scholarly journals First Insights into Photocatalytic Degradation of HDPE and LDPE Microplastics by a Mesoporous N–TiO2 Coating: Effect of Size and Shape of Microplastics

Coatings ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 658 ◽  
Author(s):  
Brenda Estefanía Llorente-García ◽  
Juan Manuel Hernández-López ◽  
Antonio Alberto Zaldívar-Cadena ◽  
Cristina Siligardi ◽  
Erika Iveth Cedillo-González
Keyword(s):  
Photocatalytic Degradation ◽  
High Density Polyethylene ◽  
Reaction Medium ◽  
Tio2 Coating ◽  
Negative Consequences ◽  
Plastic Debris ◽  
Reaction Systems ◽  
Size And Shape ◽  
Plastic Bag ◽  
Ci Calculation

Microplastics (MPs), which are small plastic debris of ≤5 mm size, are polluting the oceans with negative consequences for their biota. In this work, visible-light photocatalysis of high-density polyethylene (HDPE) and low-density polyethylene (LDPE) MPs in aqueous medium using a mesoporous N–TiO2 coating is proposed as an alternative for fighting MP pollution. Spherical primary HDPE MPs were extracted from commercially available facial scrubs, while film-shaped secondary LDPE MPs were obtained from a plastic bag. For each plastic, two different sizes were tested. Degradation was measured by mass-loss and carbonyl-index (CI) calculation. The results obtained reveal that the photocatalytic degradation of HDPE and LDPE MPs using an N–TiO2 coating was affected by the size and shape of the MPs. Smaller MPs led to higher degradation, while film-shaped MPs led to lower degradation that was related to a poorly illuminated and oxygenated reaction medium. These results set the basis for further investigation on the on the design of more effective photocatalytic-reaction systems for decreasing MP inputs to the environment.

scholarly journals On the Reaction Pathways and Growth Mechanisms of LiNbO3 Nanocrystals from the Non-Aqueous Solvothermal Alkoxide Route

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 154
Author(s):  
Mathias Urbain ◽  
Florian Riporto ◽  
Sandrine Beauquis ◽  
Virginie Monnier ◽  
Jean-Christophe Marty ◽  
...  
Keyword(s):  
Colloidal Stability ◽  
Formation Rate ◽  
Reaction Medium ◽  
Precursor Solution ◽  
Medium Composition ◽  
Shape Anisotropy ◽  
Reaction Pathways ◽  
Growth Mechanisms ◽  
Shape Distribution ◽  
Size And Shape

Phase-pure, highly crystalline sub-50 nm LiNbO3 nanocrystals were prepared from a non-aqueous solvothermal process for 72 h at 230 °C and a commercial precursor solution of mixed lithium niobium ethoxide in its parent alcohol. A systematic variation of the reaction medium composition with the addition of different amounts of co-solvent including butanol, 1,3-propanediol, 1,4-butanediol, and 1,5-pentanediol resulted in the formation of nanocrystals of adjustable mean size and shape anisotropy, as demonstrated from XRD measurements and TEM imaging. Colloidal stability of ethanol- and water-based suspensions was evaluated from dynamic light scattering (DLS)/zeta potential studies and correlated with FTIR data. Thanks to the evolution in the nanocrystal size and shape distribution we observed, as well as to the available literature on the alkoxide chemistry, the reaction pathways and growth mechanisms were finally discussed with a special attention on the monomer formation rate, leading to the nucleation step. The polar, non-perovskite crystalline structure of LiNbO3 was also evidenced to play a major role in the nanocrystal shape anisotropy.

scholarly journals Photocatalytic degradation kinetics of Orange G dye over ZnO and Ag/ZnO thin film catalysts

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Derya Tekin ◽  
Taner Tekin ◽  
Hakan Kiziltas
Keyword(s):  
Thin Film ◽  
Kinetic Model ◽  
Photocatalytic Degradation ◽  
Degradation Kinetics ◽  
Reaction Medium ◽  
Rate Equations ◽  
Zno Thin Film ◽  
Model Studies ◽  
Thin Film Catalysts ◽  
Orange G

AbstractThe degradation of water pollutants with photocatalysts is one of the most studied subjects in the past 20 years. Although considerable studies have been completed in this field, kinetic model studies are still a major inadequacy. In this study, ZnO and Ag/ZnO thin film photocatalysts were synthesized and SEM-EDS, XRD and chronoamperometric measurements were used the characterization of photocatalysts. The network kinetic model was applied the photocatalytic degradation of Orange G using ZnO and Ag/ZnO thin film photocatalysts. The photocatalytic degradation of Orange G was investigated under the different reaction medium (initial dye concentrations, temperature, light intensity). It was found that the network kinetic model is the most appropriate model for the degradation of Orange G dye on the ZnO and Ag/ZnO thin film photocatalysts. The calculated adsorption equilibrium (KB) constant and activation energy of ZnO thin film photocatalyst are 0.0191 and 21.76 kj/mol, respectively. Additionally, the calculated values for Ag/ZnO thin film photocatalyst are 0.035 and 18.32 kj/mol. The general rate equations were determined for each photocatalysts.

Photocatalytic degradation of methylene blue in water solution by multilayer TiO2 coating on HDPE

2011 ◽  
Vol 258 (5) ◽  
pp. 1738-1743 ◽  
Author(s):  
Jussi Kasanen ◽  
Janne Salstela ◽  
Mika Suvanto ◽  
Tuula T. Pakkanen
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Degradation ◽  
Water Solution ◽  
Tio2 Coating

scholarly journals Study of pyrolysis of high density polyethylene in the open system and estimation of its capability for co-pyrolysis with lignite

2018 ◽  
Vol 83 (7-8) ◽  
pp. 923-940
Author(s):  
Ivan Kojic ◽  
Achim Bechtel ◽  
Friedrich Kittinger ◽  
Nikola Stevanovic ◽  
Marko Obradovic ◽  
...  
Keyword(s):  
Open System ◽  
High Density Polyethylene ◽  
Synergetic Effect ◽  
Polar Compounds ◽  
High Density ◽  
Feed Stream ◽  
Gaseous Products ◽  
Liquid Products ◽  
Plastic Bag ◽  
Pre Treatment

Pyrolysis of high density polyethylene (HDPE) in the open system was studied. A plastic bag for food packing was used as a source of HDPE. Pyrolysis was performed at temperatures of 400, 450 and 500?C, which were chosen based on thermogravimetric analysis. The HDPE pyrolysis yielded liquid, gaseous and solid products. Temperature rise resulted in the increase of conversion of HDPE into liquid and gaseous products. The main constituents of liquid pyrolysates are 1-n-alkenes, n-alkanes and terminal n-dienes. The composition of liquid products indicates that the performed pyrolysis of HDPE could not serve as a standalone operation for the production of gasoline or diesel, but preferably as a pre-treatment to yield a product to be blended into a refinery or petrochemical feed stream. The advantage of a liquid pyrolysate in comparison to crude oil is the extremely low content of aromatic hydrocarbons and the absence of polar compounds. The gaseous products have desirable composition and consist mainly of methane and ethene. The solid residues do not produce ash by combustion and have high calorific values. Co-pyrolysis of HDPE with mineral-rich lignite indicated positive synergetic effect at 450 and 500?C, which is reflected through the increased experimental yields of liquid and gaseous products in comparison to theoretical ones.

scholarly journals Enhanced Photocatalytic Performance in Chromium(VI) Reduction and Dye Degradation using Sn3O4/SnS2 Nanocomposite and Mechanism Insight

2021 ◽  
Author(s):  
Gandharve Kumar ◽  
Rajkumar Dutta
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Degradation ◽  
Dye Degradation ◽  
Degradation Products ◽  
Degradation Mechanism ◽  
Reaction Medium ◽  
Blue Dye ◽  
Ros Scavenging ◽  
Hydrothermal Route ◽  
Inorganic Species

Abstract Detection of residual organic and inorganic species in water bodies including drinking water has led to developing strategies for their removal. Here we report a very efficient method of photoreduction of Cr (VI) and photodegradation of methylene blue dye in aqueous medium using Z-scheme heterojunction based Sn3O4/SnS2 solar photocatalyst. The photocatalyst is synthesized by hydrothermal route and it is thoroughly characterized in terms of its structural, compositional, morphological and optical properties. About 100 % of Cr (VI) reduction in 60 min and 99.6 % of methylene blue degradation in 90 min is achieve under sunlight exposure at a photocatalytic rate of 0.066 min-1 and 0.043 min-1, respectively. The total organic carbon estimation of the post-degradation reaction medium corresponded to 85.1 % (MB) mineralization. The photocatalytic degradation is attributed to in-situ generation of reactive oxygen species (ROS) e.g., superoxide radicals, hydroxide radicals, and the role of ROS towards reduction and degradation of Cr (VI) and MB respectively, is confirmed from ROS scavenging studies. The dye degradation mechanism has been discussed by analyzing the degradation products via UPLC-Q-Tof-MS. The photocatalytic degradation of methylene blue by Sn3O4/SnS2 nanocomposites is significantly enhanced as compared to SnS2 photocatalyst, attributed to Z-scheme heterojunction and the charge carrier mobility.

scholarly journals Functioned catalysts with magnetic core applied in the ibuprofen degradation

2021 ◽  
Author(s):  
Giane Gonçalves Lenzi ◽  
Mylena Ferreira Lopes ◽  
Dana Isabelly Andrade ◽  
José Salvador Napoli ◽  
Andrieli Parolin ◽  
...  
Keyword(s):  
Photocatalytic Degradation ◽  
Magnetic Separation ◽  
Reaction Medium ◽  
Solution Concentration ◽  
Magnetic Core ◽  
Organic Additive ◽  
Operation Conditions ◽  
The Matrix ◽  
Degradation Reaction ◽  
Activity Loss

Abstract In the present work, the performance of Ag/ZnO/CoFe2O4 magnetic photocatalysts in the photocatalytic degradation of Ibuprofen (IBP) was evaluated. This study considered the use of pure Ag/ZnO (5% Ag) and also use the Ag/ZnO/CoFe2O4 magnetic catalysts containing different amounts (5, 10 and 15% wt) of cobalt ferrite (CoFe2O4). The catalysts were characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and photoacoustic Spectroscopy. To carried the photocatalytic degradation reaction, different concentrations of the ibuprofen contaminant solution (10, 20 and 30 ppm) and different concentrations of photocatalyst were tested (0.3 gL−1, 0.5 gL−1 and 1.0 gL−1). The reaction parameters studied were: IBP concentration, catalyst concentration, adsorption and photolysis, influence of the matrix, radiation source (solar and artificial) and the effect of organic additive. At the end of the photocatalytic tests, the best operation conditions were defined. Considering the obtained results of degradation efficiency and magnetic separation, the optimal parameters selected to proceed with the other tests of the study were: ibuprofen solution concentration 10 ppm, Ag/ZnO/CoFe2O4(5%) catalyst at a concentration of 0.3 g L−1 and pH 4.5 of the reaction medium. The results indicated the feasibility of magnetic separation of the synthesized catalysts. A long duration test indicated that the catalyst exhibits stability throughout the degradation reaction, as more than 80% of ibuprofen was degraded after 300 minutes. The photocatalytic activity was directly affected by the ferrite load. The higher the nominal load of ferrite, the lower the performance in ibuprofen degrading. It was also observed that the smallest amount of ferrite studied was enough for the catalyst to be recovered and reused. The adsorption and photolysis tests did not show significant results in the IBP degradation. In addition, it was possible to verify that the aqueous matrix, the use of solar radiation and the addition of additive (acid formic) interfered direct in the process. The catalyst reuse tests indicated that it can be recovered and reused at least three times without considerable catalytic activity loss.

scholarly journals Waste transformation of plastic bags by wet polymer binding

2020 ◽  
Vol 307 ◽  
pp. 01042
Author(s):  
Tefy Raoelivololona ◽  
Mamiharijaona Ramaroson ◽  
Chrysostome Raminosoa
Keyword(s):  
Negative Consequences ◽  
Advanced Level ◽  
Ductile Materials ◽  
Wet Process ◽  
Plastic Bags ◽  
Cost Of Energy ◽  
Persistent Pollutants ◽  
Plastic Bag ◽  
The Cost ◽  
Toxic Fumes

Since twenty years, Madagascar suffered, by the advanced level of pollution due to the proliferation of plastic bags. They are always discarded in nature and constitute an increasingly important visual and environmental pollution in cities. And because they are easily carried and deposited everywhere by the wind, it has more negative consequences on the environment and thus on the health of the population. Plastics are among the most persistent pollutants and the problem appears when they reach the waste stage. The degradation of these plastic bags requiring more than four centuries, so the search for solutions for the use of these products is very solicited to preserve the environment. That’s why our research is consecrated into the transformation of plastic bags into pavers or bricks at a lower cost. The combustion of plastics releases large quantities of thick and toxic fumes. So, to avoid this phenomenon, our so-called “wet” process consists in heating a mixture of a Rich Carbon of Waste Element (RCWE), fusing the plastic bags as a binder and adding the sand as agglomerate. We obtain a quantity of product 3 times higher than the quantity of plastic bags used (to have 60 kg of product, we need 20 kg of plastic bags) unlike the other processes providing 5 kg of product for 20 kg of plastic bags, ie the plastic is reduced by ¼. The rest of the study focused on the melting temperature of the plastic bag in the RCWE which is approximately 110° C, the proportions between the RCWE and the plastic bag for the optimization of the cost of energy : we showed that the energy is optimal for a proportion of half (100g of RCWE for 50g of plastic), the proportions between plastics and sand (binder and agglomerate) : by weight, the binder must always be less than the agglomerate (the result is optimal in the proportion of agglomerate -binder 80 -20), the mechanical behavior : the result shows that when the quantity of plastics is the higher, the maximum stress is high, but the plastic area is low. The product is among the ductile materials, the property of which a material can permanently deform before breaking (an important factor for the deformation of materials), the permeability, and the adhesion test with the rubber.

scholarly journals TiO2 modified by ammonia as a long lifetime photocatalyst for dyes decomposition

2009 ◽  
Vol 11 (4) ◽  
pp. 1-6 ◽  
Author(s):  
Julia Choina ◽  
Diana Dolat ◽  
Ewelina Kusiak ◽  
Magdalena Janus ◽  
Antoni Morawski
Keyword(s):  
Photocatalytic Degradation ◽  
Azo Dye ◽  
Reaction Medium ◽  
Charged Surface ◽  
Reactive Red 198 ◽  
Long Lifetime ◽  
Positively Charged

TiO2 modified by ammonia as a long lifetime photocatalyst for dyes decomposition Ammonia-modified TiO2 (TiO2/N), prepared in a pressure reactor was used as the well- active and longlife photocatalyst for the azo dye (Reactive Red 198) decomposition. The effect of aeration and the different value of the pH of the reaction medium on the photocatalytic degradation of Reactive Red 198 in water has been investigated. It has been reported that the degradation is greatly influenced by the reaction pH and the faster decomposition of azo dye took place at pH 3.5. When the solution was acidic, a larger amount of azo dye on the positively charged surface of TiO2 photocatalysts was adsorbed. From the obtained results it can be seen that the effectiveness of the decolourisation of the solution was faster by using the nitrogen-modified TiO2.

Sign in / Sign up

Export Citation Format

Share Document