Development of intensified flat-plate packed-bed solar reactors for heterogeneous photocatalysis

Author(s)

Ramos, Bruno ; Carneiro, Joao Gabriel M. ; Nagamati, Leandro Issamu ; Teixeira, Antonio Carlos S. C.

• Document type: Journal article
• Source: Environmental Science and Pollution Research; v. 28, n. 19, p. 11-pg., 2021-01-07.

Abstract

Solar-driven photocatalysis is a promising water-cleaning and energy-producing technology that addresses some of the most urgent engineering problems of the twenty-first century: universal access to potable water, use of renewable energy, and mitigation of CO2 emissions. In this work, we aim at improving the efficiency of solar-driven photocatalysis by studying a novel reactor design based on microfluidic principles using 3D-printable geometries. The printed reactors had a dimensional accuracy of 97%, at a cost of less than $1 per piece. They were packed with 1.0-mm glass and steel beads coated with ZnO synthesised by a sol-gel routine, resulting in a bed with 46.6% void fraction (reaction volume of ca. 840 mu L and equivalent flow diameter of 580 mu m) and a specific surface area of 3200 m(2) m(-3). Photocatalytic experiments, under sunlight-level UV-A irradiation, showed that reactors packed with steel supports had apparent reaction rates ca. 75% higher than those packed with glass supports for the degradation of an aqueous solution of acetaminophen; however, they were strongly deactivated after the first use suggesting poor fixation. Glass supports showed no measurable deactivation after three consecutive uses. The apparent first-order reaction rate constants were between 1.9 and 9.5 x 10(-4) s(-1), ca. ten times faster than observed for conventional slurry reactors. The mass transfer was shown to be efficient (Sh > 7.7) despite the catalyst being immobilised onto fixed substrates. Finally, the proposed reactor design has the merit of a straightforward scaling out by sizing the irradiation window according to design specifications, as exemplified in the paper. (AU)

• FAPESP's process: 18/21271-6 - SOLAR DEGRADATION OF POLLUTANTS OF EMERGING CONCERN: PHOTOREACTORS AND INNOVATIVE TREATMENTS
• Grantee: Antonio Carlos Silva Costa Teixeira
• Support Opportunities: Regular Research Grants