Surface modification of polyethylene microplastic particles during the aqueous-phase ozonation process

Abstract

Microplastics coexist with the chemical reactive oxygen species in natural waters, however, there is still a lack to elucidate the effect of these radicals on the microplastic surficial oxidation. In this study, the ozonation of polyethylene microplastics was carried out under varying ozone dosages ranging from 4 to 7 mg/min for 60, 120 and 180 min, where its ozone uptake was iodometrically compared and surficial modification was spectroscopically analyzed using FTIR and XPS. For that, the lowest ozone uptake was 16% at 4 mg/min ozone supplied for 60 min whereas the highest was observed of 44% at 7 mg/min ozone added for 180 min. Moreover, in the FTIR analysis, carbonyl (1,600-1,800 cm-1) and hydroxyl (3,200-3,600 cm-1) indices were improved more than 20% and 13% when they were ozonized at 7 mg/min for 180 min compared to 4 mg/min for 60 min, respectively. XPS also revealed that 7 mg/min of ozone supplied for 180 min provided the highest of oxygen functionalities, but while there was no significant change in CC bond. It can be concluded that the surficial modification of PE including formation of oxygen functionalities could be more preferably influenced by the reaction time than ozone dosages.

Hydrophilization of Hydrophobic Mesoporous High-Density Polyethylene Membranes via Ozonation

“…In this work, to achieve marked structural surface modification of the samples, two routes are possible: prolong treatment (dozens of hours) with low ozone concentrations (~5.5 × 10 −6 mol/L) or short-term treatment with high ozone dosage (~10 −3 mol/L). According to data in the literature, the second route has been proved to be the most reliable [ 15 ]. Figure 3 presents the kinetic curves of ozone uptake by MP HDPE membrane in comparison with the blank test and pristine HDPE.…”

“…[ 20 , 45 , 46 ]. Ozonation also provides marked structural changes in diverse polymers, thus leading to the modification of their structure and properties [ 15 , 20 ].…”

“…The advantages of ozonation for surface modification of polymers [ 14 , 15 , 16 , 17 , 18 , 19 ] are primarily concerned with the high oxidative potency of ozone, available equipment, low cost, natural origin of ozone, ecological safety, efficient and controlled regimes in the reactor, and ability to treat the samples with complex surface morphology and complicated shapes [ 19 , 20 ]. In addition to the solution of practical issues, studies in this direction are deeply connected with scientific problems which involve the search for new strategies which extend the benefits of this approach and allow preparation of innovative polymeric materials with task-oriented properties as well as the assessment of the potential of ozonation for degradation of polymers and solution of ecological challenges of waste treatment.…”

Comparison of surficial modification of micro-sized polyethylene in between by UV/O3 and UVO submerged system

“…The UVO regime showed a significant difference in increasing the absorption peaks, referring to the enhanced surficial modification to that of the control (ozone-treated without UV irradiation) [27]. Conversely, the extent of surface oxidation of the PE MP particles was lower than that produced in the O 3 +UV system.…”

Coronas of micro/nano plastics: a key determinant in their risk assessments

“…Gaining insight into the biological impacts of M/NPs requires identification and quantification of the corona constitutions, raising challenges for analytical methods. In situ analysis was initially proposed to interpret the corona structures by material characterization techniques, such as ultraviolet-visible spectroscopy (UV-vis) [ 210 ], Raman spectroscopy [ 211 ], FTIR [ 212 ], X-ray photoelectron spectroscopy (XPS) [ 213 ], Auger electron spectroscopy (AES) [ 214 ], atomic force microscopy (AFM) [ 215 ], time of flight secondary ion mass spectrometry (TOF-SIMS) [ 216 ], or energy–dispersive X-ray (EDX) [ 217 ] analysis. However, most of these methods are not suitable to identify all molecular constituents in coronas.…”