Aquaculture drug degradation in persulfate by PANI-based microparticles controlled via ultrasonic field: Forced motion of “burning hot micromotors”

Abstract

The triphenylmethane derivative malachite green (tpmMaG) despite repeated prohibitions but is frequently detected in aquatic environment and draws emerging attention because of the potential poisonous effects. The polyaniline/persulfate with ultrasound catalysis (US/PANI-PS) was developed for tpmMaG removal. The effects of 12 factors and the optimization by response surface methodology (RSM) for tpmFG removal were evaluated based on the pseudo-first-kinetics (kobs). From free radical inhibition, the ratios of active species in US/PANI-PS (δ11 = 0.355, δ12 = 0.593) were close to that in US-PS (δ21 = 0.346, δ22 = 0.586) and different to that in PANI-PS and PS systems. A possible degradation pathway (hydroxylation, N-demethylation, deamination, and open-benzene ring) was explored by gas chromatography-mass spectrometer (GC/MS) and high performance liquid chromatography-mass spectrometer (HPLC-MS). The designed reactor involving the US-driven PANI was simulated by acoustic-piezoelectric interaction. From cavitation calculations, the estimated effective-mean temperature at bubble-water interface had little increasing (from 704 K to 711 K) after adding the PANI, however, the adsorption capacity of tpmMaG in reactive zone decreased from 0.0891 μM to 0.0787 μM. The mechanism (PANI hot turbo-micromotors) with US/PANI-PS was proposed. The tpmMaG was removed with a low treatment cost of 2.81 $⋅m−3 (the EE/O value 18.29 kWh⋅m−3) by US/PANI-PS, presenting a cost-effective treating process. The reusability tests and characterizations (contact angle, X-ray diffraction (XRD), and scanning electron microscope (SEM)) further confirmed the stability of PANI.