A low-cost salt-tolerant solar evaporator prepared from graphite in spent LIBs for high efficiency seawater desalination

Abstract

Interfacial photothermal evaporation technology has been greatly promoted due to the increasing demand for sustainable energy around the world. but the development of low cost and durable efficient evaporators remained challenging. In this paper, a polyurethane sponge-loaded chitosan/reconstructed graphite-based evaporator (PCRE) was successfully designed by freeze-drying technique using recycled graphite from spent lithium batteries. The PCRE demonstrated strong hydrophilic properties and exhibited a light absorption rate of 96.06 %. Under the irradiation of 1 light intensity, the photothermal conversion efficiency of PCRE can reach 91.9 %, and the evaporation rate reaches 3.85 kg m-2h−1. Thanks to the large number of hydrophilic groups in PCRE and its excellent pore structure, the enthalpy of evaporation of water inside PCRE (1.2970 kJ g−1) is much lower than that of pure water (2.4417 kJ g−1). Moreover, PCRE can effectively avoid the problem of salt deposition, and its evaporation rate can still be maintained at 3.0 kg m-2h−1 in the treatment of high-concentration brine (25 wt.%), and in long-term evaporation experiments, PCRE has demonstrated highly efficient and stable desalination performance and removal capability for real seawater and organic wastewater. Based on the excellent evaporation performance, simple preparation and low cost of this evaporator, this study provides a new idea for waste recycling in the application of interfacial photothermal evaporation.