现代化工

现代化工 ›› 2026, Vol. 46 ›› Issue (1) : 214-221. DOI: 10.16606/j.cnki.issn0253-4320.2026.01.035

科研与开发

HNTs/Fe₂O₃@PDA-PVDF复合膜的制备及其油水分离性能

毛修龙 ¹^,^* ,
周嘉华 ² ,
陈桂娥 ²

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Preparation of HNTs/Fe₂O₃@PDA-PVDF membrane for oil-water separation

Author information +

文章历史 +

Received		Published
2025-04-01		2026-01-20
Issue Date	Revised Date
2026-01-14	2025-04-01

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摘要

以聚偏氟乙烯(PVDF)为基膜,高岭土纳米管(HNTs)与氧化铁(Fe₂O₃)复合纳米颗粒(HNTs/Fe₂O₃)为改性材料,通过多巴胺的原位氧化聚合,辅助共沉积策略,构建超亲水/水下超疏油HNTs/Fe₂O₃@PDA-PVDF复合膜用于分离油水混合物。采用SEM、FT-IR、XPS、EDS和接触角测量仪等对复合膜进行表征。考察了复合膜的渗透性、分离性能以及抗污染性。结果表明,通过涂覆改性颗粒,获得的复合膜在空气中表现出超亲水性(接触角为0°)。随着HNTs/Fe₂O₃颗粒涂覆量的增加,复合膜的渗透通量和截油率均先增大后减小,涂覆量为20 mg的复合膜M3亲水性及分离性能最佳,其动态水接触角能够在2 s达到0°,纯水通量为9 945.4 L/(m²·h),油水乳液通量达3 996.2 L/(m²·h),对油水混合物的分离效率和截油率可达95%以上。考察了复合膜的抗污性能,截油后用纯水清洗,通量恢复率均在90%以上,其中膜M3的通量恢复率最高可达97.6%。最后,探究了复合膜的油水分离机理。

Abstract

A superhydrophilic/underwater superoleophobic HNTs/Fe₂O₃@PDA-PVDF membrane was constructed for separating oil-water mixture by coating kaolin nanotubes (HNTs) and iron oxide (Fe₂O₃) composite nanoparticles (HNTs/Fe₂O₃) onto polyvinylidene fluoride (PVDF) membrane through the in situ oxidation polymerization of dopamine,assisted codeposition strategy.The composite membranes were characterized by SEM,FT-IR,XPS,EDS and contact angle.The permeability,separation and pollution resistance of the composite membrane were investigated.The results show that by coating the composite nanoparticles,the modified membranes exhibit superhydrophilicity in air (contact angle 0°).With the increase of the coating amount of HNTs/Fe₂O₃ nanoparticles,the permeation flux and oil rejection increased at first and then decreased.When the coating amount was 20 mg,the modified membrane achieved the best hydrophility and separation performance.The dynamic water contact angle can reach 0° in 2 s.The pure water flux can reach 9945.4 L·m^-2·h^-1,and the oil-water emulsion flux can reach 3 996.2 L·m^-2·h^-1.The separation efficiency and oil rejection rate of oil-water mixture can reach more than 95%.The anti-fouling performance of the modified membrane was investigated.After oil interception,the flux recovery rate of the composite membrane was more than 90%,and the flux recovery rate of M3 membrane was up to 97.6%.The oil-water separation mechanism of the composite membrane was investigated.

Graphical abstract

关键词

HNTs/Fe₂O₃复合纳米颗粒 / 抗污染 / 油水分离 / 超亲水 / 聚偏氟乙烯膜

Key words

HNTs/Fe₂O₃ nanoparticles / pollution resistance / oil-water separation / superhydrophilic / PVDF membrane

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HNTs/Fe₂O₃@PDA-PVDF复合膜的制备及其油水分离性能[J]. 现代化工, 2026, 46(1): 214-221 DOI:10.16606/j.cnki.issn0253-4320.2026.01.035

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水污染是当今世界面临的一大挑战。随着工业的发展,大量含油废水被排放^[1-2],对自然环境及人类生活造成了严重的影响^[3-5]。传统的油水分离技术如重力沉降、混凝、絮凝等方法^[6-7]存在成本高、分离效率低、工艺复杂等缺点^[8-9],难以满足油水乳液分离的实际需求。近年来,膜分离技术凭借其能耗低、分离性能优异、经济性好、环保等优势,在含油废水处理领域受到了关注^[10-11]。

聚偏氟乙烯(PVDF)因兼具优异的热稳定性、柔韧性与抗化学侵蚀性而备受青睐,成为诸多过滤应用领域的主力军,特别适用于制造微滤膜与超滤膜,应对含油废水处理的难题^[12-15]。然而,PVDF膜因固有的疏水特性,易吸附油水混合物中的油滴,引发膜堵塞的风险,严重制约了分离系统长期运行的效率与稳定性^[16-17]。因此,开发新型亲水改性复合膜是实现高效分离和抗污染的关键。

近年来,人们探索了各种改性技术来改善PVDF膜的亲水性和综合性能。常见的强化PVDF膜湿润性和防污能力的方法有:将携载亲水基团的无机纳米粒子(TiO₂、SiO₂、ZnO和氧化石墨烯等)嵌入基膜中^[18],或是将富含亲水链段的有机聚合物锚定于膜表面^[19]。Alpatova等^[20]使用Fe₂O₃纳米颗粒和多壁碳纳米管对PVDF膜进行改性,制备得到了复合膜,结果表明,Fe₂O₃能有效提高膜的亲水性。Ismail等^[21]选择PVDF作为基底聚合物,并通过负载Fe₂O₃来增强膜的亲水性。结果表明,与未改性的PVDF膜相比,聚合物组分中Fe₂O₃的存在有助于提高通量和除油效率。

高岭土纳米管(HNTs)是一种天然的纳米材料,在水处理领域得到了广泛应用。近年来,HNTs在膜修饰领域引起了人们的广泛关注,这主要是因为HNTs具有以下优点^[22-23]。首先,HNTs表面含有大量的亲水性基团(—OH),显著提高了膜的亲水性^[24];其次,HNTs具有较大的比表面积和多孔的微观结构,可作为吸附剂用于废水中染料和重金属的吸附^[25]。Zeng等^[26]在PVDF膜中掺杂改性HNTs制备了D-A-HNTs@PVDF复合膜,具有较高的亲水性,但通量仅有42.2 L/(m²·h)。Zhou等^[27]提出了一种改性PVDF膜的方法,通过黏合剂多巴胺和硅烷偶联剂KH550,将亲水无机纳米颗粒固定于膜表面,实现对膜的亲水改性,改性膜具有优异的性能。但该方法对基膜要求较高,且制备时间较长。

本研究采用水热合成法制备了HNTs/Fe₂O₃纳米复合颗粒。采用简单表面涂覆法,以聚多巴胺(PDA)作为黏合剂,将HNTs/Fe₂O₃负载于PVDF膜表面,制得HNTs/Fe₂O₃@PDA-PVDF复合膜,并通过多种表征方法分析其理化性质。选择正己烷和正十六烷作为代表,配制模型乳液,探究制膜工艺参数对复合膜分离性能的影响,并考察复合膜的抗污染性能。

1 实验材料和方法

1.1 实验材料和方法

盐酸多巴胺(DA-HCl)、三羟甲基氨基甲烷盐酸盐(Tris-HCl),优级纯,上海泰坦化学股份有限公司生产;氢氧化钠、无水乙醇,分析纯,国药集团化学试剂有限公司生产;添加了聚对苯二甲酸乙二醇酯(PET)的聚偏氟乙烯膜(0.22 μm),德国德滤有限公司生产;正己烷、正十六烷,分析纯,上海泰坦化学股份有限公司生产;吐温80,化学纯,国药集团化学试剂有限公司生产;乙二醇(EG)、氯化铁(FeCl₃),分析纯,上海迈瑞尔生化科技有限公司生产;HNTs,分析纯,广州润沃材料科技有限公司生产。

扫描电子显微镜(SEM),Sigma 300,德国蔡司生产;偏光显微镜,LW150PT,西安测维光电技术有限公司生产;接触角测试仪,JC2000D1,上海中晨数字技术设备有限公司生产;X射线光电子能谱仪(XPS),ESCALAB 250Xi,赛默飞生产;傅里叶红外光谱仪,Nicolet iZ10,赛默飞生产;能量色散X射线探测器(EDX),ESCALAB 250Xi,中科瑞捷科技有限公司生产。

1.2 HNTs/Fe₂O₃@PDA复合颗粒的制备

将1 g氯化铁溶于50 mL乙二醇中,再加入1 g HNTs,超声震荡配合机械搅拌使其分散均匀。加入0.74 g氢氧化钠并剧烈搅拌1 h。将混合液倒入高压反应釜中,180℃下反应24 h。反应后冷却到室温,离心分离,并用乙醇多次洗涤,烘箱内60℃干燥6 h,得到的固体在180℃下煅烧12 h,制得HNTs/Fe₂O₃,研磨备用。

通过多巴胺自聚合制备HNTs/Fe₂O₃@PDA。配制400 mL浓度为50 mmol/L的Tris-HCl缓冲溶液,加入NaOH调节pH至8.5,加入0.4 g HNTs/Fe₂O₃与0.8 g盐酸多巴胺,超声震荡下反应2 h,离心分离,并用去离子水多次洗涤,60℃下干燥6 h,得到HNTs/Fe₂O₃@PDA复合纳米颗粒,研磨备用。

1.3 HNTs/Fe₂O₃@PDA-PVDF复合膜的制备

将PVDF膜固定在卡箍上,用无水乙醇润湿膜表面,完全润湿后,倒去无水乙醇,膜备用。

向装有20 mL浓度为50 mmol/L Tris-HCl缓冲溶液的烧杯中加入0.04 g盐酸多巴胺,超声震荡使盐酸多巴胺完全溶解,得到DA溶液。将该溶液倾倒在预处理后的PVDF膜表面,震荡反应24 h。反应过后,去除膜表面的溶液,并用去离子水多次洗涤膜表面。重复一次上述操作,得到PDA-PVDF膜。

最后,在DA溶液中加入一定量的HNTs/Fe₂O₃复合纳米颗粒,超声震荡使其在介质中分散均匀。将混合液倾倒在PDA-PVDF膜表面,震荡反应 24 h。反应后,用去离子水多次洗涤,60℃烘箱中热处理15 min,得到HNTs/Fe₂O₃@PDA-PVDF复合膜(表1)。

1.4 膜的分离性能测试

通过死端过滤装置评价复合膜的性能。裁取一定面积的圆形复合膜放入超滤杯底部,在0.15 MPa下对复合膜进行30 min预压。随后在0.1 MPa下,通过式(1)计算纯水通量J。

(1)J=Q/(A×T)

其中,J为油相液体通量,L/(m²·h);Q为滤液体积,L;A为过滤面积,m²;T表示过滤时间,h。

选用正己烷和正十六烷作为代表,配制油水乳液,用于评价膜的分离性能。将油、去离子水以及表面活性剂按照1∶50∶0.02的体积比混合,超声处理30 min,再进行12 h的剧烈搅拌,得到稳定的油水乳液。将复合膜裁剪成6 cm×6 cm的膜片,将膜片用去离子水润湿后置于死端过滤装置中,进行性能测试,分离效率(W)计算方法如式(2)。

(2)$W=({M}_{1}/{M}_{2})\times 100\mathrm{\%}$

其中,W为分离效率,%;M₁和M₂分别为过滤后渗透液的重量和渗透液的初始重量,g。

用上述含油溶液测定复合膜的截油率。使用总有机碳分析仪(TOC-L,日本岛津)测试渗透溶液和原始溶液中的含油浓度,截油率(R)用式(3)计算。

(3)$R=(1-{C}_{\mathrm{P}}/{C}_{\mathrm{F}})\times 100\mathrm{\%}$

其中,R为截油率,%;C_F和C_P分别为浑浊物质在初始溶液和渗透溶液中的浓度,g/L。

1.5 复合膜的抗污染测试

将待测膜片置于死端过滤装置中。随后,将预先配置好的油水乳液倒入,运行30 min。将膜片取下用乙醇溶液进行多次清洗,重新将膜片固定于死端过滤装置中,测其通量,通量恢复率用式(4)计算。

(4)$r=({J}_{i}/{J}_{0})\times 100\mathrm{\%}$

其中,r为通量恢复率,%;J_i和J₀分别为膜的初始纯水通量和经污染及清洗后的纯水通量,L/(m²·h)。

采用苏丹Ⅲ染色正己烷测试了原膜和复合膜的防污性能。在润湿状态下,将两个膜分别浸入正己烷中5 min,然后迅速浸入水中,最后取出,用离子水和乙醇交替洗涤,观察膜的颜色变化。

2 结果与讨论

2.1 膜的表面形貌

采用SEM表征分析M0、M1、M2、M3、M4膜的表面形貌。如图1(a)、(b)所示,PVDF膜(M0)表面具有明显的大孔结构,PDA-PVDF膜(M1)表面保持着原有的大孔结构,同时有PDA颗粒附着在膜孔中。如图1(c)~(e)所示,涂覆HNTs/Fe₂O₃@PDA纳米颗粒后,部分膜孔被复合纳米颗粒占据。随着涂覆量的增加,膜表面纳米颗粒明显增加。当涂覆量增加到30 mg时,颗粒开始在膜表面团聚堆叠,堵塞膜孔,这将影响膜的性能。

2.2 膜的表面化学成分

通过EDX、FT-IR和XPS进行膜表面化学表征,如图2。M0、M1、M2、M3、M4膜中碳(C)、氟(F)、氧(O)、氮(N)、铝(Al)、硅(Si)、铁(Fe)的EDX质量含量列于表2,可以看出M0膜含有碳、氟、氧元素,其中氧元素为添加剂PET所含。M2、M3、M4膜含有碳、氟、氧、氮、铝、硅、铁元素,结果显示随着涂覆纳米颗粒的增加,改性膜中氧、铝、硅和铁元素含量随之增加。

图2(a)为M0、M1和M3膜的FT-IR图。与M0膜相比,M1膜和M3膜在1 508 cm^-1和1 599 cm^-1处具有明显的吸收峰,分别属于C—N的伸缩振动^[28]和芳香族化合物中C—C键的伸缩振动^[29],且在3 100~3 500 cm^-1范围内出现了1个宽峰,这是由聚多巴胺中酚羟基所引起的^[30],证明聚多巴胺层的存在。此外,对于M3膜,在3 691 cm^-1和3 620 cm^-1处的吸收峰属于—OH的拉伸振动^[31],这是由膜表面HNTs/Fe₂O₃所带来的吸收峰。在793 cm^-1和748 cm^-1处出现的吸收峰可能是因为膜表面涂层中氧化铁与聚多巴胺形成的络合物,使得原有的Fe—O伸缩振动和扭曲振动发生了偏移^[32-33]。证明HNTs/Fe₂O₃@PDA-PVDF复合膜的成功制备。图2(b)是M0膜和M3膜的X射线光电子能谱(XPS)。与原始的PVDF膜相比,复合膜M3在102 eV处出现了明显的Si2p信号峰,表明HNTs/Fe₂O₃纳米粒子成功地涂覆在PVDF膜表面。图2(c)、(d)为复合膜M3的C 1s谱和O 1s谱。C 1s谱有4个信号峰,分别归属于284.8 eV的C—C峰、285.6 eV的C—N峰、286.1 eV的C=O/C—O峰和290.6 eV的C—F峰。同时,O 1s光谱中3个信号峰分别位于530.4、531.8 eV和532.4 eV,分别与Al—O/Fe—O、C—O/—OH和Si—O相关。XPS结果表明膜表面含有HNTs/Fe₂O₃@PDA纳米涂层。

2.3 膜的表面润湿性

利用动态水接触角测试表征膜表面的亲水性,结果如图3所示。M0膜在0 s时水接触角为102.6°,说明该膜具有较高的疏水性;在10 s时其水接触角降为34.8°,这是由于M0膜有大孔结构,部分水渗透进膜里面,导致接触角变小。M1膜在 0 s时水接触角为74.6°,6 s时接触角降为13.2°,在 7 s时降为0°,这是由于膜表面涂覆的聚多巴胺具有亲水性。M2、M3、M4膜在0 s时的水接触角分别为31.3°、25.9°和29.5°,最后都降为0°。这是由于HNTs/Fe₂O₃@PDA复合纳米颗粒被聚多巴胺固定在膜表面之后,增加了膜表面的粗糙度,显著增强了膜表面的亲水性。随着膜表面涂覆纳米颗粒量的增加,水接触角先降低,后又增大,这是由于颗粒含量的进一步增加,导致颗粒团聚,使得膜表面局部分散不均匀,负载饱和度下降,亲水性也随之下降。

图4是M0膜和M3膜的动态水下拒油测试图像。M0膜的水下油接触角(UWCA)为77.5°,油滴接触膜表面后就停留在膜表面。而油滴接触M3膜表面后会被排斥,说明通过在PVDF原膜表面涂覆HNTs/Fe₂O₃@PDA复合纳米颗粒,复合膜从原膜的水下亲油状态转变为水下超疏油,拒油性有所提高。

2.4 膜的渗透性能和分离性能

M0膜的纯水通量为8 815.2 L/(m²·h);有聚多巴胺涂层的M1膜,其纯水通量增加到了8 913.9 L/(m²·h),这是由于聚多巴胺上的含有丰富的亲水基团,增加了膜表面的亲水性,使膜的渗透性增强。5种膜的纯水通量如图5(a)所示,对于M2、M3、M4膜,随着复合纳米颗粒涂覆量增加,膜的纯水通量继续增大,M3膜最大,为9 945.4 L/(m²·h),但M4的纯水通量下降为9 413.7 L/(m²·h)。这是由于涂覆量增加到30 mg后,复合纳米颗粒堵塞了膜孔,这与之前的电镜图结果相吻合。

5种膜的油水乳液截留如图5(b)所示。M0膜与M1膜相比,涂覆聚多巴胺后,油水乳液的截留率明显提高。涂覆复合纳米颗粒后,截留率继续提高,随着涂覆量的增加,截留率呈先增大后减小的趋势,M3膜最大,其对于正十六烷的截留率为94.7%,对正己烷的截留率为91.2%。综合考虑膜的水接触角分析、纯水通量和油水乳液截留率,本实验以M3为实验膜进一步探索复合膜的其他性能。

M3膜的油水乳液通量和油水乳液分离效率如图6所示。M3膜对正十六烷乳液的通量为2 433.5 L/(m²·h),对正己烷乳液的通量为3 996.2 L/(m²·h),对两种油水乳液的分离效率分别为95.1%和98.2%。说明M3膜具有较好的分离效果。

M3膜对两种乳液分离效果分别如图7、图8所示。图7(a)和图8(a)实物图显示,分离前乳液呈乳白色非透明状,分离后的滤液明显呈透明澄清状,证实了M3优异的分离效果。图7(b)和图8(b)为通过光学显微镜观察的图像,分离前乳液中有明显的油滴,分离后几乎看不到油滴。表明M3膜能有效分离表面活性剂稳定的油水乳液。

2.5 膜的抗污染性能分析

膜的抗污性能是评价膜性能的重要参数。通过测量膜在分离油水乳液前后的通量,计算通量恢复率,评价其抗污染性能,各膜的通量恢复率如图9。由图9可看出,M0膜分离乳液后经乙醇清洗,通量恢复率约为71%;涂覆聚多巴胺的M1膜通量恢复率提高至84%;经过涂覆纳米复合颗粒,复合膜通量恢复率可提高至92%以上。M3膜的通量恢复率最高,超过95.8%。这表明HNTs/Fe₂O₃@PDA-PVDF复合膜在对油水乳液进行分离后能够通过清洗恢复通量。

为了验证HNTs/Fe₂O₃@PDA-PVDF复合膜的亲水拒油性,将M0膜和M3膜分别固定在装满纯水的烧杯底部,在水下将苏丹Ⅲ染色的正己烷注射到膜表面,观察油滴状态。如图10所示,当正己烷被缓慢推动到膜表面时,“小红珠”在碰触到M0膜时会粘附在膜表面,而在接触M3膜表面时会反弹而不粘附在膜上,进一步证明了M3膜出色的水下拒油防污性能。

2.6 改性膜油水乳液分离机理

首先,对HNTs进行表面改性,在其表面原位生成球状Fe₂O₃来增加颗粒的表面粗糙度。再利用多巴胺自聚合将HNTs/Fe₂O₃固定在PVDF膜表面,提高膜的表面亲水性。HNTs具有亲水性羟基,PDA含有亲水性氨基,这些基团使PVDF膜表面具有超亲水疏油性,为油水分离提供了基础。

为了进一步研究膜分离油水乳液的机理,对侵入压力(ΔP)和相应的润湿理论进行讨论,ΔP的计算式如下:

(5)$\mathrm{\Delta }P=2\gamma /R=-\left[\right(2\gamma \mathrm{c}\mathrm{o}\mathrm{s}\theta )/d]$

式中,R为半月面的半径,m;γ为液体表面张力,N/m;θ为接触角,°;d为膜孔半径,m。

由式(5)可知,当接触角θ大于90°时,侵入压力ΔP>0,膜表面能够承受一定的外部压力。相反,当θ小于90°时,侵入压力ΔP<0,在这种情况下,液体可以自发地渗透到毛孔中,完全湿润膜^[34]。图11(a)为M3膜在水和空气下的润湿模型。由于HNTs/Fe₂O₃@PDA-PVDF膜的超亲水性(WCA≈0°),其被水湿润时,水能在其表面铺展开来。此时,油滴会沉积在这个系统上,液-液-空气相界面的表面张力会产生力的平衡,从而使油滴停留在膜上。基于这一理论,复合膜在油水分离过程具有较高截油率和较高分离效率,分离过程示意图如图11(b)所示。

3 结论

通过真空辅助操作,使用沉积法成功地在PVDF超滤膜表面涂覆HNTs/Fe₂O₃@PDA复合颗粒,涂层在PVDF膜表面形成粗糙的层次并引入了大量的亲水基团,使制得的复合膜具有超亲水性/水下超疏油性。经过改性的M3膜水接触角低至0°,纯水通量达到9 945.4 L/(m²·h),油水乳液通量达到3 996.2 L/(m²·h)。M3膜对正己烷和正十六烷油水乳液的截油率达到94.7%,分离效率达98.2%。同时该复合膜具有出色的抗污染性(FRR>97.6%)。这种改性策略制备的超亲水复合膜在实际含油废水处理中具有巨大的应用潜力。

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