Adsorption of methylene blue dye from the aqueous solution via bio-adsorption in the inverse fluidized-bed adsorption column using the torrefied rice husk

Khalid Khazzal Hummadi,Sha Luo,Songbo He

doi:10.1016/j.chemosphere.2021.131907

Khalid Khazzal Hummadi, Sha Luo + Show 1 more

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https://doi.org/10.1016/j.chemosphere.2021.131907

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Abstract

In this work, the inverse fluidized-bed bio-adsorption column is applied for the first time and is demonstrated using the torrefied rice husk (TRH) for the removal of methylene blue from the solution. The bio-adsorbents were characterized by BET, FI-IR, and SEM. The inverse fluidized-bed adsorption column using TRH becomes saturated in the 95-min continuous adsorption, during which the breakthrough time is 22 min, the overall MB removal (R) is 84%, and the adsorption capacity (Qexp) on the TRH is 6.82 mg g−1. These adsorption characteristics are superior to those in the fixed-bed adsorption column (R of 52% and Qexp of 2.76 mg g−1) at a lower flow rate (100 vs. 283 cm3 min−1). Torrefaction of RH significantly increases the surface area (28 vs. 9 m2 g−1) and enhances the surface functional groups, leading to an improved maximum equilibrium adsorption amount from 21.5 to 38.0 mg g−1 according to Langmuir model in the batch adsorption system. Besides, the increased Qexp on the TRH is also obtained in the inverse fluidized-bed (5.25 vs. 2.77 mg g−1, 89% higher) and the fixed-bed (2.76 vs. 1.53 mg g−1, 80% higher) adsorption columns compared to that on the RH.

Highlights

Textile dyeing applying the colorants to the textile materials consumes over 50% of the dyes produced globally and discharges about 10–15% of the colors in the effluent (Varjani et al, 2021)
The adsorption capacity of the bio-adsorption of MB on the Rice husk (RH) and torrefied rice husk (TRH) was first studied in the batch adsorption system, in which the initial MB concentration was 6 mg L− 1
The equilibrium adsorption amount of MB is decreased from qe of 17 to 0.4 mg g− 1 and from qe of 31 to 0.4 mg g− 1

Summary

Introduction

Textile dyeing applying the colorants to the textile materials (e.g., fiber and fabrics) consumes over 50% of the dyes produced globally (over 0.7 million tons per annum) and discharges about 10–15% of the colors in the effluent (Varjani et al, 2021). The textile effluent contains suspended solids and the recalcitrant organic molecules in the aqueous solution, causing the high chemical and biochemical oxygen demand (Yaseen and Scholz, 2019). Rice husk (abbreviated as RH) is an interesting bio-adsorbent, which is abundantly available (over 150 million tons per annum as the rice milling by-product) and consists of cellulose, hemicelluloses, lignin, hydrated silica, and some other minerals (Zou and Yang, 2019). The floristic fiber and the abun dant functional groups (e.g., carboxyl, hydroxy, and amidogen) on the RH surface make it applicable to the bio-adsorption process for the removal of the variety of the dyes (Table 1)

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