Sevgi POLAT, Perviz SAYAN, Nurseli GÖRENER

SÜKSİNİK ASİT VARLIĞINDA STRUVİT KRİSTALİZASYONUNUN İNCELENMESİ

Bu çalışmada, saf ortamda ve süksinik asidin katkı maddesi olarak kullanıldığı ortamda üretilen struvit kristallerinin yapısal, morfolojik ve termal özellikleri incelenmiştir. Elde edilen kristaller, XRD, FTIR ve SEM analizleri ile karakterize edilmiş; kristallerin tane boyutu, şekil parametreleri, filtrasyon karakteristiği ve yüzey yükünde meydana gelen değişimler belirlenmiştir. Süksinik asit konsantrasyonunun artmasıyla kristal morfolojisinde, tane boyutunda ve şekil parametrelerinde önemli değişiklikler meydana gelmiştir. Saf ortam ile karşılaştırıldığında kristal morfolojisinde meydana gelen değişimlere bağlı olarak kristallerin filtrasyon karakteristiği de değişmiştir. Katkı konsantrasyonunun artışına bağlı olarak filtrasyon hızında artış, spesifik kek direncinde ise düşüş olduğu belirlenmiştir. Saf ortamda struvit kristallerinin spefisifik kek direnci 4,72×109 m/kg iken bu değer 250 ppm katkı konsantrsayonu için 1,03×109 m/kg olarak hesaplanmıştır. Elde edilen kristal ürünlerin aynı zamanda termal bozunma davranışları, bozunma kinetiği ve termodinamiği Coats-Redfern modeli kullanılarak incelenmiştir. Mevcut çalışma ile endüstriyel açıdan özellikle atık su arıtıma tesislerinde boru içlerinde tıkanmalara neden olan struvitin morfolojik yapısının süksinik asit ile değiştirilebildiği ve filtrasyon ile ortamdan daha kolay uzaklaştırılabilecek forma dönüştürüldüğü ortaya koyulmuştur. Aynı zamanda struvitin termal bozunma kinetiğinin ve termodinamiğinin belirlenmesi de katkı maddesi olarak kullanılan süksinik asidin etkisini belirlemek açısından önemli katkılar sağlamıştır.

Investigation of Struvite Crystallization in the Presence of Succinic Acid

In this study, the structural, morphological and thermal properties of the struvite crystals obtained with and without succinic acid were investigated. The crystals obtained were characterized by XRD, SEM and FTIR analysis; and the variations in their particle size, shape parameters, filtration characteristics and surface charge were determined. The significant changes in the morphology and particle size of the struvite occurred along with the increase in succinic acid concentration. Compared to pure media, the filtration characteristics of the crystals modified depending on the changes in crystal morphology. It was determined that the filtration rate increased, and the specific cake resistance decreased based on the increment of additive concentration. The specific cake resistance was calculated to be 1.03×109 m/kg for 250 ppm additive concentration while it was 4.72×109 m/kg for pure media. Moreover, the thermal decomposition behavior, kinetics and thermodynamics of the struvite obtained were investigated by Coats-Redfern model. This study has revealed that the morphology of struvite leading to clogging problems in pipes especially in wastewater treatment plants from the industrial point of view could be changed by succinic acid and easily removed from the media. The understanding of thermal decomposition kinetics and thermodynamics of struvite has provided important contributions in terms of the determination of additive effects.

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