Petal-like g-C3N4 Enhances the Photocatalyst Removal of Hexavalent Chromium

Abstract

The rapid progress of modern industry not only brings convenience to people’s lives, but also brings negative effects. Industrial development produces a large amount of waste metal, which brings harm to the environment and human health. Carbon nitride (g-C3N4) was successfully prepared using the thermal-polymerization method and petal-like g-C3N4 (CA-g-C3N4) was impregnated with citric acid (CA). Compared with g-C3N4, CA-g-C3N4 showed extremely high photocatalytic activity because the petal-like g-C3N4 (CA-g-C3N4) had a larger specific surface area, which increased the active sites on the surface of the photocatalyst and improved the photocatalytic activity. After citric acid treatment, the removal of hexavalent chromium (Cr(VI)) by g-C3N4 increased from 48% to 93%. The photocatalytic materials were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) and UV-vis diffuse reflectance spectra (UV-vis). In summary, this study confirmed that citric acid can improve the photocatalytic activity of g-C3N4 by increasing its specific surface area and the active site of the photocatalytic material so as to achieve the purpose of removing hexavalent chromium from water.

Visible Light Photoactivity of g-C3N4/MoS2 Nanocomposites for Water Remediation of Hexavalent Chromium

“…The X-ray photoelectron spectroscopy (XPS) spectra of and CNM (1:2) and used CNM (1:2) are displayed in Figure 3, and the spectra of g-C 3 N 4 were shown in previous articles [30]. The survey spectra of CNM (1:2) and used CNM (1:2) are shown in Figure 3a, the main elements are C, N, O, S and Mo, indicating g-C 3 N 4 and MoS 2 were successfully combined.…”

“…Graphitic carbon nitride (g-C 3 N 4 )'s band gap is 2.7 eV; it is a common photocatalyst with high stability and environmental friendliness [25][26][27]. Currently, thermal polycondensation is commonly used in the preparatory work of g-C 3 N 4 , which makes the preparation of g-C 3 N 4 simple [28][29][30]. However, due to the rapid recombination rate of photo-generated electrons and holes and the low light absorption range and surface range [31][32][33], the photocatalytic performance of g-C 3 N 4 photocatalysts is low, which makes the use of g-C 3 N 4 limited.…”

Nano revolution: pioneering the future of water reclamation with micro-/nano-robots

“…In Fig. 1, it can be seen that materials produced at the micro- and nanoscales that are used to build MNRs tend to possess several essential characteristics, including (i) propulsion: these robots can move independently, either by using chemical fuel or in response to external forces; 33,34 (ii) multifunctionality: they are versatile and capable of performing specific tasks, making them adaptable for various applications; 35,36 (iii) taxis: MNRs can adapt to environmental cues, such as exposure to light (phototaxis), gradients in chemical substances (chemotaxis), or magnetic fields (magnetotaxis); 7,37 (iv) communication: they can communicate with nearby robots, enabling synchronized operations while exchanging vital information; 32 (v) collective behavior: the robots can collaborate and work together in groups, enhancing process efficiency or undertaking complex tasks beyond the capabilities of individual units. 32 MNRs typically range from 10 nm to 100 μm, while nanorobots are smaller, measuring less than 1 μm.…”

Thermal reflux to synthesise C3N4 nanostructures with high yield and enhanced photocatalytic activity in hydrogen evolution

“…In these synthesis methods, the thermal polymerization method is well-known for its safe and simple preparation process in which melamine, urea or thiourea are usually used as the raw materials to prepare g-C 3 N 4 . 17,18 The CN heterocycles in these raw materials self-assemble to become a large polymer which forms a planar structure consisting of triazine and heptazine rings under heating. 19 However, the vaporized temperature of these typical raw materials is far lower than the temperature to form g-C 3 N 4 (typically 550–600 °C).…”