Improving of Thixotropic Properties of Bentonite Dispersions in Rheological Applications

Öz

In this study, the improvement of the rheological properties of bentonites by alkaline activation was investigated. The characterizations of the samples used in the study were determined by X-ray fluorescence spectroscopy (XRF), particle size distribution (PSD), cation exchange capacity (CEC), specific surface area (SSA) analysis and scanning electron microscopy (SEM) images. The rheological properties of the suspensions were determined by apparent viscosity (AV), plastic viscosity (PV), yield point (YP) and gel strength (GS) measurements. In addition, static filtration analysis was performed and thixotropic properties were determined by shear thinning index (STI) and thixotropy index (TI) calculations. Rheological flow parameters were calculated using the least squares method (LSM) and the model equations were created according to the Herschel-Bulkley flow model (HBM). As a result of the analyzes, it was determined that the alkaline activation process improved the rheological and thixotropic properties of bentonite dispersions. Also, the rheogram curves indicate that the suspensions showed a shear-thinning flow behavior. In the HBM evaluation, it was determined that the best flow properties belonged to EB (0.9987 R2) in raw samples and NB (0.9985 R2) in activated samples.

Anahtar Kelimeler

• Bentonite
• Activation
• Shear stress
• Viscosity
• Rheological modelling

Reolojik Uygulamalarda Bentonit Dispersiyonlarının Tiksotropik Özelliklerinin İyileştirilmesi

Öz

Bu çalışmada, bentonitlerin reolojik özelliklerinin alkali aktivasyonla iyileştirilmesi araştırılmıştır. Çalışma kapsamında kullanılan numunelerin karakterizasyonları X-ışını floresans spektroskopisi (XRF), tanecik boyut dağılımı (PSD), katyon değişim kapasitesi (CEC), spesifik yüzey alanı (SSA) analizleri ve taramalı elektron mikroskobu (SEM) görüntüleri ile belirlenmiştir. Süspansiyonların reolojik özellikleri görünür viskozite (AV), plastic viskozite (PV), kopma noktası (YP) ve jel kuvveti (GS) ölçümleri ile belirlenmiştir. Ayrıca statik filtrasyon analizi yapılmış olup, tiksotropik özellikleri kayma incelme indeksi (STI) ve tiksotropi indeksi (TI) hesaplamaları ile belirlenmiştir. Reolojik akış parametreleri en küçük kareler yöntemi (EKK) kullanılarak hesaplanmış olup, model denklemleri Herschel-Bulkley akış modeline (HBM) göre oluşturulmuştur. Yapılan analizler sonucunda alkali aktivasyon işleminin bentonit dispersiyonlarının reolojik ve tiksotropik özelliklerini iyileştirdiği belirlenmiştir. Ayrıca, reogram eğrileri süspansiyonların kayma incelme davranışı gösteren bir akış gösterdiğini ifade etmektedir. HBM reolojik model değerlendirmesinde en iyi akış özelliklerinin ham numunelerde EB kodlu numuneye (0,9987 R2), aktivasyonlu numunelerde ise NB kodlu numuneye (0,9985 R2) ait olduğu belirlenmiştir.

Anahtar Kelimeler

• Bentonit
• Aktivasyon
• Kayma gerilmesi
• Viskozite
• Reolojik modelleme

Kaynakça

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