scholarly journals Deposition of Hydroxyapatite on Silica Made from Rice Husk Ash to Produce the Powder Component of Calcium Phosphate Cement

Author(s):  
Tri Windarti ◽  
Widjijono Widjijono ◽  
Nuryono Nuryono

Hydroxyapatite (HA) has been deposited on silica (SiO2) particles to produce HA-SiO2 composite that will be used as the powder component of calcium phosphate cement. HA was expected to be on the composite surface to maintain its bioactivity. SiO2 was made by the sol-gel method, in which silicate solution was extracted from rice husk ash with NaOH solution. Deposition of HA on SiO2 was carried out by wet chemical deposition method at various Ca/Si molar ratio (in a range of 5–25) followed by calcination at 600 °C for 2 h. Results showed that HA was successfully deposited on SiO2 particles. The cell parameters of the HA crystals were slightly distorted by the presence of SiO2 and HA in the composite had a bigger cell volume than pure HA. The crystallite size of HA in the composites increased with the increase of the Ca/Si ratio but the values were smaller than pure HA. SiO2 acted as a morphology directing agent. At low Ca/Si ratio, the HA-SiO2 particles were in a form of short rod-like particles with sizes of < 50 nm, while at high Ca/Si ratio, a mixture of short and long rod-like particles with the size of < 100 nm was obtained. The zeta potential of composites was almost similar to pure HA. These properties indicated that HA-SiO2 composites support the bioactivity of injectable calcium phosphate cement.

2017 ◽  
Vol 729 ◽  
pp. 24-29
Author(s):  
Thitipob Sirisoontornpanit ◽  
Atichat Wongkoblab ◽  
Supunnee Junpirom

SUZ-4 zeolite was synthesized by the sol-gel technique, followed by hydrothermal process. The effect of the molar ratio of rice husk ash based silicon dioxide to silica solution was investigated. The synthesized zeolite was characterized by XRD, SEM, N2 adsorption and temperature programmed desorption. The results show that the SUZ-4 zeolite was formed for all investigated conditions. However, the formation of MER zeolite occurred as an impurity for the content of rice husk ash higher than 75%. A needle shape crystal with mainly microporous structure is the feature of synthesized SUZ-4 zeolite. The result of temperature programmed desorption indicated that the chemical surface property of obtained SUZ-4 zeolite was weak acid sites.


2021 ◽  
Vol 55 (6) ◽  
Author(s):  
Trung Kien Pham ◽  
Tran Ngo Quan

In this paper, we report on synthesizing xonotlite, calcium silicate hydrate (CSH), via a hydrothermal reaction using rice husk from the Mekong Delta, Vietnam. The rice husks were burnt at 1000 °C for 3 h. Grey rice husk ash was collected, then mixed with Ca(OH)2 at a Ca/Si molar ratio of 1 : 1. This was followed by a hydrothermal reaction at 180 °C for 24 h and 48 h to obtain the xonotlite mineral. Before and after adsorption, 3-mm xonotlite pellets were thoroughly characterized using X-ray diffractometry (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM) and ultraviolet-visible (UV-VIS) spectroscopy. This material has potential application in chromium(III) removal during a chrome-plating process. The adsorption efficiency of the 3-mm pellet samples reached more than 76 % after 12 h.


2019 ◽  
Vol 20 (1) ◽  
pp. 16 ◽  
Author(s):  
Duha Hussien Attol ◽  
Hayder Hamied Mihsen

Rice husk ash (RHA) was used to prepare sodium silicate, which in turn was functionalized with 3-(chloropropyl)triethoxysilane employing the sol-gel technique to form RHACCl. Chloro group in RHACCl was replaced with iodo group forming RHACI. Ethylenediamine was immobilized on RHACI in order to prepare it for the reaction with salicylaldehyde to form a silica derivative-salen. FT-IR analysis indicated the presence of secondary amine and –NH and C=N absorption bands. XRD analysis revealed the occurrence of the broad diffused peak with maximum intensity at 22–23° (2θ). BET measurements showed also that the surface area of the prepared compound is 274.55 m2/g. Elemental analysis proved the existence of nitrogen in the structure of the prepared compound. The silica derivative-salen showed high potential for extraction and removal of heavy contaminating metal ions Ni(II), Cu(II), and Co(II) from aqueous solutions. The kinetic study demonstrates that the adsorption of the metal ions follows the pseudo-second order.


2021 ◽  
Vol 315 ◽  
pp. 16-24
Author(s):  
Somyote Kongkarat ◽  
Meekaruna Boonyaratchinda ◽  
Chirakit Chobtham

Ferrosilicon alloy has been commercially produced in an electric furnace at 1700 - 1750 °C, using quartz as a silica source. With an aim to reduce production cost, rice husk ash (RHA) had been introduced to the process as a silica source. The present study reports an in-depth investigation on the ferrosilicon alloy formation at 1550 °C via carbothermic reduction using RHA with coal and graphite. Blend A: RHA/Fe2O3/Coal and B: RHA/Fe2O3/Graphite were prepared according to the C/O molar ratio of 1/1. The well-mixed samples were compacted into a pellet and then heated at 1550 °C in the tube furnace for 30 and 60 minutes while the argon flowing at the rate of 1 L/min. XRD and SEM results show that the bulk metal mainly composes of FeSi phase, while SiC and other slag phases adhere at the surface of the droplet. Characteristics of the carbonaceous materials, especially ash oxides content affect the kinetic of ferrosilicon formation. Silicon concentration in the produced metal droplets was measured using an ICP technique. For blend A, Si content in the metal was 18.3 wt% and 81.9 wt% after 30 and 60 minutes, respectively. While, Si recovery in the metal for blend B reached 88.4 wt% since 30 minutes. The experimental results show that the production of ferrosilicon alloy from RHA can be produced at 1550 °C, which the temperature lower than that of the commercial method by 150-200 °C. The finding in this research is beneficial for ferrosilicon and agricultural industries and thus promotes the sustainable steelmaking industry.


2008 ◽  
Vol 62 (10-11) ◽  
pp. 1476-1479 ◽  
Author(s):  
T. Witoon ◽  
M. Chareonpanich ◽  
J. Limtrakul

2018 ◽  
Vol 197 ◽  
pp. 05002 ◽  
Author(s):  
Citra Deliana Dewi Sundari ◽  
Soni Setiadji ◽  
Yusuf Rohmatullah ◽  
Sanusi Sanusi ◽  
Denia Febby Nurbaeti ◽  
...  

Rice husk has a high silica content, so it can be utilized as silica source for zeolite synthesis. In this research, synthesis of zeolite L has been done using silica from rice husk ash without organic template. The synthesized zeolite L is then used as an adsorbent to adsorb methylene blue dye. The steps of zeolite L synthesis include: silica extraction from rice husk ash using NaOH and zeolite L synthesis using hydrothermal method with molar ratio 10 SiO2: Al2O3: 4 K2O: 100 H2O at 170°C for 24 hours. The resulting Zeolite L was then characterized by XRD and SEM. The absorption capacity of methylene blue solution by zeolite L was observed experimentally through the effect of pH of the solution, contact time, and initial concentration of the solution, then determining the isotherm and its absorption kinetics. From XRD and SEM results of zeolite L sample, it is shown that zeolite L has been formed and its particle morphology is a hollow cylinder with cylinder diameter of 0.049 - 0.123 μm. The adsorption process refers to the Freundlich isotherm model which provides the highest correlation coefficient. The methylene blue adsorption process by zeolite L follows pseudo second-order kinetics.


2005 ◽  
Vol 284-286 ◽  
pp. 19-22 ◽  
Author(s):  
M.P. Hofmann ◽  
Uwe Gbureck ◽  
Liam M. Grover ◽  
J.E. Barralet

This study sought to examine the efficiency of coating cement powder reactants in order to reduce the solubility rate of reactants and thereby increase setting times of cement systems. In this investigation magnesium and sodium stearate salts were used to coat the highly soluble monocalcium phosphate monohydrate (MCPM) powder component of a hydraulic brushite forming calcium phosphate cement system with b-tricalcium phosphate (b-TCP) as other component. The results showed that stearate coating of the MCPM reactant could lead to a 100% increase in setting and working times without affecting compressive strength of the set cement when applied with the appropriate P/L-ratio.


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