Meltblown fabric vs nanofiber membrane,which is better for fabricating personal protective equipments

The coronavirus disease 2019 (COVID-19) pandemic has led to a great demand on the personal protection products such as reusable masks.As a key raw material for masks,meltblown fabrics play an important role in rejection of aerosols.However,the electrostatic dominated aerosol rejection mechanism of melt-blown fabrics prevents the mask from maintaining the desired protective effect after the static charge degradation.Herein,novel reusable masks with high aerosols rejection efficiency were fabricated by the introduction of spider-web bionic nanofiber membrane (nano cobweb-biomimetic membrane).The reuse stability of meltblown and nanofiber membrane mask was separately evaluated by infiltrating water,75％ alcohol solution,and exposing under ultraviolet (UV) light.After the water immersion test,the filtration efficiency of meltblown mask was decreased to about 79％,while the nanofiber membrane was maintained at 99％.The same phenomenon could be observed after the 75％ alcohol treatment,a high filtration efficiency of 99％ was maintained in nanofiber membrane,but obvious negative effect was observed in meltblown mask,which decreased to about 50％.In addition,after long-term expose under UV light,no filtration efficiency decrease was observed in nanofiber membrane,which provide a suitable way to disinfect the potential carried virus.This work successfully achieved the daily disinfection and reuse of masks,which effectively alleviate the shortage of masks during this special period.     

油水强化分离技术

油水混合物广泛存在于各类工业过程中,其体系性质、强化分离技术一直是化工分离领域研究的重要课题之一。以沉降、旋流、电聚结等常规物理分离技术配合化学药剂破乳的传统分离方法,存在分离效率低、二次污染等问题,近年来以多物理场耦合、新型分离材料等为代表的强化分离技术的发展受到广泛关注。本文以石油工业中大体量的油包水型原油乳状液和水包油型含油污水乳状液的分离为对象,阐述了油水混合物的形成、体系分类及其基本理化性质,通过分析微观界面膜指出打破乳状液的稳定性是强化分离的关键,并从常规分离技术、外场强化、分离材料、耦合强化等方面系统介绍了各类分离技术及其特点,最后对油水强化分离技术的研究和发展方向进行了展望。     

微孔膜法油水分离——表面性质及微观结构的研究进展

石油炼制和化工过程存在大量油水混合物体系,影响生产过程稳定性,也会造成环境污染,亟需高效低成本的油水分离技术。与气浮、离心、化学混凝等传统油水分离技术相比,微孔膜技术通过油或水的选择性渗透实现分离,具有操作简单、分离效率高、运行成本低等众多优点。然而,微孔膜处理油水混合物的分离效率和加工能力同时取决于膜材料的表面性质（表面浸润性能）和微孔结构（分离通道的尺寸效应）。本文首先基于表面润湿现象和尺寸筛分机制介绍了膜法油水分离的原理,然后从上述两个角度出发综述了近年来微孔膜法油水分离的相关研究进展,最后指出微孔膜法油水分离在迈向工业化应用的过程中还需解决的一些问题,并对未来膜材料表面性质和微孔结构的研究进行了展望。     

Coalescence separation of oil water emulsion on amphiphobic fluorocarbon polymer and silica nanoparticles coated fiber-bed coalescer

Discharging untreated oily wastewater into the environment disrupts the ecological balance, which is a global problem that requires urgent solutions. Superhydrophilic and superoleophilic fibrous medium(FM) effectively separated oil–water emulsion as it was hydrophobic underwater. But its separation efficiencies(SEs) first increased to 98.9%,then dropped to 97.6% in 10 min because of oil-fouling. To tackle this problem, FM deposited with 0%–10% silica nanoparticle(NPsFMs), then coated by fluorocarbon polymer(X-[CH_2CH_2O]_nCH_2CH_2O-Y-NH-COOCH_2C_4F_9)(FCNPs FMs), was used to enhance its roughness and regulate its initial wettability to improve the anti-fouling property. FCFM and FCNPs FMs were hydrophobic and oleophobic in air and oleophobic underwater. Their water contact angles, oil contact angles and oil contact angles were 115.3°–121.1°, 128.8°–136.5°, and 131.6°–136.7°, respectively,meeting the requirement of 90°–140° for coalescence separation. FCNPs FM-5 had the best separation performance with a constant value of 99.8% in 10 min, while that of FCNPs FM-10 slightly decreased to 99.5%. Theoretical released droplet(TRD) diameter, calculated by the square root of the product of pore radius and fiber diameter, was used for the evaluation of coalescence performance. Analyzed by two ideal models, TRD diameter and fiber diameter showed a parabola type relationship, proving that the separation efficiency was a collaborative work of wettability, pore size and fiber diameter. Also, it explained the SEs reduction from FCNPs FM-5 to FCNPs FM-10 was revelent to the three parameters. Moreover, FCNPsFMs effectively separated emulsions stabilized by cationic surfactant CTAB(SEs:97.3%–98.4%) and anionic surfactant SDBS(SEs: 91.3%–93.4%). But they had an adverse effect on nonionic surfactant Tween-80 emulsion separation(SEs: 94.0%–71.76%). Emulsions made by diverse oils can be effectively separated:octane(SEs: 99.4%–100%), rapeseed oil(SEs: 97.3%–98.8%), and diesel(SEs: 95.2%–97.0%). These findings provide new insights for designing novel materials for oil–water separation by coalescence mechanism.     

Electrospinning organic solvent resistant preoxidized poly(acrylonitrile) nanofiber membrane and its properties

A high performance preoxidized poly(acrylonitrile) (O-PAN) nanofiber membrane with excellent solvent resistance, thermal stability and flexibility was fabricated by the preoxidation of electrospun PAN nanofiber membrane. The performance of resultant O-PAN nanofiber membrane was optimized by altering the PAN concentration and preoxidation temperature. The results showed that the O-PAN nanofiber membrane which made from PAN concentration of 14% (mass) and preoxidation temperature of 250.0 ℃ have a more optimal comprehensive performance. In the long-term separation test of SiO₂ particle (1 μm) in DMAc suspension, the permeate flux of O-PAN nanofiber membrane stabilized at 227.91 L·m^-2·h^-1 (25 ℃, 0.05 MPa) while the SiO₂ rejection above 99.6%, which showed excellent solvent resistance and separation performance. In order to further explore the application of the O-PAN nanofiber membrane, the O-PAN nanofiber membrane was treated with fluoride and used in oil/water separation process. The O-PAN nanofiber membrane after hydrophobic treatment showed excellent hydrophobicity and good oil/water separation performance with the permeate flux about 969.59 L·m^-2·h^-1 while the separation efficiency above 96.1%. The O-PAN nanofiber membrane exhibited a potential application prospect in harsh environment separation.     

注气对油水分离水力旋流器流场影响模拟分析

采用雷诺应力湍流模型、混合模型和离散相模型对注气型油水分离水力旋流器进行数值模拟,得到其内部流场的速度分布和油滴粒子运动轨迹,分析对比了注气前后进口流量、分流比和充气量对分离效率的影响,数值计算结果与文献实验值进行了比较。结果表明,充气后流场速度增加,油滴粒子逃逸时间缩短,旋流器分离效率提高5%~10%,在一定条件下气浮对旋流分离起到强化作用。     

超亲水天然多酚改性膜的制备及其油水分离性能

为研发绿色环保、制备工艺简单的油水分离材料，以单宁酸(TA)和聚乙二醇(PEG)为改性剂，聚偏氟乙烯(PVDF)膜为基底，通过简单浸渍法，制备了超亲水复合膜(TAPE膜)。采用SEM、AFM、FTIR、XPS和接触角测定仪对TAPE膜进行了表征和分析，并考察了TAPE膜的油水分离性能、耐磨性能和稳定性。结果表明，TAPE膜具有多孔微纳米粗糙结构，当TA含量为蒸馏水质量的1.75%时，该膜的水接触角和水下油接触角分别为0°和156°，表现出超亲水性和水下超疏油性。在0.09 MPa工作压力下，TAPE膜分离水包油乳液的膜通量为1146.4 L/(m²·h)，是原始PVDF膜的30倍，该膜对油水混合液和水包油乳液的分离效率均可达99.9%。此外，TAPE膜具有良好的稳定性，膜表面经砂纸(320目)磨损(100 g载重)25次后水接触角仍高达152°。     

SiO2改性聚丙烯纤维棉对油水乳状液的高效分离

近年来,基于特殊润湿性理论制备表面具有微纳米粗糙结构的多孔材料成为油水分离领域研究的重点。为了满足不同环境下对不同形式油-水乳状液高效高通量分离的需求,该研究利用纳米SiO2颗粒对聚丙烯（PP）纤维棉有针对性地亲（疏）水改性,构建了系列不同润湿性和粗糙度的PP纤维棉,探究了不同孔隙度和表面能的PP纤维棉对W/O及O/W型乳状液的分离性能,结果表明,经过亲（疏）水改性后的PP纤维棉对水/正己烷和水/甲苯乳状液的分离效率都高于99.5%,通量高于700 L/(m2·h),并针对不同形式油-水乳状液阐释其相应的分离机制,为后续油-水乳状液分离材料的科学设计和可控制备提供了理论依据。     

利用吸收-水合耦合法从氨弛放气中回收氢气的研究(英文)

In this work, the absorption-hydration hybrid method was used to recover (hydrogen + nitrogen) from (hydrogen + nitrogen + methane + argon) tail gas mixtures of synthetic ammonia plant through hydrate forma-tion/dissociation. A high-pressure reactor with magnetic stirrer was used to study the separation efficiency. The in-fluences of the concentration of anti-agglomerant, temperature, pressure, initial gas-liquid volume ratio, and oil-water volume ratio on the separation efficiency were systematically investigated in the presence of tetrahydro-furan (THF). Anti-agglomerant was used to disperse hydrate particles into the condensate phase for water-in-oil emulsion system. Since nitrogen is the material for ammonia production, the objective production in our separation process is (hydrogen + nitrogen). Our experimental results show that by adopting appropriate operating conditions, high concentration of (hydrogen + nitrogen) can be obtained using the proposed technology based on forming hydrate.     

β-SiAlON ceramic membranes modified with SiO2 nanoparticles with high rejection rate in oil-water emulsion separation

Porous ceramic membranes with high mechanical strength are suitable for oil-water emulsion separation. Nonetheless, it is difficult to prepare ceramic membranes with a small pore size and a good antifouling ability. In this work, SiO₂ nanoparticles were used to modify β-SiAlON ceramic membranes, which were successfully utilized to remove small oil droplets from oil-water emulsion. The modified membranes displayed a narrow pore size (the average pore size decreased from 1.05?µm, in the unmodified membrane, to 0.65?µm), and gas and water fluxes which are suitable for oil-water separation. Oil rejection rate was always higher than 90% under various pressures (1.0–2.0?bar) and flow velocities (1.0?3.0?L?min^?1) tested, which is considerably higher (60%) than the rejection rate of the unmodified membrane (which was 39.8%). Moreover, the modified membranes exhibited a good antifouling ability, since flux declined by only 7.0% after three recoveries via a simple ultrasonic treatment, over a total running period of 10?h. Accordingly, the produced membranes can be qualified for further consideration in oily wastewater treatment.     

仿鱼鳞PDA纳米片复合滤膜的制备及油水分离性能

以聚多巴胺(PDA)为原料、Mg(OH)₂为模板剂，采用液相沉积法原位包覆Mg(OH)₂纳米片制备了PDA纳米片，再以疏水棉布为基底，PDA纳米片为覆盖层制备了PDA纳米片复合滤膜(简称复合滤膜)。通过SEM、TEM、BET、FTIR、XPS、XRD和接触角测量仪对复合滤膜进行了结构表征，同时测定了复合滤膜对油水混合物和乳化油的分离性能、循环使用性能和抗污染性能。结果表明，PDA纳米片的引入显著地增加了复合滤膜的表面粗糙度，在自重作用下复合滤膜对油水混合物和乳化油(均以环己烷为油相)的渗透通量分别为2866.24和1015.13 L/(m²·h)，分离效率达99.5%，且复合滤膜在重复使用10次后，其对乳化油的渗透通量为798.11 L/(m²·h)，分离效率达98.1%。此外，PDA纳米片还具有普适性，能覆盖在不同基底上进行乳化油分离，具有良好的应用前景。     

油水乳液分离吸附材料的分离原理、构建方法和分离性能

采用吸附材料进行油水分离是经济且非常有效的方法。吸附材料主要有无机材料、合成高分子材料和天然有机纤维材料等。相比较而言，天然有机纤维材料为可再生生物质资源，来源广泛、生物降解性好，可有效防止二次污染，具有良好的发展潜力，备受关注。本文首先简要介绍了油水乳液稳定性的影响因素，然后综述了油水分离材料的分离原理、构建方法和分离性能等研究进展，并总结了油水乳液分离材料的表征及其分离性能的评价指标。特别地，重点总结了天然有机纤维基吸附材料分离油水乳液的研究进展。最后指出研究智能响应型天然有机纤维基油水乳液分离吸附材料是重要的发展方向。     

面向油水分离的无机膜制备及应用进展

膜技术是处理含油污水及含水油液的有效分离方法。无机膜材料由于可调变的表面性质和良好的稳定性,即使在苛刻的条件下,在分离油水方面表现出优异的分离性能。本文首先阐述了设计与制备油水分离膜的理论基础,包括分离过程中压力驱动力和膜表面特性对膜通量和选择性的影响;然后综述了当前国内外用于油水分离的无机膜的制备及其应用进展,重点介绍分子筛膜、金属氧化物/金属氢氧化物膜和氧化石墨烯膜等的研究,分析了在不同油水混合物中研究者们调控无机膜表面性能的策略,提出膜表面润湿性和膜结构是提高膜分离效率和抗污染性的关键;最后指出抵制含大量表面活性剂、碱液及有机聚合物种的乳化油对膜造成污染,是无机膜亟需解决的问题,并展望了无机膜在分离油水方面的发展方向。     

聚结技术及其乳化油水分离性能

聚结分离是一种利用油、水两相对材料浸润性的不同而实现乳化液滴聚结长大并最终通过重力沉降实现油水分离的物理方法,这种方法结构可控性好、分离效率高、运行成本低,是乳化油水分离领域的研究热点。本文首先对聚结分离方法进行详细阐述,介绍了聚结分离原理和影响因素;总结了近年来国内外学者对聚结材料表面改性和修饰等方面的研究。通过调控聚结材料的表面具有特殊浸润性,可显著提高油水分离效率;系统介绍聚结分离器的分类及其应用。最后阐述了聚结分离技术在石油化工领域的应用。本文对聚结分离技术进行展望,指出可以进一步研究实际液滴聚结过程和分离效果影响因素,应深入研究分离器在乳化油水分离过程中液滴聚结行为、机理、控制机制将是研究的重点。     

超亲水/水下超疏油膜的制备及油水分离性能

工业生产和频繁的溢油事故产生大量的含油废水,其高效分离依然面临全球性的挑战。具有仿生浸润特性的膜可以选择性透过水或油,分离效率高且操作简单而广泛应用于油水分离。本文通过一步浸渍法将TiO₂纳米颗粒和聚乙烯吡咯烷酮（PVP）原位固化到不锈钢网上制备了具有微/纳米层级结构的超亲水/水下超疏油油水分离膜。重点考察了TiO₂/PVP涂覆液浓度（质量分数1%、3%、5%、7%、9%）对膜的浸润特性和油水分离性能的影响。实验结果表明,不同TiO₂/PVP浓度改性的膜具有超亲水/水下超疏油特性,水的接触角均为0°,在水中油的接触角达160°,油水分离效率大于99.5%。膜通量随浓度的增大先减小后增加,当质量分数为3%时膜通量最大为8422.5L/（m²·h）。经过30次连续油水分离后,其分离效率仍大于99.5%,表明TiO₂/PVP-SS （stainless steel）膜有良好的耐久性和稳定性。因此,TiO₂/PVP-SS仿生特殊浸润膜材料在油水分离领域具有经济、高效、环境友好的潜在优势。     

脱乙酰基改性乙酸纤维薄膜对乳化油分离及积垢机理的探究

利用静电纺丝制造乙酸纤维素膜（CA纤维膜）,并利用添加TiO₂及脱乙酰基（d-CA）对CA纤维膜进行改性,后续对膜过滤特性、渗透通量、油水乳化液去除效率、反洗特性及积垢机制进行讨究。结果显示,CA纤维膜通过TiO₂及d-CA改性后可以提高膜的热稳定性及亲水性能,并得到稳定的纯水通量和过滤通量;最佳的比例为TiO₂@d-18.5%CA纤维膜,在40kPa跨膜压差、60min的操作条件下,其纯水通量、过滤通量、1g/L油水乳化液去除效率以及反洗后通量分别为824.8L/(m²·h)、(311.3±12.5)L/(m²·h)、93.6%±1.1%、451.5L/(m²·h);另外,添加TiO₂可能导致油水乳化液在膜表面不可逆阻力比例的增加,脱乙酰基改性CA纤维膜则可以降低膜自身阻力及增加可逆阻力的比例,提高CA纤维膜在油水分离方面的潜力。     

烧结温度对TiO2/不锈钢中空纤维复合膜结构和性能的影响

不锈钢中空纤维膜基膜孔径大,直接涂覆分离层容易产生表面缺陷。在二氧化钛悬浮液中加入聚乙烯醇作为黏结剂,通过真空辅助抽滤法在不锈钢中空纤维基膜表面形成一层均匀的分离层。通过高温烧结得到了TiO₂/不锈钢中空纤维复合膜,考察了烧结温度对于TiO₂/不锈钢中空纤维复合膜表面分离层形貌和结构的影响。不同烧结温度时,TiO₂/不锈钢中空纤维复合膜的表面形貌有所差异;随着烧结温度的升高,不锈钢复合膜的孔径和纯水通量均先升高再下降。当烧结温度为500℃时,表面涂层均匀,孔径分布集中,水通量较高。最后,以SPT-500膜测试了水包油乳液分离效果,分离效率达到99%以上,且具有良好的抗污染性能。     

油水重力分离原理及聚结破乳机理初探

对油水重力分离的基本原理进行了阐述,并对油水乳状液聚结破乳机理进行了探讨。分析表明,从浅池原理和聚结原理入手,可对分离器的结构和聚结板的材料进行优化,以提高其流动特性以及分离性能;若有效地分离油水两相,必须施加外力场,使得坚固的界面膜削弱并破坏,促进其聚结破乳;应根据聚结破乳发生的条件对分离器的结构进行优化,以保证其具有优良的水力特性。     

乳化剂对动态膜分离油水乳化液过程的影响

利用管状陶瓷膜基氧化锆动态膜分离油水乳化液，研究了4种工业常见乳化剂[斯盘80（SP-80）、十二烷基磺酸钠（SDS）、十二烷基硫酸钠（SLS）和十二烷基苯磺酸钠（SDBS）]对分离过程的影响。利用正交实验方法考察了乳化剂种类和浓度、乳化液温度和流量以及操作压力对过程的影响。正交实验结果表明，在SDS、1.0 g/L、50℃、120L/h和0.14MPa操作条件下，油水混合物稳定渗透通量最大。单因素实验结果表明，当乳化剂浓度增大时，稳定渗透通量减小；当乳化液温度升高时，稳定渗透通量先增加后降低。无机盐离子Na⁺、Ca²⁺和Al³⁺的存在均可使稳定渗透通量增加。当Al³⁺大于0.75g/L时，乳化液的稳定性被完全破坏，更有利于提高渗透通量。基于实验结果，采用分子模拟方法研究了不同实验条件下乳化剂的乳化效果，分析了SDS的油水界面形成能（E）和水的界面扩散系数（D）与乳化剂浓度和乳化液温度的关系。模拟结果表明，E和D绝对值均随着乳化剂浓度和乳化液温度增加而增大。实验和模拟结果均表明，乳化剂的乳化效果决定了油滴的平均粒径，基于油水分离的堵塞机理，也由此影响了稳定渗透通量。模拟结果从微观角度解释了实验现象，研究结果可为动态膜处理油水乳化液的工业应用提供依据。     

油水分离膜表面结构可控合成及性能研究

石油开采过程中会产生大量的油水混合物,每天生产生活中也会产生大量含油废水,如何处理这些油水混合物,是环境保护和可持续发展的重大需求。针对含油量较高的油水混合物,本工作制备了疏水-超亲油分离膜。以机械性能较好的泡沫镍为过滤基体,采用电沉积方法,在泡沫镍表面沉积铜颗粒,构筑亲油疏水表面。研究了沉积电位和沉积时间对表面结构的影响,并测试了分离膜表面结构、表面粗糙度及水滴在膜表面的接触角,并对所制备的分离膜进行油水分离性能测试和多次循环的稳定性测试。结果表明,所制备的分离膜具有良好的循环分离性能,对于油水混合物循环十次后分离效率仍在90%以上。本研究为高效油水分离膜材料开发提供了新思路,并拓展了电化学表面改性的应用领域。