Microplastics are ubiquitous in our daily life because of their low cost, portability, durability, and processability. However, since their chemical inert character and their accumulation problems exhibited a great threat to the sustainable development and ecocystem. Photo degradation of microplastic is a clean removal green technology. Therefore, in this study polyvinyl chloride (PVC), polypropylene (PP) microplastics was photodegraded with a novel heterogenous nanocomposite namely Bi2WO6 / Fe3O4 nanocomposite. The effects of increasing Bi2WO6 / Fe3O4  nanocomposite concentrations, PP and PVC concentrations, photodegradation time, pH, temperature on the photodegradation yields of PP and PVC yields were examined.For maximum PVC and PP yields (99% and 98%) the optimized conditions were as follows: Ph=5, 1.5 mg/l Bi2WO6 / Fe3O4  nanocomposite concentration, 800 mg/l PVC and PP concentrations, 15 min photodegradation time, 40 W/m2 sun ligth power, 30 Oc temperature and 0,9 mg/l Cl-1, SO4-2, BrO3-1, PO4-3 and CO3-2 ion concentrations. The XRD analysis showed that the cristal structure of Fe3O4/Bi2WO6 nanocomposite originated from the Bi2WO6 not from Fe3O4. The XPS disturbances of Fe3O4/Bi2WO6 nanocomposite showed the presence of Fe, W, O, and Bi elements.TEM and SEM imaged showed that  the Fe3O4/Bi2WO6  nanocomposite  exhibited a palm shape with  uniform structure of Bi and Fe. HR-TEM analyses showed that the nanocomposite exhibited a 2D (dimensional)-2D heterostructure...

Polyvinyl chloride (PVC) and polypropylene (PP), as engineering plastics, are extensively used in  life and industry .They are found as microplastic in aquatic, marine, and soil environments.  PVC and related plastic products are non-biodegradable in natural environment because of their chemical inertness(1). The PVC plastics become one of the main sources of “white pollution”. Traditional processing methods, such as garbage deposit or incineration, cause a serious secondary pollution. Therefore, the development of degradable PVC plastics becomes an important issue. There are some disadvantages in these PVC plastics, mainly the long degradation cycle and the incompleteness of the degradation, which limit their practical applications(2). Polyvinyl Chloride (PVC or Vinyl) is an economical and versatile thermoplastic polymer. It is widely used in the building and construction industry to produce door and window profiles. It also finds use in:drinking and wastewater pipes, wire and cable insulation, medical devices, etc. It is the world’s third-largest thermoplastic by volume after polyethylene and polypropylene(3-6). It is a white, brittle solid material available in powder form or granules. PVC is now replacing traditional building materials in several applications. These materials include wood, metal, concrete, rubber, ceramics, etc. in several applications. This is due to its versatile properties such as: lightweight, durable, low cost, and easy processability.  Polypropylene (PP) is a type of polyolefin that is slightly harder than polyethylene. It is a commodity plastic with low density and high heat resistance. It finds application in packaging, automotive, consumer goods, medical, cast films, etc(7-9). A lot of studies showed that MP pollution  in the surface water  consisted of polypropylene (PP),  and polyvinyl chloride (PVC). The pollution of these MPs  cause to diferent interactions  affecting their migration and  transformations(10-12). The photodegradation of MPs in the environment during solar irradiation and the photolyzis  of  PP and PVC and OH radical production   via ultraviolet ligth  is an phenomenon. As a result, that the photolyzis  PP and PVC were feasible process  during their photodegradation. The photodegradable PVC and PP by some photocomposites exhibited their  ability to decomposibiliy properties It is important to note that the  during the photocatalytic degradation of PVC  And PP  dioxins were not produced and the decomposition  intermediates were not toxic to the  environmental ecocystems(13-20). It has been reported that reactive oxygen species produced from the photodegradation of  irradiated PP and PVC  MPs increases the absorption of UV energy(21-25.  During irradiation of MP  the release of volatile and dissolved organic matters can be performed. Although Fe3O4/SiO2/TiO2 nanocomposites with enhanced photocatalytic activity and fast magnetic separability can be used in the photodegradation of PP and PVC low removal yields was detected. Fe3O4/metal hybrid nanostructures with polymers as such as Fe3O4@C@Cu2O nanostructure can be used in the microplastics degradation. However, the synthesis of these magnetic nanocomposites requires some linker organics like  silica, polymers, carbon  making the synthesis  more favorable and decrease the saturation magnetization (Ms) of the generated nanocomposites. Some magnetic nanocomposites like Fe3O4@Bi2O3  and Fe3O4/WO3 can be used in the photodegradation of some organics(26-30). Fe3O4 exhibited rapid recombination of photogenerated carriers. The Z-scheme heterojunction exhibited  ultimate light absorption capacity and goog separation yield of charge carriers has  magnetic properties and can cause easy to recover the nanocomposite. The Fe3O4 can adhere to the semiconductor material and Fe3O4  can directly contact  with Bi2WO6 to form heterojunctions. This increase the photodegradation yields  by elevated increases the contact area between the two substances ending with  high electron  transfer to the pollutants(18-22) . Bi2WO6  has a hydrophilic surface, can be dispersed in water is simple, cheap and high stable. Previous studies have already demonstrated that Bi6WO12  exhibited  higher optical absorption at a wavelength above 440 nm than Bi2O3 or WO3, by enhancing the  photocatalytic activity under solar illumination . The structure of Bi2WO6 exhibited crystalline properties  and is generated by   (Bi2O2)n2n+ layers and perovskite-like (WO4)n2n− layers. However, However  some times exhibited low photocatalytic activity in visible light region and the separation and recovery of this nano metal oxide was not possible(32-34). Magnetic separation provides an effective way for recycling the magnetic composites by providing appropriate external magnet areas. Supermagnetic Fe3O4 was associated with the photocatalyst to obtain a recoverable composite. The magnetic  Fe3O4-Bi2WO6 was used in β-cyclodextrin (β-CD) removal with high-efficiency as carrier separation and semiconductor stabilization(35-38). The photodegradation yields of pollutants can be attributed to the  its hydrophilic external surface, hydrophobic interior, and specific cavity diameter. Fe3O4-Bi2WO6 nanocomposite  was used in the photocatalytic degradation of sunset yellow dye, of  sulfamethoxazole, phenol, and rhodamine B  dyes. However Fe3O4-Bi2WO6  nanocomposite was not used yet for the photodegradation of micropollutants(39-40). Therefore, in this study it was aimed to detect  the photocatalytic capacities of PVC and PP microplastics under sunligth by using Fe3O4-Bi2WO6 nanocomposite. The photodegradation yields were investigated and the impacts of different reaction factors on the photodegradation, such as the amount of photocatalyst, the initial concentration of PP and PVC, photodegradation time, temperature, sun ligth water, initial pH and the presence of some ions were examined. The structure, morphology of the Fe3O4-Bi2WO6  nanocomposite were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), field emission transmission electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS) and  Fourier transformation infrared spectra (FT-IR) spectroscopy analysis. 

The molecular formula of PVC and PP were illustrated in Picture 1.

PV

PVC

Synthesis of Bi2WO6 samples

For Bi2WO6 production, 0.98 g Bi(NO3)3·5H2O was dissolved in 35 mL distilled water to form a homogeneous solution and stirred for 20 min and sonicated  during  40 min. Then 0.33 g Na2WO4·2H2O was dissolved in 30 mL and stirred for 40 min. After the pH was adjusted  to 6.00. Then, the mixture was maintained at 180 °C for 12 h in an autoclave. The precipitate was rinsed with distilled water and ethanol for four times. The obtained product was dried at 80 °C and denoted as bulk-Bi2WO6. Subsequently, the bulk-Bi2WO6 samples were calcined at  a temperature of 450 °C, for four h. The corresponding products were named as Bi2WO6.

Synthesis of Fe3O4 Nanosheets

For generation of Fe3O4 nanocomposite  69 mmol Fe(NO3)3·9H2O was dissolved in 35 mL of the deionized water. It was mixed during  15 min. The pH of the solution  was adjusted to  7.0 . Then the mixture  was heated in a water bath at 60 °C for 8 h and at 130 °C for 5 h. During heating with N2 at  600 °C, it was roasted for 6 min. Then Fe3O4  nanocomposite  was retained.

Synthesis of the Fe3O4/Bi2WO6  Nanocomposite

In the production of Fe3O4/Bi2WO6 nanocomposite  certain  amounts of Fe3O4  (0.1, 3, , 9, 12 %)  was dissolved in 40 mL of deionized water for 40 min. Then, 0,1 ml of Bi(NO3)3·5H2O and Na2WO4·2H2O was dissolved into 30 mL 0,1 N HNO3 and 30 mL of 1 mol·L–1 NaOH solution, respectively. The Bi(NO3)3·5H2O solution and Na2WO4·2H2O solution were added to the Fe3O4 mixture. After mixing  the mixture was cleaned  in an autoclave at a temperature of 120 °C for 10 h. The settled  chemical was washed with the deionized water. The sample was dried at 50 °C for 14 h. As a result  Fe3O4/Bi2WO6  nanocomposite was obtained. 

Characterization of Fe3O4/Bi2WO6  Nanocomposite

The crystal structure of the nanocomposite was performed by  XRD (MerCK, USA) at the angleck, range of 2θ = 8–100° using Cu-Kα irradiation (λ = 0.15418 nm). The morphologies and structures were examined by SEM (Zeiss Sigma HD, Germany) and FESEM (Tecnai G2 F20 S-TWIN TMP, USA). FT-IR was performed on Nicolet iS50 (Thermo Fisher Scientific, USA) spectrophotometer in the range of 400–4000 cm−1. The chemical status and elemental compositions were analyzed by XPS (Thermo Fisher Scientific, USA) with monochromatic Al-Kα source (hν = 1486.6 eV, 6 mA × 12 kV).

 Photocatalytic degradation of PVC and PP

The photocatalytic activities of the Fe3O4/Bi2WO6  nanocomposite was investigated by the degradation of PVC and PP under sunligth  irradiation. In the  experiments certain amount of  Fe3O4/Bi2WO6  nanocomposite , PVC and PP concentrations were suspended into 100 mL distilled water. After certain photodegradation times  2 mL of samples were withdrawn and centrifuged. 

Measurements of PVC and PP concentrations 

For PVC measurements  ion chromatography (C-IC) was used.. Hydrogen chloride (HCl) was quantitatively released from PVC during thermal decomposition and trapped in an absorption solution. Selectivity of the marker HCl in complex environmental samples was ensured using cleanup via pressurized liquid extraction (PLE) with methanol at 100 °C (discarded) and tetrahydrofuran at 185 °C (collected).The  recoveries was around  85.5 ± 11.5% . PP was measured by gas chromatography/ mass spectrometry (Py-GC/MS). Samples was pre-rinsed with analytical grade MilliQ® water (Millipore, Burlington MA, USA) after adding 15 ml of TRIS-HCl buffer (400 mM Tris-HCL, pH 8, 0.5% SDS, Trizbase T6791, HCl H1758, Sigma). The samples were then filtered over a mm GF/F glass fiber filter, diameter 25 mm, mesh size 700 nm (1825–025, Whatman, Maidstone, United Kingdom). To ensure removal of any plastic contamination present, filters were always heated in a 500 °C muffle oven purged with nitrogen prior to filtration.

Xrd Results Of Fe3o4/Bi2wo6  Nanocomposite

XRD analysis were performed to detect the  crystallinity of the nanocomposite. The XRD. The  diffraction peaks of Bi2WO6 at 2θ = 29.88, 34.99, 48.77, and 56.11° correspond to the (114), (021), (221), and (315) crystal disturbances  of Bi2WO6( Figure 1) .The XRD spectra of Fe3O4 indicates  four peaks at 2θ = 18,88,  31.87, 37.09, and 63.18° corresponding  to the (112), (221), (313), and (442) crystal peaks (Figure 1). The XRD results of Fe3O4/Bi2WO6  nanocomposite showed that disturbed  Fe3O4 was not  not visible  in the whole nanocomposite indicating the presence of low ratio of the  Fe3O4.  Therefore, the Fe3O4/Bi2WO6  nanocomposite  exhibited low crystallinity . This confirm that the cristal structure of Fe3O4/Bi2WO6  nanocomposite originated from the Bi2WO6  not from Fe3O4. 

Figure 1: XRD spectra of Fe3O4,  Bi2WO4, and  Fe3O4/ Bi2WO4 nanocomposite

XPS results of Fe3O4/Bi2WO6  Nanocomposite

The peaks of XPS spectra of the Fe3O4/Bi2WO6  nanocomposite  showed the presence  of Fe, W, O, and Bi elements (Figure 2). The peak disturbances relevant to Bi is doped  at 162.8 and 166.9 eV, respectively. This showed the presence of Bi3+ in the Fe3O4/Bi2WO6  Nanocomposite (Figure 2). The  bands at 713.9 and 726.7 eV,  can be defined as  Fe 2p3/2 and Fe 2p1/2 . This shows  the presence  of Fe2+ and Fe3+.  The existence of Fe3+ and Fe2+ indicates the presence of  Fe3O4. The spectrum diagram at 533.9 and 532.6 eV of O 1s indicates  the presence of  Bi–O and W–O as [WO4]2– and [Bi2O2]2+, respectively. The peak  at 527.8 eV is indexed to Fe–O bonds. Fe3O4 was witheen Bi2WO6 and during phpotooxidation the   electrons activated in the  holes.

Figure 2: XPS analysis for  Seri 1(Counts (au ) for W 4f), Seri 2( Counts (au ) for  Bi  W 4f ej, Seri 3(Counts (au ) for  Bi 4d  O 1s) and Seri 4(Counts (au ) for  Fe 2p

SEM and TEM  results of Fe3O4/Bi2WO6  Nanocomposite

 The SEM and TEM images of Fe3O4  were illustrated in Figure 3a and 3b,respectively. From Figure 3a a palm shape was observed for   Fe3O4/Bi2WO6  Nanocomposite. It is uniform structure and every palm  is stacked to the main catalyst. The thickness of the nanocomposite was 35 nm. The negatif charge  of the Fe3O4  surface leads to the homogen adsorption of Bi3+ on the surface of Fe3O4/Bi2WO6  Nanocomposite. In the next steps, Bi3+ d react with WO42- and Bi2WO6 was generated. 

Figure 3: SEM (a) and TEM analyses results of Fe3O4/Bi2WO6  Nanocomposite

HR-TEM results of Fe3O4/Bi2WO6  Nanocomposite

HR-TEM analyses ( Figure 4a) showed the  flake structure of the nanocomposite.  The  2D (dimensional)-2D heterostructure of the nanocomposite  has a  heterojunction  structure cause to  grow of Bi2WO6 around of the Fe3O4..The lattice fringes of Fe3O4/Bi2WO6  Nanocomposite corresponded to the (022) plane of Bi2WO6. Figure 4b exhibits the Fe, Bi, O and W ingredients. The bonds of the interface between Fe3O4 and Bi2WO6  facilitate the transfer of electrons and advice the separation of electron–hole pairs during photocatalysis. 

Figure 4: HR-TEM analysis results (a) , Fe, Bi, O and W  in the   Fe3O4 / Bi2WO6 nanocomposite Magnetization of Fe3O4/Bi2WO6 nanocomposite

The magnetization versus magnetic field (M-H loop) for Fe3O4/Bi2WO6 nanocomposite was shown ın Figure 5. A saturation magnetization (Ms) value of 28 emu/g was obtained, which is higher than Fe3O4. The magnetic hysteresis loop indicated  a coercivity of  90 Oe. This provides a good separation of Fe3O4/Bi2WO6 nanocomposite from the liquids  with an external magnetic field.

Figure 5: Magnetization versus applied magnetic field for Fe3O4/Bi2WO6 nanocomposite

FTIR spectra of Fe3O4, Bi2WO6, and Fe3O4/Bi2WO6 nanocomposite

The peaks around  573 cm−1 can be defined  to Fe-O-Fe vibration of magnetite phase. The peak examined near 565 cm−1  show the disturbances after photodegradation (Figure 6). The observed shift can be attributed to the binding of PVC and PP to the surface Fe3O4/Bi2WO6 nanocomposite. The same figure also exhibited the FTIR spectrum relevant to  Bi2WO6. Observed peaks at 733 cm−1 and 578 cm−1 are  defined by the doping  Bi, O and WO, respectively. The  peaks at 1380 cm−1 and 1628 cm−1   were relevant to CH and OH. In Figs. S2c and S2d, the  maximum peaks of the Fe3O4/Bi2WO6 nanocomposite detected near 3333 cm−1 can be attributed to OH vibration of bonded water. The Bi2WO6 bands at 450–1790 cm−1 were attributed to BiOBi, WO bondings.After photodegradation  the FTIR data of Fe3O4/Bi2WO6 nanocomposite indicates the presence of  small amount of organics doped on  the surface of  nanocomposite.

Figure 6: FTIR spectra of Fe3O4,  Bi2WO6, raw Fe3O4/Bi2WO6 nanocomposite and after photodegradation process Operational conditions affecting the photodegradation of polyvinyl chloride (PVC) and  polypropylene (PP)

Effect of pH on the photocatalysis of PVC and PP

The surface of the  is positively charged in acidic conditions and negatively charged in the basic medium. Fe3O4/Bi2WO6  has higher oxidizing activity in lower acidic pH. The optimum pH for  maximum photodegradation of polyvinyl chloride (PVC) and  polypropylene (PP)  ( 99% and 98%,respectively) is 5 whilst exhibited lowest photodegradation at pH 8 ( 56% and 50%,respectively)( Table 1). At optimal pH, during PVC and PP photodegradation the  negatively charged groups of  the microplastics strongly interact with the positively charged surface of the Fe3O4/Bi2WO6  nanocomposite  in an acidic medium The pH of zero-point charge (pHpzc) for Fe3O4/Bi2WO6  nanocomposite  is 6.1. Thus, below pHpzc, Fe3O4/Bi2WO6  nanocomposite   surface acquires a positive charge to attract to the negatively charged PVC and PP. Under these conditions PVC and PP  concentrated on the Fe3O4/Bi2WO6  nanocomposite  surface. The lectrostatic repulsion between the negatively charged PVC and PP and the negative charge of the Fe3O4/Bi2WO6  nanocomposite  surface above pHpzc  retards the doping  of the PVC and PP  resulting in lower photocatalytic activity. In this study higher pH is not suitable for photodegradation of  PVC and PP due to  competes with the organic pollutants for getting doped on the Fe3O4/Bi2WO6  nanocomposite  surface. However, lower pH increase the doping  PVC and PP, therefore, increase the efficiency of the PVC and PP photodegradations. 

Table 1: Variations of PVC and PP photodegradation yields versus pH

Effect of Fe3O4/Bi2WO6  nanocomposite concentrations on  PVC and PP photodegradation yields

The efficiency of the PVC and PP photodegradation is relevant with Fe3O4/Bi2WO6  nanocomposite concentrations.  As the Fe3O4/Bi2WO6  nanocomposite concentration  was increased the PVC and PP photodegradations yields increased.  As the the Fe3O4/Bi2WO6  concentration was increased from 0,5 mg/l up to 1 and 1.5 mg/l  the PVC and PP phodegradation yields were increased from 67%, 64% to  82% , 80% and to 99%, 98%,respectively( Table 2).  Further increase of nanocomposite concentrations to  2.0 , 2.5 and 3.0 mg/l did not affect the PVC and PP photodegradation yields.   Nanocomposite  surface area elevated  with the increase in the amount  nanocomposite loading. The meaning  of the large surface area is the presence of active  sites  and the presence of  high cencentrations of  OH• radicals. However, as the Fe3O4/Bi2WO6  nanocomposite  concentration was increased to  2 and 3 mg/l the linear correlation between nanocomposite and microplastics  was not detected. Excess concentration of the catalyst turned the solution turbid and increase light dispersion resulting in the lower light penetration for effective photodegradationof PVC and PP. 

Table2: Variations of   PVC and PP photodegradation yields versus Fe3O4/Bi2WO6  nanocomposite concentrations

Effect of Concentrations of PVC and PP on  PVC and PP photodegradation yields

For maximal PVC and PP photodegradation yields the optimal PVC and PP concentrations  should be studied. The PVC and PP concentrations were increased from  20 mg/l up to  40,  80, 150, 300, 500, 600, 800, 1000, 1200 and 1500 mg/l. As the PVC and PP concentration were increased  the pollutant yields were detected as 99 and 98% up to a PVC and PP concentrations of 1200 mg/l,respectively( Table 3). Furher increse of  PVC and PP concentrations the microplastic  photodegradation yields sligthly decreased to 89% and 88%, respectively. At 20-150 mg/l PVC and PP concentrations the yields of micropollutants were 76% and 75% .Although  the photodegradation is lower at a lower initial PVC and PP concentrations the photodegradation yields elevated  to a certain micropollutant  concentration and then began to decrease at high micropollutant concentrations. Increasing PVC and PP levels cause to doping of  these organics  on the surface of the nanocomposite . Then  ligth penetration coming to nanocomposite surface decreased. The relathionship between PVC and PP and molecules and the active sites  of the Fe3O4/Bi2WO6  nanocomposite   is  extremely high at low micropollutant concentrations. The the photons and OH radical concentrations going to  the Fe3O4/Bi2WO6  nanocomposite   surface also elevated when the micropollutants  concentrations were elevated. As a result, these conditions cause to decrease of the  photon and OH concentrations reaching on the surface of Fe3O4/Bi2WO6  nanocomposite   ending with low photodegradation yields. 

Table 3:  Effect  PVC and PP Concentrations on PVC and PP photodegradation yields

Effect of some ions namely Cl−, SO42−, BrO3−, PO43−, CO32−, HCO3 on PVC and PP photodegradation yields

In industries produced microplastics like PVC and PP   some chemicals like KCl, Na2SO4, Bi3BrO, Na3PO43−, Ca2CO3  and NaHO3  were used during  polymerisation of raw feding material. However, inorganic ions like Fe2+, Ag+, Zn2+, Na+, Cl−, SO42−, BrO3−, PO43−, CO32−, HCO3− and persulphate ions; some times effect negatively the process  or  can stimulate the  photodegradation efficiency and can be decrease the 

photodegradation  duration. İt was found that low concentrations of Cl−, SO42−, BrO3−, PO43−, CO32−, HCO3 ions did not affect ( 0.1, 0.3, 0.5 , 0.9 mg/l) the photodegradation yields of PVC and PP( Table 4). High concentration of these ions ( 2, 4 and 6 mg/l) decrease the PVC and PP photodegradation yields to 87% and 85%,respectively. The reason of this can be attributed to the quenching effects   for OH radicals.  CO32−, HCO3−  lowered the microplastic yields   by  scavenging the OH• radical productions . 

Table 4: Effects of Cl−, SO42−, BrO3−, PO43−, CO32−, HCO3concentrations  on PVC and PP photodegradation yields

Effect of Temperatures on PVC and PP photodegradation yields

In this study, it was found that as the temperature was increased from 15 oC to 22 and to  30oC the phtodegradation yields of PVC and PP increased from 56%, 59% to 99% and  from 55% and to 57% and 98% (Table 5). Furher increase of temperature to  40 and 50 oC affected negatively the microplastic photodegradation yields.  80-76% and 79%- 75% photodegradation yields were detected for PP and PVC under aforementioned temperatures. Although increasing of  temperature elevated the photodegradation efficiency,  higher temperature did not provides to generation of enough  OH radicals  and continous electron–hole recombinations  were not occurred.  In heterogeneous photocatalytic systems, temperature was found to have an indirect effect on the photodegradation of microplastics. In particular, low temperatures accelerates the doping of PVS and PP  on the surface of Fe3O4/Bi2WO6  nanocomposite.    At elavated the increasing of the disturbing of the PVC and PP microplastics elevates  the kinetic energy. The high  kinetic energy in the microplastics can be emitted from photodegradation yields. 

Table 5: Effect of Temperatures on  PVC and PP photodegradation yields

Effect of  Sun Light Intensity on  PVC and PP photodegradation yields

 In this study as the sun ligth intensity increased from10 W/m2 to 20 W/m2 the PVC and PP yields increased from 76% and 74% to 89 and 88%  At 40 W/ms sun ligth intensity maximum PVC and PP photodegradation yields was detected as 99% and 98%,respectively( Table 6).. Furher increase of sun ligth intensity to 60 and 80 W/m2 the pollutant yields decreased to 78% and 75%. At 100 W/m2 the yşields decreased to 56% and T% for PVC and PP, respectively. At high light intensity photons per unit time and unit area decreased  ending with low photocatalytic activity.The unwanted electron–hole recombination is high when irradiated at high sun ligth intensity ending with decreased photodegradation yields. At elevated light intensity electron–hole pairs recombination is high thus results  with low PVC and PP yields 

Table 6: Variations of PVC and PP photodegradation yields versus Sun Light Intensity

Effect of Irradiation Time on  PVC and PP photodegradation yields

The photodegradation capacity of the Fe3O4/Bi2WO6  nanocomposite  versus PVC and PP yields were investigated during irradiation time. The PVC and PP photodegradation yields increased   from 59%, 56%  to  79%, 76% with an increase in the photodegradation time from 5 min to 10  min (Table 7). After 15 min photodegradation time the yields of PVC  and PP reached 99% and 98%,respectively. This attributes to an increase in the formation of more OH• and O2•− with irradiation time. However, the photodegradatiın yield decreased after an optimum time. This optimum time depends on the catalysts as well as the types of  microplastics.  After 20 min photodegradation  the PVC and  PP photodegradation yields  decreased sligtly to 90% amd 89%.  The reduced rate of degradation after a certain time limit is attributed to the difficulty in the photooxidation of the intermediate products. The photodegrataion efficiency is a function of irradiation time. At the beginning of the photodegradation,  high rate formation of OH•  process  improve the PVC and PP yields.  After 20 min OH molecules between  surface and bulk phase hindered the filling of remaining active sites in the Fe3O4/Bi2WO6  nanocomposite.After  30 and 40 min the photodegradation yields tends to a constant value of 79% and 76% for PVC and PP.

Table 7: Variation of  PVC and PP photodegradation yields versus photodegradation time

The  results of PVC and PP photodegradation high photocatalytic activity of Fe3O4/Bi2WO6 nanocomposites under sunlight conditions. The high performance and durability of this composite can be attributed to the high photocatalytic capacity due to enhanced visible sun  light absorption. The PVC and PP photodegradation behavior, the influencing factors were investigated in this study.