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Catalytic reduction of N-nitrosodimethylamine with nanophase nickel–boron

Paper ID Volume ID Publish Year Pages File Format Full-Text
47952 46486 2009 9 PDF Available
Title
Catalytic reduction of N-nitrosodimethylamine with nanophase nickel–boron
Abstract

Recent work by the authors shows that toxic N-nitrosamines, widely detected in disinfected wastewater and drinking water and recalcitrant towards conventional treatment processes, can be rapidly reduced to less hazardous products by treatment with hydrogen and Raney nickel catalysts. Unfortunately, Raney Ni catalysts are pyrophoric when dry and are readily deactivated when exposed to air, severely limiting their application for water treatment. In this work, a non-pyrophoric and air-tolerant nickel–boron (NiB) catalyst is described, and its reactivity with N-nitrosodimethylamine (NDMA) is quantified. The catalyst, prepared by aqueous reduction of NiCl2 with NaBH4, has an elemental composition of 85 wt.% Ni and 7 wt.% B. Nanophase primary catalyst particles are formed and aggregate in micrometer-sized assemblies in solution. The catalyst has a specific surface area of 18 m2 g−1, and the surface contains Ni(0) and B in a mixture of oxidation states (0/+III). Kinetic studies show that NDMA is rapidly reduced via hydrogenation to dimethylamine and ammonia in H2(g)-saturated (PH2=1 atmPH2=1 atm) aqueous NiB suspensions, with mass- and surface area-normalized first-order rate constants of 29.5 ± 2.4 L gNi−1 h−1 and 1.38 ± 0.11 L mcat−2 h−1, respectively. Although the mass-normalized rate constant is less than that measured for Raney Ni, the surface area-normalized rate constant is greater, suggesting higher intrinsic reactivity of the NiB surface if the availability of surface sites for NDMA reactions on either catalyst surface is not significantly affected by aggregation of the catalyst nanoparticles. Kinetic studies show that reactivity of the NiB catalyst with NDMA is unaffected by solution pH and extended pre-exposure of the dry catalyst to air (Raney Ni is immediately deactivated by exposure to air). The NiB catalyst is also more tolerant of dissolved oxygen and low concentrations of dissolved (bi)sulfide than Raney Ni, suggesting potential for greater catalyst longevity during water treatment applications.

Keywords
NDMA; Nickel–boron; Disinfection byproducts; Hydrogenation; Water treatment
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Catalytic reduction of N-nitrosodimethylamine with nanophase nickel–boron
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 90, Issues 1–2, 25 July 2009, Pages 175–183
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us