Removal of tannins and polyhydroxy phenols by electro‐chemical techniques

Abstract

The removal of tannins and their basic molecules such as catechol, pyrogallol, phloroglucinol and resorcinol was studied by electro-flotation and electro-oxidation techniques. Iron rods and triple oxide (TaO 2 /RuO 2 /IrO 2 ) coated titanium rods were used as electrodes for electro-flotation and electrooxidation respectively. Interaction of tannins and polyhydroxy phenols with iron oxy-hydroxide formed by anodic dissolution of iron was studied by UV-Visible, FT-IR and zeta-potential measurements. GC-MS was used to identify the intermediate compounds formed during electro-oxidation. Catechol, pyrogallol, phloroglucinol and resorcinol were found to be mineralized in the presence of triple oxide (TaO 2 /RuO 2 /IrO 2 ) coated titanium electrodes. Catechol and pyrogallol were found to form insoluble organo-metal complexes while resorcinol and phloroglucinol were found to adsorb on iron oxy-hydroxide. The sludge thus formed was simultaneously separated from the aqueous phase by hydrogen bubbles. It was observed that the power consumption is relatively high for electro-oxidation compared with electroflotation. The effects of pH and reaction time on their removal were also studied and the results are discussed.

Electrochemical degradation of 17β-estradiol (E2) at boron-doped diamond (Si/BDD) thin film electrode

“…It was also observed that the chlorinated E2 compound was not degraded until the electrolysis time 180 min. Earlier studies have shown that the electro generation of chlorine-based oxidants such as ClO − and Cl 2 , can play active role in oxidation process of the organics [28][29][30]. Nevertheless, no such degradation was observed in the case of chlorinated E2 compound.…”

Enzymatic treatments of pulp using laccase and hydrophobic compounds

“…With respect to the gallate compounds, the Initial spectra presented a peak at 275 ± 1 nm, characteristic of phenol groups and common for this family of compounds (Berden and Meerts, 1996;Murugananthan et al, 2005). After the addition of laccase, a new shoulder appeared at the range of 240-260 nm, whereas the initial peak was overlapped by absorbances from reaction products (data shown in Appendix A).…”

Lignin depolymerization (LDP) in alcohol over nickel-based catalysts via a fragmentation–hydrogenolysis process

“…[44][45][46][47][48][49][50][51] In a typical run, birch sawdust (1.0 g) and methanol (10 mL) were placed in a 50 mL Teon-lined autoclave reactor. The mixture was stirred for 30 min before sealing.…”