Zunaida Zakaria
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Preferred name
Zunaida Zakaria
Official Name
Zunaida, Zakaria
Alternative Name
Zakaria, Zunaida
Zunaida, Z.
Zakaria, Z.
Main Affiliation
Scopus Author ID
57217205824
Researcher ID
M-6958-2019

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  • Publication
    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.
      1  30
  • Publication
    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.
      1  27
  • Publication
    Influence of acid concentration on thermomechanical, tensile and thermal properties of cyclized natural rubber
    ( 2023-08-01)
    Jaratrotkamjorn R.
    ;
    Hayeemasae N.
    ;
    Zunaida Zakaria
    ;
    Masa A.
    Properties of cyclized natural rubbers (NR) with various degrees of cyclization (∼4-22%) were investigated in this study. Prior to compounding with rubber additives, the cyclized rubbers were initially prepared by dropping various concentrations of acid (5-30 wt%) to the NR latex, followed by coagulation and drying. The results revealed that the degree of cyclization increased with acid concentration. Increased ring structure formation in the modified NR tended to increase the torque difference during crosslinking, as the cyclic ring structures acted as steric hindrances. The crosslink density was found to decrease with increasing cyclization level due to the loss of active sites for crosslink formation, increasing swelling capability of the cyclized rubbers. The 100% and 300% moduli, tensile strength and extensibility of the NR reduced with increasing degree of cyclization due to a reduction of crosslink density. As a result of cyclic structure formation and a reduction of unsaturated double bonds in the NR, the stability of cyclized NR at elevated temperatures was improved over the pure NR, in a manner dependent on the level of cyclization. Single glass transition temperature was seen in the NR while two glass transition temperatures were noticed in the cyclized NR. The thermal stability of 22% cyclized NR was 50°C higher than that of the pure NR and the aging properties of the cyclized NRs were also greater mainly due to a reduction of unsaturated double bonds. This suggests that cyclized NR may find applications in products requiring thermal resistance.
      2  11