Publication: Struvite crystallization in the presence of the additives
Abstract
Bu çalışma, saf ortamda ve katkı maddesi olarak asetik asit, oksalik asit ve trikarbalilik asidin kullanıldığı ortamda hazırlanan struvit kristallerinin karakteristiğini ve termal bozunma kinetiğini incelemektedir. İlk olarak, saf ortamda ve katkı maddeleri varlığında elde edilen kristallerin yapısı, fonksiyonel grupları, yüzey yükü, morfolojisi, tane boyutu ve filtrasyon karakteristiği belirlenmiştir. Mevcut çalışmada, kullanılan tüm karboksilik asitlerin elde edilen struvit kristallerinin yüzey elektrik yükünü, tane boyutunu ve morfolojisini önemli ölçüde etkilediği ortaya koyulmuştur. FTIR analizi ile struvitin yapısındaki çeşitli fonksiyonel grupların varlığı ortaya koyulmuştur. 200 ppm oksalik asit varlığında elde edilen struvite kristallerinin en düşük kek direncine ve en yüksek filtrasyon hızına sahip olduğu belirlenmiştir. Bir sonraki adımda, kristallerin termal bozunması incelenmiş ve elde edilen veriler Coast-Redfern kinetik modeli temel alınarak struvitin dehidrasyon kinetiğinin belirlenmesi amacı ile kullanılmıştır. Saf ortam, asetik asit, oksalik asit ve trikarbalilik asit varlığında elde edilen struvit kristallerinin ortalama aktivasyon enerjisi sırası ile 134.5, 96.3, 111.5 ve 97.0 kJ/ mol olarak hesaplanmıştır. Bu çalışmanın sonuçları, struvit kristallerinin morfolojisinin değiştirilmesinde kullanılacak olan katkı maddelerinin seçiminde ve struvit kristallerinin dehidrasyon kinetiği mekanizmasının açıklanmasında faydalı bilgileri ortaya koymuştur.
This study reports the characteristics and thermal decomposition kinetics of struvite crystals prepared with and without acetic acid, oxalic acid, and tricarballylic acid as additives. Firstly, the structure, functional groups, surface charge, morphology, particle size, and filtration characteristics of the crystals produced in the absence and presence of the additives were determined. All carboxylic acids utilized in this study were found to significantly affect the surface electrical charge, size, and morphology of the prepared struvite crystals. FTIR analysis revealed the presence of various functional groups in the struvite. With oxalic acid as the additive at a concentration of 200 ppm, the struvite was the most filterable with the lowest cake resistance and highest filtration rate. In the next step, the thermal decomposition of the crystals was examined and the obtained data were used to investigate the dehydration kinetics of the struvite based on a Coats–Redfern kinetic model. The average activation energies of struvite crystals prepared without and with acetic, oxalic, and tricarballylic acid were calculated to be 134.5, 96.3, 111.5, and 97.0 kJ/ mol respectively. Thus, the results of this work are useful for selection of a struvite morphology modifier and explaining the mechanism of the dehydration kinetics of struvite crystals.
This study reports the characteristics and thermal decomposition kinetics of struvite crystals prepared with and without acetic acid, oxalic acid, and tricarballylic acid as additives. Firstly, the structure, functional groups, surface charge, morphology, particle size, and filtration characteristics of the crystals produced in the absence and presence of the additives were determined. All carboxylic acids utilized in this study were found to significantly affect the surface electrical charge, size, and morphology of the prepared struvite crystals. FTIR analysis revealed the presence of various functional groups in the struvite. With oxalic acid as the additive at a concentration of 200 ppm, the struvite was the most filterable with the lowest cake resistance and highest filtration rate. In the next step, the thermal decomposition of the crystals was examined and the obtained data were used to investigate the dehydration kinetics of the struvite based on a Coats–Redfern kinetic model. The average activation energies of struvite crystals prepared without and with acetic, oxalic, and tricarballylic acid were calculated to be 134.5, 96.3, 111.5, and 97.0 kJ/ mol respectively. Thus, the results of this work are useful for selection of a struvite morphology modifier and explaining the mechanism of the dehydration kinetics of struvite crystals.