Effect of Koh Activation on Hydrochars Surface: Ft-Ir Analysis

Abstract

Abstract. Hydrothermal carbonization has been proven as one of the simplest and most efficient technologies to produce a variety of carbon-based hydrochars with various applications. Like other types of biochars, hydrochar has reactive, functionalized/aromatic surfaces. Those properties make hydrochar a potential low-cost adsorbent for water purification and soil remediation. In order to increase its ability to remove heavy metal contaminants from aqueous solutions, chemical modification/activation of hydrochar surface using KOH has been suggested. The presented FT-IR spectroscopy analysis of hydrochars obtained from grape pomace and miscanthus (Miscanthus×giganteus) showed that KOH modification increased the oxygen-containing functional groups on hydrochar surfaces and its aromaticity. As a result, activated hydrochars may demonstrate enhanced sorption efficiency.

Adsorption of hexavalent chromium onto alkali‐modified biochar derived from Lepironia articulata: A kinetic, equilibrium, and thermodynamic study

“…Si‐O‐Si vibrations are observed at 1,096 cm −1 that mostly disappeared after treating with KOH. Alkali activation did not affect the groups around 1,320 cm −1 (C–O stretching), 1,161 cm −1 (–C–O–C– in cellulose), and between 1,060 and 1,030 cm −1 (C–OH alcohol and/alkyl substituted ethers groups), and the bands between 720 and 590 cm −1 were attributed to alcohol and –OH out‐of‐plane bending (Mihajlović et al, ).…”

“…Being cost‐effective, good efficiency, and ease of use, modification of biochar using alkali treatment is an appealing technique. In general, by improving surface oxygen functional groups (SOFGs), removing ash, increasing surface area, and replacing surface charges, alkali modification advances the adsorption of metal anions, metal cations, and several ionic organic compounds by biochar (Huang et al, ; Ji, Li, Zhu, Wang, & Lin, ; Li et al, ; Mihajlović et al, ; Tseng, Tseng, Wu, Hu, & Wang, ).…”

Experimental and Computational Evaluation of Heavy Metal Cation Adsorption for Molecular Design of Hydrothermal Char

“…Mild alkali treatment is insufficient to break or form covalent bonds present in this structure [82], which is consistent with the negligible change in surface area associated with alkali treatment (see Table 1). That stated, Mihajlovic et al [92] proposed that hydrolytic degradation of OFGs can sometimes occur during alkali treatment, and re-arrangement of the hydrochar structure from its hypothesized form would complicate attempts to model the binding site. Accordingly, we searched for evidence of bond breaking in the spectra shown in Figure 2.…”

Application of sludge-derived KOH-activated hydrochar in the adsorptive removal of orthophosphate

“…Similar FTIR spectra were obtained for PRHC and POHC, wherein activation has resulted in the increased intensity of O–H, C–H, aromatic C C, aromatic C O and C–H stretching, eventually resulting in broad band shift. 29 However, the band at 1404 cm −1 showed reduced intensity due to partial hydrolytic degradation of cellulose after activation. 30 The reduction of the peak at 1026 cm −1 corresponding to C–O–C vibrations was due to OH deprotonation at the surface of KOH-activated hydrochars.…”