Photocatalytic Oxidation of Urea on Surface-Modified Bi₂WO₆ with trans-4-Stilbenecarboxaldehyde

Abstract

Modification of the Bi2WO6 surface with trans-4-stilbenecarboxaldehyde (4SCA) by the equilibrium adsorption method and its application in photoredox reactions under solar irradiation were studied. The modification of the surface of Bi2WO6 at acidic pH implied an acetal-type interaction with the aldehyde, and then the separation of the solid at neutral pH guaranteed the irreversible covalent functionalization. Langmuir isotherm measurements and infrared spectroscopy support the surface modification. Studies based on stationary and time-resolved photoluminescence spectroscopy showed the effect on the dynamics (lifetime) of charge carrier deactivation due to surface modification. A higher rate of formation of the hydroxyl radical using Bi2WO6–4SCA as compared to Bi2WO6 was measured. The photocatalytic tests carried out in a tubular bench reactor (TBR) showed improvements of the modified Bi2WO6 in the mineralization of urea. In addition, the latter process became faster as the initial urea concentration was decreased. Langmuir–Hinshelwood kinetic parameters for urea oxidation were measured and discussed. These findings are important to understand the deactivation dynamics of excited electrons at the semiconductor–electrolyte interphase and to optimize the conditions necessary to carry out an efficient photoredox reaction (e.g., degradation of an important pollutant such as urea).

Anodic Process of Nano-Ni Hydroxides for the Urea Oxidation Reaction and Its Electrochemical Removal with a Lower Energy Input

“…Nitrogen contaminants are energy-intensive for their proper treatments, and therefore nowadays the use of renewable energy inputs and sustainable processes is increasingly receiving attention. Electrochemical catalytic conversion toward their smaller molecules leading to energy saving is of importance in a variety of areas, including fuel cells, energy storage, wastewater treatment, and electrochemical sensors for medical, food, and environmental analysis. − Particularly, much attention has been paid to the electrolysis of urea-rich wastewater owing to its ability to produce hydrogen as an alternative fuel, while cleaning wastewater. − Direct urea fuel cells based on electro-oxidation of urea at the anode and oxidant (oxygen or hydrogen peroxide) reduction at the cathode have also been developed recently for the purpose of energy production accompanied by purifying urea-rich sewage. − …”

Sodium Alginate–CuS Nanostructures Synthesized at the Gel–Liquid Interface: An Efficient Photocatalyst for Redox Reaction and Water Remediation

“…Recently, photocatalysis has gained significant importance owing to its environmentally friendly process, where no additional energy is required during the degradation process. − Additionally, harvesting visible light for an efficient photoconversion process has gained tremendous scientific importance. From this point of view, nanostructures, that can efficiently absorb visible light and generate charge carriers, have shown promise toward enzymatic and chemical photoreactions. − Moreover, nanomaterials, in the form of zeolite, oxide, and sulfide synthesized by a variety of techniques, have shown potential for multifunctional modern-day applications. − However, the best photocatalysts should be abundant, inexpensive, safe, extremely durable, and reusable. As a result, diverse transitional metal sulfides, oxides, and chalcogenides are studied as photocatalysts for water remediation under various conditions due to the flexibility in adjusting the morphology and band gaps. − Among the photocatalysts, copper sulfide (CuS) has attracted substantial attention due to its high stability, suitable band gap, and appropriate morphology. , Therefore, various techniques are developed to synthesize CuS with different morphologies. − The synergy between covalent conjugation of folic acid with graphene oxide and subsequent deposition of CuS nanoflowers as a ternary photocatalyst assisted in the efficient degradation of aqueous solutions of rhodamine B, methylene blue (MB), methyl orange (MO), and alizarin red under NIR irradiation .…”

Bubble-propelled micromotors for ammonia generation

“…Many studies have been carried out in the field of environmental remediation for the removal of organic pollutants from contaminated water, including pharmaceutical, agriculture, and dye waste sources. [1][2][3][4][5][6] Among these emerging contaminants, urea has been gaining prominence because it is a common pollutant from residential activities, being the main component of urine, and from different industrial processes. Therefore, the accumulation of urea in the wastewater of big cities is becoming a great problem because its biodegradation is not enough to avoid related environmental risks, like eutrophication in coastal waters.…”

“…Many studies have been carried out in the field of environmental remediation for the removal of organic pollutants from contaminated water, including pharmaceutical, agriculture, and dye waste sources. 1–6…”