Thollwana Andretta Makhetha

NH2-ZIF-8@SGO thin-film composite membrane for textile wastewater treatment and enhanced antifouling performance. This study focuses on developing the amine-functionalized zeolitic imidazole framework-8 (NH2-ZIF-8) encapsulated onto sulfone-functionalized graphene oxide (SGO) to enhance the properties of the PA-TFC membrane for textile wastewater treatment. Zeolitic imidazole framework-8 (ZIF-8) and graphene oxide (GO) were both functionalized with 3-amino-1,2,4-triazole (Atz) and sulfanilic acid, respectively, to achieve NH2-ZIF-8@SGO. The composition of NH2-ZIF-8 was varied on SGO via the in-situ growth method to acquire the optimum formulation of the NH2-ZIF-8@SGO composite. The optimum 0.5% formulation of NH2-ZIF-8@SGO was embedded into the PA layer to enhance membrane performance. The results confirmed that NH2-ZIF-8@SGO-modified TFC membranes exhibited improved water flux and fouling resistance with ∼90% water flux recovery. In addition, the TFC membranes rejected above 99% of textile wastewater primarily through size exclusion and the Donnan exclusion mechanism. These results show that NH2-ZIF-8@SGO increases the hydrophilicity of the PA-TFC membrane and contributes to its high rejection efficiency, improved antifouling performance, and prolonged operational lifespan.

Wider adoption of membrane technology is hindered by fouling and flux/rejection challenges. Recent practice in mitigating these is to incorporate hydrophilic and porous fillers. Herein the addition of hydrophilic graphene oxide (GO) in conjunction with porous mixed ZIFs (ZIF-67/ZIF-8) crystallites were used as inorganic fillers in the preparation of polyphenylenesulfone (PPSU) ultrafiltration (UF) membranes. The morphology of the resultant composite membranes was assessed using atomic force microscopy (AFM) and scanning electron microscopy (SEM) whilst surface hydrophilicity through water contact angle. The pure water flux (PWF) and membrane permeability were found to increase with increasing filler content. This was attributed to the combined hydrophilicity of GO and porous structure of the ZIF materials because of increasing alternative water pathways in the membrane matrix with increasing filler content. Furthermore, the increase in the ZIF component led to increasing bovine serum albumin (BSA) fouling resistance as demonstrated by increasing fouling recovery ratio (FRR). The dye rejection was due to a combination of electrostatic interaction between the fillers and the dyes as well as size exclusion. The chemical interactions between the ZIFs and the dyes resulted in slightly different rejection profiles for the smaller dyes, the cationic methylene blue being rejected less efficiently than the anionic methyl orange, potentially leading to their separation. The larger anionic dye, Congo red was rejected predominately through size exclusion.

This study reports on the antibacterial efficacy of both the TiO₂ and TiO₂/Cu nanoparticles prepared through the sol-gel method. The materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET) analysis. The SEM and TEM showed the spherical morphology of the nanoparticles, while EDX and XPS confirmed the incorporation of Cu into the TiO₂ nanoparticles. The XRD confirmed the formation of the tetragonal anatase phase of TiO₂/Cu while the FTIR revealed the functional groups linked to the doped TiO₂ nanoparticles. The thermal stability of TiO₂/Cu was found to be lower than pure TiO₂. Moreover, TiO₂ and the doped TiO₂ nanoparticles were notably effective against Bacillus subtilis(B. subtilis) andEscherichia coli(E. coli); however, the addition of Cu to TiO₂ did not have any effect on the antibacterial activity probably due to the lower weight content in the composites. Interestingly, the antibacterial efficiency was determined to be 90 and 80% against B. subtilis and E. coli, respectively.

A series of Zeolitic imidazole framework-8 (ZIF-8) clusters supported on graphene oxide (ZIF-8@GO) nanocomposites were prepared by varying the ratios of ZIF-8 to GO. The resultant nanocomposites were characterized using various techniques, such as Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), thermogravimetric analysis (TGA), Fourier Transform Infrared (FTIR) and Raman spectroscopy. These nanocomposites were incorporated into the thin film layer during interfacial polymerisation process of m-phenylenediamine (aqueous phase which contained the dispersed nanocomposites) and trimesoyl chloride (TMC, organic phase) at room temperature onto polyethersulfone (PES) ultrafiltration (UF) support membrane. The membrane surface morphology, cross section and surface roughness were characterized using SEM and AFM, respectively. Compared to the baseline membranes, the thin film nanofiltration (TFN) membranes exhibited improved pure water flux (from 1.66 up to 7.9 L.m⁻²h⁻¹), salt rejection (from 40 to 98%) and fouling resistance (33 to 88%). Optimum ZIF-8 to GO ratio was established as indicated in observed pure water flux, salt rejection and BSA fouling resistance. Therefore, a balance in hydrophilic and porous effect of the filler was observed to lead to this observed membrane behaviour suggesting that careful filler design can result in performance gain for thin film composite (TFC) membranes for water treatment application.