Competition adsorption of malachite green and rhodamine B on polyethylene and polyvinyl chloride microplastics in aqueous environment

Abstract

Microplastics (MPs) will cause compound pollution by combining with organic pollutants in the aqueous environment. It is important for environmental protection to study the adsorption mechanism of different MPs for pollutants. In this study, the adsorption behaviors of malachite green (MG) and rhodamine B (RhB) on polyethylene (PE) and polyvinyl chloride (PVC) were studied in single systems and binary systems, separately. The results show that in single system, the adsorptions of between MPs for pollutants (MG and RhB) are more consistent with the pseudo-second-order kinetics and Freundlich isotherm model, the adsorption capacity of both MPs for MG is greater than that of RhB. The adsorption capacities of MG and RhB were 7.68 mg/g and 2.83 mg/g for PVC, 4.52 mg/g and 1.27 mg/g for PE. In the binary system, there exist competitive adsorption between MG and RhB on MPs. And the adsorption capacities of PVC for the two dyes are stronger than those of PE. This is attributed to the strong halogen-hydrogen bond between the two dyes and PVC, and the larger specific surface area of PVC. This study revealed the interaction and competitive adsorption mechanism between binary dyes and MPs, which is of great significance for understanding the interactions between dyes and MPs in the multi-component systems.

Adsorption of Pyrethroids in Water by Calcined Shell Powder: Preparation, Characterization, and Mechanistic Analysis

“…Adsorption isotherms could be used to analyze the interaction between the adsorbent and the adsorbed materials at an equilibrium state [ 20 ]. Langmuir model (Equation (6)) is based on the adsorbate being monolayer and uniformly adsorbed on the surface of the adsorbent, and there exists no interaction between the adsorbates.…”

“…Peinemann et al successfully removed phosphate from a lactic acid-containing fermentation broth using a shell powder, and the phosphate removal efficiency was as high as 95% after 2 h [ 17 ]. Notably, most studies on the adsorption of environmental pollutants have focused on metal ions [ 18 , 19 ], dyes [ 20 , 21 ], and pesticides [ 22 ], and much progress has been made in the study of conventional pesticide adsorption, while reports on the adsorption of newer generations of insecticides such as pyrethroids are rare.…”

Influence of Hydrothermal Modification on Adsorptive Performance of Clay Minerals for Malachite Green

“…The maximum q e (q e,max ) was achieved within the pH 0 range of 6.0~8.0 (i.e., about 290 mg/g), and was 61% higher than that of CM. H + or Na + in the solution competed with MG for adsorption when pH 0 was too low or too high [39]. Therefore, it was more conducive to the adsorption of granules when pH 0 was in the neutral range (the pH of adsorption reaching equilibrium (pH e ) was basically in a near neutral state).…”