Adsorption Isotherms of Citric Acid Acting as a Growth‐Suppressor onto the (100) and (111) Faces of Sodium Chloride Crystals in Supersaturated Aqueous Solution

Abstract

The growth-starting supercooling DT G , a degree of supercooling at which a crystal starts to grow when the solution is continuously cooled, was measured in supersaturated aqueous solutions in the presence of citric acid as an impurity 1) . It was measured both for the (100) and (111) faces of sodium chloride crystals. From the measured data of DT G , the Langmuir constants of the (100) and (111) faces were determined at pH = 4.5 to be 6.16 ± 0.88 L/mol and 12.5 ± 2.0 L/mol, respectively. This DT G method is a convenient method for the determination of adsorption isotherms of an impurity onto specific crystallographic faces of a crystal.

Is Dual Morphology of Rock‐Salt Crystals Possible with a Single Additive? The Answer Is Yes, with Barbituric Acid

“…Furthermore, the report showed that NTA can work in much smaller quantity compared to other known organic additives 5p. The ionic forms of NTA have been suggested to be important for such morphological changes in NaCl crystals, which has also been observed with citric acid 5m,n. Both NTA and citric acid are flexible in nature with more than one similar binding sites, however, with these additives not all the sites bind to the NaCl surfaces 5p,n.…”

“…The design strategy based on the additive recognition at inorganic surfaces has been found to be successful in controlling the morphology 8. Further, molecular modeling studies were employed to examine the recognition of additives with different properties including lattice fit,5e,f multipoint adsorption,9 conformation of the additives,5j pH5m,o. Recently, a similar study predicted that nitrilotriacetic acid (NTA) acts as a habit modifier of NaCl,5p which however was reported to be ineffective on NaCl crystals 9.…”

Ionization and Conformational Equilibria of Citric Acid: Delocalized Proton Binding in Solution

“…4 It is also involved in di erential adsorption on crystal surfaces leading to di erential growing of crystal geometries. 5 All these properties are pH-dependent, so that a detailed knowledge of the ionization mechanism of this small molecule is necessary. However, most of the studies on 2 NMR is probably the most versatile and has been widely used in the micro-speciation of a vast array of ionizable molecules ranging from proteins to small molecules.…”

Nacl’ Ün Çekirdeklenme Kinetiğine Ağır Metal Safsızlıklarının Etkisi

“…Sodyum klorür, elde edildiği kaynağa bağlı olarak, farklı derişimlerde olmak üzere daha çok KCl, MgCl 2 , SrCl 2 , NaBr, NaI, NaF, Na 2 SO 4 , NaBO 2 , Na 2 CO 3 , ZnSO 4 , CuSO 4 , PbCl 2 , K 4 Fe(CN) 6 safsızlıklarını içermektedir.…”

“…Akışkan yatak kristalizöründe PbCl 2 , K 4 Fe(CN) 6 .3H 2 O ve MgCl 2 safsızlıklarının etkilerinin incelendiği bir çalışmada söz konusu katkıların büyüme/çözünme hızını azalttığı ve çözünürlük değişimine sebep olduğu tespit edilmiştir [2]. Tek kristal ölçüm sisteminde yapılan çalışmalarda; 15 farklı inorganik safsızlığın NaCl'ün büyüme/çözünme hızlarını değiştirdiği [3], NaCl'ün büyümesini yavaşlatıcı etkisi bilinen sitrik asidin (100) ve (111) yüzeylerinin [4], PbCl 2 ' ün ise (100) yüzeyinin büyüme davranışını değiştirdiği belirlenmiştir [5]. Metastabil bölge genişliği deney sisteminde ve derişim değişimlerinin incelendiği kolon sisteminde gerçekleştirilen bir çalışmada ise, CrN 3 O 9 .9H 2 O ve PbSO 4 safsızlıklarının NaCl'ün partikül boyutunu etkilediği tespit edilmiştir [6].…”