chlorobenzene degradation by electro-heterogeneous catalysis in aqueous solution

Chlorobenzene degradation by electro-heterogeneous catalysis in

aqueous solution: intermediates and reaction mechanism

WANG Jiade, MEI Yu, LIU Chenliang, CHEN Jianmeng

IntroductionChlorobenzene (CB)

SolventsHeat transfer agentsInsect repellentsDeodorantDegreasersIntermediates in dye and

pesticide synthesis

Introduction

CB = Pollutant

IntroductionMethods

Catalytic hydrodehalogenationThermal oxidationElectrochemical (EC) dechlorinationEC-assisted heterogeneous catalysis

ObjectivesTo identify the parameters that may affect the

electro-heterogeneous catalysis processTo further probe the catalytic dechlorination

kinetics

ExperimentApparatus

catalyzed oxidation reactor was a glass trough vessel (15 L)

β-PbO2 electrode (15 cm x 5 cm)Support electrolyte -> Na2SO4 (0–0.15 g/L)Temperature -> 25°C ± 1°CCatalyst

Mn-Sn-Sb/γ-Al2O3

AnalysisTwo similar samples were collected at 0, 30, 60, 90

and 120 min

Results and DiscussionCharacterization of the Catalyst

Results and DiscussionEffect of the Current Density

Results and Discussion

Results and DiscussionEffect of Initial pH

Results and DiscussionEffect of electrolyte Concentration

Results and DiscussionComparison of Electro-heterogeneous Catalysis

and Electrochemical Process for Degradation of Chlorobenzene

Results and DiscussionIntermediates and Possible Reaction

Mechanism

Results and Discussion

ConclusionThe degradation efficiency of CB was almost 100% with an

initial CB concentration of 50 mg/L, current density 15 mA/cm2, initial pH 10.0, electrolyte concentration 0.10 mol/L, and temperature 25°C at 90 min.

Under the same conditions, the degradation efficiency of CB was only 51% by the EC process, which showed that electro-heterogeneous catalysis was more efficient than EC alone.

The experimental results indicated that Mn-Sn-Sb/γ-Al2O3 catalyst could accelerate the degradation of CB.

Intermediate products, including phenol, benzoquinone, biphenyl, vinylbenzoic acid, and butenedioic acid were detected by GC/MS.

CritiqueThe title directly states the main purpose of the

study.The interpretation of the results can be easily

understood through figures.The objectives of the study are satisfied.

RecommendationsOther pollutants can be usedOther temperatures can be considered.Detailed mechanism of electro-heterogeneous

catalysis