A highly efficient, low-cost, and sustainable method of water purification and desalination using solar-driven interfacial evaporation.

Abstract

Water scarcity has become one of the most daunting global challenges, and as a result, a continuous supply of potable water has become a bane to most societies. Techniques such as distillation and reverse osmosis have been adopted in the production of potable water but these processes are energy-consuming and highly expensive making them less attractive to many households. A viable economical technique is the removal of salt from seawater or brackish water through a solar distiller. This research was based on the design of a low-cost and new improved solar distiller which was made up of a wooden basin and an inclined glass cover. In the basin is contained sea or brackish water and photothermal materials which include recycled materials that act as an insulation material, an evaporation structure, and a solar absorber. These photothermal materials were designed and fabricated to meet with the current state-of-the-art method of evaporation which is solar interfacial evaporation. The fabricated materials were characterized using scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The solar distiller and photo thermal materials were evaluated for their efficiencies via real-time outdoor experiments using solar energy. The rate of evaporation was calculated, while parameters such as pH, conductivity, Total dissolved solids (TDS) and salinity were analyzed on the freshwater collected and compared with the standard of drinking water by the World Health Organisation (WHO) and South African National Standard (SANS241). Heavy metal concentration in the water samples and remediated water collected were analyzed using inductively coupled plasma optical emission spectroscopy (ICP-OES) and compared with the WHO and SANS241 standards as well. The findings could provide adequate and affordable potable water to all households irrespective of societal status and it will reduce the cost of health management, as many diseases associated with consumption of untreated water can be drastically reduced. This is in-line with South Africa’s National Development Plan (NDP) 2030 and the United Nations’ Sustainable Development Goals (SDGs).