现代化工

现代化工 ›› 2025, Vol. 45 ›› Issue (1) : 190-194. DOI: 10.16606/j.cnki.issn0253-4320.2025.01.033

科研与开发

MIL-53(Fe、Al)/PSf共混膜的制备与性能研究

作者信息 +

Preparation and performance study of MIL-53(Fe,Al)/PSf blended membrane

Author information +

文章历史 +

Received		Published
2024-03-25		2025-01-20
Issue Date	Revised Date
2025-01-17	2024-03-25

PDF (3387K)

摘要

通过溶剂热法合成了双金属有机框架MIL-53(Fe、Al)亲水性材料,与聚砜(PSf)共混并通过非溶剂致相分离法制备MIL-53(Fe、Al)/PSf共混膜。探究了MIL-53(Fe、Al)的添加质量分数对共混膜的结构和亲水性、渗透性、截留性以及抗污染性能的影响。结果表明,当MIL-53(Fe、Al)的添加质量分数为0.3%时,与原膜相比,水接触角降低了28.81°,达到54.78°;纯水通量提高了10.21倍,达到179.15 L/(m²·h·bar)。MIL-53(Fe、Al)的加入,显著提高了PSf超滤膜的亲水性和抗污染性能。

Abstract

MIL-53 (Fe,Al),a bimetallic organic framework hydrophilic material,is synthesized via solvothermal method,and blended with polysulfone (PSf) to prepare MIL-53 (Fe,Al)/PSf blended membrane through non-solvent induced phase separation method.Influences of the addition amount of MIL-53 (Fe,Al) on the structure,hydrophilicity,permeability,retention,and anti-fouling performances of the blended membrane are explored.It is shown that the water contact angle of the blended membrane is 28.81° less than that of the original membrane,reaching 54.78° when the addition amount of MIL-53 (Fe,Al) is 0.3 wt%.The pure water flux of the membrane increases by 10.21 times,reaching 179.15 L/(m²·h·bar).The addition of MIL-53 (Fe,Al) significantly improves the hydrophilicity and anti-fouling performance of PSf ultrafiltration membrane.

Graphical abstract

关键词

双金属有机框架 / 抗污染性 / 亲水性 / 共混膜 / 聚砜

Key words

bimetallic organic framework / pollution resistance / hydrophilicity / blended membrane / polysulfone

引用本文

引用格式 ▾

[Author(id=1241353055955809153, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, orderNo=0, firstName=null, middleName=null, lastName=null, nameCn=null, orcid=null, stid=null, country=null, authorPic=null, dead=0, email=zhangmei8132@126.com, emailSecond=null, emailThird=null, correspondingAuthor=1, authorType=1, ext={EN=AuthorExt(id=1241353055985169284, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, authorId=1241353055955809153, language=EN, stringName=Mei ZHANG, firstName=Mei, middleName=null, lastName=ZHANG, prefix=null, suffix=null, authorComment=null, nameInitials=null, affiliation=null, department=null, xref=^*, address=College of Chemistry and Chemical Engineering, Northeast Petroleum University, Daqing 163318, China, bio=null, bioImg=null, bioContent=null, aboutCorrespAuthor=null), CN=AuthorExt(id=1241353056018723719, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, authorId=1241353055955809153, language=CN, stringName=张梅, firstName=null, middleName=null, lastName=null, prefix=null, suffix=null, authorComment=null, nameInitials=null, affiliation=null, department=null, xref=^*, address=东北石油大学化学化工学院,黑龙江大庆 163318, bio=null, bioImg=null, bioContent=null, aboutCorrespAuthor=null)}, companyList=[AuthorCompany(id=1241353055922254716, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, xref=null, ext=[AuthorCompanyExt(id=1241353055926449021, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, companyId=1241353055922254716, language=EN, country=null, province=null, city=null, postcode=null, companyName=null, departmentName=null, remark=College of Chemistry and Chemical Engineering, Northeast Petroleum University, Daqing 163318, China), AuthorCompanyExt(id=1241353055930643326, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, companyId=1241353055922254716, language=CN, country=null, province=null, city=null, postcode=null, companyName=null, departmentName=null, remark=东北石油大学化学化工学院,黑龙江大庆 163318)])]), Author(id=1241353056043889545, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, orderNo=1, firstName=null, middleName=null, lastName=null, nameCn=null, orcid=null, stid=null, country=null, authorPic=null, dead=0, email=null, emailSecond=null, emailThird=null, correspondingAuthor=0, authorType=1, ext={EN=AuthorExt(id=1241353056069055373, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, authorId=1241353056043889545, language=EN, stringName=Bo LI, firstName=Bo, middleName=null, lastName=LI, prefix=null, suffix=null, authorComment=null, nameInitials=null, affiliation=null, department=null, xref=null, address=College of Chemistry and Chemical Engineering, Northeast Petroleum University, Daqing 163318, China, bio=null, bioImg=null, bioContent=null, aboutCorrespAuthor=null), CN=AuthorExt(id=1241353056090026897, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, authorId=1241353056043889545, language=CN, stringName=李博, firstName=null, middleName=null, lastName=null, prefix=null, suffix=null, authorComment=null, nameInitials=null, affiliation=null, department=null, xref=null, address=东北石油大学化学化工学院,黑龙江大庆 163318, bio=null, bioImg=null, bioContent=null, aboutCorrespAuthor=null)}, companyList=[AuthorCompany(id=1241353055922254716, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, xref=null, ext=[AuthorCompanyExt(id=1241353055926449021, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, companyId=1241353055922254716, language=EN, country=null, province=null, city=null, postcode=null, companyName=null, departmentName=null, remark=College of Chemistry and Chemical Engineering, Northeast Petroleum University, Daqing 163318, China), AuthorCompanyExt(id=1241353055930643326, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, companyId=1241353055922254716, language=CN, country=null, province=null, city=null, postcode=null, companyName=null, departmentName=null, remark=东北石油大学化学化工学院,黑龙江大庆 163318)])]), Author(id=1241353056119387029, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, orderNo=2, firstName=null, middleName=null, lastName=null, nameCn=null, orcid=null, stid=null, country=null, authorPic=null, dead=0, email=null, emailSecond=null, emailThird=null, correspondingAuthor=0, authorType=1, ext={EN=AuthorExt(id=1241353056152941465, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, authorId=1241353056119387029, language=EN, stringName=Lei GAN, firstName=Lei, middleName=null, lastName=GAN, prefix=null, suffix=null, authorComment=null, nameInitials=null, affiliation=null, department=null, xref=null, address=College of Chemistry and Chemical Engineering, Northeast Petroleum University, Daqing 163318, China, bio=null, bioImg=null, bioContent=null, aboutCorrespAuthor=null), CN=AuthorExt(id=1241353056207467419, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, authorId=1241353056119387029, language=CN, stringName=甘磊, firstName=null, middleName=null, lastName=null, prefix=null, suffix=null, authorComment=null, nameInitials=null, affiliation=null, department=null, xref=null, address=东北石油大学化学化工学院,黑龙江大庆 163318, bio=null, bioImg=null, bioContent=null, aboutCorrespAuthor=null)}, companyList=[AuthorCompany(id=1241353055922254716, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, xref=null, ext=[AuthorCompanyExt(id=1241353055926449021, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, companyId=1241353055922254716, language=EN, country=null, province=null, city=null, postcode=null, companyName=null, departmentName=null, remark=College of Chemistry and Chemical Engineering, Northeast Petroleum University, Daqing 163318, China), AuthorCompanyExt(id=1241353055930643326, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, companyId=1241353055922254716, language=CN, country=null, province=null, city=null, postcode=null, companyName=null, departmentName=null, remark=东北石油大学化学化工学院,黑龙江大庆 163318)])]), Author(id=1241353056232633244, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, orderNo=3, firstName=null, middleName=null, lastName=null, nameCn=null, orcid=null, stid=null, country=null, authorPic=null, dead=0, email=null, emailSecond=null, emailThird=null, correspondingAuthor=0, authorType=1, ext={EN=AuthorExt(id=1241353056261993374, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, authorId=1241353056232633244, language=EN, stringName=Han-bo YOU, firstName=Han-bo, middleName=null, lastName=YOU, prefix=null, suffix=null, authorComment=null, nameInitials=null, affiliation=null, department=null, xref=null, address=College of Chemistry and Chemical Engineering, Northeast Petroleum University, Daqing 163318, China, bio=null, bioImg=null, bioContent=null, aboutCorrespAuthor=null), CN=AuthorExt(id=1241353056282964895, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, authorId=1241353056232633244, language=CN, stringName=尤涵博, firstName=null, middleName=null, lastName=null, prefix=null, suffix=null, authorComment=null, nameInitials=null, affiliation=null, department=null, xref=null, address=东北石油大学化学化工学院,黑龙江大庆 163318, bio=null, bioImg=null, bioContent=null, aboutCorrespAuthor=null)}, companyList=[AuthorCompany(id=1241353055922254716, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, xref=null, ext=[AuthorCompanyExt(id=1241353055926449021, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, companyId=1241353055922254716, language=EN, country=null, province=null, city=null, postcode=null, companyName=null, departmentName=null, remark=College of Chemistry and Chemical Engineering, Northeast Petroleum University, Daqing 163318, China), AuthorCompanyExt(id=1241353055930643326, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, companyId=1241353055922254716, language=CN, country=null, province=null, city=null, postcode=null, companyName=null, departmentName=null, remark=东北石油大学化学化工学院,黑龙江大庆 163318)])]), Author(id=1241353056308130721, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, orderNo=4, firstName=null, middleName=null, lastName=null, nameCn=null, orcid=null, stid=null, country=null, authorPic=null, dead=0, email=null, emailSecond=null, emailThird=null, correspondingAuthor=0, authorType=1, ext={EN=AuthorExt(id=1241353056337490851, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, authorId=1241353056308130721, language=EN, stringName=Wei-xue ZHAO, firstName=Wei-xue, middleName=null, lastName=ZHAO, prefix=null, suffix=null, authorComment=null, nameInitials=null, affiliation=null, department=null, xref=null, address=College of Chemistry and Chemical Engineering, Northeast Petroleum University, Daqing 163318, China, bio=null, bioImg=null, bioContent=null, aboutCorrespAuthor=null), CN=AuthorExt(id=1241353056362656677, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, authorId=1241353056308130721, language=CN, stringName=赵维雪, firstName=null, middleName=null, lastName=null, prefix=null, suffix=null, authorComment=null, nameInitials=null, affiliation=null, department=null, xref=null, address=东北石油大学化学化工学院,黑龙江大庆 163318, bio=null, bioImg=null, bioContent=null, aboutCorrespAuthor=null)}, companyList=[AuthorCompany(id=1241353055922254716, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, xref=null, ext=[AuthorCompanyExt(id=1241353055926449021, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, companyId=1241353055922254716, language=EN, country=null, province=null, city=null, postcode=null, companyName=null, departmentName=null, remark=College of Chemistry and Chemical Engineering, Northeast Petroleum University, Daqing 163318, China), AuthorCompanyExt(id=1241353055930643326, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1240719916061389602, companyId=1241353055922254716, language=CN, country=null, province=null, city=null, postcode=null, companyName=null, departmentName=null, remark=东北石油大学化学化工学院,黑龙江大庆 163318)])])] 张梅,李博,甘磊,尤涵博,赵维雪. MIL-53(Fe、Al)/PSf共混膜的制备与性能研究[J]. 现代化工, 2025, 45(1): 190-194 DOI:10.16606/j.cnki.issn0253-4320.2025.01.033

登录浏览全文

4963

注册一个新账户忘记密码

聚砜(PSf)因其良好的热稳定性、耐酸碱性、耐用的机械性能和良好的成膜性能等优异性能,在超滤膜材料领域发挥着越来越重要的作用^[1]。然而,由于PSf膜固有的疏水性,废水中含有的有机或非有机物质很容易吸附或沉积在膜表面或孔隙中,从而导致膜污染。膜污染降低了膜的性能和寿命,是膜应用的主要障碍^[2]。研究表明,对PSf超滤膜进行共混亲水改性,可在保留疏水膜的良好稳定性同时,通过在膜表面形成水化层来提升透水性和对蛋白质的防污性^[3]。

尽管将MOFs添加到超滤膜中制备杂化膜的研究已经取得了很大进展,但仍有很大的改进空间。与单金属MOFs相比,双金属MOFs(BMOFs)在结构、孔隙率、活性位点、吸附、选择性和稳定性等方面都有很大的提高^[4]。Dipeshkumar等^[5]利用溶胶-凝胶法合成了双金属(ZIF-8-67)有机框架,与PVDF共混制备杂化膜。对制备的混合基质膜进行性能评价,结果表明,杂化膜比原膜显示出更高的水通量和脱盐率。

MIL-53(Fe)作为MOFs中最具有代表性的一种,有可调节的化学功能、为水提供额外通道的孔结构、相对较高的比表面积以及较好的亲水性^[6]。MIL-53(Al)具有高的比表面积和强的吸附力。Al³⁺被认为是修改母体MIL-53(Fe)骨架的潜在候选者,Al³⁺和Fe³⁺之间离子半径的差异可以增强孔隙率,形成新的Al³⁺吸附位点^[7]。因此,笔者合成了双金属有机框架MIL-53(Fe、Al),并与PSf共混制备MIL-53(Fe、Al)/PSf膜。考察了PSf超滤膜的亲水性以及抗污染性能。

1 实验部分

1.1 仪器与试剂

X射线衍射仪(XRD,D8 ADVANC型),德国BRUKER/AXS公司生产;傅里叶变换红外光谱仪(FT-IR,TENSOR 27型),德国布鲁克仪器有限公司生产;接触角测量仪(DSA100型),德国KRUSS公司生产;扫描电子显微镜(SEM,JSM 6500F型),日本日立株式会社生产;紫外-可见分光光度计(UV-1800型),日本岛津公司生产。

PSf(P-3500)、FeCl₃·6H₂O、AlCl₃·6H₂O、聚乙烯吡咯烷酮(PVP)、对苯二甲酸(H₂BDC),分析纯,上海阿拉丁生化科技股份有限公司生产;N,N-二甲基甲酰胺(DMF)、N,N-二甲基乙酰胺(DMAc),分析纯,济南双盈化工有限公司生产,均未进一步纯化;无水乙醇,分析纯,天津市大茂化学试剂厂生产;牛血清白蛋白(BSA),分析纯,北京博尔西科技有限公司生产;去离子水为实验室自制。

1.2 MIL-53(Fe、Al)的合成

在文献[8]中所述方法的基础上,采用溶剂热法合成MIL-53(Fe、Al)。选取n(Fe)∶n(Al)分别为1∶0.1、1∶0.25、1∶0.5和1∶0.75,将定量的FeCl₃·6H₂O、AlCl₃·6H₂O以及H₂BDC(0.815 2 g,4.5 mmol)溶解在40 mL的DMF溶液中,超声混匀后转移至聚四氟乙烯内衬的不锈钢高压釜中,在150℃的条件下反应15 h后降至室温,依次用DMF、无水乙醇和去离子水洗涤离心,转移至真空干燥箱,60℃下干燥48 h,所得浅黄色粉末即为MIL-53(Fe、Al)。

1.3 MIL-53(Fe、Al)/PSf共混膜的制备

将14%的PSf、8%的PVP和不同添加量的MIL-53(Fe、Al)均溶于DMAc中形成混合体系,转至油浴锅中进行加热搅拌,静置脱泡,得到均一的铸膜液。采用非溶剂致相分离法进行制膜。将铸膜液均匀地倒在玻璃板上,匀速刮膜,在空气中静置5~10 s,将玻璃板转移到25℃的去离子水中,期间多次更换去离子水以保证充分去除溶剂。最后将膜取出干燥,备用。添加剂质量分数为0%、0.1%、0.3%、0.5%、0.7%、0.9%制备的膜分别命名为A-0、A-1、A-2、A-3、A-4、A-5。

1.4 MIL-53(Fe、Al)的表征

利用X射线衍射仪分析样品的晶型结构,Cu靶Kα为射线源,波长λ=1.540 6 Å,管电压为45 kV,管电流为30 mA,扫描范围2θ为5~50°,扫描速率为5°/min;利用傅里叶红外光谱仪(FT-IR,TENSOR 27)分析样品的化学成分,波长范围为 500~4 000 cm^-1。

1.5 MIL-53(Fe、Al)/PSf共混膜的表征

1.5.1 形貌结构

通过X射线光电子能谱仪测定膜的表面组成;利用场发射扫描电子显微镜观察膜横截面结构,测试前需对膜进行液氮脆断和60 s喷金处理,加速电压选为5 kV,结合能量分散谱学元素分析(EDS)对共混膜的元素进行分析;利用接触角测量仪测量膜的静态水接触角。

膜的孔隙率通过经典的重量法测定^[9],裁取一定面积的膜片,去离子水中充分浸泡后,拭去表面多余的水分之后称重(W_w),将膜片放入烘箱中干燥,再次称重(W_d),计算膜的孔隙率:

(1)

$ε = [(W w - W d) / (ρ w A δ)] × 100 %$

式中:ε为膜的孔隙率,%;W_w为湿重,g;W_d为干重,g;ρ_w为水的密度,g/cm³;A为膜有效表面积,m²;δ为膜横截面宽度,m。

1.5.2 纯水通量和截留性能测试

裁取一定面积的圆膜放入超滤杯底部,在 2×10⁵ Pa的压力下压实30 min后,在10⁵ Pa的操作压力下,读取一定时间内渗透纯水的体积,计算纯水通量:

(2)

$J = V / (A · Δ t · Δ p)$

式中:J为膜的纯水通量,L/(m²·h·bar);V为一定时间下收集的纯水的体积,L;A为膜的有效表面积,m²;Δt为操作时间,h;ΔP为操作压力,Pa。

配制1 g/L的BSA溶液,按照水通量测试步骤测试膜的截留能力,通过紫外-可见分光光度计测量渗透后的溶液在280 nm下对应的吸光度。根据标准BSA溶液吸光度与浓度曲线求出其浓度值,并计算截留率:

(3)

$R = (1 - C P / C f) × 100 %$

式中:R为膜的截留率,%;C_p为过滤后的BSA溶液质量浓度,g/L;C_f为原始BSA溶液的质量浓度,g/L。

1.6 抗污染性能测试

首先,在1 MPa压力下使去离子水透过面积一定的膜片,过滤1 h,期间每隔10 min读取1次过滤液的体积,计算出通量J₁;在压力不变的情况下,将滤液换为BSA溶液对膜进行1 h的过滤,也是每 10 min记录1次过滤液体积,计算出通量J_p;然后再将BSA溶液换为去离子水重复第1次操作,计算出通量为J₂,对膜交替进行5 h的过滤实验。通过以下公式计算结果评价膜的抗污染性能:

(4) $F R R=\left(J_{1} / J_{2}\right) \times 100 \%$

(5) $R_{\mathrm{t}}=\left(1-J_{\mathrm{p}} / J_{1}\right) \times 100 \%$

(6) $R_{\mathrm{r}}=\left[\left(J_{2}-J_{\mathrm{p}}\right) / J_{1}\right] \times 100 \%$

(7) $R_{\mathrm{ir}}=\left[\left(J_{1}-J_{2}\right) / J_{1}\right] \times 100 \%$

式中:J₁为第1次纯水通量,L/(m²·h·bar);J_p为BSA通量,L/(m²·h·bar);J₂为第2次纯水通量,L/(m²·h·bar);FRR为恢复通量,%;R_t为总污染阻力;R_r为可逆污染阻力;R_ir为不可逆污染阻力。

2 结果与讨论

2.1 MIL-53(Fe、Al)的表征分析

通过XRD分析合成的MIL-53(Fe、Al)的晶型结构,结果如图1所示。由图1(a)中可以看出,MIL-53(Fe、Al)表现出与单金属MOFs相似的衍射峰,表明2种金属的加入不会改变MOF的晶体结构。然而,MIL-53(Fe、Al)主衍射峰的强度明显弱于单金属MOFs的强度,这是因为与单金属MOF相比,双金属MOF中2种金属的含量较低。XRD图谱中显示的变化与文献[10]中报道的变化相似。从图1(b)中可以看出,随着Al³⁺质量分数的增加,双金属MOFs在2θ为12.7°和25.6°处的峰向较低的角度移动。这可归因于Al³⁺的离子半径(0.054 nm)小于Fe³⁺(0.065 nm),一部分Al³⁺取代了Fe³⁺导致峰值变低,表明Al成功地结合到MIL-53(Fe)的框架中^[11]。当n(Al³⁺)/n(Fe³⁺)=0.1时,衍射峰的强度较高且峰都很清晰。因此,采用n(Al³⁺)/n(Fe³⁺)为0.1时合成的MIL-53(Fe、Al)进行后续实验。

通过FT-IR分析验证合成的MIL-53(Fe、Al)的官能团的存在。合成的MIL-53(Fe、Al)的FT-IR谱图如图2所示。由图2中可以看出,1 704 cm^-1处出现的峰为羧基的C=O拉伸振动;在1 570 cm^-1和1 397 cm^-1处的吸收峰分别对应于羧基上O=C—O键的不对称拉伸振动和对称拉伸振动;在MIL-53(Fe)中,540 cm^-1处出现的吸收峰为Fe—O键拉伸振动,而在MIL-53(Fe、Al)中,658 cm^-1和600 cm^-1处的峰分别对应于Al³⁺和Fe³⁺与有机配体之间形成的Al—O和Fe—O键。证明金属离子通过Fe—O和Al—O配位键与对苯二甲酸连接形成网络结构^[12]。进一步证实了MIL-53(Fe、Al)的合成。

2.2 MIL-53(Fe、Al)/PSf共混膜的表征分析

2.2.1 形貌结构

通过SEM观察所制备的MIL-53(Fe、Al)/PSf共混膜横截面形貌。MIL-53(Fe、Al)/PSf共混膜SEM和EDS图如图3所示。从图3(a)~图3(c)中可以看出,所有膜均为非对称膜结构,与A-0和A-3相比,A-2的中部指状结构较多,表面海绵状结构较薄。这是由于MIL-53(Fe、Al)亲水性颗粒的掺入使得水的渗透率变快,导致在相分离过程中大大提高了溶剂与非溶剂的交换速率而产生的瞬时分层,加速了聚合物的分散和固化过程,并获得了具有更多孔隙率的膜^[13]。但是当MIL-53(Fe、Al)的加入量过多会造成铸膜液的黏度增加,从而减缓溶剂与非溶剂的交换速率,使得形成较厚的表层和较少的指状结构。从图3(d)中可以看出,通过EDS谱图可以证实MIL-53(Fe、Al)成功添加到PSf中。

2.2.2 孔隙率和亲水性

膜的渗透性能是由孔隙率和亲水性共同决定的。亲疏水性可由表面水接触角的大小分析。不同MIL-53(Fe、Al)添加量的MIL-53(Fe、Al)/PSf共混膜的孔隙率和静态水接触角如表1所示。由表1可知,A-2时孔隙率最高为83.46%。比原膜(A-0)高了54.45%。这归因于MIL-53(Fe、Al)的亲水性,从而在相分离过程中更容易迁移到表面,最终形成较大的孔。当MIL-53(Fe、Al)质量分数大于0.3%时孔隙率有所下降,这是因为MIL-53(Fe、Al)在膜中出现团聚,导致堵塞膜孔,从而使孔隙率下降。

MIL-53(Fe、Al)的加入大大降低了PSf膜水接触角,提高了其亲水性。这是由于MIL-53(Fe、Al)具有亲水性,亲水性羧基官能团的存在大大提高了所制备的混合基质膜的表面能。使得共混膜与水分子形成氢键,产生范德华力,从而增强膜表面润湿性^[5]。

2.2.3 渗透性能和截留性能

通过纯水通量评估膜的溶剂渗透能力。MIL-53(Fe、Al)/PSf共混膜的纯水通量以及截留率如表2所示。由表2中可以看出,A-2时的纯水通量为179.15 L/(m²·h·bar),是A-0的10.21倍。说明MIL-53(Fe、Al)的加入,显著提高了PSf超滤膜的渗透性能。当MIL-53(Fe、Al)负载质量分数大于0.3%时,共混膜的纯水通量会逐渐下降,这是由于MIL-53(Fe、Al)逐渐变多的过程会导致铸膜液的黏度逐渐增大,黏度大小会影响相分离过程中非溶剂与溶剂的相转换速率,导致共混膜孔道变少。此外,MIL-53(Fe、Al)的团聚也会降低膜的纯水通量。

用BSA溶液作模拟污染物探究膜的截留能力。由表2中可以看出,在MIL-53(Fe)质量分数为0.3%时,BSA截留率达到最大,为93.21%。这是因为MIL-53(Fe、Al)是亲水性材料,在相分离过程中有一部分会迁移到膜的表面,进一步能与水分子形成氢键,从而形成水化层,提高了截留率。此外,MIL-53(Fe、Al)的表面活性位点可以吸附一些BSA分子,从而提高膜的截留能力。当MIL-53(Fe、Al)的添加质量分数超过0.3%时,截留率会有所下降,这是由于MIL-53(Fe、Al)会团聚,从而导致膜的表面亲水性会降低,难以形成水化层,因此,截留率会略有下降。

2.2.4 超滤膜的抗污染性能

结垢会严重影响膜的过滤性能,污垢会导致膜的效率降低、膜寿命缩短以及洗涤成本增加。因此,需要研究MIL-53(Fe、Al)/PSf共混膜的抗污染性能。

不同MIL-53(Fe、Al)质量分数的MIL-53(Fe、Al)/PSf共混膜的通量随时间的变化情况如图4所示。从图4中可以看出,当用BSA溶液代替去离子水时,所有共混膜的渗透通量都急剧下降。这主要是由膜污染和浓度极化引起的^[14]。即使用纯水进行充分反洗后,由于产生一部分顽固的污垢,所有膜的渗透通量也不能恢复到其初始值。交替测试2次发现,A-2膜仍能达到较好的渗透性能。

MIL-53(Fe、Al)/PSf共混膜的抗污染性能如表3所示。由表3中可以看出,A-2的通量恢复率最大为90.04%,比A-0(73.69%)提高了16.35%。有两方面主要原因:一方面,由于亲水性材料MIL-53(Fe、Al)的加入,导致更多的水分子被吸引到亲水表面形成紧凑的水屏障,限制了BSA大分子和膜之间的相互作用;另一方面,共混膜比纯膜具有更光滑的表面,可以防止蛋白质在膜的表面沉淀,提高了去除效率^[15],因此大大提高了共混膜的恢复通量。

进一步计算了共混膜污垢阻力比(R_t、R_r和R_ir)。R_t由R_ir和R_r组成,对于可逆污染(R_r),吸附的BSA分子松散地附着在膜表面,可以通过简单冲洗去除,然而,对于不可逆污染(R_ir),通过化学清洗也仅仅只是去除其吸附的BSA大分子。A-2的污染主要是可逆污染,可以通过物理清洗去除大部分污染物。随着MIL-53(Fe、Al)添加质量分数的增加,R_r/R_t均出现先增大后减小趋势,而R_ir/R_t出现先减小后增大趋势,A-2时两者差值最大,说明此时的MIL-53(Fe、Al)/PSf共混膜抗污染性能最好。

3 结论

通过溶剂热法成功合成了MIL-53(Fe、Al),并且采用非溶剂致相分离法制备了MIL-53(Fe、Al)/PSf共混膜,通过其孔隙率、水接触角、水通量、抗污染性能等探究不同MIL-53(Fe、Al)掺杂量的MIL-53(Fe)/PSf共混膜的性能。结果表明:当MIL-53(Fe、Al)的质量分数为0.3%时,共混膜的性能最优,与原膜相比,水接触角降低了28.81°,达到54.78°;纯水通量提高了10.21倍,达到179.15 L/(m²·h·bar);对BSA的截留率由89.21%改善到了93.21%。且MIL-53(Fe、Al)掺杂到PSf中增强了其抗污染能力,提高了可逆污染率,使得混合膜更不易受到污染或通过简单水洗方法就可使通量恢复到较高水平。

参考文献

原文顺序 | 出版日期 | 本文引用

[1]	Sabrin S M, Hasbullah H, Jye L W, et al. Permeable and antifouling PSf-Cys-CuO ultrafiltration membrane for separation of biological macromolecules proteins[J]. Environmental Quality Management, 2023, 33(3):103-112.

[2]	Ponnaiyan P, Nammalvar G. Enhanced performance of PSf/PVP polymer membrane by silver incorporation[J]. Polymer Bulletin, 2020, 77(1):197-212.

[3]	Huang Q, Ding Z, Lu H, et al. Honeycomb-like SBA-15 parceled in 2D GO for ultrafiltration membranes fabrication with ultrahigh permeability and enhanced anti-fouling performance[J]. Separation and Purification Technology, 2023,325:124694.

[4]	Luo J, Luo X, Gan Y, et al. Advantages of bimetallic organic frameworks in the adsorption,catalysis and detection for water contaminants[J]. Nanomaterials, 2023, 13(15):2194.

[5]	Kachhadiya D D, Murthy Z V P. Preparation and characterization of ZIF-8 and ZIF-67 engineered PVDF mixed-matrix membranes:Stability enhancement in pervaporation study[J]. Environmental Science:Water Research & Technology, 2023, 9(5):1502-1517.

[6]	Xie L H, Xu M M, Liu X M, et al. Hydrophobic metal-organic frameworks:Assessment,construction,and diverse applications[J]. Advanced Science, 2020, 7(4):1901758.

[7]	Le V N, Nguyen V C, Nguyen H T, et al. Facile synthesis of bimetallic MIL-100(Fe,Al) for enhancing CO₂ Adsorption performance[J]. Microporous and Mesoporous Materials, 2023,360:112716.

[8]	Wu Q, Siddique M S, Guo Y, et al. Low-crystalline bimetallic metal-organic frameworks as an excellent platform for photo-Fenton degradation of organic contaminants:Intensified synergism between hetero-metal nodes[J]. Applied Catalysis B:Environmental, 2021,286:119950.

[9]	Cheng L, Zhou Z, Li L, et al. PVDF/MOFs mixed matrix ultrafiltration membrane for efficient water treatment[J]. Frontiers in Chemistry, 2022,10:985750.

[10]	Chen X, Liu X, Zhu L, et al. One-step fabrication of novel MIL-53(Fe,Al) for synergistic adsorption-photocatalytic degradation of tetracycline[J]. Chemosphere, 2022,291:133032.

[11]	Zheng X, Shen L, Lin F, et al. Bimetallic metal-organic frameworks MIL-53(xAl-yFe) as efficient catalysts for H₂S selective oxidation[J]. Inorganic Chemistry, 2022, 61(8):3774-3784.

[12]	Khodayari A, Sohrabnezhad S. Fabrication of MIL-53(Al)/Ag/AgCl plasmonic nanocomposite:An improved metal organic framework based photocatalyst for degradation of some organic pollutants[J]. Journal of Solid State Chemistry, 2021,297:122087.

[13]	Jalali A, Shockravi A, Vatanpour V, et al. Preparation and characterization of novel microporous ultrafiltration PES membranes using synthesized hydrophilic polysulfide-amide copolymer as an additive in the casting solution[J]. Microporous and Mesoporous Materials, 2016,228:1-13.

[14]	Sun H, Tang B, Wu P. Hydrophilic hollow zeolitic imidazolate framework-8 modified ultrafiltration membranes with significantly enhanced water separation properties[J]. Journal of Membrane Science, 2018,551:283-293.

[15]	Yang L, Wang Z, Zhang J. Highly permeable zeolite imidazolate framework composite membranes fabricated via a chelation-assisted interfacial reaction[J]. Journal of Materials Chemistry A, 2017, 5(29):15342-15355.