Enhanced removal of methylene blue dye from its aqueous solutions using humic acid-functionalized alumina nanoparticles

摘要

Recently, greater emphasis has been laid on the designing of nano-materials to improve the efficiency of treatment processes. Therefore, in the wake of technological improvement, a novel adsorbent humic acid-functionalized alumina (HAFA) nanoparticles were designed and have been tested for their decolorisation potential for methylene blue dye from aqueous solutions. HAFA nanoparticles were synthesized by the precipitation method and the qualitative aspect of the synthesized nanoparticles were explored by using various techniques, namely N-2 adsorption-desorption measurements, Fourier transform infrared spectroscopy, X-ray diffraction analysis, scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, thermogravimetric analysis and zero point charge analysis. The effects of different parameters like pH value, initial contact time and concentration of the adsorbent solution were investigated to optimized the removal of methylene blue. Rate constants determination were explored by employing pseudo-first-order, and pseudo-second-order kinetic models and the latter was found to be the best simulated. Moreover, for gaining insight into the adsorption interaction, sorption data were further interpreted through Weber-Morris and Boyd models. The adsorption equilibrium data were best elucidated by Freundlich's isotherm model and the maximum adsorption capacity of the HAFA nanoparticles was evaluated as 438.4 mg/g at 323 K. An adsorbent reusability study suggested that HAFA nanoparticles could be efficiently used for up to five cycles without compromising the adsorption capacity. Moreover, column investigation was also conducted, and results suggested that the breakthrough time could be easily enhanced by controlling the column bed height and effluent flow rate. A maximum breakthrough of 23 h was achieved with a column bed height of 7.5 cm.