Photocatalysis and adsorption kinetics of azo dyes by nanoparticles of nickel oxide and copper oxide and their nanocomposite in an aqueous medium

Abstract

Background Azo dyes are recalcitrant organic pollutants present in textile industry effluents. Conventional treatment methods to remove them come with a range of disadvantages. Nanoparticles and their nanocomposites offer more efficient, less expensive and easy to handle wastewater treatment alternative. Methods In this study, nanoparticles of nickel oxide (NiO-NPs), copper oxide (CuO-NPs) and their nanocomposite (NiO/CuO-NC) were synthesized using co-precipitation method. The functional groups present on the surface of synthesized nanomaterials were verified using Fourier-transform infrared spectroscopy (FTIR). Surface morphology was assessed using scanning electron microscopy (SEM) whereas purity, shape and size of the crystallite were determined using X-ray diffraction (XRD) technique. The potential of these nanomaterials to degrade three dyes i.e., Reactive Red-2 (RR-2), Reactive Black-5 (RB-5) and Orange II sodium salt (OII) azo dyes, was determined in an aqueous medium under visible light (photocatalysis). The photodegradation effectiveness of all nanomaterials was evaluated under different factors like nanomaterial dose (0.02–0.1 g 10 mL−1), concentration of dyes (20–100 mg L−1), and irradiation time (60–120 min). They were also assessed for their potential to adsorb RR-2 and OII dyes. Results Results revealed that at optimum concentration (60 mgL−1) of RR-2, RB-5, and OII dyes, NiO-NPs degraded 90, 82 and 83%, CuO-NPs degraded 49, 34, and 44%, whereas the nanocomposite NiO/CuO-NC degraded 92, 93, and 96% of the said dyes respectively. The nanomaterials were categorized as the efficient degraders of the dyes in the order: NiO/CuO-NC > NiO-NPs > CuO-NPs. The highest degradation potential shown by the nanocomposite was attributed to its large surface area, small particles size, and quick reactions which were proved by advance analytical techniques. The equilibrium and kinetic adsorption of RR-2 and OII on NiO-NPs, CuO-NPs, and NiO/CuO-NC were well explained with Langmuir and Pseudo second order model, respectively (R2 ≥ 0.96). The maximum RR-2 adsorption (103 mg/g) was obtained with NiO/CuO-NC. It is concluded that nanocomposites are more efficient and promising for the dyes degradation from industrial wastewater as compared with dyes adsorption onto individual NPs. Thus, the nanocomposite NiO/CuO-NC can be an excellent candidate for photodegradation as well as the adsorption of the dyes in aqueous media.

Z-scheme NiO/g-C3N4 nanocomposites prepared using phyto-mediated nickel nanoparticles for the efficient photocatalytic degradation

“…The photocatalytic activity of NiO/g-C 3 N 4 prepared in this work is compared with other NiO-based photocatalysts. From various previous papers, it can be summarized that the photocatalytic activity from this work towards TC degradation is lower compared with NiO/rGO which demonstrated the high DE (99%) in 30 min [ 41 ], but comparable respect to the activity of NiO NPs and NiO/CuO nanocomposite, ZnO/NiFe 2 O 4 /Co 3 O 4 VO 4 ,/NiFe 2 O 4 and NiAl-LDH [ [42] , [43] , [44] , [45] ]. From RhB photocatalytic oxidation experiment, the activity of this work is also less than NiAl-LDH [ 42 ], but comparable with the activity of graphene oxide/Fe 3 O 4 /NiO [ 46 ], and MoS 2 /NiS 2 [ 47 ].…”

The Biosynthesis of Nickel Oxide Nanoparticles: An Eco-Friendly Approach for Azo Dye Decolorization and Industrial Wastewater Treatment

“…The results revealed that the NiO-NPs were effective in degrading these dye molecules, with a degradation efficiency of 89% for FG and 77% for RB. Ahsan et al (2022) [53] synthesized nickel oxide nanoparticles (NiO-NPs), copper oxide nanoparticles (CuO-NPs), and their nanocomposite (NiO/CuO-NC) via precipitation method. Results revealed that at an optimum concentration (60 mg L −1 ) of RR-2, RB-5, and OII, the dyes were degraded 90, 82, and 83% by NiO-NPs; 49, 34, and 44% degraded by CuO-NPs; whereas the nanocomposite NiO/CuO-NC was degraded by 92, 93, and 96%, respectively.…”