MSc

Coconut is a vital crop of Kerala, potential substitute for conventional timber.
However, it is susceptible to termites, red palm weevils, bark weevils, shot hole or bark
borers, and other pathogens. Traditional wood preservatives like Chromated Copper
Arsenate and Chromated Copper Borate pose environmental risks. To address these
challenges, researchers are exploring the concept of nanotechnology as a potential
solution for wood protection. Nanoparticle has high efficiency to maintain wood natural
color, and controlled release of active ingredients at a low concentration, making them a
priority for future wood protection applications. As there is limited research on coconut's
durability, degradability, and biocide properties of nanoparticles study has been
conducted to understand the same.
The copper and zinc nanoparticle was prepared by chemical reduction and
precipitation method respectively. Medium and high density coconut wood was
impregnated with this nanoparticles at 1%, 2.5% and 5% concentration. Two method of
impregnation was carried out i.e., coating with fixative and pressure without fixative.
Later, these samples were undergone chemical retention test, leaching test, subterranean
termite test, weatherability test and water absorption test according to various standards
of ASTM and AWPA. Nested anova was carried out to know the significant difference
among various factors and their levels.
Chemical reduction and precipitation method of copper and zinc nanoparticle
preparation yielded 65.06% and 70.15% respectively. The SEM image of copper and zinc
nanoparticles confirmed to have irregular cuboidal and flake shape with average size of
173.66 nm and 105.44 nm respectively. The presence of copper and zinc in the
nanoparticles was verified by EDX analysis. The presence of the corresponding
nanoparticles' metal-hydroxyl and metal-oxide groups was verified by the FTIR
spectrum. XRD analysis shows that most of the copper in copper nanoparticles is present
as copper oxide and cuprous oxide whereas, zinc nanoparticles as zinc oxide.
The chemical retention of both pressure and coating treatment had significantly
varied among various density, and nanoparticle concentrations. Among density, medium
density had shown higher retention than high density. Concentration of 5% zinc and 5%
xxix
copper treated to medium density had shown greater retention among various
nanoparticle concentration. The chemical leaching test showed that high leaching of
nanoparticles occurred during initial stage. Pressure treated coconut wood with
nanoparticles statistically varied between various density, nanoparticle and its
concentration. High density had shown low leaching compared to medium density.
Among nanoparticle and its concentration, zinc has shown the least leachability when
compared to control. Same trend was seen in coating method.
The subterranean termite test (no-choice) shown significant variation for mass
loss and visual appearance among various density, and nanoparticles. While there was no
significant difference seen with respect to different nanoparticle concentrations. Among
density class medium was susceptible to termite attacks. Copper treated sample shown
significant resistant to termite damage when compared to zinc treated sample.
Statistically significant variation among density, nanoparticle and its concentration was
seen in a weatherability test. High density sample was least susceptible to mass loss and
greying. Zinc and copper treated sample shown excellent resistant to mass loss and
greying as compared to control. Water absorption test shows a remarkable variation
among density, nanoparticle and its concentration in the coconut wood treated by pressure
and coating. Medium density shown greater water absorption and volume swelling
percentage. Among nanoparticles, control shown more water absorption and volume
swelling percentage.
Hence, nanoparticles in wood preservation offer improved durability and
performance due to their small size and unique properties. They offer enhanced resistance
to leaching, termites, and other environmental factors, leading increased lifespan for
wood-based products. However, further research is needed to ensure the safe and
responsible application of nanoparticle-based wood preservation technologies, while
considering cost and scalability