Water Purification through Bioconversion of Phenol Compounds by Tyrosinase and Chemical Adsorption by Chitosan Beads

Abstract

Enzymatic removal of various phenol compounds from artificial wastewater was undertaken by the combined use of mushroom tyrosinase (EC 1.14.18.1) and chitosan beads as function of pH value, temperature, tyrosinase dose, and hydrogen peroxide-to-substrate ratio. Chitosan film incubated in a p-crersol+tyrosinase mixture had the main peaks at 400-470 nm assigned to chemically adsorbed quinone derivatives, which increased over the immersion time. These results indicate that removal of phenol compounds is caused by their tyrosinase-catalyzed oxidation to the corresponding quinone derivatives and the subsequent chemical adsorption on the chitosan film. The optimum conditions for quinone adsorption were determined to be pH 7 and 45 degrees C for p-cresol. Some alkyl-substituted phenol compounds were removed by adsorption of quinone derivatives enzymatically generated on the chitosan beads, and the % removal for p-cresol, 4-ethylphenol, 4-n-propylphenol, 4-n-butylphenol, and p-chlorophenol went up to 93%. In addition, 4-tert-butylphenol underwent tyrosinase-catalyzed oxidation in the presence of hydrogen peroxide. This procedure was applicable to removal of chlorophenols and alkyl-substituted phenols.

Use of chitosan for removal of bisphenol A and bisphenol derivatives through tyrosinase‐catalyzed quinone oxidation

“…[59][60][61][62][63] The peak position at 385 nm obtained in this study was in agreement with those assigned to quinone derivatives enzymatically generated from alkylphenols. 62 The emergence of the peak at 385 nm and color development of the solution support quinone generation from BPA by mushroom tyrosinase. Here, bisquinone derivatives can be possibly generated in addition to monoquinone derivatives with a unreacted phenolic AOH group because BPA has two phenolic groups.…”

“…A solution of 20 mm 3 was injected and the absorption spectra were determined. 62,63,65 RESULTS AND DISCUSSION…”

“…64 Alternatively, in our previous articles crosslinked chitosan beads were dispersed in solutions of alkylphenols and chlorophenols containing tyrosinase. 62,63 Then, alkylphenols and chlorophenols were effectively removed through chemisorption of quinone derivatives on chitosan beads. It should be noted that an increase in the amount of chitosan Figure 1 Chemical structures of chitosan and BPA and bisphenol derivatives used in this study.…”

Removal of phenols and dyes from wastewater using native and recombinant oxidative enzymes

“…Šta više, studija ove agencije je pokazala da korišćenje hlora za dezinfekciju fenolne vode može da dovede do stvaranja toksiĉnog 2-hlorfenola (EPA, 1980). Gornja granica odreĊena regulativama za ispuštanje fenolne otpadne vode u otvorene tokove se razlikuje od zemlje do zemlje, ali se uglavnom kreće oko 10 mg/L (Yamada et al, 2005). U Republici Srbiji ispuštanje otpadne vode je regulisano mnoštvom zakona i pravilnika koji se većim dijelom slažu sa meĊunarodnim zakonima, poput pravila EPA da se fenol u vodi za piće ne smije nalaziti u koncentraciji većoj od 1 µg/L.…”

“…Opisanim tretmanom koncentracija halogenfenola je smanjena ispod 10 mg/L što je gornja granica odreĊena regulativama za ispuštanje fenolne otpadne vode u otvorene tokove (Yamada et al, 2005). Skoro podjednako uspješan je postupak koji koristi peroksidazu iz gorke tikve (Ashraf i Husain, 2010).…”