Date of Award

2013

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Civil and Environmental Engineering

First Advisor

Biswas, Nihar

Second Advisor

Taylor, Keith E.

Keywords

Pure sciences, Applied sciences, Competitive adsorption, Concentrating sbp, Phenolicprecipitates, Preciptiates recycling, Soybean peroxidase

Rights

CC BY-NC-ND 4.0

Abstract

Studies on soybean peroxidase-catalyzed phenolic precipitates revealed that SBP trapped in precipitates during phenol polymerization retains activity. Contrary to the end-product inactivation model, recycling precipitates effectively utilized the active SBP. The minimum SBP concentration required for the subsequent batch reaction removal of 1 mM phenol from aqueous solution was reduced from 1.2 to 0.5 U/mL. SBP adsorption on precipitates was proven to be reversible by the addition of Triton X-100. Thus, a new explanation of the fate of SBP during the reaction is suggested: SBP is immobilized in-situ in an active form with reduction of specific activity rather than inactivation. Extending the study to the phenol removal reaction in the presence of polyethylene glycol, sodium dodecyl sulfate or Triton X-100 suggested some new explanations for each additive's protection mechanism. In addition, SBP and Triton X-100 adsorption was characterized by a Langmuir adsorption isotherm. Competitive adsorption between protein and non-ionic surfactant and the 'orogenic displacement mechanism' were used to explain and characterize the elution phenomenon. A quantitative relationship between SBP elution in a function of Triton X-100 concentration and precipitates concentration was established using a logistic function. A process using phenolic precipitates as the affinity matrix for concentrating SBP from dilute solution was developed. Both single-batch and consecutive cycles of operations were conducted. The process yielded a high recovery rate, and it is suitable for producing a low cost enzyme concentrate to be used in industrial wastewater treatment.

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