Dearsenication of Liquid Hydrocarbons and Interaction between Arsenic Compounds and Cuprous Probes

The interaction between alkylarsines and transition metal probes (Cu+ and CuCl) in liquid hydrocarbon was studied using density functional theory, the B3LYP method and the 6-311+G(2df,2p) basis set. Results showed that the most stable interaction mode of the alkylarsines with Cu+ or CuCl was a classic tetrahedral structure. A higher alkyl substitution number led to a more negative interaction energy (E-0) and more stable alkylarsine-Cu+ or alkylarsine-CuCl complexes. The energy difference (Delta E) between the interaction orbital of arsines and Cu+ or CuCl had a linear correlation to E-0 (R-2 >= 0.99). A feedback of electrons from the As-Cu bond to the C-As bond and/or H-As anti-bond in alkylarsine-Cu+ complexes existed while a similar feedback phenomenon did not appear in alkylarsine-CuCl complexes. Alkyl substitution did not decrease the interaction capability between the arsines and the active purification component. If the selective adsorption for arsines can be achieved, even if competing compounds exists, the key factor that affects arsenic removal performance will be the diffusion of arsines into the pores of the purificants. Thiophene compounds in the liquid hydrocarbon did not affect the selectivity of the arsinic adsorptive separation, however, the existence of mercaptans such as CH3SH decreased the adsorption of monoalkylarsines. For the development of new purificants for the removal of arsenic, an expansion of the support pore to increase diffusion should be considered and the active component should have a relatively lower Delta E, stronger electron feedback in formed complexes, weaker interactions with mercaptans and stronger interactions with monoalkylarsines.