Adsorption of Methylene blue and Methyl orange on nano zero-valent iron (nZVI) coated biochar: column adsorption experiments
Wenchuan Ding, Alphonse Habineza, Xiaolan Zeng, Zhuoyi Yan, Jun Yan, Guang Yang
Abstract
ABSTRACT Despite its attractiveness and combinatorial effectiveness, the biochar supported nanoscale zero-valent iron particles (nZVI) composite has not been applied in a multi-dye system and fixed bed column experiments. The present work aimed at preparing a corn cob biochar coated with nZVI particles to obtain an efficient low-cost adsorbent and investigate its potential to remove two synthetic dyes Methylene blue (MB) and Methyl orange (MO) from their single and mixture using column experiments. Brunauer–Emmett–Teller surface analyzer, scanning electron microscopy-energy-dispersive X-ray analysis, X-ray diffraction, Zetasizer Nano ZS90 and Fourier-transform infrared spectroscopy have been used to investigated the physico-chemical properties of the prepared adsorbent and explore the dynamics of competition, selectivity and adsorption mechanisms involved in dyes removal from their mixture. The MB antagonistic action vis-à-vis MO removal was high in column binary dye adsorption experiments. Experimental data of MB removal were fitted to non-linear Thomas and Yoon–Nelson models, the former fitting the best with R 2 = 0.9886. The dynamic absorption capacity ( q b ) was 15 mg/g, the column removal efficiency 89.64% and the highest adsorption capacity 118.056 mg/g. Dyes’ adsorption mechanism involved mainly electrostatic attractions, adsorbent surface sorption and pore diffusion. The complexity of the breakthrough curve of MO and non-attainment of the bed column exhaustion time suggest further detailed research studies.