Dechlorination of pentachlorophenol (PCP) in aqueous solution on novel Pd-loaded electrode modified with PPy–SDBS composite film

Abstract

Pentachlorophenol (PCP) is a persistent pollutant and a suspected human carcinogen. It can be found in the air, water, and soil and enters the environment through evaporation from treated wood surfaces, industrial spills, and disposal at uncontrolled hazardous waste sites. Ecotoxicity of PCP necessitates the development of rapid and reliable remediation techniques. Electrocatalytic hydrogenolysis (ECH) has been proven as a promising method for detoxification of halogenated wastes, due to its rapid reaction rate, low apparatus cost, mild reaction conditions, and absence of secondary contaminants. Challenge for the application of ECH is to prepare a Pd-coated cathode with high stability, high catalytic activity, and low Pd loading level. In this work, Pd/polypyrrole-sodium dodecyl benzene sulfonate/meshed Ti (Pd/PPy-SDBS/Ti) electrode was prepared and was characterized by cyclic voltammetry, scanning electron microscopy, X-ray diffraction, and inductively coupled plasma-atomic emission spectrometry. Electrochemically reductive dechlorination of PCP on the Pd/PPy-SDBS/Ti electrode in aqueous solution was investigated. Pd microparticles were uniformly dispersed on PPy-SDBS film which was previously electrodeposited on the meshed Ti supporting electrode. The loading of Pd on the electrode was 0.72 mg cm(-2). Electrocatalytic dechlorination of PCP was performed in a two-compartment cell separated by cation-exchange membrane. The PCP removal on the Pd/PPy-SDBS/Ti electrode could reach 100 % within 70 min with dechlorination current 3 mA when PCP initial concentration was 10 mg L(-1) and initial pH was 2.4. Conversion of PCP on the Pd/PPy-SDBS/Ti electrode followed pseudo-first-order kinetics, and the apparent activation energy was 13.0 kJ mol(-1). The removal of PCP still kept 100 % after 70 min dechlorination when the Pd/PPy-SDBS/Ti cathode was reused ten times. The electrode exhibited promising dechlorination potential with high electrocatalytic activity, good stability, and low cost.

Modification of a Pd-loaded electrode with a carbon nanotubes–polypyrrole interlayer and its dechlorination performance for 2,3-dichlorophenol

“…In previous studies, 23 Pd particles deposited on the surface of Pd/PPy-SDBS/Ti electrode with conch-like shape, interestingly, the surface morphology of the Pd/CNTs-PPy/Ti electrode in this study appeared "pinpoint" shape, more compact and uniform, which could provide higher specic surface area and larger reaction contact sites for dechlorination process. This may be due to the effect of pulsed-current electrodeposition.…”

“…The analytical equipments and methods for cyclic voltammetry (CV), transmission microscope (TEM), scanning electron microscope (SEM), X-ray diffractometer (XRD), inductively coupled plasma-atomic emission spectrometry (ICP-AES), and ion chromatography (IC) followed our previous relevant research. 31,32 The level of CNTs surface charge was characterized by the zeta potential (Microtrac Zetatrac, USA), the concentration of CNTs dispersion was 0.5 mg mL À1 , which pH value was adjusted by H 2 SO 4 solution and NaOH solution. The concentrations of 2,3-DCP and intermediate products were detected by high performance liquid chromatography (HPLC, waters 1525 binary pump and waters 2489 UV/visible detector, USA, C18 column, Kromasil) at wavelength of 280 nm.…”

“…Polypyrrole (PPy), a typical conductive polymer with high electrical conductivity and chemical stability, can be used as support material to obtain highly dispersed metallic particles. 18,19 In our previous studies, [20][21][22][23] PPy modied composite Pd electrodes shown higher electrochemical activity for CPs dechlorination, indicating the PPy was conducive to Pd particles deposition dispersedly, and it can also play co-catalysis role.…”

Understanding Electrocatalytic Hydrodechlorination of Chlorophenols on Palladium-Modified Cathode in Aqueous Solution

“…In our previous work, Pd-loaded electrodes, modified with a polypyrrole (PPY) interlayer, were prepared and employed for the dechlorination of CPs in aqueous solution, which showed good stability and high activity. 18−22…”

“…In this paper, we aimed at obtaining further details on the ECH process: (i) how does pH affect the ECH and (ii) what is the type of electrode process for ECH. Therefore, the Pd-modified titanium mesh sodium dodecyl benzene sulfonate (SDBS)-doped PPY interlayer (Pd/PPY-SBDS/Ti) electrode, 22 reported in our previous work for pentachlorophenol dechlorination, was employed for dechlorination experiments under specific conditions.…”