Abstract
An exceedingly facile green approach that produces a reliable adsorbent based on a transition metal such as Iron (Fe) using Mangifera indica leaf extract at room temperature is described. A single pot method was used for synthesis with no capping agents, surfactants or other templates. The main intention of this study is to synthesize iron nanoparticles from leaf extract (Mangifera indica) and examine its degradation potential for photo-catalytic removal of dyes (Congo red and brilliant green) from wastewater. Characterization of synthesized nanoparticles was executed by pHpzc, scanning electron microscopy and Fourier transform infrared spectroscopy studies and results confirm the presence of iron nano-sheets with biomolecules. All photo-catalytic experimental results were assessed by sum of squared estimate of errors and simple linear regression R2 with dye concentration, pH, contact time and dose rate as dependent and independent variables. Adsorption experimental data was verified by kinetics and isothermal models. Results showed that Langmuir and pseudo second order models give best fitness towards the photo-catalytic adsorption procedure. Thermodynamics revealed that adsorption mechanism is endothermic, described by the values of changes in Gibbs free energy, enthalpy and entropy, and is chemisorption in nature, with spontaneous processes. Overall photo-catalytic adsorption execution with synthesized iron nanoparticles and simple biomass of Mangifera indica gives satisfactory results for treating dye wastewater.
Highlights
Characterization of green synthesized Fe-NPs was monitored by scanning electron microscopy (SEM) (Hitachi S 4800) and Fourier transform infrared (FT-IR) (FTIR-400S Shimadzu) techniques
Structural morphology of Fe-NPs from Mangifera indica enhances the photo-catalytic degradation of Brilliant green (BG) and Congo red (CR) dyes as compared to biomass powder of Mangifera indica
The holes in valence band serve as oxidizing agent that leads to the oxidative reduction of dyes (Equation (12)), while the conduction band electrons behave as reducing agent that reduces adsorbent surface oxygen, leading to reductive degradation of dyes (CR and BG). This simple study showed that green synthesized Fe-NPs made by single pot method have spherical shape, dense nano-sheets with thickness of 20 to 50 nm, as shown by SEM and FT-IR analysis
Summary
Various techniques including adsorption with photo-catalytic degradation, photo-degradation, coagulation, chemical oxidation (Ajitha et al ), electro-chemical oxidation and microbiological treatment have been utilized. Among these processes, adsorption has become a superior procedure for wastewater treatment rather than other techniques due to its simple operating properties, high efficiency, convenience and economy (Chen et al ; Shu et al ). With respect to the current reported problem, photo-catalysts, e.g. surface modified TiO2 NPs (Mohammadi & Aliakbarzadeh ), Ag NPs from Polygonum (Bonnia et al ) and zinc sulfide NPs (Ghaedi et al ), were studied, as photo-catalytic and hydrophobic properties of NPs with breakdown of organic pollutants provides an efficient reductive, high reactivity, chemically stable and low cost procedure.
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