Removal of phenol by enzymatic oxidation and flotation

Abstract

This work presents a process for phenol removal comprising a reaction step in which phenol is polymerized in the presence of an enzyme followed by a separation step involving dissolved air flotation (DAF). A crude preparation from horseradish roots was used as a low purity source of the enzyme horseradish peroxidase (HRP). The technical feasibility of the process was studied at bench scale using 1 to 10 mM synthetic phenol solutions. Experimental results showed the potential of the proposed technique. A phenol conversion higher than 99 % was observed at the polymerization step and an efficiency higher than 94 % was achieved at the separation stage. Despite the use of a low purity source of HRP, which increases the input of organic matter, the chemical oxygen demand (COD) decreased by 50 %

Formation of bioactive benzofuran via oxidative coupling, using coconut water (Cocos nucifera L.) as biocatalyst

“…This ambiguous behavior is explained by the action of an auxiliary protein that is present in the natural environment, but absent in the purified commercial enzyme. In previous studies, it was shown that synthetases present in natural extracts would be responsible for the alignment of phenoxyl radicals 3 . These radicals are produced primarily by the action of peroxidases (see Scheme S2, in the supplementary material).…”

“…These biocatalysts are an emerging eco-friendly alternative that can be used in oxidative reactions, given that their selectivity is superior to that of other chemocatalysts. Moreover, the enzymatic treatment efficiency seems to be independent of the enzyme purity; therefore, it is possible to utilize a crude enzyme preparation instead of a purified one, thus minimizing chemical production costs 3 . The reduction of peroxides at the expense of electron-donating substrates makes PODs useful in a number of biotechnological applications 4 .…”

Biological removal of phenol from wastewaters: a mini review

“…Peroxidases are the most widely reported enzymes for phenol polymerization when compared with other enzymes. Authors have reported the use of purified horseradish peroxidase (HRP) to remove 30 different phenols and aromatics amines (Wilberg et al 2000;Cooper and Nicell 1996). Phenol conversion is activated by H 2 O 2 ; the enzyme catalyzes the oxidation of aromatic compounds, forming free radicals which undergo spontaneous polymerisation (Wilberg et al 2002).…”

“…On the other hand, lack of hydrogen peroxide during the reaction step limits the rate of reaction. The semi-batch addition of H 2 O 2 to maintain an optimized ratio between hydrogen peroxide and enzyme concentrations was found to suppress this inhibition (Kulkarni and Kaware 2013;Wilberg et al 2000).…”

“…Wilberg et al (2000) used an enzymatic process for phenol removal comprising a reaction step in which phenol was polymerized in the presence of an HRP enzyme. Experimental results showed the potential of the proposed technique having a conversion higher than 99 %.…”