Synergy of Bio-Chemical Processes for Photocatalytic and Photoelectrochemical Wastewater Treatment (eBook)

Elvis Fosso-Kankeu, Sadanand Pandey, Soumya Pandit (Herausgeber)

eBook Download: EPUB

2024 | 1. Auflage
288 Seiten
Wiley (Verlag)
978-1-394-19788-0 (ISBN)

Infos

The concept of photoelectrochemistry applied to microbial fuel cells could be the future of sustainable wastewater treatment and for hydrogen recovery as a valuable energy source.

With the increase of recalcitrant organic pollutants in industrial wastewater, the need for a sustainable bio-electrochemical process has become pressing in order to ensure that treatment processes are coupled with some beneficiation advantages. Microbial fuel cells combine wastewater treatment and biological power generation. However, the resistance of these organic pollutants to biological degradation requires further adjustment of the system to improve sustainability through maximization of energy production.

Solar energy conversion using photocatalysis has drawn huge attention for its potential to provide renewable and sustainable energy. Furthermore, it might be the solution to serious environmental and energy-related problems. It has been widely understood for several years that the top global issues today are concerned with securing a clean supply of water and ensuring a reasonable price for clean energy. Researchers are studying advanced materials and processes to produce clean, renewable hydrogen fuel through photocatalytic and photoelectrocatalytic water splitting, as well as to reduce carbon dioxide from the air into fuels through photocatalysis. Limited progress is occurring in these areas.

The purpose of this book is to comprehensively cover the evolvement in the conceptualization and application of photocatalytic fuel cells, as well as make a critical assessment of the contribution in the field of sustainable wastewater treatment and renewable energy production.

This book contains nine specialized chapters that provide comprehensive coverage of the design of photocatalytic fuel cells and their applications, including environmental remediation, chemical synthesis, green energy generation, model simulation for scaling up processes and implementation, and most importantly maximization of hydrogen evolution, recovery, and applications.

Audience

A wide audience of academics, industrial researchers, and graduate students working in heterogeneous photocatalysis, fuel cells, sustainable chemistry, nanotechnology, chemical engineering, environmental protection, and surfaces and interfaces, will find this book useful. The book is also important for professionals, namely environmental managers, water treatment plants managers and operators, water authorities, government regulatory bodies officers, and environmentalists.

Sadanand Pandey, PhD, is a professor in the School of Bioengineering and Food Technology, Faculty of Applied Sciences and Biotechnology, Shoolini University, India. He was a Kothari fellow at the prestigious Indian Institute of Science (2011-2013) and NRF scientist at the University of Johannesburg, South Africa (2014-2018). He has published more than 100 SCI Journal articles, many book chapters, and several contributions to scientific meetings and co-edited books. His research activities span the disciplines of polymer chemistry, materials science, nanotechnology, and sustainable and advanced materials.

Elvis Fosso-Kankeu, PhD, is a professor in the Department of Metallurgy at the University of Johannesburg, South Africa. He has published more than 250 papers including journal articles, books, book chapters and conference proceeding papers. He has won several research awards including the National Science and Technology Forum Award in South Africa. His research focuses on the hydrometallurgical extraction of metal from solid phases, prediction of pollutants dispersion from industrial areas, and development of effective and sustainable methods for the removal of inorganic and organic pollutants from polluted water.

Soumya Pandit, PhD, is a senior assistant professor at Sharda University, Greater Noida, Delhi, India. He pursued his doctoral studies from the Department of Biotechnology, Indian Institute of Technology, Kharagpur in 2015. He has authored more than 70 research and review papers in peer-reviewed journals, and his research areas include microbial electrochemical systems for bioenergy harvesting, bacterial biofilm and biofouling study, biohythane production, microalgal biomass production for biofuel, nanomaterial synthesis and application in bioenergy harvesting and biofouling mitigation.

Textauszug

1
A Comprehensive Review of Graphitic Carbon Nitride (GCN/GC3N4) as a Promising Photocatalyst

Pragna M. Shivannavar1, Chiranth Srirangapatna Puttasrinivasa1, Sharmila Suresh1, Charan Kumar Kachintaya2, Lingaraju Honnur Gurusiddappa3, Supreeth Mohan Kumar4 and Shankramma Kalikeri1*

1Division of Nanoscience and Technology, School of Lifesciences, JSS Academy of Higher Education and Research, Sri Shivarathreeshwara Nagara, Mysuru, Karnataka, India

2#9A, Shankar Colony I Cross, SN Pet, Ballari, India

3Department of Environmental Science, School of Lifesciences, JSS Academy of Higher Education and Research, Sri Shivarathreeshwara Nagara, Mysuru, Karnataka, India

4Department of Microbiology, School of Life Sciences, JSS Academy of Higher Education and Research, Sri Shivarathreeshwara Nagara, Mysuru, Karnataka, India

Abstract

Over the last few decades, there has been a surge in interest in solar energy utilization due to the growing awareness of environmental protection and energy conservation. Photocatalysis has developed as one of the most crating tools for removal of pollutants in water and energy production. Due to the large bandgap and charge recombination, researchers are still struggling to meet the requirements of energy conversion efficacy. As a result, in the search for an active photocatalyst, graphitic carbon nitride (gC3N4/GCN), an active polymeric semiconductor, has sparked a vanguard of interest in the next generation of researchers. We highlighted crucial challenges associated with GCN technologies and severe opportunities in the aspect of developing upcoming groups of GCN-based materials in environmental fields. We also pointed the future directions and focused on GCN and GCN-based advanced functional materials. Hopefully, this review can establish a link between the newly developed GCN materials and actual requirements for future commercial applications.

Keywords: Graphitic carbon nitride (gC3N4), visible light, wastewater treatment, sustainability

1.1 Introduction

Water is an important resource for humans as it is used for cleaning, drinking, cooking, and many more daily needs. The growth in population and industrialization has become the reason for the scarcity of clean water. Wastewater treatment has been gaining great interest to obtain clean water, and many ways have been used for the water treatment. The industries that manufacture paper, textiles, tanneries, photography, and food use azo dyes the most [1–5]. They are thought to be non-biodegradable in aerobic circumstances and are hazardous to the environment. Because the azo dye precursors are carcinogenic and immediately impair human health when consumed in water without any prior treatment, they have a significant negative environmental impact [1–3]. Conventional methods of wastewater treatment include membrane filtration [6, 7], “activated sludge process” [8, 9], coagulation, sedimentation, reverse osmosis. Membrane filtration is the frequently used conventional method because of its easier operation and effortless synthesis, but they also have few drawbacks such as membrane material instability durability, fouling resistance, and lesser water flux [10–12]. Also, the other conventional methods that are used have few drawbacks such as they do not remove the hazardous wastes completely and are time-consuming [13]. Thus, other advanced methods are needed to be developed for efficient treatment of the wastewater.

Advanced oxidation process (AOP) is a type of advanced method where chemical treatment is done to remove organic pollutants through oxidation reactions with hydroxyl radicals [5]. AOP is an efficient and developing method with the application of new apparatus, and also they do not have any secondary products at the end of the process [14, 15]. Photocatalysis is one such AOP that is gaining more interest as a method for wastewater treatment. This process results in the formation of benign products distinctive from the conventional methods where the pollutants are passed from one medium to the other [5]. The advantages of photocatalysis method includes mild operating conditions, cost effective, no secondary pollutant generation, less time, lesser chemical input, and eco-friendly [16, 17]. Photocatalyst is a key character for the efficiency of the photocatalytic process. An ideal photocatalyst used for photocatalysis must be sustainable, visible-light–driven [5, 18], environmentally friendly, economically feasible, and highly stable [19]. Semiconductors are generally used as photo-catalyst. They may be metal-based inorganic photocatalysts such as TaON [20], BiVO4 [21], CdS [22, 23], Ta3N5 [24, 25], ZnlnS4, and CulnS2 [26, 27] as well as metal oxide photocatalysts such as BiOCl [28], Ag3PO4 [29], TiO2 [30, 31], WO3 [32], and BiOBr [33]. These metal nanoparticles (NPs) also have limitations, such as lower efficiency, instability, higher costs, environmental toxicity, and its photo-corrosion, which are the causes for its unsuitability as photocatalysts [34, 35].

To overcome these issues, non-metal photocatalysts are developed, which consists of earth abundant elements such as carbon, sulfur, nitrogen, and phosphorous [36, 37]. Organic polymeric photocatalysts are among the non-metallic photocatalysts that is gaining importance these days for their wide applications. GCN is one such graphene based photocatalyst, with enhanced surface area and greater light harvesting efficiency, which increases its photocatalytic activity, and GCN-based photocatalyst is discussed in this chapter. Also, this chapter gives an insight of the modification of GCN to improve their photocatalytic activity.

1.2 GCN as a Photocatalyst

GCN is a non-metal polymeric photocatalyst that is gaining great interest from research perspective in the field of semiconductor photocatalysts. It is an n-type semiconductor. Allotropes of carbon nitride (C3N4) are α-C3N4, β-C3N4, and g-C3N4, pseudo-cubic and cubic-C3N4, of which, under ambient condition, g-C3N4 is a stable allotropic form [38, 39]. The building blocks of GCN are tri-s-triazine (C6N7) and triazine (C3N3) units that are depicted in Figure 1.1 [40, 41]. Observations have been made that “C6N7 units are more stable than the C3N3 units” [42]. It is composed of nitrogen (N) and carbon (C) that are piled up in layers of tri-s-triazine linked through amino groups [43]. Figure 1.2 shows the polymerized GCN [44]; GCN is also called as “melon” and has gained importance as photocatalyst because of its easy procedure of synthesis, better thermal and chemical stability, low cost, and enhanced visible-light absorption [45–47]. The valence band and conduction band of GCN are positioned at -1.1 eV and +1.6 eV, respectively, which makes the bandgap of GCN to be 2.7eV [48]. The bonds present between the layers, i.e., the van der Waals force of attraction gives GCN its chemical stability [48]. The color of GCN ranges from light yellow to brownish [49, 50]. Figure 1.3 shows “the photocatalytic mechanism for mineralization of the dyes”; as shown in the figure, the production of signals (charge carrier) is the indication for the start of the photocatalytic reaction; when GCN is illuminated with enough energy, “the photon’s energy is transferred to the electrons in the valence band, which are then excited to the conduction band and produce holes in the valence band.” The electron–hole pair then moves to the surface of GCN, where the holes in the valence band are consumed by the oxidizing electron donors, and the “protons are reduced to hydrogen by the electrons in the conduction band.” Table 1.1 shows the GCN nanoparticles for dye degradation and other applications.

Figure 1.1 Triazine and tri-s-triazine units.

Figure 1.2 Polymerized structure of GCN.

According to J. Xu et al. (2013), single atomic layer GCN nanosheets are fabricated using the chemical exfoliation process with dicyanamide as a precursor, which results in single atomic layer GCN nanosheets with greater intrinsic properties. They utilized 25 mg of the GCN to accelerate under artificial visible light (500-W Xenon lamp) for degradation of MB, and it was found that 94% of the dye was degraded within 4 h. “It is generally recognized that high surface area, light absorption, and charge transport have a greater influence on photocatalytic activity.”

Figure 1.3 Photocatalysis mechanism of dye.

Li et al. (2015) reported the synthesis of nanorods using template-free infrared heating, a bottom-up fabrication approach with different powers such as 35%, 40%, 50%, 70%, and 100% with dicyanamide as precursor. The infrared heating greatly affects the morphology of the above synthesized GCN nanorods and also the heat provided by the infrared method is more effective than the heat by calcination method. Fifty milligrams of the prepared photocatalyst was added to 20 vol% of methanol that was used as sacrificial agent under a visible light (300-W Xe arc lamp) and the hydrogen evolution rate found to be 57.8 μmol/h. This was the first study for the synthesis...

Produkt-Details

• Erscheint lt. Verlag: 19.9.2024
• Sprache: englisch
• Themenwelt: Naturwissenschaften ► Chemie
• ISBN-10: 1-394-19788-8 / 1394197888
• ISBN-13: 978-1-394-19788-0 / 9781394197880