The aim of this study was to remove non-biodegradable colored compounds from biologically treated baker's yeast effluent using an antifouling membrane in order to facilitate reuse of the wastewater. To get this purpose, in a facile effort, a new nanofiller, citric acid functionalized tannic acid (CA-f-TA), was synthesized by employing a simple, economical and green method. The produced nanofiller was used in the fabrication of polyethersulfone (PES) nanofiltration (NF) membranes. The influence of CA-f-TA on the cross section morphology, pore size, porosity, water content, hydrophilic properties, and roughness of the modified PES/NF membrane was evaluated. The performance of the fabricated membranes was analyzed as pure water flux (PWF), antifouling and dye rejection capacity. Based on obtained results, incorporation of the CA-f-TA nanofiller resulted in an increase in the PWF from 23.5 to 23.6 and 34.4 kg m-2 h-1 for the membranes blended with CA-f-TA-1, CA-f-TA-0.5 and CA-f-TA-0.1, respectively, in contrast to 16.4 kg m-2 h-1 for the reference membrane. The antifouling characteristics of the prepared membranes dramatically raised owing to improvement in smoothness and hydrophilicity of membrane surface. The synthesized NF membrane with 1 wt% CA-f-TA nanofiller had the highest flux recovery ratio (FRR, 93.2%) and dye rejection (95.7% for Direct Red 16 (DR 16) and 97% for biologically treated baker's yeast wastewater), and the lowest irreversible fouling resistance (6.8%). Furthermore, PWF of 34 kg m-2 h-1, FRR of 97%, TSS and turbidity removal efficiencies of 100%, and COD removal efficiency of 80% were obtained using the 1 wt% CA-f-TA membrane after filtration of a field sample i.e. biologically treated baker's yeast wastewater over a 1-h filtration.

In this research, the manufacture and properties of polyethersulfone (PES)-based mixed matrix nanofiltration (MM-NF) membranes modified with β-cyclodextrin functionalized multiwalled carbon nanotubes (β-CD/MWCNTs) were studied. The β-CD/MWCNTs nanocomposite was synthesized using the soft cutting method. Stable dispersivity of the resulting nanocomposite was checked for 12 h. Then, the membranes containing up to 1 wt% β-CD/MWCNTs were prepared using conventional phase inversion method. The impact of varied mass loadings of the β-CD/MWCNTs on the morphological features and performance of the amended membranes was evaluated. It was deduced that membrane hydrophilicity, porosity, pore size, water contents, dye rejection and antifouling capacity were noticeably improved after incorporating the β-CD/MWCNTs nanomaterials. In comparison with the bare membrane, the β-CD/MWCNTs amended membranes displayed higher hydrophilicity, and consequently pure water flux (PWF). Since β-CD can exploit the structure advantages of MWCNTs via enhancement of the dispersivity, devoting unique features to the β-CD/MWCNTs nanomaterial. The 0.1 wt% nanocomposite membrane sample revealed the highest pure water flux of 21.5 Kg/m².h due to increase in pore size (5.0 nm). While, the membrane contributed with the β-CD/MWCNTs-0.5 revealed better performance in terms of dye rejection and antifouling capability than the bare and modified membranes. It indicated a dye rejection of above 92%, flux recovery ratio (FRR) of 89% and an irreversible resistance of 11.1%. The β-CD/MWCNTs-0.5 acted as a potential nanofiller in nanofiltration (NF) membranes improving their antifouling performance at different operational conditions.