Microplastics and organics – A comparative study of sorption of triclosan and malachite green onto polyethylene

Abstract

This study aims to elucidate interaction of organics with microplastics in a comparative manner via the use of two model compounds (i.e., triclosan and malachite green) having different physicochemical properties, onto polyethylene (PE). TCS, is hydrophobic with low solubility, while MG is hydrophilic with high aqueous solubility. Kinetic studies indicate faster sorption (teq = 24 h) and equilibrium studies show much higher capacity (qe = 6,921 mg/g) for TCS, when compared to those of MG (teq = 5 d, qe = 221 mg/g). While pseudo-kinetic model fits sorption of both organics to PE, equilibrium isotherms as well as the results on effect of particle size and pH indicate dissimilar sorption mechanisms. Considering pHPZC = 2, observation of favourable sorption of TCS in acidic region and sorption being unaffected by particle size was explained by TCS sorption to be dominated by hydrophobic interactions in amorph regions of PE. Higher removal of MG was observed at lower surface charge of PE, and a clear favourable impact of surface area on MG sorptive capacity pointed to the presence of non-specific van der Waals type interactions on the surface of PE. Mechanistic evaluations presented here contribute to our understanding of interaction of MPs with organics in aquatic ecosystems.

Comparative study of degradation of pharmaceutical and personal care products in wastewater by advanced oxidation processes: Fenton, UV/H2O2, UV/TiO2

“…In the Fenton process, as the pK a of the compound (7.8) is high at acidic pH, ionization cannot be at the desired level, and therefore, it shows lower reactivity, and accordingly, TRC removal becomes difficult. [41,42] During optimization studies, it was discovered that lower chemical doses effectively eliminated DFC, IBU, and PRC. As a result, the operating range for DFC and IBU was determined to be 0.035-0.210 mM, whereas for PRC, it was 0.075-0.140 mM.…”