Browsing by Author "Philip, Joseph Y. N."

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    Cashew Nut Shell Liquid as an Alternative Corrosion Inhibitor for Carbon Steels.
    (2001) Philip, Joseph Y. N.; Buchweishaija, Joseph; Mkayula, Lupituko L.
    Cashew Nut Shell Liquid (CNSL) has been tested as a corrosion inhibitor for carbon steel in 3% aqueous NaCl solution (pH 6) saturated with carbon dioxide gas at 30°C under static conditions using ac-impedance and potentiodynamic polarisation techniques. It was found that CNSL reduces the extent of the electrochemical processes taking place on carbon steel undergoing corrosion. The corrosion rate of the carbon steel was reduced by over 92 % when only 300 ppm of CNSL was applied. This indicates that CNSL is a potential corrosion inhibitor for carbon steels in CO2 environment.
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    Cashew Nut Shell Liquid as an Alternative Corrosion Inhibitor for Carbon Steels.
    (College of Natural and Applied Sciences, 2001) Philip, Joseph Y. N.; Buchweishaija, Joseph; Mkayula, Lupituko L.
    Cashew Nut Shell Liquid (CNSL) has been tested as a corrosion inhibitor for carbon steel in 3% aqueous NaCl solution (pH 6) saturated with carbon dioxide gas at 30°C under static conditions using ac-impedance and potentiodynamic polarisation techniques. It was found that CNSL reduces the extent of the electrochemical processes taking place on carbon steel undergoing corrosion. The corrosion rate of the carbon steel was reduced by over 92 % when only 300 ppm of CNSL was applied. This indicates that CNSL is a potential corrosion inhibitor for carbon steels in CO2 environment.
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    Corrosion Inhibition of Amino Pentadecylphenols (APPs) Derived from Cashew Nut Shell Liquid on Mild Steel in Acidic Medium
    (Scientific Research Publishing, 2016) Philip, Joseph Y. N.; Buchweishaija, Joseph; Mwakalesi, Alinanuswe
    In this study, corrosion inhibiting properties of amino pentadecylphenols (APPs) derived from Cashew Nut Shell Liquid (CNSL) on mild steel in aerated 0.10 M HCl at 303 K were studied using Electrochemical Impedance Spectroscopy (EIS) and potentiodynamic polarization measurements. Both methods indicated the potential of a mixture of amino pentadecyphenols to serve as a corrosion inhibitor in mild steel in 0.10 M HCl. Corrosion inhibition efficiencies were observed to increase with increase in the inhibitor concentration, with maximum corrosion inhibition of about 98% at inhibitor concentration of 600 ppm. The adsorption of the inhibitor on mild steel surface was found to obey Temkin adsorption isotherm, signifying physical adsorption of the inhibitor molecules on mild steel surface.
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    The Influence of Aliphatic Side Chain of Anacardic Acid on Molecular Recognition Properties of Imprinted Polymers
    (2012) Philip, Joseph Y. N.; Buchweishaija, Joseph; Mkayula, Lupituko L.
    The objective of this work was to determine the influence of the aliphatic side chain of anacardic acid on molecular recognition properties of imprinted polymers made from anacardanyl methacrylate (AnMcr). Salicylic methacrylate (SaMcr), a structural analog of AnMcr, was synthesized and used as a functional monomer to prepare imprinted polymers for comparison with AnMcr-based polymers. Using divinylbenzene (DVB) as a cross linker and racemic propranolol as a model template, irregular monolithic particles of poly(SaMcr-co-DVB)m were synthesized in toluene, and spherical beads of poly(SaMcr-co-DVB)b and poly(AnMcr-co-DVB)b were synthesized in acetonitrile by precipitation polymerization. Although imprinted irregular monolithic particles, poly(SaMcr-co-DVB)m, tested in toluene containing 0.5% acetic acid, displayed relatively low specific propranolol binding, they showed high molecular selectivity. For the spherical beads tested in acetonitrile, both imprinted poly(AnMcr-co-DVB)b and poly(SaMcrco-DVB)b showed obvious specific propranolol binding despite the use of polar organic solvent during imprinting. Imprinted poly(AnMcr-co-DVB)b showed higher molecular selectivity than imprinted poly(SaMcr-co-DVB)b. Interestingly, the presence of the aliphatic side chain in AnMcr resulted in more uniform imprinted beads as compared to particle agglomerates obtained from SaMcr in the presence of propranolol template. Therefore, the aliphatic side chain of anacardic acid improves both molecular recognition of imprinted polymers as well as the formation of uniform imprinted spherical beads.
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    Isolation of Anacardic Acid from Natural Cashew Nut Shell Liquid (CNSL) Using Supercritical Carbon Dioxide
    (ACS, 2008) Philip, Joseph Y. N.; Da Cruz Francisco, José; Dey, Estera S.; Buchweishaija, Joseph; Mkayula, Lupituko L.; Ye, Lei
    Solvent extracted cashew nut shell liquid (CNSL), conventionally known as natural CNSL, is a mixture of several alkenyl phenols. One of these alkenyl phenols is anacardic acid, which is present at the highest concentration. In view of anticipated industrial applications of anacardic acid, the objective of this work was to isolate anacardic acid from natural CNSL by supercritical carbon dioxide (scCO2). In this study, the solubility data for natural CNSL in scCO2 under a range of operating conditions of pressure (100, 200, and 300 bar), temperature (40 and 50 °C), and CO2 flow rate (5, 10, and 15 g min−1) were established. The best scCO2 working conditions were found to be 50 °C and 300 bar at a flow rate of 5 g min−1 CO2. Using 3 g of sample (CNSL/solid adsorbent = 1/2) under these scCO2 conditions, it was possible to quantitatively isolate high purity anacardic acid from crude natural CNSL (82% of total anacardic acid) within 150 min. The anacardic acid isolated by scCO2 was analyzed by different spectroscopic techniques (UV−vis, FT-IR, and 1H NMR) and HPLC analysis, indicating that the anacardic acid isolated by scCO2 has better quality than that obtained through a conventional method involving several chemical conversion steps.
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    Isolation of Anacardic Acid from Natural Cashew Nut Shell Liquid (CNSL) Using Supercritical Carbon Dioxide
    (American Chemical Society, 2008) Philip, Joseph Y. N.; Da Cruz Francisco, José; Dey, Estera S.; Buchweishaija, Joseph; Mkayula, Lupituko L.; Ye, Lei
    Solvent extracted cashew nut shell liquid (CNSL), conventionally known as natural CNSL, is a mixture of several alkenyl phenols. One of these alkenyl phenols is anacardic acid, which is present at the highest concentration. In view of anticipated industrial applications of anacardic acid, the objective of this work was to isolate anacardic acid from natural CNSL by supercritical carbon dioxide (scCO2). In this study, the solubility data for natural CNSL in scCO2 under a range of operating conditions of pressure (100, 200, and 300 bar), temperature (40 and 50 °C), and CO2 flow rate (5, 10, and 15 g min−1) were established. The best scCO2 working conditions were found to be 50 °C and 300 bar at a flow rate of 5 g min−1 CO2. Using 3 g of sample (CNSL/solid adsorbent = 1/2) under these scCO2 conditions, it was possible to quantitatively isolate high purity anacardic acid from crude natural CNSL (82% of total anacardic acid) within 150 min. The anacardic acid isolated by scCO2 was analyzed by different spectroscopic techniques (UV−vis, FT-IR, and 1H NMR) and HPLC analysis, indicating that the anacardic acid isolated by scCO2 has better quality than that obtained through a conventional method involving several chemical conversion steps.
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    Mechanistic Studies of Carbon Steel Corrosion Inhibition by Cashew Nut Shell Liquid
    (2002) Philip, Joseph Y. N.; Buchweishaija, Joseph; Mkayula, Lupituko L.
    The inhibition mechanism of the Cashew Nut Shell Liquid (CNSL) on SAE 1008 carbon steel corrosion in CO 2 saturated 3% NaCl solutions has been studied by weight loss, UV/VIS and electrochemical techniques. The phenoxide, R-Ar-O-ions from the CNSL inhibitor were found to be responsible for the reduction of the corrosion rate of the carbon steel. Also, it was observed that the surface charge of the carbon steel electrodes was positive with respect to the solutions containing CNSL inhibitor. It is likely that the electrostatic attraction between the mechanism of the CNSL inhibitor adsorption involved the positively charged metal surface and the phenoxide ions via their negative ends.
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    Mechanistic Studies of Carbon Steel Corrosion Inhibition by Cashew Nut Shell Liquid
    (2002) Philip, Joseph Y. N.; Buchweishaija, Joseph; Mkayula, Lupituko L.
    The inhibition mechanism of the Cashew Nut Shell Liquid (CNSL) on SAE 1008 carbon steel corrosion in CO2 saturated 3% NaCl solutions has been studied by weight loss, UV/VIS and electrochemical techniques. The phenoxide, R-Ar-O- ions from the CNSL inhibitor were found to be responsible for the reduction of the corrosion rate of the carbon steel. Also, it was observed that the surface charge of the carbon steel electrodes was positive with respect to the solutions containing CNSL inhibitor. It is likely that the mechanism of the CNSL inhibitor adsorption involved the electrostatic attraction between the positively charged metal surface and the phenoxide ions via their negative ends.
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    Preparation of Molecularly Imprinted Polymers Using Anacardic Acid Monomers Derived from Cashew Nut Shell Liquid
    (ACS, 2007) Philip, Joseph Y. N.; Buchweishaija, Joseph; Mkayula, Lupituko L.; Ye, Lei
    The objective of this work was to use monomers from cashew (Anacardium occidentale L.) nut shells to develop molecularly imprinted polymers. Cashew nut shell liquid (CNSL) is a cheap and renewable agro byproduct consisting of versatile monomers. Solvent-extracted CNSL contains over 80% anacardic acid (AnAc) with more than 90% degree of unsaturation in its C15 side chain. From AnAc monomer, anacardanyl acrylate (AnAcr) and anacardanyl methacrylate (AnMcr) monomers were synthesized and their chemical structures were characterized by Fourier transform IR and NMR. Different imprinted bulk polymers based on AnAc, AnAcr, and AnMcr functional monomers have been prepared. In the present study, each functional monomer was separately copolymerized in toluene with ethylene glycol dimethacrylate and divinylbenzene as cross-linkers, using racemic propranolol as a model template. While the AnAc based polymer revealed a meager rebinding ability, the imprinted polymers made from AnAcr and AnMcr displayed highly specific propranolol binding. At a polymer concentration of 2 mg/mL, AnAcr and AnMcr based imprinted polymers were able to bind over 50% of trace propranolol (initial concentration 1.2 nM). Under the same condition propranolol uptake by the two nonimprinted control polymers was less than 20%. Chiral recognition properties of these polymers were further confirmed using tritium-labeled (S)-propranolol as a tracer in displacement experiments, suggesting that the apparent affinity of the imprinted chiral sites for the correct enantiomer is at least 10 times that of the mismatched (R)-propranolol. Moreover, cross reactivity studies of these polymers showed that the (S)-imprinted sites have higher cross-reactivity toward (R,S)-metoprolol than (R)-propranolol and (R)-timolol.
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    Synthesis of Poly (APP-co-EGDMA) Particles Using Monomers Derived from Cashew Nut Shell Liquid for the Removal of Cr (III) from Aqueous Solutions
    (Scientific Research Publishing, 2013) Wilson, Joseph; Philip, Joseph Y. N.; Mdoe, James E. G.
    This work was aimed at synthesizing Cashew Nut Shell Liquid (CNSL) based polymer particles for adsorption of Cr(III) ions from aqueous solutions. Natural CNSL was used as a starting material in synthesizing amino pentadecylphenols (APP). This was achieved through isolating anacardic acid from the CNSL via calcium anacardate procedure, followed by hydrogenation of the alkenyl side chains, and subsequently decarboxylating the product to form 3-pentadecylphenol, which was then nitrated and reduced to a mixture of APP. APP were co-polymerized with ethylene glycol dimethacrylate (EGDMA) to form poly(APP-co-EGDMA) particles. The chemical structures of the synthesized compounds were confirmed by Fourier Transform IR and 1H-NMR. The co-polymer particles were characterized by Scanning Electron Microscopy (SEM) to establish their morphological properties. The prepared co-polymer particles were found to have -NH loading of 46 mmol/g and a maximum adsorption capacity for Cr(III) ions of 16 mg per g of dry polymer particles. The spent polymer particles were recoverable and reusable.