Hakimah Osman
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Preferred name
Hakimah Osman
Official Name
Hakimah, Osman
Alternative Name
Osman, Hakimah
Osman, H.
Main Affiliation
Scopus Author ID
7005733143
Researcher ID
AAT-9920-2020

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Physical and compressive stress of rice husk ash macroballoons in syntactic foam: Effect of rice husk ash layer

2024-04-01 , Zakir N.I.M. , Hasbullah S.Z. , Zakaria Z. , Hakimah Osman , Masa A.

The objective of this study is to investigate the effect of the rice husk ash (RHA) layer on the physical and compression properties of macroballoons in syntactic foam. The epoxy mixture was used to coat the surfaces of the expanded polystyrene (EPS) beads template, and the beads were rolled on the RHA and left at room temperature to produce E1RHAM macroballoon. The procedure was repeated to produce the second layer (E2RHAM) and third layer (E3RHAM) of the RHA macroballoon. The macroballoons were then post-cured in the air-circulating oven to shrink the EPS beads to produce hollow structures. The macroballoons were embedded in the epoxy mixture to produce epoxy syntactic foam. The syntactic foams with E1RHAM, E2RHAM, and E3RHAM were characterized in terms of physical and compression properties, respectively. It was found that E2RHAM exhibited the highest compressive stress and compressive modulus followed by E1RHAM and E3RHAM. The wall thickness of E2RHAM is 1.405 mm followed by E1RHAM at 0.745 mm and E3RHAM at 1.0701 mm. E2RHAM also has compressive strength and compressive modulus at 37.5 MPa and 925.03 MPa respectively followed by E1RHAM at 25 MPa and 642.86 MPa, and E2RHAM at 16 MPa and 168.08 MPa.

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Effect of Different Foaming Temperature on Properties of NaHCO3 – Natural Rubber Latex Foam

2023-01-01 , Smail M.S. , Zunaida Zakaria , Hakimah Osman , Masa A. , Leemsuthep A.

High volatile fatty acid natural rubber latex foam (H-VFA NRLF) was prepared via the Dunlop process using sodium bicarbonate, NaHCO3 as the blowing agent. The influence of different foaming temperatures (140 ℃, 150 ℃, 160 ℃, 170 ℃, and 180 ℃) on relative foam density, average cell size, cell size distribution frequency and compression stress-strain of H-VFA NRLF were studied. The average cell sizes were related to the relative foam density of H-VFA NRLF. As the temperature increased, the relative foam density increased, and eventually the average cell size decreased due to high amount of gas generated by blowing agents simultaneously. Meanwhile, smaller cell sizes were distributed as the temperature increased. It was found that the optimum temperature for H-VFA NRLF was 150 ℃ due to the lowest relative foam density and significantly larger uniform cell size were produced. Thus, the lowest compression stress up to 60% of strain was found at 150 ℃ and increased with increasing temperature. The mechanical properties were correlated with the morphology and physical properties of the H-VFA NRLF, respectively.

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The adsorption of remazol red dye using porous activated carbon (PAC) from rice husk ash treated using alkali treatment

2024-04-01 , Zakir N.I.M. , Zakaria Z. , Hakimah Osman , Masa A.

This research investigated the adsorption of 50 mg/L of Remazol Red (RR) dye using porous activated carbon (PAC) prepared from rice husk ash (RHA) via alkali treatment. Two type of alkali were used, namely sodium hydroxide (NaOH) and potassium hydroxide (KOH), with four different concentrations (0.5 M, 1.0 M, 1.5 M and 2.0 M) using without any mechanical agitation. This study is significant as it used shorter processing time and lower temperature during the preparation of PAC compared to conventional treatment using furnace with higher processing temperature and longer time. The PAC was prepared by mixing RHA into the alkali solution (NaOH and KOH) for 2 hours and then washed using distilled water until the pH became neutral. The adsorption test was conducted using RR dye for 6 hours, tested using UV spectrophotometer and characterized using SEM, EDX and FTIR. Results showed that 1.0 Na-PAC had a higher adsorption percentage of 84% dye removal at 360 minutes, while 2.0 K-PAC had79% dye removal. It can be concluded that Na-PAC has a higher removal percentage of RR dye at different concentrations than K-PAC.

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Effect of Activating Agent on Porous Activated Carbon in Alginate Macrobeads for Removal of Remazol Red Dye

2024-06-07 , Zakir N.I.M. , Zunaida Zakaria , Hakimah Osman , Hafiza Shukor , Masa A.

Alginate macrobeads filled with porous activated carbon (PAC) treated using different types of chemical activating agents were prepared in this study. Rice husk ash (RHA) was treated using five types of chemicals, such as sodium hydroxide (NaOH), potassium hydroxide (KOH), zinc chloride (ZnCl2), hydrochloric acid (HCl) and citric acid, at a low temperature (~80°C) for 2 hours to produce PAC with high porosity and compared to the conventional process using furnace with a high processing temperature. A biopolymer, namely sodium alginate, was used to hold the PAC powder to produce an immobilized structure of PAC in macrobeads form. Adsorption of remazol red (RR) dye using macrobeads was measured using UV-spectrophotometer, while the morphology and composition of PAC were observed using scanning electron microscope (SEM) and energy dispersive X-ray (EDX), respectively. The functional groups of PAC were identified using attenuated total reflection Fourier transform infrared (ATR-FTIR). The results indicated that the alkali treated PAC successfully removed up to ~99% of the dye in 120 minutes, while the acid treated PAC could only remove ~30% the dye at the same time. This demonstrated that alkaline treatment produced PAC with higher porosity structure and the PAC produced using NaOH has high adsorption of RR dye.

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