Adsorption of chlorobenzenes on ultrafine diamond modified with palladium and nickel nanoparticles

Abstract

Dynamic sorption is used to study the adsorption properties of palladium and nickel nanoparticles immobilized on a surface of ultrafine diamond (UFD). The test adsorbates are n-alkanes (C6-C8), benzene, chloroform, diethyl ether, chlorobenzene, and o-dichlorobenzene. For each adsorbate, the adsorption isotherms are measured, the isosteric heats of adsorption and contributions to them from the energies of dispersion Qdisp and specific (donor-acceptor) Qspec interactions are calculated, and the electron-donor and electron-acceptor characteristics of the surface of the original UFD and the UFDs with immobilized metal nanoparticles are estimated. It is shown that chlorobenzene is sorbed by the physical adsorption mechanisms on the original support and on a sample modified with nickel nanoparticles, and is chemisorbed on a support modified with palladium nanoparticles. The highest heats of chemisorption are obtained on UFD modified with Pd nanoclusters; a surface of UFD modified with Ni nanoclusters is less active with respect to these chlorobenzenes than a surface of unmodified UFD. Benzene, chloroform, and diethyl ether are sorbed on unmodified and modified UFDs by a physical adsorption mechanism; the highest and lowest values of Qspec for these materials are obtained on UFDs modified with Pd and Ni nanoclusters, respectively.