An enhanced removal of para-nitrophenol (PNP) from water media using CaAl-layered double hydroxide-loaded magnetic g-CN nanocomposite

• Published in: Journal of water process engineering 2022-04, Vol.46, p.102516, Article 102516
• Main Authors: Noorani Khomeyrani, Seyedeh Fatemeh, Ghalami-Choobar, Bahram, Ahmadi Azqhandi, Mohammad Hossein, Foroughi, Maryam
• Format: Article
• Language: English
• Subjects: Adsorption; ANFIS; CCD; GRNN; Modeling; Phenolic compounds
• ISSN: 2214-7144; 2214-7144
• DOI: 10.1016/j.jwpe.2021.102516

A novel nanocomposite benefiting from the advantages of graphite carbon nitride (g-CN) adsorption, magnetic nanoparticles (Fe3O4) fast and easy separation along with an avoided aggregation, and photocatalyst properties of Ca-Al-LDH (called CaAl-LDH/g-CN@Fe3O4 Nanocomposite) was successfully synthesized as confirmed by techniques of X-ray diffraction (XRD), scanning electron microscope (SEM), Transmission electron microscopy (TEM), Thermal gravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR) and Brunauer, Emmett and Teller (BET), and then evaluated for Para nitro phenol (PNP) adsorption under different operational parameters of PNP initial concentration, temperature, nanocomposite (NC) dose, and sonication time. At the genetic algorithm-specified optimum conditions a removal efficiency of 88.8% and adsorption capacity of 21.13 mg/L would be attainable if the parameters were set at 38.45 °C, 10.24 mg, and 11.8 min, respectively. The process was also tried for modeling using different approaches of response surface methodology (RSM), general regression neural network (GRNN), and adaptive network-based fuzzy inference system (ANFIS), exhibited much more reliable statistics (R2 = 0.999, RMSE = 0.0082, MAE = 0.0069, SSE = 0.0034, and χ2 = 0.0072). The isotherm, kinetic, and thermodynamic studies showed a heterogenous, multi-layer, and chemisorption process with an endothermic, feasible, and spontaneous nature as the two first ones well followed by Dubinin-Radushkevich (R2 > 0.999) and pseudo-second-order (R2 > 0.99) models, and the second one displayed the negative Enthalpy (∆Ho), positive Entropy (∆So), and negative Gibb's energy (∆Go) values. The mechanism of action showed that the process was mainly mediated by π-π conjugate interactions, electrostatic attractions, and hydrogen bonding. In addition, the developed NC was found to be recyclable over four times without significant breakthrough in the efficiency (>80%). The findings of this study suggest that CaAl-LDH/g-CN@Fe3O4 NC can be considered as a potential option for remediation of NP-containing water media, although the obstacles of scaling-up are still need to be overcome. [Display omitted] •Mechanisms for remarkable capacity and selectivity of CaAl-LDH/g-CN@Fe3O4 NC are addressed.•PNP is removed via hydrogen bonding, electrostatic and precipitation interactions.•CaAl-LDH/g-CN@Fe3O4 NC was successfully prepared using a hydrothermal method.•ANIFS, GRNN and RSM based CCD was used for