Sawdust based hydtrothermal carbon as adsorbent for removal of sterols from water

Abstract

Nowadays, various types of inexpensive, sustainable and renewable lignocellulosic waste materials are increasingly being utilized as precursors for carbon adsorbents production. The usage of the lignocellulosic wastes for production of carbon materials is very attractive from the point of decreasing waste disposal costs and improving environment protection through the waste recycling and producing useful products. In this work, carbon adsorbents were obtained starting from beech sawdust (a waste from the wood industry), and using hydrothermal carbonization, followed by activation in the presence of KOH as an activating agent. By varying the activation parameters, activated hydrothermal carbon (AcHTC) samples with different characteristics were obtained. The specific surface area of AcHTC samples was examined by N2 adsorption, while the nature and thermal stability of the surface oxygen groups was investigated by Fourier transform infrared spectroscopy and temperature programmed desorption method. The possibility of using AcHTC samples as adsorbents was tested using water solution of eleven sterols belonging to the different classes (human/animal and plant sterols). These sterols, usually present at a very high concentrations in wastewater influent and effluent samples, can cause numerous endocrine disorders and therefore should be removed from the aquatic environment. Obtained results showed that activated carbons based on hydrothermally treated sawdust were highly efficient adsorbents, completely removing all tested sterols from water.