T. Y. Yee; M. Omar Fatehah
Abstract
Silicon dioxide (SiO2) in nanoscale had been detected as waste product in river water for the past two decades and it is recently proven to have adverse effects toward human and animal health, the ecosystem and water treatment system. The removal of SiO2 nanoparticles (NPs) from water still remains a ...
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Silicon dioxide (SiO2) in nanoscale had been detected as waste product in river water for the past two decades and it is recently proven to have adverse effects toward human and animal health, the ecosystem and water treatment system. The removal of SiO2 nanoparticles (NPs) from water still remains a challenge due to its small size and unknown interactions within the water body. In this study, dynamic light scattering (DLS) technique was applied to characterize SiO2 in terms of surface charge and particle size as a function of pH within the range of 2 to 11 to analyze the aggregation behavior and significance of the intermolacular interactions in deionized (DI) water and tap water. DLS analysis identified both pH values of the point of zero charge (pHPZC) of SiO2 NPs in DI water and tap water at pH 3.2 and pH 2.8 respectively. The initial pH was discovered at 7.1 in tap water with a mean particle size of 346 nm and an average surface charge value of -27 mV compared to initial pH of DI water which was 5.4 with mean particle size of 295 nm and an average surface charge value of -33 mV. It was found that both in DI water and tap water, SiO2 NPs aggregated and increased in particle size but reduced in surface charge when pH slowly decreased towards their respective pHPZC from the initial pH by adding 0.25M of hydrochloric acid. The mean particle size at pHPZC in DI water is measured at 1750 nm larger compared to the mean particle size in tap water indicating that the presence of other ions in tap water suppressed the aggregation process. In conclusion, results suggests that pH does influence the surface charge of SiO2 NPs and affect the stability behavior and its interaction processes in aqueous suspensions.
A. K. Norani; R. Hashim; O. Sulaiman; S. Hiziroglu; S. Ujang; W. N. A. Wan Nadhari
Abstract
The main objectives of this study were to evaluate the biodegradation behaviour of experimental particleboard bonded with modified 30 % of PVOH, 70 % of Oil palm starch and 3 % of nano silicon dioxide (SiO2). Boric acid at 2 % was also added as a cross-linker to PVOH in modified oil palm starch to enhance ...
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The main objectives of this study were to evaluate the biodegradation behaviour of experimental particleboard bonded with modified 30 % of PVOH, 70 % of Oil palm starch and 3 % of nano silicon dioxide (SiO2). Boric acid at 2 % was also added as a cross-linker to PVOH in modified oil palm starch to enhance decay resistant for the samples. All the particleboards were evaluated by soil burial, borer and fungal strains tests. The samples were then compared with particleboard bonded with native oil palm starch and commercial urea formaldehyde (UF). The results indicated that particleboards bonded with modified PVOH/Oil palm starch were more resistant than particleboard bonded with their native starch and thus can be used as a potential binder for green particleboard in future. The SiO2 also showed a significant effect towards modified oil palm starch as compared to their native oil palm starch and commercial binder.
