Corncob as an effective, eco-friendly, and economic biosorbent for removing the azo dye Direct Yellow 27 from aqueous solutions.

Nayda Karina Berber-Villamar,César Mateo Flores-Ortiz,Alma Rosa Netzahuatl-Muñoz,Eliseo Cristiani-Urbina,Liliana Morales-Barrera,Griselda Ma Chávez-Camarillo,Amitava Mukherjee

doi:10.1371/journal.pone.0196428

Nayda Karina Berber-Villamar, César Mateo Flores-Ortiz + Show 5 more

Open Access

https://doi.org/10.1371/journal.pone.0196428

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Abstract

The corncob is an agricultural waste generated in huge quantities during corn processing. In this paper, we tested the capacity of corncob particles for water purification by removing the azo dye Direct Yellow 27 (DY27) via biosorption. The biosorption process was investigated in terms of the kinetics, equilibria, and thermodynamics. Batch biosorption studies showed that the biosorption performance has strong inverse correlations to the solution pH and the corncob particle size, and it increases quickly with increasing contact time and initial dye concentration. The pseudo-second-order kinetic model provides the best fit to the experimental data, whereas the Redlich-Peterson isotherm model is most suitable for describing the observed equilibrium biosorption. The biosorption process is exothermic, spontaneous, and physisorption in character. Fourier transform infrared (FTIR) spectroscopy and confocal scanning laser microscopy (CSLM) studies suggest that lignocellulose and proteins play key roles in the biosorption of DY27 from aqueous solutions by corncob. Furthermore, after biosorption onto the corncob, the dye can be effectively desorbed using 0.1 M NaOH solution. Therefore, the corncob can be used as a promising biosorbent to remediate DY27-contaminated water and wastewater.

Highlights

Synthetic organic dyes are extensively used in many technologies, such as textiles, printing, paper making, leather tanning, rubber, food processing, plastics, cosmetics, hair coloring, pharmaceuticals, photography, agricultural research, light-harvesting arrays, and photoelectrochemical cells [1,2,3]
The value of 6.83 is close to that reported by Leyva-Ramos et al [38], who attributed the weak acidity of natural corncob to the slightly higher concentration of acid sites than that of the basic ones
The present work clearly demonstrates the feasibility of utilizing corncob as a novel, effective, efficient, eco-friendly, and inexpensive biosorbent for the removal of Direct Yellow 27 (DY27) dye from aqueous solutions

Summary

Introduction

Synthetic organic dyes are extensively used in many technologies, such as textiles, printing, paper making, leather tanning, rubber, food processing, plastics, cosmetics, hair coloring, pharmaceuticals, photography, agricultural research, light-harvesting arrays, and photoelectrochemical cells [1,2,3]. Biosorption of Direct Yellow 27 dye from aqueous solutions by corncob industrial wastewaters [4] Such wastewaters are often discharged directly into natural water bodies without treatment. Even a very small amount of dye (less than 1 mg L-1) can markedly color the water, making it unfit for human consumption [6, 7]. Such colored water has reduced sunlight penetration, which lowers photosynthetic activities in the water and increases the heterotrophic activity that depletes dissolved oxygen [8]. The impurities and (bio)transformation products of certain synthetic dyes directly affect human health due to their acute and/or chronic toxicity; allergenic, mutagenic, carcinogenic, genotoxic, cytotoxic, estrogenic, and anti-estrogenic activities; and immune suppression effects [9,10,11,12]

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