Browsing by Author "Magufuli, John P. J"

Now showing 1 - 1 of 1
  • Thumbnail Image
    Item
    The potential of anacardic acid self - assembled monolayers from cashew nut shell liquid as corrosion protection coatings
    (University of Dar es Salaam, 2009) Magufuli, John P. J
    The main goal of this study was to assess the potential of the agro-waste, Cashew Nut Shell Liquid (CNSL) as a novel source of compounds for preparation of Self-Assembled Monolayers (SAMs) with the capability to modify surfaces of engineering metals and protect them against corrosion attack. The study therefore aimed at the formation of SAMs using a compound prepared from CNSL and asses its ability to protect the substrate against corrosion. This thesis reports on the synthesis of 2-hydroxy-4-pentadecylbenzoic acid (iso-anacardic acid) from anacardic acid and cardanol which are major constituents of CNSL as the starting material. The saturated anacardic acid isolated from natural CNSL was successfully used to synthesize the isomeric compound 2-hydroxy-4-pentadecylbenzoic acid. Also the study reveals that 3-pentadecylphenol (cardanol) a major constituent of technical CNSL can be used as the starting material for the synthesis of iso-anacardic acid.Thesynthesized 2-hydroxy-4-pentadecylbenzoic acid (iso-anacardic acid) was successfully used for the formation of SAMs on mild steel surface using T-BAG deposition method in THF solution. The film was characterized by the contact angle, FTIR, AFM and optical microscopy. Through these measurements it was established that SAMs form a homogeneous bound film on the mild steel surface which was not removed by rising with sonication in THF. The film has shown to be covalently bonded (chemisorption) on the substrate surface. A mechanism for its formation through a nucleophilic substitution reaction forming an iso-anacardate in a tridentate mode is suggested. The performance of iso-anacardic acid - SAMs as protective coating against corrosion of mild steel in aerated 3% NaCI solution was assessed by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and weight loss methods. These studies reveal that the iso-anacardic acid - SAMs on mild steel provide good protection against corrosion in the chloride environment. It was established that the percentage corrosion protection performance was on average found to be 99.9%. As part of ongoing investigations concerning utilization of agro-waste, CNSL, we describe for the first time the potential use of its constituent, cardanol/anacardic acid to synthesize 2-hydroxy-4-pentadecylbenzoic acid as a good coating material which exhibits good bonding and corrosion protection properties on mild steel. This work has established that iso-anacardic acid would be one of the promising surface treatments to replace the conventional phosphoric acid treatment.