Highly efficient and simultaneous catalytic reduction of multiple toxic dyes and nitrophenols waste water using highly active bimetallic PdO–NiO nanocomposite

Abstract

Azo dyes and nitrophenols have been widely used in the various industry which are highly toxic and affecting the photosynthetic cycle of aquatic organism. The industry disposals increase the accumulation of azo compounds in the environment. In the present study, we synthesized the low cost, PdO-doped NiO hetero-mixture via simple hydrothermal combined calcination process. The morphology results proved that, the spherical PdO nanoparticles are evenly doped with NiO nanoparticles. The band gap values of metal oxides NiO, PdO and PdO–NiO composite were found to be 4.05 eV, 3.84 eV and 4.24 eV, respectively. The high optical bandgap (Eg) value for composite suggests that the PdO interface and NiO interface are closely combined in the composite. The catalytic activity of the PdO–NiO was analyzed for the reduction of different toxic azo compounds namely, 4-nitrophenol (NP), 2,4-dinitrophenol (DNP), 2,4,6-trinitrophenol (TNP), methylene blue (MB), rhodamine B (RhB) and methyl orange (MO) separately and their mixture with the presence of a NaBH4. For the first time, the large volume of the toxic azo compounds was reduced into non-toxic compounds with high reduction rate. The proposed PdO–NiO catalyst exhibit excellent rate constant 0.1667, 0.0997, 0.0686 min−1 for NP, DNP and TNT and 0.099, 0.0416 and 0.0896 min−1 for MB, RhB and MO dyes respectively which is higher rate constant than the previously reported catalysts. Mainly, PdO–NiO completes the reduction of mixture of azo compounds within 8 min. Further, PdO–NiO exhibit stable reduction rate of azo compounds over five cycles with no significant loss. Hence, the proposed low cost and high efficient PdO–NiO catalyst could be the promising catalyst for degradation of azo compounds.

Synthesis of Water-Stable Ferrocene-Encapsulated Ni-MOF Nanoadsorbents for Enhanced Removal Capacity for Arsenites As(III) Ions at Neutral pH

“…Additionally, the Ni characteristic appeared at 652 nm, whereas Fc spectra show typical intense absorption peak at 440 nm due to Fe(d–d) electron transitions. From UV–vis spectra, band gap energy was derived for all adsorbents using the Schuster–Kubelka–Munk function ( α h ν ) n = A ( h ν − E normalg ) Band gap energy was predicted by extrapolating against photon energy and is presented in Figure f. The parent compounds Ni-MOF and Fc show the band gap energy of 2.63 and 2.39 eV, respectively.…”

In situ synthesis of metal (Bi0)–semiconductor [BiOX (X = Cl, Br, and I)] nanocomposites as a highly effective catalyst for the reduction of 4-nitrophenol to 4-aminophenol

“…[7][8][9][10][11] Therefore, the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) represents the predominant approach for circumventing these issues since 4-AP exhibits a lower degree of toxicity in comparison to 4-NP. 12,13 The 4-AP is a most important intermediate for the preparation of a number of drugs such as analgesic and antipyretic drugs. Besides this, 4-AP also has many uses in different areas such as photographic developer, corrosion inhibitor, synthetic colors, hair-dyeing agent, and so forth.…”

Photoluminescence and Photocatalytic Properties of MWNTs Decorated with Fe-Doped ZnO Nanoparticles

“…Over time, researchers have attempted to find effective solutions to surmount these problems. Conventional methods such as adsorption, coagulation, ion flotation [ 10 ], sedimentation [ 11 ] and ozone electrolysis [ 12 ] have led to satisfactory results, but present some shortcomings, such as [ 13 ] the large consumption of chemical reagents, generation of secondary waste products and high costs [ 14 ]. The advanced oxidation process (AOP) provides an efficient alternative to the efficient elimination of dyes from water through reactive oxygen species (ROS) generation [ 15 ].…”