Triple-hybrid solar still incorporating an automated concave reflector, paraffin wax–graphene quantum dot thermal storage, and capillary fiber wick for produced-water desalination from oilfields
摘要
Water scarcity and produced-water (PW) management challenge arid oil-producing regions. This study presents a hybrid solar still integrating three synergistic enhancements: an automated concave reflector, a capillary fiber wick, and packed-bed hollow iron spheres filled with nanoenhanced phase change material (paraffin wax with graphene quantum dots, GQDs). Optimization of GQD concentrations (0–10%) identified 4% as optimal, achieving 40% reduction in thermal charging time while maintaining sustained nocturnal heat release over 4000 s. The capillary wick increased evaporation rates by an order of magnitude (0.07–0.958 L h−1 at 50 °C). Fouling mitigation strategies including “+” suspension and gravity-assisted drainage were addressed. The concave reflector alone elevated internal temperatures to 93 °C, achieving 2.25 L day−1 a tenfold increase over conventional stills. Adding the wick raised productivity to 3.37 L/day, while full integration with nano-PCM spheres extended operation six hours post-sunset, culminating in 5.2 L day−1 a 25-fold improvement. Using real PW from the Nasiriyah oilfield (TDS > 550 g L−1), this triple-hybrid approach offers a sustainable, low-cost solution for produced-water desalination in remote applications.
Graphical abstract