Catalytic dechlorination of polychlorinated biphenyls in soil by palladium–iron bimetallic catalyst

Chemical Engineering Journal

Zhang

2012

In this study, a novel two-stage process, i.e. first stage for hydrogen species generation at 150°C and second stage for PCB dechlorination at 330°C, was developed for efficient PCB degradation in subcritical water with nanoscale Ni/Fe particles. The obtained results showed that over 92% of PCBs was completely converted into 1-alkyl-benzenes during this process. The addition of hydrogen donors could greatly enhance PCB dechlorination in descending order: oxalic acid % HAc > NaH 2 PO 4 % KH 2 PO 4 . The anion introduced along with H + played the crucial role in overall dechlorination process due to the undesired reaction between anion and reactive nanoscale Ni/Fe. Oxalic acid was quite effective for the generation of hydrogen species by supply more available H + without undesired side reaction. In contrast, phosphate could react with Ni/Fe rapidly to form complex precipitates on particle surface and thereby block the reactive sites of particle following suspension of dechlorination. In addition, low 150°C at first stage as compared to 330°C at second stage favored the dissolution and adsorption of hydrogen on Ni surface for catalyzing to form more reactive hydrogen species used for rapid dechlorination.

Section: Dechlorination Productsmentioning

confidence: 93%

An integrated two-stage process for effective dechlorination of polychlorinated biphenyls in subcritical water in the presence of hydrogen donors

Zhu

Chemical Engineering Journal

Zhang

2012

“…[28][29][30] Although Pd/Fe nanoparticles are able to e±ciently remove polychlorinated biphenyls (PCBs), 31,32 the superior corrosion stability and lower cost of Ni/Fe nanoparticles may provide more valuable applications. 33 Furthermore, it is reported that no accumulation of toxic byproducts has been observed during dechlorination by Ni/Fe nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Ni/Fe Nanoparticles Utilizing PVP–SDS Bound Micelles as a Template to Remove PCB77

Ding

Zhao

et al. 2015

NANO

In the present study, Ni/Fe nanoparticles were synthesized using bound micelles as a template and 3, 3 0 , 4, 4 0 -tetrachlorobiphenyl (PCB77) as the target contaminant. The dual bound micelles, which are composed of polyvinylpyrrolidone (PVP) and sodium dodecyl sulfate (SDS), were found to be superior to single-component templates for the dispersion of metallic ions and thus directed the synthesis of Ni/Fe nanoparticles with improved properties. After characterization of the di®erent nanoparticles, it was found that the sustained e®ectiveness of PVP-SDS bound micelles a®orded specialized structures with two gradations of Ni/Fe nanoparticles, correlating to more active sites and higher activity. The improved activity of the Ni/Fe nanoparticles was nally exhibited by the higher ratio (99.3% in 72 h) and e±ciency (k obs of 0.0674 h À1 ) of PCB77 removal. Herein, the utilization of PVP-SDS bound micelles is proposed as a template for the improvement of iron-based nanoparticles and correlated research.

“…Varanasi et al (2007) mixed iron nanoparticles into PCB-contaminated soil and attempted to maximize PCB destruction. He et al (2009) used ZVI and Pd/Fe for remediating PCBs-contaminated soil at room temperature. However, PCBs are water insoluble and strongly adsorbed in soil colloid particles.…”

Section: Introductionmentioning

confidence: 99%

Automatic pH control system enhances the dechlorination of 2,4,4′-trichlorobiphenyl and extracted PCBs from contaminated soil by nanoscale Fe0 and Pd/Fe0

Zhou

et al. 2011

Environ Sci Pollut Res