Biochar from Wood Chips and Corn Cobs for Adsorption of Thioflavin T and Erythrosine B.

Martin Pipíška,Milan Hvostik,Eva Klára Krajčíková,Ivona Černičková,Gerhard Soja,Vladimír Frišták,Mária Kaňuchová,Pellegrino Conte,Libor Ďuriška

doi:10.3390/ma15041492

Abstract

Biochars from wood chips (WC) and corn cobs (CC) were prepared by slow pyrolysis and used for sorption separation of erythrosine B (EB) and thioflavin T (TT) in batch experiments. Biochar-based adsorbents were extensively characterized using FTIR, XRD, SEM-EDX, and XPS techniques. The kinetics studies revealed that adsorption on external surfaces was the rate-limiting step for the removal of TT on both WC and CC biochar, while intraparticle diffusion was the rate-limiting step for the adsorption of EB. Maximal experimental adsorption capacities Qmaxexp of TT reached 182 ± 5 (WC) and 45 ± 2 mg g−1 (CC), and EB 12.7 ± 0.9 (WC) and 1.5 ± 0.4 mg g−1 (CC), respectively, thereby indicating a higher affinity of biochars for TT. The adsorption mechanism was found to be associated with π-π interaction, hydrogen bonding, and pore filling. Application of the innovative dynamic approach based on fast-field-cycling NMR relaxometry indicates that variations in the retention of water-soluble dyes could be explained by distinct water dynamics in the porous structures of WC and CC. The obtained results suggest that studied biochars will be more effective in adsorbing of cationic than anionic dyes from contaminated effluents.

Highlights

Introduction iationsIn recent decades, there has been an enormous raise in the production and application of synthetic dyes
wood chips (WC) and corn cobs (CC) biochars obtained by the pH drift method were 8.3 and 8.5, respectively
The adsorption properties of thioflavin T (TT) and erythrosine B (EB) on the biochars prepared by slow pyrolysis of wood chips (WC) and corn cobs (CC) were successfully investigated and compared

Summary

Introduction

Introduction iationsIn recent decades, there has been an enormous raise in the production and application of synthetic dyes. It is not surprising that the long-term utilization of synthetic dyes in a different range of industries such as the textile and food industries and the manufacture of pulp, paper, and dyestuffs have resulted in widespread water contamination [2,3]. Due to their low fixation rates, a large number of dyes are discharged into wastewater, and currently used dyes (e.g., in the textile industry) are generally stable and not highly toxic or carcinogenic, in some circumstances their degradation products could be more harmful to the aquatic ecosystem [4].

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Conclusion