Insight into Organic Pollutant Adsorption Characteristics on a g-C₃N₄ Surface by Attenuated Total Reflection Spectroscopy and Molecular Dynamics Simulation

Abstract

Herein the adsorption characteristics of zwitterionic dye pollutant Rhodamine B (Rh + B − ) on a g-C 3 N 4 surface were investigated by both an attenuated total reflection spectroscopy (ATRS) experiment and a molecular dynamics simulation (MDS). For experimental investigation, g-C 3 N 4 was coated on a silica optical fiber (SOF) surface to fabricate an adsorption film. According to the ATRS response, adsorption thermodynamics and thermodynamics results were in situ obtained and evaluated. The isothermal Langmuir model was used to calculate the adsorption equilibrium constants (K ads ) and adsorption energies (ΔG ads ) for Rh + B − as 27.25 × 10 4 M −1 and −31.01 kJ mol −1 , respectively, which indicated the spontaneous adsorption behavior of Rh + B − at the g-C 3 N 4 surface. Using dynamic Elovich modeling, the rate constants of Rh + B − were found to be k 1 = 0.0063 min −1 and k 2 = 0.0004 min −1 , which indicated two-stage adsorption at the g-C 3 N 4 surface. For theoretical simulation, adsorption configurations and adsorption energies were systematically calculated by a molecular dynamics simulation (MDS) . Rh + B − molecules were inclined to orient in a parallel position at the g-C 3 N 4 surface during low concentration but a perpendicular position at the g-C 3 N 4 surface during high concentration. Combined with experimental and calculation results, this work revealed the microscopic adsorption performance and elucidated the intermolecular interaction between localized interfaces of g-C 3 N 4 and hazardous dye pollutant. We propose an adsorption model to explain the process of surface interaction, which is based on molecular orientation and a force-driven mechanism. Electrostatic attraction and π−π interaction dominated the adsorption interaction with an adsorption energy of ΔG low(ads) = −38.96 kJ mol −1 for low Rh + B − concentration, and electrostatic attraction dominated the adsorption interaction with an adsorption energy of ΔG high(ads) = −25.76 kJ mol −1 for high Rh + B − concentration. This work can provide a fundamental basis for a dye-pollutants removal application by g-C 3 N 4 in both adsorption and photocatalyzation.

Synergistic Generation of Radicals by Formic Acid/H2O2/g-C3N4 Nanosheets for Ultra-efficient Oxidative Photodegradation of Rhodamine B

“…Water pollution is an enormous threat to the environment and human health. Photocatalyzed degradation of water pollutants is a sustainable approach to deal with this environmental crisis. − Rhodamine B (RhB), a xanthene class dye widely applied in paint, plastic, paper, and printing industries, is a highly toxic refractory pollutant, which might cause mutation and carcinogenesis when accumulated in human bodies. , Hence, RhB has been used as the modeling organic pollutant in various degradation studies ,− for its appropriate photostability and easy detection via UV–vis spectroscopy. Two pathways exist for the degradation of RhB, i.e.…”

“…1−4 Rhodamine B (RhB), a xanthene class dye widely applied in paint, plastic, paper, and printing industries, is a highly toxic refractory pollutant, which might cause mutation and carcinogenesis when accumulated in human bodies. 5,6 Hence, RhB has been used as the modeling organic pollutant in various degradation studies 5,7−9 for its appropriate photostability and easy detection via UV−vis spectroscopy. Two pathways exist for the degradation of RhB, i.e., oxidative 2,7,8 and reductive 5,9 pathways.…”

Test study and molecular dynamics simulation of Fe3+ modified TiO2 absorbing automobile exhaust

“…In other words, the adhesion work is the difference between the total energy of a whole-body (formed by adsorption of automobile exhaust and TiO 2 ) and the sum of the surface energy of vehicle exhaust and TiO 2 respectively before adsorption. The larger the adhesion work value between automobile exhaust and TiO 2 , the more difficult the automobile exhaust to separate from the surface of TiO 2 , which means that the adsorption is more difficult to be destroyed [ 41 , 42 ]. The calculation method is shown in Eq ( 4 ).…”

Flexible Synthesis of Bio-Hydroxyapatite/Chitosan Hydrogel Beads for Highly Efficient Orange G Dye Removal: Batch and Recirculating Fixed-Bed Column Study

“…The main benefits of adsorption process include their simplicity, highly cost-effective and economically energy consumption, environmental friendliness, and recyclability. 9,10 Numerous studies are being conducted to discover low-cost, eco-friendly materials to eliminate pollutants in aqueous environments. 11 Crucial importance has been gained on the biomaterials as adsorbents to remove contaminants, which can reduce the process cost substantially and make the adsorption method more ecological and feasible.…”

“…To mitigate and prevent dye pollution, several treatment methods have been implemented to clean up colored effluents, such as coagulation-flocculation, photocatalysis, membrane filtration, and adsorption. , Nevertheless, the adsorption process is considered to be an effective and simple method that is relatively free from the concerns of generating unwanted byproducts and has a good percentage of dye removal. The main benefits of adsorption process include their simplicity, highly cost-effective and economically energy consumption, environmental friendliness, and recyclability. , …”