STUDY ON THE ADSORPTION OF SOME ALKALI EARTH METALS ON NANO-SILICA GEL
Mahmoud Samy Mohamed Fahmy;
Abstract
The aim of this study is scale prevention through adsorption method using different synthesized silica gel at different conditions (initial concentration of the adsorbate, contact time, shaking speed, initial pH, and temperature) to obtain the highest adsorption capacity.
Silica gels were synthesized and characterized using different ruts: conventional-hydrothermal aging using different acids as gelation reagents, and microwave aging using different surfactants.
Their adsorption capacity were tested on concentrated authentic brine (800ppm) of Mg2+, Ca2+, Sr2+ and Ba2+ at the optimum conditions and their efficiency were compared.
The XRD patterns for the prepared samples showed large hump peak which is characteristic for the amorphous nature of the silica gel.
The TGA thermal analysis showed weight loss in two steps: (1) at 30 – 200 °C about 6% – 10% of the weight was lost due to the desorption of physical adsorbed water, (2) at 200 - 700 °C, about 5% of the weight was lost due to dehydroxylation reaction.
The FTIR spectrums showed a broad absorption band at 3457 cm-1 due to OH groups within the sample that confirms the formation of silica gel.
The HRTEM reveled nano cylindrical rods of 400 nm in length and 80 nm in diameter for silica gel synthesized using citric acid as hydrolysis catalyst.
Also DLS showed two maxima of the average particle size at ~ 52 nm and ~ 176 nm that confirmed the TEM images.
The nitrogen adsorption-desorption isothers could be classified as type II and type IV isotherms and show H1 hysteresis loop indicating mesoporous structure of the prepared silica gel samples.
The BET calculations revealed that the silica gel prepared by microwave in presence of Pluronic P-123 had the highest surface area ~ 424 m2/g with respect to the silica gel prepared by different acids via conventional method and/or different surfactants via microwave irradiation.
The adsorption capacity of the silica gel prepared by different acids reveals that the citric acid was the best hydrolysis catalyst for preparation of silica gel adsorbents.
The adsorption capacity of microwave adsorbents showed that as the microwave energy increases the adsorption decreases which reconcile with the decreases of surface area of the samples. The silica gel sample prepared in presence of microwave irradiation of power 100 watt for 30 seconds showed the highest surface area and the best adsorption.
The use of surfactant as a template increases the pore radius of the prepared silica gel from micropores to mesopores enhancing the adsorption capacity.
Four types of two parameter isotherms (Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherms) had been studied to describe the solid-liquid sorption system.
In general, the data obtained from the adsorption
Silica gels were synthesized and characterized using different ruts: conventional-hydrothermal aging using different acids as gelation reagents, and microwave aging using different surfactants.
Their adsorption capacity were tested on concentrated authentic brine (800ppm) of Mg2+, Ca2+, Sr2+ and Ba2+ at the optimum conditions and their efficiency were compared.
The XRD patterns for the prepared samples showed large hump peak which is characteristic for the amorphous nature of the silica gel.
The TGA thermal analysis showed weight loss in two steps: (1) at 30 – 200 °C about 6% – 10% of the weight was lost due to the desorption of physical adsorbed water, (2) at 200 - 700 °C, about 5% of the weight was lost due to dehydroxylation reaction.
The FTIR spectrums showed a broad absorption band at 3457 cm-1 due to OH groups within the sample that confirms the formation of silica gel.
The HRTEM reveled nano cylindrical rods of 400 nm in length and 80 nm in diameter for silica gel synthesized using citric acid as hydrolysis catalyst.
Also DLS showed two maxima of the average particle size at ~ 52 nm and ~ 176 nm that confirmed the TEM images.
The nitrogen adsorption-desorption isothers could be classified as type II and type IV isotherms and show H1 hysteresis loop indicating mesoporous structure of the prepared silica gel samples.
The BET calculations revealed that the silica gel prepared by microwave in presence of Pluronic P-123 had the highest surface area ~ 424 m2/g with respect to the silica gel prepared by different acids via conventional method and/or different surfactants via microwave irradiation.
The adsorption capacity of the silica gel prepared by different acids reveals that the citric acid was the best hydrolysis catalyst for preparation of silica gel adsorbents.
The adsorption capacity of microwave adsorbents showed that as the microwave energy increases the adsorption decreases which reconcile with the decreases of surface area of the samples. The silica gel sample prepared in presence of microwave irradiation of power 100 watt for 30 seconds showed the highest surface area and the best adsorption.
The use of surfactant as a template increases the pore radius of the prepared silica gel from micropores to mesopores enhancing the adsorption capacity.
Four types of two parameter isotherms (Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherms) had been studied to describe the solid-liquid sorption system.
In general, the data obtained from the adsorption
Other data
| Title | STUDY ON THE ADSORPTION OF SOME ALKALI EARTH METALS ON NANO-SILICA GEL | Other Titles | دراسة امتزاز بعض المعادن القلوية الأرضية باستخدام السيلكا جل نانونية الحجم | Authors | Mahmoud Samy Mohamed Fahmy | Issue Date | 2014 |
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