%0 Journal Article
%T Inhibitory Action of Artemisia annua Extracts and Artemisinin on the Corrosion of Mild Steel in H2SO4 Solution
%A P. C. Okafor
%A V. E. Ebiekpe
%A C. F. Azike
%A G. E. Egbung
%A E. A. Brisibe
%A E. E. Ebenso
%J International Journal of Corrosion
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/768729
%X The action of ethanol (EEAA), acid (AEAA), and toluene (TEAA) extracts from Artemisia annua and Artemisinin (ATS) on mild steel corrosion in H2SO4 solutions was investigated using gravimetric and gasometric techniques. The extracts and ATS functioned as good inhibitors, and their inhibition efficiencies (%IE) followed the trend: EEAA > AEAA > TEAA > ATS. %IE increased with increase in inhibitors concentration and decreased with increase in temperature. The enhanced %IE values of the extracts were attributed to synergistic effect of the components of the plant extracts with ATS. The adsorption of the inhibitors was consistent with Langmuir isotherm. Physisorption is proposed as the mechanism of inhibition. 1. Introduction Present trend in research on environmental friendly corrosion inhibitors is taking us back to exploring the use of natural products as possible sources of cheap, nontoxic, and ecofriendly corrosion inhibitors. These natural products are either synthesized or extracted from aromatic herbs, spices, and medicinal plants. Of increasing interest is the use of medicinal plant extracts as corrosion inhibitors for metals in acid solutions. This is because these plants serve as incredibly rich sources of naturally synthesized chemical compounds that are environmentally acceptable, inexpensive, readily available, and renewable sources of materials [1, 2]. These chemicals include alkaloids, flavonoids, terpenoids, glycosides, tannins, saponins, fats and oils, and carbohydrates, and so forth [3¨C11]. The complex composition of phytochemicals in plant extracts makes it difficult to attempt to assign the inhibition ability to a particular constituent. Some researchers have, however, ascribed the inhibition efficiency of these medicinal plants to their active components used for medical purposes [3]. We have recently attempted to assign the inhibition ability to some constituents by studying the inhibitive effect of different parts of a given plant with variable concentrations of the phytochemicals on acid corrosion [4¨C7]. Another most probable method would be the use of different solvents in the extraction process and comparing their inhibition efficiencies. This is yet to be explored in most of the reported work on corrosion inhibition of plant extracts. Artemisia annua is native to Asia, most probably China, but is currently cultivated in many countries including Nigeria, mainly as a source of artemisinin, an important natural sesquiterpene lactone with antimalarial effect against susceptible and multidrug resistant Plasmodium spp. The plant is a
%U http://www.hindawi.com/journals/ijc/2012/768729/