Abstract:
Volatile Organic Compounds (VOCs’) have aroused concern in many parts of the
world especially in large cities due to their negative impacts to the environment. In
the presence of sunlight, VOCs’ react with NO
gases to produce tropospheric ozone,
a powerful oxidant and pollutant to the atmosphere. Although most of the VOCs’
originate from petroleum products and internal combustion engine exhausts and
plants, a significant amount is derived from solvent based coatings. This study reports
the findings of environmentally friendly and less toxic reactive diluents synthesized
from Cashew Nut Shell Liquid (CNSL) based products. CNSL is a by-product from
cashew nut processing and contains anarcardic acid, cardol, 2-methyl-cardol and
cardanol, decarboxylated anarcardic acid. CNSL is not currently utilized in Kenya. It
was extracted from cashew nut shells by cold solvent extraction process using nhexane
solvent. The percentage yield of CNSL obtained was found to be 30.9 ± 0.2.
Cardanol was isolated using methanol and ammonia solution as the solvents in a ratio
of 8:5, respectively. The percentage yield of cardanol obtained was 63.93 ± 0.2%.
Cardanol was modified via transesterification and methylation with acetic anhydride
and methyl iodide, respectively. The percentage yield of cardanyl acetate obtained
was 58.94 ± 0.01% and that of cardanyl methyl ether was found to be 52.39 ± 0.01%.
Cardanol, cardanyl methyl ether and cardanyl acetate were also characterized using
Finnigan Gas Chromatography Mass Selective Detector 8000 and a parent peak of m/z
= 108 observed for all the three products. The effects of cardanyl methyl ether,
cardanyl acetate and neat cardanol on the properties of alkyd-based coatings film were
x
investigated including pencil hardness which was found to be 4H for all the
formulations compared to 5H for the control. Coatings formed had good adhesion,
good drying time and pencil hardness and would be expected to be cheaper since
Cashew Nut Shell Liquid is a renewable raw material from waste. VOCs’ reduction
was achieved to the extent of 39% compared to conventional commercial products.
Drying time study showed that drying time can be altered variously by types and level
of diluent added.
