Biodegradable hydrogel with excellent portability, stability and anti-pollution performance in solar-driven seawater desalination

Abstract

Solar-driven interfacial evaporation technology holds great potential for efficiently utilizing solar energy to convert untapped water sources into clean water. This study developed a cellulose nanofiber (CNF)/polyvinyl alcohol (PVA)/multi-walled carbon nanotubes (MWCNTs) hydrogel-based evaporator (PCC) using low-cost wood pulp cellulose as the raw material. The experimental results revealed that the PCC hydrogel evaporator achieved a water evaporation rate of 1.61 kg·m−2·h−1 under 1 sun irradiation (solar intensity of 1 kW·m−2). Assisted by the three-dimensional interconnected hydrophilic network, the hydrogel exhibited excellent water supply capabilities, with water transport dominating within the hydrogel, enabling continuous steam generation from seawater. And the water layer formed by the super-hydrophilic pore wall structure was also beneficial to activating water, promoting the diffusion of high-concentration salt water, and enhancing the underwater oil repellent ability. After multiple compression-recovery performance tests, the PCC maintained stable evaporation performance, which greatly enhanced portability during use. In addition, the application of PCC evaporators in the fields of seawater desalination, wastewater treatment, and agricultural irrigation had shown excellent results, confirming the potential application value of this evaporator. Combined with its environmental friendliness, cost-effectiveness, and other advantages, it had broad development prospects.