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shojaee farah abady H, asilian mahabady H, Khavanin A, abbaszadeh M. The impact of chemical and thermal refining on adsorption capacity of Iranian natural diatomite. johe 2018; 5 (1) :8-15
URL: http://johe.umsha.ac.ir/article-1-323-en.html

Introduction: One of the factors that affects the rate of adsorption and removal of pollutants is the level of bed surface. Today, the use of active carbon substrates, synthetic zeolite such as Y and ZSM-5, are of great efficiency due to their high surface. In this research, diatomite modification was carried out using chemical and thermal processes to increase the bed surface and also the amount of adsorption capacity.
Methods: After washing with distilled water the crude sample of diatomite was purified with 1 M solution of hydrochloric acid in two stages of 6 hours under the temperature of 70 degrees and finally it was calcinated at the temperature of 750 degrees for 4 hours. Eventually, its characteristics’ such as Specific surface area, the pure distribution, sorption – desorption isotherms and its adsorption capacity was studied.
Results: Acid refinication increases the specific surface area 2.2 times compared to an example of which only washed with deionized water. Furthermore, the rate of SiO₂  reached 88 %. By calcinating the sample, the specific surface decreased 16.4 % and crystalline structure Increased. The results of XRF and XRD indicated that most of diatomite combination was respectively cristobalite, quartz and feldspar. And also the amount of adsorption capacity at Break point and saturation after modification was respectively 131% and 97% increased.
Conclusion: results indicated that with the modification of diatomite, and its calcinating at the temperature of 750 degrees, surface area and adsorption capacity increased, but did not increase significantly compared to the existing substrates such as active carbon and synthetic zeolite types and its Requires to more study.