WATER DECONTAMINATION BY SUNLIGHT-DRIVEN FLOATING
PHOTOCATALYTIC SYSTEMS

Fabrication of floating g-C₃N₄/rGO photocatalyst for dye wastewater treatment

Nila Davari, Viviane Yargeau, Daria C. Boffito*

Chemical Engineering Research Day, Canada (Montréal), March 2023

We investigated the photocatalytic activity of floating g-C₃N₄/rGOunder simulated sunlight to eliminate Methyl Orange as a model of dye contaminants. XRD and FTIR analyses approved the decoration of rGO with g-C₃N₄ as an n-type photocatalyst. According to the SEM-EDX analysis, g-C₃N₄/rGO floating photocatalyst had a hollow structure with an elemental composition containing 34.4% carbon, 63.3% nitrogen, and 2.3% oxygen. The as-prepared g-C₃N₄/rGO floating photocatalyst completely degraded Methyl Orange (10 ppm) during 120 min irradiation by simulated sunlight. Moreover, the floating g-C₃N₄/rGO exhibited good stability, which kept its photocatalytic activity after five cycles. The results indicated that the floating g-C₃N₄/rGO could be a promising photocatalyst to purify pollutants.

Photocatalytic Activity of g-C₃N₄ Immobilized on Floating Polyurethane Foam

Nila Davari, Mohamed Gar Alalm, Maryam Mokhtarifar, Claudia L. Bianchi, Ermelinda Falletta, Viviane Yargeau, Daria C. Boffito*

The 27^th International Symposium for Chemical Reaction Engineering (ISCRE 27), Canada (Québec City), June 2023

Abstract

We evaluated the photocatalytic activity of floating g-C₃N₄ to degrade Methyl Orange as a model of dye pollutants. g-C₃N₄ was synthesized by the calcination of melamine and then immobilized onto PU foam through incipient wetness impregnation.
Characterization techniques included XRD, DRS, and FESEM-EDS analyses.
g-C₃N₄@PU photocatalyst could completely eliminate Methyl Orange dye during 300 min irradiation by simulated sunlight. The reusability experiments also indicated that g-C3N4 could be active after five cycles. The scavenging of free radical species revealed that all three active species (i.e., photogenerated holes, hydroxy radicals, and superoxide anions) had significant contributions to the photocatalytic degradation of Methyl Orange.

DOWNLOAD

Application of Floating Titanium Nanotube Photocatalyst for Bisphenol A Degradation

N. Davari, M. G. Galloni, E. Falletta, C. L. Bianchi, V. Yargeau, D. C. Boffito*

The 10^th International Symposium on Group Five Elements, Canada (Montréal)
June 2023

Introduction

Recent reports show that 2.4 billion people suffer from unsafe drinking water. Photocatalysis is a green solution to provide clean water. The exposure of a photocatalyst to a light irradiation source generates free radicals, which react with organic pollutants present in the water, resulting in the degradation of contaminant. We aim to fabricate a floating photocatalyst involving a 1D Titania nanotube immobilized on Polyurethane foam (TNTs@PU) to remove pollutants from water.

DOWNLOAD

Sunlight-driven degradation of non-steroidal anti-inflammatory drugs by innovative floating photocatalysts

June 2023

7^th Green & Sustainable Chemistry Conference, Dresden (Germany)

Abstract

Among the most well-known pharmaceuticals, non-steroidal anti-inflammatory drugs (NSAIDs) are characterized by a broad scope of properties widely used in human and veterinary medicine.

Because of the growth and aging of the world population, high consumption of NSAIDs has been recorded in the last few years. Consequently, an increase in concentrations of pharmaceuticals in surface waters is on the rise, also due to the low removal efficiency of wastewater treatment plants. Although these drugs have been known for a long time, some information about them is still limited, such as their presence in water bodies, distribution, and eco-toxicological effects.

The traditional wastewater treatment plants have not been effective and efficient enough to remove these pharmaceuticals. To overcome this limitation, new routes are being evaluated for their efficiency in removing these pollutants. Advanced oxidation processes (AOPs) can successfully remove pharmaceuticals from wastewater. Among all the possible exploitable strategies in this field, heterogeneous photocatalysis has emerged as an interesting strategy, operating under mild conditions and degrading many pollutants without adding chemical oxidants. Although TiO₂ is still the most used semiconductor due to its chemical and physical stability, good photoactivity, and low cost, researchers are willing to replace it with new smart materials because of its limited activity under solar light and low thermal stability. Moreover, new floating substrates were employed to immobilize photocatalysts to overcome problems related to the use of slurry systems for water purification. Since their closeness to the water surface, these devices can be fully irradiated by the light source, better oxygenated, and easily recovered and reused. Herein, we present our recent results in the NSAIDs degradation under solar light irradiation by innovative visible active photocatalysts (g-C₃N₄, BiOX) immobilized on natural floating materials (Lightweight Expanded Clay Aggregate (LECA), alginates’ spheres).

Photocatalysis challenges the obstacles to sustainability: advanced floating materials for wastewater remediation

January 2023

The 6^th Global Public Health Conference

The present poster has been selected as the winner of the Poster Award competition of the event The 6^th Global Public Health Conference (GLOBEHEAL 2023)

DOWNLOAD

pH-Driven Selective Adsorption of Multi-Dyes Solutions by Loofah Sponge and Polyaniline-Modified Loofah Sponge

M. G. Galloni, V. Bortolotto, E. Falletta and C. L. Bianchi

Polymers - Volume 14, Issue 22, November 2022
https://doi.org/10.3390/polym14224897

 

Abstract

In the last decades, sorbent materials characterized by low selectivity have been developed for the removal of pollutants (in particular dyes) from wastewater. However, following the circular economy perspective, the possibility to selectively adsorb and desorb dyes molecules today represents an unavoidable challenge deserving to be faced.
Herein, we propose a sequential treatment based on the use of PANI-modified loofah (P-LS) and loofah sponge (LS) to selectively adsorb cationic (rhodamine, RHB, and methylene blue, MB) and anionic (methyl orange, MO) dyes mixed in aqueous solution by tuning the adsorption pH (100% MO removal by P-LS and 100% and 70% abatement of MB and RHB, respectively, by LS).

The system maintained high sorption activity for five consecutive cycles.
A simple and effective regeneration procedure for the spent adsorbents permits the recovery of the initial sorption capability of the materials (81% for MO, ca. 85% for both RHB and MB, respectively) and, at the same time, the selective release of most of the adsorbed cationic dyes (50% of the adsorbed MB and 50% of the adsorbed RHB), although the procedure failed regarding the release of the anionic component.
This approach paved the way to overcome the traditional procedure based on an indiscriminate removal/degradation of pollutants, making the industrial wastewater a potential source of useful chemicals.

Flyer SunFloat Project

October 2022

The present flyer resumes the status of our research activity done in the first two years of SUNFLOAT project.

DOWNLOAD

 

Mechanisms and pathways of PFAS degradation by advanced oxidation and reduction processes: A critical review

M. Gar Alalm and D. C. Boffito

Chemical Engineering Journal - Volume 450, December 2022
https://doi.org/10.1016/j.cej.2022.138352

 

Abstract

Numerous studies have demonstrated the degradation of perfluoroalkyl substances (PFAS) by advanced oxidation or reduction processes. Howbeit, the current literature lacks a comprehensive and comparative overview of the various degradation pathways and mechanisms. This systematic review compiles and analyzes the mechanisms and degradation pathways of PFAS by persulfate activation, photocatalysis, UV/sulfite, electron beam, electrochemical oxidation, plasma, ozonation, and sonochemical oxidation.

We found that the degradation pathways of Perfluorocarboxylic acids (PFCAs) and Perfluoroalkanesulfonic acids (PFSAs) were investigated more than any other PFAS.
This review implies that the defluorination and degradation pathways of PFAS are reliant on the type of dominant reactive oxidant or reductive species. For instance, holes usually oxidize PFAS to unstable perfluoroalkyl radicals accompanied by losing head groups, whereas hydroxyl and superoxide radicals cleave C–C and C-F bonds.
On the other hand, hydrated electrons directly eliminate the head group followed by releasing CF2 units.
Furthermore, the imposed crystal facets and functional groups of the introduced catalytic surfaces in the case of heterogeneous catalysis (e.g., photocatalysts) affected the degradation pathways and defluorination rates by anchoring PFAS molecules from the head groups (e.g., carboxylate and sulfonate group).

This study lays the groundwork for future research to analyze and elucidate the transformation products and pathways of PFAS in various treatment systems.

Ultrasound-assisted and spray-drying synthesis of floating TiO₂-Ag@PU photocatalyst for Methyl Orange degradation under simulated sunlight

N. Davari, M. Mokhtarifar, C. L. Bianchi, E. Falletta, and D. C. Boffito

Canadian Chemical Engineering Conference - October 2022

 

Abstract

As a result of global population growth and industrial development, water pollution is one of the major current environmental issues. Scientific and industrial communities have investigated efficient and economical technologies to address water pollution problems.
Photocatalysis is a promising method to mineralize organic compounds using photoactive materials under light irradiation. Besides, the fabrication of water-floating photocatalysts has received much attention thanks to the high efficiency and technological advantages.

In this research we synthesized a micro-sized TiO₂-2%Ag photocatalyst supported on a floating Polyurethane foam using ultrasound and spray dryer to degrade Methyl Orange under simulated sunlight. We characterized the photocatalyst with XRD, XRF, FESEM-EDS, and TEM analyses.
XRD determined the phase of anatase and rutile in TiO₂-2%Ag photocatalyst, and the lattice parameters of TiO₂-2%Ag were changed by adding Ag, which may be related to the doping of Ag in the TiO₂ lattice. Based on XRF results, TiO₂-2%Ag photocatalyst had 70.87±1% of Ti and 1.72±0.11% of Ag, and FESEM and TEM confirmed the presence of Ag nanoparticles.
Moreover, EDS elemental mapping demonstrated the homogeneous distribution of Ag in the structure of the TiO₂-2%Ag, with the particle size of 105 nm for the Ag-doped TiO2 photocatalyst. We completely degraded 10 mg/L of Methyl Orange at 300 min with TiO₂-2%Ag@PU photocatalyst, and the floating photocatalyst was still stable for five reuse cycles. Moreover, Ag in TiO₂-2%Ag photocatalyst increased the degradation efficiency of Methyl Orange by 10% and applying ultrasound in the synthesis of TiO2-2%Ag@PU photocatalyst resulted in a 15% rise in the degradation efficiency.

Olive Mill Wastewater Remediation: From Conventional Approaches to Photocatalytic Processes by Easily Recoverable Materials

M. G. Galloni, E. Ferrara, E. Falletta and C. L. Bianchi

Catalysts MDPI - Volume 12, August 2022
https://doi.org/10.3390/catal12080923

 

Abstract

Olive oil production in Mediterranean countries represents a crucial market, especially for Spain, Italy, and Greece.
However, although this sector plays a significant role in the European economy, it also leads to dramatic environmental consequences. Waste generated from olive oil production processes can be divided into solid waste and olive mill wastewaters (OMWW). These latter are characterized by high levels of organic compounds (i.e., polyphenols) that have been efficiently removed because of their hazardous environmental effects.
Over the years, in this regard, several strategies have been primarily investigated, but all of them are characterized by advantages and weaknesses, which need to be overcome.
Moreover, in recent years, each country has developed national legislation to regulate this type of waste, in line with the EU legislation. In this scenario, the present review provides an insight into the different methods used for treating olive mill wastewaters paying particular attention to the recent advances related to the development of more efficient photocatalytic approaches.
In this regard, the most advanced photocatalysts should also be easily recoverable and considered valid alternatives to the currently used conventional systems. In this context, the optimization of innovative systems is today’s object of hard work by the research community due to the profound potential they can offer in real applications. This review provides an overview of OMWW treatment methods, highlighting advantages and disadvantages and discussing the still unresolved critical issues.

Floatable graphitic carbon nitride/alginate beads for the photodegradation of organic pollutants under solar light irradiation

E. Falletta, M. Longhi, A. Di Michele, D. C. Boffito, C. L. Bianchi

Journal of Cleaner Production - Volume 371, August 2022
https://doi.org/10.1016/j.jclepro.2022.133641

 

Abstract

Graphitic carbon nitride, both as powder and alginate floating beads, was synthesized by an easy and cheap approach using two different precursors (melamine and urea) and properly characterized by several techniques.
The effect of the type of precursor on the photoactive properties of the final materials was investigated. Their activity towards the photodegradation of different pollutants (dyes, drugs, and herbicides) both in ultrapure water and simulated drinking water under solar light irradiation was investigated, reaching extraordinarily high photodegradation results (99% for diclofenac and rhodamine B and 90% for isoproturon) compared to the literature.
The floating photocatalysts showed good stability during recycling maintaining high performances after 5-time usage without post-treatment. Finally, liquid chromatography equipped with mass spectrometry (UPLC/MS) was used to identify the main by-products formed during the photodegradation tests, and a plausible transformation pathway has been proposed.

Sustainable Solar Light Photodegradation of Diclofenac by Nano- and Micro-Sized SrTiO₃

M. G. Galloni, G. Cerrato, A. Giordana, E. Falletta and C. L. Bianchi

Catalysts MDPI - Volume 12, July 2022
https://doi.org/10.3390/catal12080804

 

Abstract

Currently, photocatalytic reactions under solar illumination have attracted worldwide attention due to the tremendous set of associated environmental problems. Taking sunlight into account, it is indispensable to develop highly effective photocatalysts. Strontium titanate, SrTiO₃ (STO), is a cubic perovskite-type semiconductor, an inexpensive material with high thermal stability and corrosion resistance that exhibits a similar energy bandgap to TiO₂ and can represent an interesting alternative in photocatalytic applications. Particle size can significantly affect both photocatalytic and photoelectrochemical properties of a photocatalyst, thus altering the photooxidation of organic pollutants in air or water.
In this context, this research aims at investigating the photocatalytic features of nano- and micro-sized commercial STO powders towards the photodegradation of diclofenac (DFC), a non-steroidal, anti-inflammatory drug, widely used as analgesic, antiarthritic, and antirheumatic. Both nano- and micro-STO photocatalysts exhibited remarkable photocatalytic efficiency towards DCF, reaching photodegradation efficiency higher than 90% within one hour.
Results obtained in simulated drinking water were also compared to those obtained in ultrapure water. Both STOs showed good stability during recycling tests, maintaining high performances after three cycles. Eventually, active species were identified using various scavengers by trapping holes and radicals generated during the photocatalytic degradation process.

An innovative “concentrate and destroy” for water remediation by bismuth oxyhalides as adsorptive photocatalysts

July 2022

The continuous release of toxic chemicals in the environment requires efficient solutions in the view of preserving the Earth even more. Among all the possible strategies to use, those related to advanced oxidation processes result interesting. In this work, an innovative “concentrate and destroy” approach for water remediation has been developed using bismuth oxyhalides (BiOX, X = Br, I) as adsorptive photocatalysts in the abatement of model pollutants (i.e., rhodamine B, RhB, and gallic acid, GA).
Results indicated the superior photoactivity of BiOBr with respect to BiOI. Indeed, BiOBr was able to almost full convert both RhB and GA after 210 min of photocatalytic test under solar light irradiation. The encouraging results obtained open the future possibility to support these materials in floating devices for real applications.

DOWNLOAD

A floating TiO₂-Ag@PU photocatalyst photocatalyst for methyl orange removal under simulated sunlight

N. Davari, M. Gar Alalm, C. L. Bianchi, E. Falletta, and D. C. Boffito

ECS Montréal Student Symposium - April 2022

Abstract

The widespread of biorecalcitrant pollutants in the aquatic system has recently encouraged the developing of innovative and inexpensive materials to selectively degrade these pollutants. However, the skepticism about the fate and impacts of novel materials (e.g., nanoscale photocatalysts) has hindered the large-scale applications.
To overcome this issue, we developed an Ag doped TiO₂ supported on a floating polyurethane foam (Ag-TiO₂-PU) which keeps the photocatalyst inside the reactor and allows the reuse without the need of the tedious collecting step.
The successful doping of Ag in the lattice of TiO₂ was confirmed by X-ray diffraction (XRD) and X-ray fluorescence (XRF) analyses.
A remarkable reduction of the bandgap was also observed due to the Ag doping which suggests the activity under wider spectra of solar light. The developed system achieved a complete degradation of methyl orange with an initial concentration of 10 mg/L in 300 min and showed high stability for four cycles of reuse without regeneration or further treatment.

Ultrasound-assisted synthesis of TiO₂-2%Ag photocatalyst supported on floating Polyurethane foam for water treatment

N. Davari, M. Mokhtarifar, C. L. Bianchi, E. Falletta, and D. C. Boffito

Chemical Engineering Research Days - March 2022

 

Abstract

In the present study, we fabricated a TiO₂-2%Ag photocatalyst supported on a floating Polyurethane foam (TiO₂-2%Ag@PU) for the degradation of Methyl Orange dye (MO) in contaminated water under simulated sunlight. X-ray diffraction (XRD) and X-ray fluorescence (XRF) analyses confirmed the successful doping of Ag into TiO₂.
The presence of Ag on TiO₂-2%Ag@PU photocatalyst resulted in a 10% increase in MO photocatalysis. In addition, the effect of ultrasound on the performance of the floating TiO₂-2%Ag@PU photocatalyst was examined.
According to the results, the application of ultrasound in the floating photocatalyst synthesis increased the degradation efficiency of MO by 15%.
We obtained the complete degradation with 10 mg/L MO and 1 g/L TiO₂-2%Ag@PU at 300 min. Moreover, the floating photocatalyst was still active and stable after four recycle tests. The results indicated that the floating TiO₂-2%Ag@PU can be a promising photocatalyst for the treatment of MO in polluted water.

Doped-polyaniline based sorbents for the simultaneous removal of heavy metals and dyes from water: Unravelling the role of synthesis method and doping agent

C. L. Bianchi, R. Djellabia, C. Della Pina, E. Falletta

Chemosphere - Volume 286, Part 3, January 2022
https://doi.org/10.1016/j.chemosphere.2021.131941

 

Abstract

Recently, the engineering of alternative adsorbents with better functional and sorbing ability towards the purification of wastewaters has received much attention from the scientific community.
Currently polymers, in particular, are regarded as attractive soft materials in the eld of environmental remediation due to their several unique properties. In this regard, the synthesis method is key point to fabricate polymer-based adsorbent with targeted characteristics.

In the present work, four polyaniline (PANIs) samples were synthesized by two alternative chemical approaches, a traditional one and an eco-friendly one, and two different dopants were used, HCl and H₂SO₄, respectively.
All PANIs were characterized for their thermal, optical, morphological, and structural properties and their capability to remove simultaneously dyes and heavy metals from water have been investigated. It was deduced that the sorption ability is dependent on the as-synthesized PANI using different procedures and dopants. All the PANIs from traditional method showed high levels of pollutants removal (from 89 to 97%).

Even though the materials obtained from the green way are overall less active, H₂SO₄-doped corresponding polymer showed high sorption capability (75–97%).
Finally, the most performing PANIs were selected for recycling tests exhibiting high sorption ef ciency retention up to four runs without any regeneration treat- ment. Most important, the cycling tests were stopped well before the sample sorption limit could be reached.

Solar Light Photoactive Floating Polyaniline/TiO₂Composites for Water Remediation

E. Falletta, A. Bruni, M. Sartirana, D. C. Boffito, G. Cerrato, A. Giordana, R. Djellabi, E. S. Khatibi and C. L. Bianchi

Nanomaterials 2021, 11(11), 3071
https://doi.org/10.3390/nano11113071

 

Abstract

In the present study, the development of innovative polyurethane-polyaniline/TiO₂ modified floating materials applied in the sorption and photodegradation of rhodamine B from water matrix under solar light irradiation is reported.

All the materials were fabricated with inexpensive and easy approaches and were properly characterized. The effect of the kind of polyaniline (PANI) dopant on the materials’ behavior was investigated, as well as the role of the conducting polymer in the pollutant abatement on the basis of its physico-chemical characteristics. Rhodamine B is removed by adsorption and/or photodegradation processes depending on the type of doping agent used for PANI protonation. The best materials were subjected to recycle tests in order to demonstrate their stability under the reaction conditions.

The main transformation products formed during the photodegradation process were identified by ultraperformance liquid chromatography-mass spectrometry (UPLC/MS). The results demonstrated that photoactive floating PANI/TiO₂ composites are useful alternatives to common powder photocatalysts for the degradation of cationic dyes.

Comparison of the photoactivity of several semiconductor oxides in floating aerogel and suspension systems towards the reduction of Cr(VI) under visible light

R. Djellabi, X. Zhao, M. Frias Ordonez, E. Falletta, C. L. Bianchi

Chemosphere - Volume 281, October 2021
https://doi.org/10.1016/j.chemosphere.2021.130839

 

Abstract

A massive amount of research has been done over the last three decades to develop photoactive materials which could be suitable for real-world use in water remediation sector.
Water-floating photocatalysts could be one of the best options due to their technological characteristics in terms of efficiency and reasonability including a high oxygenation of the photocatalyst surface, a fully sunlight irradiation, easy recovery and reuse.
In the present study, aerogel water-floating based materials were fabricated using poly(vinyl alcohol) and polyvinylidene fluoride as a polymer platform, and loaded with different semiconductors such as g-C₃N₄, MoO₃, Bi₂O₃, Fe₂O₃ or WO₃.
The photocatalytic efficiencies of aerogel floating materials and the suspension of above-mentioned semiconductors were compared evaluating the photoreduction of Cr(VI) under visible light (λ > 420 nm).
The results showed that Fe₂O₃ suspension was the most efficient but the slowest in floating system. On the contrary, g-C₃N₄ exhibited a good performance in suspension system, and on top of that it was very effective in floating system, wherein it ensures a total reduction of 10 ppm-Cr(VI) to Cr(III) within 20 min.

Innovative Floating Materials For Water Remediation Under Sunlight

October 2021

Recently, the field of research has been led towards the production of innovative and inexpensive materials able to degrade emerging compounds, such as persistent organic pollutants (POPs). In this regard, heterogeneous photocatalysis offers a green solution for water remediation.
Furthermore, a photocatalytic floating device can be adopted to overcome issues related to the use of catalyst- based slurry systems and to maximize light utilization. In the present work, photoactive materials were prepared immobilizing visible light responsive catalysts on floating supports (synthetic and natural polymers, inorganic materials) and tested towards the degradation of a model molecule (Rhodamine B RHB).

DOWNLOAD

Nanoporous polyanilines as sorbents for dyes and heavy metals

October 2021

Every year, from 300 to 500 millions of tons of solvents, heavy metals, toxic sewage sludges and others industrial waste are released in water.
The most employed approach for waste abatement is based on the use of activated carbon thanks to its high surface area, high porosity and low selectivity. The main disadvantage of this material is the necessity to activate and regenerate it through thermic treatment at high temperature or using solvents, causing additional costs.
In this regard, the necessity to develop innovative materials is crucial. The present study is focused on the “green” synthesis and characterization of porous polyanilines (PANI), characterized by specific features that make them useful for the removal of two classes of wastewater pollutants: organic dyes (methylene blue, MB, and acid green, AG) and heavy metals (Pb⁺², Cd⁺² and Cr⁺⁶).

DOWNLOAD

SWOT analysis of photocatalytic materials towards large scale environmental remediation

R. Djellabi, R. Giannantonio, E. Falletta and C. L. Bianchi

Current Opinion in Chemical Engineering - Volume 33, September 2021, 100696
https://doi.org/10.1016/j.coche.2021.100696

 

Abstract

After a long process of intense fundamental and scientific research, the question of the suitability of photocatalytic technology to address real environmental problems is still alive.
Although photocatalysis has exceptional and unique properties, it still suffers from some technical problems that limit its large-scale transfer.
Furthermore, part of the scientific community focuses on research impossible to apply in industry due to both costs and technical difficulties in large-scale transfer, and testing conditions are often very far from real ones.
In this report, a SWOT analysis of photocatalytic technology is conducted in order to assess whether its main strengths can enable it to seize relevant opportunities for large-scale investment and commercialization of photocatalytic solutions, despite its weaknesses and external threats.
Exploiting and extending all the properties of photocatalysis can transform a plain chemical process in a real and truly competitive technology.

Floating Smart Materials For Water Decontamination Under Solar Light

September 2021

Recently, groundwater pollution has driven the necessity to develop innovative and inexpensive smart-materials able to degrade toxic compounds, that lower drinking-water quality. In this regard, heterogeneous photocatalysis offers a green solution for water remediation. Titanium dioxide (TiO₂) is the most used photocatalyst, however, to broaden its band-gap extending the photo-response to the visible region, it can be doped with conductive polymers, such as polyaniline (PANI).
Moreover, a floating device can be adopted to overcome issues related to the use of slurry systems and maximize light utilization. Synthetic polymers, such as polyurethane (PU), have been commonly employed as floating materials for their light-weight, stability, and low cost. In the present work, visible light photoactive devices were prepared immobilizing PANI/TiO₂ composites on floating PU foams.

DOWNLOAD

Innovative floatable O-g-C₃N₄ alginate spheres for water remediation under solar light

September 2021

In the last decades, the attention to freshwater pollution has further attracted research towards heterogeneous photocatalysis. g-C₃N₄ has promising features as a metal-free photocatalyst considering its visible-light response, simple synthetic pathway, and cheap production cost.
Moreover, floating devices can be adopted to overcome issues related to its recovery in slurry systems and maximize light utilization. Among the different materials that can be used as floating matrices, natural polymers, such as alginate, occupy a special place for high availability, low cost, and green impact. In the present study, g-C₃N₄ and O-doped g-C₃N₄-alginate photocatalysts were properly synthesized and tested to degrade a dye (rhodamine B) and two contaminants of emerging concern (diclofenac and isoproturon), outperforming TiO₂-alginates used as the benchmark.

DOWNLOAD

Piezo-enhanced photocatalytic diclofenac mineralization over ZnO

D. Meroni, C. L. Bianchi, D. C. Boffito, G.Cerrato, A. Bruni, M. Sartiranaa, E. Falletta

Ultrasonics Sonochemistry - Volume 75, July 2021, 105615
https://doi.org/10.1016/j.ultsonch.2021.105615

 

Abstract

The degradation of diclofenac has been realized for the rst time by a piezo-enhanced sonophotocatalytic approach based on ZnO.
The sonophotocatalytic degradation showed a slight enhancement in the degradation of the parent compound, whereas strong synergistic effects were observed for the mineralization process when suitable ZnO morphologies are used, reaching 70% of complete degradation of 25 ppm diclofenac using 0.1 g/L ZnO in 360 min.
Tests in a complex water matrix show enhanced diclofenac removal, outperforming a TiO2 benchmark photocatalyst.
These promising experimental results promote this process as a good alternative to traditional degradation approaches for remediation of real water matrices.

Floating photocatalysts for a sustainable environmental remediation exploiting sunlight

C. L. Bianchi, E. Falletta, A. Bruni, M. Sartirana, M. Gar Alalm, N. Davari, and D. C. Boffito

International Conference on Hierarchically Structured Materials (ICHSM) April 2021

Abstract

The chemical industry of the forthcoming years will be shaped by a number of emerging global megatrends strictly related to the demand of innovative materials able to solve new needs in different fields. Among them, environmental deterioration and the scarcity of fresh water have become imperative global issues to be solved nowadays. About 2.4 billion people are exposed to diseases caused by inadequate water sanitation. Additionally, a variety of organic and inorganic compounds, which arise either from anthropic activities or naturally, also contaminates drinking water lowering its quality.

In the last three decades, many efforts have been addressed to develop photoactive materials which could be suitable for real-world use in the field of water remediation. In this regard, water-floating photocatalysts could represent good alternatives to traditional materials thanks to their characteristics in terms of efficiency and reasonability including a high oxygenation of the photocatalyst surface, a fully solar irradiation, easy recovery and reuse.
Thanks to its high photocatalytic activity and good stability TiO₂ has been proved to be an excellent photocatalyst. However, because of its wide band gap (3.2 eV) its efficiency under solar light is dramatically limited. Hence, much effort has been devoted to improve the utilization of solar light by extending the photoresponse of TiO₂ to the visible region.

In this regard, conducting polymers (CPs), such as polyaniline (PANI) and polypyrrole (PPy), represent promising sensitizers to extend the spectral response of TiO2 to visible light. On the basis of our experience in the field of CPs preparation by innovative green approaches and in the advanced oxidation technologies, in the present talk, very recent results will be exposed on the use of CPs-modified TiO₂ 3D materials floating on the water surface and fully exploiting solar irradiation.
In this very preliminary tests, the degradation of two classes of pollutants has been investigated and the best materials were subjected to recycle tests in order to demonstrate their stability under the reaction conditions.

Flyer SunFloat Project

January 2021

The development of an affordable proof-of-concept device will help to improve the life quality of populations affected by water scarcity.
It will also raise awareness of the importance of sunlight as a sustainable resource for water pollution remediation.

DOWNLOAD