11783-021-1412-8

摘要:

•The history of biological and artificial water channels is reviewed.

关键词: Aquaporins     Artificial water channels     Biomimetic membranes     Chemical separation and water purification    

Biodegradable, superhydrophobic walnut wood membrane for the separation of oil/water mixtures

《化学科学与工程前沿(英文)》 2022年 第16卷 第9期   页码 1377-1386 doi: 10.1007/s11705-022-2157-z

摘要: The preparation of environmentally friendly oil/water separation materials remains a great challenge. Freeze-drying of wood after lignin removal yields wood aerogels, which can be used as substrates to prepare fluorine-free environmentally friendly superhydrophobic materials, However, they are more suitable for absorption rather than filtration applications due to their poor strength. A study using cross-sections of pristine wood chips as substrates retains the original strength of wood, but the use of the cross-sectional of wood pieces limits their thickness, strength, and size. In this paper, a degradable fluorine-free superhydrophobic film (max. water contact angle of approximately 164.2°) with self-cleaning and abrasion resistance characteristics was prepared by a one-step method using pristine and activated walnut longitudinal section films as the substrate, with tetraethyl orthosilicate as a precursor and dodecyltriethoxysilane as a modifier. The tensile strength results show that superhydrophobic films with pristine or activated wood substrates maintained the strength of pristine wood and were 2.2 times stronger than the wood aerogel substrate. In addition, after cross-laminating the two samples, the films had the ability to separate oil and water by continuous filtration with high efficiency (98.5%) and flux (approximately 1.3 × 103 L∙m‒2∙h‒1). The method has potential for the large-scale fabrication of degradable superhydrophobic filtration separation membranes.

关键词: wood nanotechnology     superhydrophobic     biodegradable     surface modification     oil/water separation    

Fabrication of a superhydrophilic/underwater superoleophobic stainless steel mesh for oil/water separation

《化学科学与工程前沿(英文)》 2023年 第17卷 第1期   页码 46-55 doi: 10.1007/s11705-022-2170-2

摘要: Because of the increasing amount of oily wastewater produced each day, it is important to develop superhydrophilic/underwater superoleophobic oil/water separation membranes with ultrahigh flux and high separation efficiency. In this paper, a superhydrophilic/underwater superoleophobic N-isopropylacrylamide-coated stainless steel mesh was prepared through a simple and convenient graft polymerization approach. The obtained mesh was able to separate oil/water mixtures only by gravity. In addition, the mesh showed high-efficiency separation ability (99.2%) and ultrahigh flux (235239 L∙m–2∙h–1). Importantly, due to the complex cross-linked bilayer structure, the prepared mesh exhibited good recycling performance and chemical stability in highly saline, alkaline and acidic environments.

关键词: oil/water separation     N-isopropylacrylamide     stainless steel mesh     ultrahigh flux    

Functional flax fiber with UV-induced switchable wettability for multipurpose oil-water separation

《环境科学与工程前沿(英文)》 2022年 第16卷 第12期 doi: 10.1007/s11783-022-1588-6

摘要:

● A PAA-ZnO-HDTMS flax fiber with UV-induced switchable wettability was developed.

关键词: Flax fiber     Switchable wettability     ZnO-HDTMS coating     Oil-water separation    

Imprinted membranes for sustainable separation processes

Laura Donato, Enrico Drioli

《化学科学与工程前沿(英文)》 2021年 第15卷 第4期   页码 775-792 doi: 10.1007/s11705-020-1991-0

摘要: The rapid industrial growth and the necessity of recovering and recycling raw materials increased the interest in the production of highly selective and efficient separation tools. In this perspective, a relevant input was given by the membrane-based technology and the production of imprinted membranes, which possess specific recognition properties at molecular and ionic level, offers the possibility of developing sustainable and green processes. Furthermore, the integration of imprinted membranes with traditional or membrane-based approaches is a promising strategy in the logic of process intensification, which means the combination of different operations in a single apparatus. This work discusses the concept and separation mechanisms of imprinted membranes. Furthermore, it presents an overview of their application in organic solvent nanofiltration, for the removal of toxic agents and recovery solvent, as well as valuable compounds. The recent advances in water treatment, such as pesticide removal and recovery of metal ions, are also discussed. Finally, potential applications of imprinted membranes in hybrid processes are highlighted, and a look into the future of membrane separations for water treatment and recovery of critical raw materials is offered.

关键词: sustainable processes     membrane separation     molecular recognition     imprinted membranes     water treatment    

Easily-manufactured paper-based materials with high porosity for adsorption/separation applications in

《化学科学与工程前沿(英文)》 2023年 第17卷 第7期   页码 830-839 doi: 10.1007/s11705-022-2267-7

摘要: A multi-functional porous paper-based material was prepared from grass pulp by simple pore-forming and green cross-linking method. As a pore-forming agent, calcium citrate increased the porosity of the paper-based material from 30% to 69% while retaining the mechanical strength. The covalent cross-linking of citric acid between cellulose fibers improved both the wet strength and adsorption capacity. In addition, owing to the introduction of high-content carboxyl groups as well as the construction of hierarchical micro-nano structure, the underwater oil contact angle was up to 165°. The separation efficiency of the emulsified oil was 99.3%, and the water flux was up to 2020 L·m–2·h–1. The theoretical maximum adsorption capacities of cadmium ion, lead ion and methylene blue reached 136, 229 and 128.9 mg·g–1, respectively. The continuous purification of complex wastewater can be achieved by using paper-based materials combined with filtration technology. This work provides a simple, low cost and environmental approach for the treatment of complex wastewater containing insoluble oil, organic dyes, and heavy metal ions.

关键词: adsorption     oil–water separation     underwater superoleophobicity     wastewater treatment    

MILP synthesis of separation processes for waste oil-in-water emulsions treatment

Zorka N. Pintarič,Gorazd P. Škof,Zdravko Kravanja

《化学科学与工程前沿(英文)》 2016年 第10卷 第1期   页码 120-130 doi: 10.1007/s11705-016-1559-1

摘要: This paper presents a novel synthesis method for designing integrated processes for oil-in-water (O/W) emulsions treatment. General superstructure involving alternative separation technologies is developed and modelled as a mixed integer linear programming (MILP) model for maximum annual profit. Separation processes in the superstructure are divided into three main sections of which the pretreatment and final treatment are limited to the selection of one alternative (or bypass) only, while within the intermediate section various combinations of different technologies in series can be selected. Integrated processes composed of selected separation techniques for given ranges of input chemical oxygen demand (COD) can be proposed by applying parametric analyses within the superstructure approach. This approach has been applied to an existing industrial case study for deriving optimal combinations of technologies for treating diverse oil-in-water emulsions within the range of input COD values between 1000 mg?L and 145000 mg?L . The optimal solution represents a flexible and profitable process for reducing the COD values below maximal allowable limits for discharging effluent into surface water.

关键词: oil-in-water emulsion     chemical oxygen demand     superstructure     process synthesis     MILP    

Repeated batch fermentation with water recycling and cell separation for microbial lipid production

Yumei WANG, Wei LIU, Jie BAO

《化学科学与工程前沿(英文)》 2012年 第6卷 第4期   页码 453-460 doi: 10.1007/s11705-012-1210-8

摘要: Large waste water disposal was the major problem in microbial lipid fermentation because of low yield of lipid. In this study, the repeated batch fermentation was investigated for reducing waste water generated in the lipid fermentation of an oleaginous yeast CX1 strain. The waste fermentation broth was recycled in the next batch operation after the cells were separated using two different methods, centrifugation and flocculation. Two different sugar substrates, glucose and inulin, were applied to the proposed operation. The result showed that at least 70% of the waste water was reduced, while lipid production maintained satisfactory in the initial four cycles. Furthermore, it is suggested that CX1 cells might produce certain naturally occurring inulin hydrolyzing enzyme(s) for obtaining fructose and glucose from inulin directly. Our method provided a practical option for reducing the waste water generated from microbial lipid fermentation.

关键词: batch fermentation     microbial lipid     Trichosporon cutaneum CX1     flocculation     waste water recycle    

Functional magnetic nanoparticles for facile viable but nonculturable bacteria separation and purification

Chunming Wang, Huirong Lin, Chengsong Ye

《环境科学与工程前沿(英文)》 2016年 第10卷 第6期 doi: 10.1007/s11783-016-0874-6

摘要: The functional surface-modified MNPs were capable of capture with high efficiency. After induced to VBNC state by chlorination, cells could be separated by MNPs with an additional incubation process. This study provides a facile and economic method for VBNC cell enrichment and purification. GRAPHIC ABSTRACT Viable But Nonculturable (VBNC) Bacteria, which represent a unique population of microorganisms in drinking water systems, have become a potential threat to human health. Current studies on VBNC cells usually fail to obtain pure VBNC state bacteria, which may lead to inaccurate results. We therefore introduce a novel method of VBNC cell separation and purification in this paper. PAH-coated magnetic nanoparticles (MNPs) were synthesized and found to be capable of capturing and releasing bacterial cells with high efficiency. With the aid of an additional incubation step, VBNC cells were easily isolated and purified from normal bacteria using functional MNPs. Our method represents a new technique that can be utilized in studies of VBNCs.

关键词: Drinking water biosafety     VBNC     Nanoparticles     Magnetic separation and purification    

properties of a silver particle-coated and 1-dodecanethiol-modified superhydrophobic melamine sponge for oil/waterseparation

《化学科学与工程前沿(英文)》 2022年 第16卷 第8期   页码 1237-1246 doi: 10.1007/s11705-022-2140-8

摘要: A Ag particle-coated and 1-dodecanethiol-modified melamine sponge (Ag-DDT-MS) was prepared through surface roughness by coating silver particles and subsequent grafting of a hydrophobic long hydrocarbon chain. Superhydrophobic and 3D porous Ag-DDT-MS was characterized by Fourier transform infrared spectroscopy, scanning electron microscope, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The water contact angle of Ag-DDT-MS reached 159.2°. Ag-DDT-MS exhibited excellent absorption capacity for high viscous oils and organic solvents, ranging from 42.8 to 105.2 g∙g−1. The absorbed oils can be easily collected by the mechanical pressing process, and the oil recovery rate was satisfactory, more than 90% after 20 recycles. Ag-DDT-MS material also demonstrated good stability and excellent compression-recovery ability, keeping 88.6% of the initial height after ten compression-release cycles.

关键词: melamine sponge     oil-absorbing material     hydrophobic     oil-water separation     oil absorption capacity    

标题 作者 时间 类型 操作

Mechanism of ethanol/water reverse separation through a functional graphene membrane: a molecular simulation

期刊论文

Effects of baffles on separation of aqueous ethanol solution with hollow fibers

Zhihong YANG, Guoliang ZHANG, Lan LIN, Danping REN, Qin MENG, Hongzi ZHANG

期刊论文

Theoretical study on Janus graphene oxide membrane for water transport

Quan Liu, Mingqiang Chen, Yangyang Mao, Gongping Liu

期刊论文

Investigation of bubble diameter and flow regime between water and dilute aqueous ethanol solutions in

Baharak SAJJADI, Mostafa Keshavarz MORAVEJI, Reza DAVARNEJAD

期刊论文

Highly hydrophobic oil−water separation membrane: reutilization of waste reverse osmosis membrane

期刊论文

Bioinspired and biomimetic membranes for water purification and chemical separation: A review

期刊论文

Biodegradable, superhydrophobic walnut wood membrane for the separation of oil/water mixtures

期刊论文

Fabrication of a superhydrophilic/underwater superoleophobic stainless steel mesh for oil/water separation

期刊论文

Functional flax fiber with UV-induced switchable wettability for multipurpose oil-water separation

期刊论文

Imprinted membranes for sustainable separation processes

Laura Donato, Enrico Drioli

期刊论文

Easily-manufactured paper-based materials with high porosity for adsorption/separation applications in

期刊论文

MILP synthesis of separation processes for waste oil-in-water emulsions treatment

Zorka N. Pintarič,Gorazd P. Škof,Zdravko Kravanja

期刊论文

Repeated batch fermentation with water recycling and cell separation for microbial lipid production

Yumei WANG, Wei LIU, Jie BAO

期刊论文

Functional magnetic nanoparticles for facile viable but nonculturable bacteria separation and purification

Chunming Wang, Huirong Lin, Chengsong Ye

期刊论文

properties of a silver particle-coated and 1-dodecanethiol-modified superhydrophobic melamine sponge for oil/waterseparation

期刊论文