Optimized TiO₂/GO/PES Forward Osmosis Membrane for Wastewater Reclamation Using Qarun Lake Brine as a Draw Solution

This study presents an innovative approach to fabricating high-efficiency forward osmosis (FO) membranes by embedding TiO₂/graphene oxide (GO) nanocomposites into polyethersulfone (PES) using the phase inversion method. The nanocomposite ratios (GO: TNPs = 1:1, 1:2, and 2:1) were systematically optimized and further enhanced through thermal post-treatment (TPES, TC1–TC3) to improve membrane performance. Comprehensive characterization—including XRD, SEM, and particle distribution analysis—confirmed successful integration, with TC3 (GO: TNPs = 2:1) displaying superior structural uniformity and crystallinity. TiO₂/GO nanohybrids exhibit crystallite sizes of 74.5 nm (TiO₂) and 23.17 nm (GO), with SEM images showing GO nanosheets coated by TiO₂ structures and particle size averaging 158.7 ± 34.8 nm. Functionally, thermally modified membranes demonstrated enhanced water flux (128 LMH) and minimized reverse salt flux (0.038 GMH) in FO mode using 2 M NaCl as the draw solution. The Js/Jw ratio (0.2 × 10⁻³ g/L) and resistance to humic acid fouling emphasize the composite’s effectiveness in real-world conditions. A key finding is the determination of critical concentration factors (CCF) for grey water (2.80) and municipal wastewater (2.85), suggesting a threshold for optimal FO operation. Importantly, the study introduces a novel dual-stage PRO–FO system utilizing Qarun Lake water as the draw solution and grey water as the feed solution, respectively. This sequence demonstrated progressive reduction of total dissolved solids (TDS), underscoring its feasibility for sustainable reuse applications, including irrigation, aquaculture, and low-pressure RO. Overall, the integration of TiO₂/GO nanocomposites and the two-stage osmosis design offers scalable, energy-efficient solutions for environmental remediation and decentralized water treatment.