A rational strategy for substantially enhancing the solar-utilization efficiency and organic-pollutant-degradation rate via mediated central processing unit filling

Abstract

The effective application of solar thermal energy can enormously stimulate the potential of solar energy as a viable alternative to fossil fuel from the analysis of the present conversion efficiencies of solar energy. The efficiency can be further boosted by combining with other forms of solar energy, e.g., electricity. Based on the foregoing standpoint, a strategy of large-scale input of thermal energy superimposed on electricity is proposed for applying solar energy to wastewater purification in this study. The hybrid operation could significantly accelerate the thermodynamic and kinetic rates for chemical reactions. Herein, a reactor named central processing unit (CPU) was designed to serve as the transfer station for wastewater treatment. The CPU allows continuous cleaning of wastewater in contrast to ordinary intermittent processes. Generally, two different experimental systems were set up involving electric-field-induced pyrolysis (media-free) and high-temp-induced electrolysis (filled with solid media). Regarding the former, solar electricity was employed for the field intensity. While for the latter, the electrolysis function was coupled with the field intensity. The optimal treatment effect of the media-free system was obtained at 160 °C with a phenol degradation rate of 37.1% and COD removal rate of 36.04%. The purification operations of the system filled with a solid media were carried out with quartz sand and alumina as the cell fillings, respectively. A markedly improved outcome was achieved at 140 °C, with a degradation rate of 95.57% and COD removal rate of 92.51% in the alumina-mediated unit, while the indices with the quartz sand fillings were 65.68% and 64.15%, respectively. The synergistic strategy of solar utilization and the experimental results present a novel approach for treating wastewater that is efficient, continuous, green, and catalyst-free.