Synthesis of Photothermal Hydrogel for Solar Water Distillation and Multiple Applications

Abstract

The earth's surface is covered with 71% of water. However, people are facing freshwater issues due to the increase in industries and the rapid growth of the population. Out of the total water available, only 3% of water can be utilized directly for the needs. So, a sustainable and affordable technique is required to make fresh water from the water reservoirs. In this context, the hydrogel-based solar evaporator has shown excellent results. By reducing the energy needed for the evaporation of water through the formation of more intermediate water, this type of evaporator has enhanced solar vapor generation efficiency significantly. However, along with high vapor generation, an evaporator must be designed to simultaneously purify wastewater containing radioactive elements, organic dyes, and low-boiling-point contaminants to ensure the purity of the evaporated water. Herein, we have prepared a multifunctional bilayer hydrogelbased solar evaporator (CSG@CDG) by chemical crosslinking of Carboxy Methyl Cellulose (CMC), amidoxime-modified chitosan (CSA), and chitosan (CS) in the bottom layer and carbonized Desmoschatya bipinnata (CD) as photothermal material in the top layer. This evaporator shows a high evaporation rate of 2 kg m-2 h -1 under one sun. In addition to that, the presence of the amidoxime group in the polymer matrix helps to capture radioactive U (VI) from the natural seawater.