Development, Synthesis and Characterization of Tannin/Bentonite-Derived Biochar for Water and Wastewater Treatment from Methylene Blue

Abstract

Novel hybrid carbon–mineral materials were synthesized by the mechanochemical activation of a mixture of tannin and bentonite in a ball mill with further pyrolysis in an argon atmosphere at 800 °C. The influence of the initial mixture ingredients content on the structural, textural, and thermal characteristics of biochars has been described using X-ray diffraction, Raman and Fourier-transform infrared spectroscopy, nitrogen adsorption–desorption, and scanning electron microscopy. The influence of bentonite clay on the carbon phase characteristics due to the formation of more heat-resistant and structured nanocarbon particles in biochars has been proven. The adsorption effectiveness of the materials towards methylene blue was studied. The adsorption data were analyzed applying Langmuir and Freundlich isotherms with high determination coefficients (R2) in the range of 0.983–0.999 (Langmuir) and 0.783–0.957 (Freundlich). The maximum adsorption amount of MB was 5.78 mg/g. The adsorption efficiency of biochars with respect to phenol was also examined. It was shown that the hybrid biochars show differentiated selectivity to the adsorption of organic compounds. It was concluded that the physicochemical properties of the surface of biochars play an important role in the adsorption effectiveness, making them a good candidate for water and wastewater remediation processes.

Effect of pyrolysis temperature and hydrothermal activation on structure, physicochemical, thermal and dye adsorption characteristics of the biocarbons

“…They are considered toxic, carcinogenic, non-biodegradable, and environmentally dangerous substances, therefore, their removal from wastewater and water is a very important undertaking. [16] The most effective and inexpensive method is adsorption on porous sorbents due to the great efficiency of the process. The commonly used materials for this purpose are activated carbon materials.…”

“…Dyes are synthetic or natural compounds characterized by complex, aromatic structures of the molecules. They are considered toxic, carcinogenic, non‐biodegradable, and environmentally dangerous substances, therefore, their removal from wastewater and water is a very important undertaking [16] . The most effective and inexpensive method is adsorption on porous sorbents due to the great efficiency of the process.…”