Pilot scale degradation of Sulfamerazine using different venturi based hydrodynamic cavitation and ultrasound reactors in combination with oxidation processes

Abstract

In the present investigation, a sulfonamide drug named Sulfamerazine was degraded using the 5 L pilot scale hydrodynamic cavitation equipped with three different venturis namely circular (HCCV), slit (HCSV), and dual-slit venturi (HCDSV) operating at 4 bar inlet pressure. The novel HCDSV was successfully designed and applied for the first time to improve the cavitational activities and a subsequent increased ˙OH radical generation. The SMZ degradation achieved using individual HCDSV was 41.54% in comparison to 27.69% and 21.54% for HCSV and HCCV respectively, clearly showing the benefits for intensification. The resistance coefficient (convergent and divergent sections of the venturi), number of passes, and cavitation number significantly influence the cavitational activities, and HCDSV was observed to be the most efficient design based on these parameters. A pilot scale US reactor (USR) was likewise used for the degradation of SMZ at a similar capacity. The combination of hydrodynamic and acoustic cavitation with H2O2, PS, PMS, Fenton and Fenton-like processes were successfully demonstrated on a pilot scale investigation. The combined approach of Fenton (Fe2+ at 0.75 mM and H2O2 at 0.7 mM) coupled with hydrodynamic or acoustic cavitation was the most proficient approach, with maximum SMZ degradation of 96.92% and 97.25% achieved for HCDSV/Fe2+/H2O2 and USR/Fe2+/H2O2 (at 22 +44 kHz), respectively. The estimated cost of treatment for HCDSV/Fe2+/H2O2 and USR/Fe2+/H2O2 (at 22 +44 kHz) approaches were 0.1780 and 0.4583 ₹/L respectively, establishing HCDSV/Fe2+/H2O2 as the most effective method in terms of SMZ degradation as well as cost of degradation.