Green Synthesis, Characterization, and Application of Teff Straw-Assisted ZnO Nanoparticle for Removal of Methylene Blue Dye from Textile Industry Wastewater

Abstract

Contamination of water resources by methylene blue dye has become a source of environmental concern because of its toxicity thus causing significant harm to human organs and having an impact on aquatic lives. Although Zinc Oxide nanoparticles synthesized by chemical and physical methods have been developed for the removal of methylene blue dye wastewater by adsorption method, Zinc Oxide nanoparticles lose reactivity towards the adsorbate, posing toxicity to the environment, instability, and agglomeration problematic. Hence, surface modified; green synthesized Zinc Oxide nanoparticles are alternative adsorbent, which form stable and alleviate agglomeration in the Zinc Oxide nanoparticles synthesis for methylene blue dye removal are required. The emphasis of this thesis is on the green synthesis, characterization, and application of Zinc oxide teff straw assisted nanoparticles for the removal of methylene blue dye from textile wastewater.Teff straw-assisted Zinc Oxide nanoparticles were synthesized by reduction of Zinc nitrate hexahydrate solution using neem leaf extract as a capping agent. The physicochemical properties of Teff straw assisted Zinc Oxide nanoparticles were characterized using, X-ray diffraction and Fourier transform-infrared spectroscopy, analysis confirmed that the surface of Zinc oxide nanoparticles was efficiently functionalized. The X-ray diffraction analysis revealed the presence of Zinc oxide in the synthesized Teff straw-assisted Zinc Oxide nanoparticles with an average crystalline size of 27.196 nm. Series adsorption experiments were conducted to examine the removal efficiency of methylene blue dye on Teff straw-assisted Zinc Oxide nanoparticles and the effect of various adsorption parameters from Textile Wastewaters. It was found that pH, the dose of Teff straw assisted Zinc Oxide nanoparticles, contact time and initial concentration affects the removal of methylene blue dye. A response surface methodology with the central composite design was used for the optimization of removal efficiency of methylene blue dye onto the adsorbent’s surface. The optimal conditions selected using the design tool were 6.904 pH, 68.489 mg/L initial methylene blue dye concentration,0.265 g dosage of Teff straw assisted Zinc Oxide nanoparticles, and 77.873 min contact time providing a predicted value of 99.769 % removal efficiency and this was adequately fit into the Freundlich isotherm model with correlation coefficient of 0.99. Also, the water quality parameters in real textile wastewater were determined and its removal efficiency was 92.5%