محمدصادق فتاحي مله اميرخاني

Graphene quantum dots (GQDs) have emerged as a new class of zero-dimensional carbon nanomaterials possessing unique size-dependent electronic, optical, chemical, and physical properties. This work focused on the development of facile, sustainable hydrothermal synthesis routes to produce tailored GQDs with controlled surface functionalities. Two types of GQDs were synthesized: amine-functionalized GQDs (AGQDs) and glutamic acid-modified GQDs (Glu-GQDs). The objective was to systematically tailor the GQD surface functionality to modulate membrane properties and performance for water treatment applications.The AGQDs and Glu-GQDs were synthesized from citric acid precursors and thoroughly characterized using transmission electron microscopy (TEM), XRD, Fourier-transform infrared spectroscopy (FTIR), and Raman spectroscopy to confirm successful synthesis of quantum-confined GQDs. The surface functionalities were found to allow stable aqueous dispersion. The impact of GQD concentration on membrane performance was investigated, with AGQD concentrations ranging from 0.01% to 0.1% wt and Glu-GQD concentrations ranging from 0.05% to 0.2% wt. The eva‎luation of TFN membranes revealed significant improvements in flux while maintaining adequate solute rejection rates. For 0.03% wt AGQD-incorporated TFN membranes, Na2SO4 rejection decreased slightly from 97.2% to 94.04%, while flux increased from 8.22 to 12.9 LMH.bar⁻¹. Similarly, for 0.1% wt Glu-GQD-incorporated TFN membranes, Na2SO4 rejection decreased to 95.08%, with a remarkable flux increase to 16.56 LMH.bar⁻¹. Notably, flux exhibited a substantial 56.93% increase for AGQD and an impressive 101.45% increase for Glu-GQD, underscoring the effectiveness of GQD incorporation in improving membrane performance. salt rejection results indicated the following trend: Na2SO4 > CaSO4 > MgSO4 > MgCl2 > NaCl > CaCl2. These findings highlight the selectivity of the TFN membranes in rejecting various salts, with Na2SO4 demonstrating the highest rejection rate. Overall, this study showcases the potential of GQD-modified TFN membranes as promising candidates for desalination and water purification applications. The significant increase in flux, coupled with a minor decrease in salt rejection, suggests that GQD incorporation could lead to more efficient and sustainable water treatment processes, addressing the ever-growing global demand for clean and fresh water resources.

نانوفيلتراسيون , نمك‌زدايي , غشاي نانوكامپوزيت فيلم نازك(TFN) , نقاط كوانتومي گرافن

Nanofiltration , desalination , Thin Film Nanocomposite (TFN) membrane , graphene quantum dot

Mohammad Sadegh Fattahi Mele-Amirkhani

Toraj Mohammadi