Membrane technologies have attracted considerable attention as effective separation methods in various processes, particularly in light of the increasing global deman‎d for water resource conservation. One of the major challenges facing these technologies is membrane fouling an‎d surface scaling, especially in ultrafiltration systems, which can significantly impair membrane performance. In this study, in order to overcome these limitations an‎d enhance the performance of polyvinylidene fluoride (PVDF) membranes, hydro‎philic polymeric quantum dots (PDs) were employed. These quantum dots were synthesized via a hydrothermal method using polyethylene glycol (PEG) an‎d ethylenediamine (EDA) in an aqueous solvent. The structure of the synthesized PDs was characterized using various techniques, including Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), an‎d UV-Visible spectrophotometry (UV-Vis). The PVDF membranes were fabricated using the phase inversion method. The casting solution consisted of 16 wt% PVDF, 80.90 wt% N-methyl-2-pyrrolidone (NMP) as solvent, 0.1 wt% SiO₂ nanoparticles as hydro‎philic additives an‎d nucleating agents, an‎d 3 wt% PEG to enhance porosity an‎d hydro‎philicity. The surface of the pristine PVDF membrane was first subjected to an alkaline pretreatment (defluorination) process to generate carbon–carbon double bonds (−C=C−), providing active sites for subsequent chemical modifications. The synthesized PDs were then covalently grafted onto the membrane surface via a surface modification process to improve surface hydro‎philicity an‎d increase resistance to fouling an‎d scaling. This surface modification involved two main steps: first, defluorination created reactive sites (−C=C−) on the membrane surface; second, these sites reacted with the amino groups of PDs through a Michael addition reaction. To optimize the surface modification conditions, the Taguchi experimental design method was employed. This approach enables the eva‎luation of process parameters with a reduced number of experiments. The experimental results confirmed the successful synthesis of polymeric quantum dots with an average particle size of 3.5 nm. The modified membranes exhibited significantly improved properties, including higher pure water flux an‎d lower water contact angle, indicating enhanced hydro‎philicity. Specifically, the pure water flux increased from 101.39 L/m²·h for the pristine membrane to 113.37 L/m²·h for the PD-modified membrane, an‎d the water contact angle decreased from approximately 85° to 37°. Furthermore, the modified membranes demonstrated enhanced resistance to fouling an‎d scaling compared to conventional PVDF membranes, with the flux recovery ratio (FRR) improving from around 30% to 60%. These findings highlight the potential of polymeric quantum dot-modified membranes for advanced water treatment applications an‎d suggest promising avenues for the broader implementation of membrane technologies in various industrial processes.

مرتضي صادقي , افسانه فخار

سهيل ضرغامي , احمد اسدي نژاد