A super-hydrophilic honeycomb activated carbon evaporator for simultaneous salt rejection and VOCs removal during solar-driven seawater desalination

Abstract

Salt accumulation and volatile organic compounds (VOCs) entering condensed freshwater are two main drawbacks in the new approach of solar-driven seawater desalination. In this work, a super-hydrophilic honeycomb activated carbon (SHHAC) evaporator was fabricated for simultaneous salt rejection and VOCs removal. The optimal water evaporation rate of the SHHAC evaporator was as high as 1.50 kg·m−2·h−1 under one sun illumination with the corresponding photothermal conversion efficiency of 99.4 %. Due to the super-hydrophilic properties, high water absorption capacity, fast water absorption rate and unique honeycomb structure of SHHAC, the salt-rejection property of the SHHAC evaporator was achieved by flowing back the concentrated brine to the underneath seawater. Simultaneously, the distillation concentration ratio (RD) of phenol was reduced from 75 % to 0 % by the SHHAC evaporator resulting in zero phenol entering condensed freshwater. Finally, the potential application of the SHHAC evaporator was demonstrated by an expanded outdoor experiment using the real seawater as the feedwater.