Degradation of PVA (polyvinyl alcohol) in wastewater by advanced oxidation processes

Abstract

Advanced oxidation processes (AOPs) constitute a promising technology to treat wastewater containing organic pollutants that are not easily biodegradable. They have received increasing attention in the research and development of wastewater treatment technologies in recent decades for their removal or degradation of recalcitrant pollutants or as pretreatments to convert pollutants into smaller compounds, which can be treated using conventional biological methods. Polyvinyl alcohol (PVA) is a typical refractory organic pollutant. It has received special attention due to its low biodegradability and the large amount of PVA-containing wastewater discharged from textile and paper mills. This review focuses on PVA removal and PVA wastewater pretreatment by AOPs, which include ozonation, Fenton oxidation, persulfate oxidation, ultrasound cavitation, ionizing radiation, photocatalytic oxidation, wet air oxidation and electrochemical oxidation. The mechanistic degradation pathways of PVA by AOPs are also discussed. In addition, a new classification of AOPs is applied for PVA treatment.

Development of two dosimetry systems based on basic violet dye for possible use as radiation dosimeters

“…We can conclude that, -C = N-breakdown is accomplished by a reduction process for the hydrogen radical produced as a result of water fragmentation in equation ( 1) and polymer fragmentation (Sun et al, 2017), that upon gamma irradiation chlorine atom was released from the dye structure as a free radical chlorine atom that reacts with hydrogen atom as free radical to form HCl which makes fast chemical reaction and degradation of the dye from purple to colorless and as shown in equations ( 2) and (3) leading to the absence of the main source of color. By increasing the absorbed dose, the number of free radicals increases, which breaks down the functional group and the chromophores disappear also, the recombination between Cl of dye and hydrogen radical produce HCl which leads to color bleaching (complete degradation).…”

Composite Poly(vinyl alcohol)-Based Nanofibers Embedding Differently-Shaped Gold Nanoparticles: Preparation and Characterization

“…For the sake of completeness, Figure 4 c reports the reflectance spectra of the pristine PVA nanofibers before (black line) and after (gray line) annealing. Interestingly, the thermal treatment generates a decrease in the diffuse reflectance in the visible spectral range that induces a yellowish color to the fibers, most likely due to the occurrence of molecular changes induced by macromolecular thermolysis [ 45 , 46 ]. As such, the signals corresponding to the absorbance of the AuNPs cannot be clearly distinguished in the annealed fibers.…”

Degradation of Polyvinyl Alcohol in US Wastewater Treatment Plants and Subsequent Nationwide Emission Estimate

“…However, a combination of UV-chlorine treatment resulted in 92% degradation within 10 min and 100% in 20 min. Advanced oxidation technologies have been documented to eliminate PVA completely from wastewater in a matter of minutes [ 15 ]. These processes can be expensive and thus not cost-effective for the municipality.…”

“…This can inhibit oxygen transfer, causing irreparable harm to aquatic life [ 10 ]. Additionally, because of its hydrophilicity, PVA has the potential to adsorb dangerous chemicals or contaminants [ 11 ], such as antibiotics [ 12 ] or heavy metals [ 13 , 14 , 15 ], at high concentrations. These can then concentrate up food chains [ 16 ], posing a threat to the environment, similar to behavior of traditional polluted plastics.…”