Mitigation of Water Eutrophication Using Positively Charged Self-Assembled Functionalized Multi-Walled Carbon Nanotubes/Graphene Oxide-Based Polylactic Acid Membrane

Abstract

Polylactides are a prominent class of biocompatible and biodegradable polymers that can be used to fabricate membranes for wastewater treatment. Excessive nutrient (phosphorus and nitrogen) concentrations in water bodies are a serious concern that has resulted in widespread health problems and potable water shortages. There are several limitations in applying conventional techniques of nutrient removal. For this reason, adsorptive membrane application has received considerable attention due to its exceptional performance in the wastewater treatment. In this study, ultrafiltration (UF) membranes were prepared using different concentrations of polylactic acid (PLA) (15, 18, 20 and 22 wt.%) via the Loeb–Sourirajan method. Then the optimum concentration of PLA was incorporated with functionalized multi-walled carbon nanotubes graphene oxide(f-MWCNT)/(GO) nanohybrid prepared via self-assembly, to fabricate nanocomposite membranes. Different loadings of f-MWCNT/GO ranging from 0% to 6 wt.% were used. Scanning electron microscope (SEM), thermogravimetric analyzer (TGA), and Fourier-transform infrared (FTIR) analyses, along with few others analyses were used to characterize the membranes. In addition, the following analyses: water flux, porosity, contact angle (CA), nutrient rejection using both synthetic and raw wastewaters, etc. were carried out to study the effect of f-MWCNT/GO inclusion on the performance of the membranes. Results indicated that the addition of f-MWCNT-GO resulted in a drop in the DI water CA from 70±1.8° in the pristine PLA membrane to 58.8±1.5° in the 6 wt.% f-MWCNT/GO/PLA membrane. Moreover, the water flux was 5 times higher in the 6 wt.% f-MWCNT/GO/PLA membrane compared to the pristine PLA. The 1.5 wt.% f-MWCNT/GO/PLA membrane removed ~81% and ~90% of ammoniacal-nitrogen (NH4+-N) and ~46% and ~71% of phosphate (PO43--P) ions using synthetic and raw wastewater, respectively. Such membranes have the potential to be utilized in real wastewater treatment applications.

Date of Award	Dec 2021
Original language	American English