Surface complexation reactions of inorganic anions on hydrotalcite-like compounds.
نویسندگان
چکیده
Complexation reactions of environmentally important inorganic anions such as nitrate, chloride, sulfate, arsenate, and phosphate on the surface of hydrotalcite-like compounds (HT) were investigated to understand the role of HT in the immobilization of hazardous anions in an alkaline environment. The effects of surface complexation reactions on the solid state properties of HT were also evaluated to understand their stability. Synthetic HT was used for the adsorption and post-adsorption experiments. The obtained adsorption isotherms showed that the order of selectivity of HT for anions was NO(3)<Cl<SO(4)<<AsO(4)<PO(4). To distinguish the adsorption mechanisms (inner-sphere complexes or outer-sphere complexes) of these anions, zeta potential measurements and infrared absorption spectroscopic analysis were performed. The results indicated that NO(3) and Cl were adsorbed as diffuse ions on the outer surfaces of the HT, while SO(4) formed outer-sphere complexes with a strong electrostatic interaction. Moreover, AsO(4) and PO(4) formed inner-sphere complexes via a ligand substitution reaction on the HT surfaces. And it was suggested that oxyanions with low ionic potential, such as AsO(4) and PO(4), had a tendency to form inner-sphere complexes with the HT surfaces. The formation of inner-sphere complexes shifted the isoelectric point and the surface charge of the HT. Furthermore, the solubility of the HT was reduced by the inner-sphere complexes with PO(4) and AsO(4). It was revealed that the formation of inner-sphere complexes on the HT surfaces contributed to the stabilization of the HT, as well as a decrease in the mobility of these anions.
منابع مشابه
Effect of hydrotalcite-like compounds on the aqueous solubility of some poorly water-soluble drugs.
A new approach of improving drug dissolution properties is described. This method exploits the property of a carrier owing to the hydrotalcite-type anionic clays (HTlc). HTlc is an inorganic layered solid that lodges anionic compounds among its layers. As HTlc dissolves at acidic pH values (pH < 4), the anions intercalated among the layers are promptly released in the medium. In this article so...
متن کاملInorganic nanolayers: structure, preparation, and biomedical applications
Hydrotalcite-like compounds are two-dimensional inorganic nanolayers also known as clay minerals or anionic clays or layered double hydroxides/layered hydroxy salts, and have emerged as a single type of material with numerous biomedical applications, such as drug delivery, gene delivery, cosmetics, and biosensing. Inorganic nanolayers are promising materials due to their fascinating properties,...
متن کامل2H Solid-State NMR Investigation of Terephthalate Dynamics and Orientation inMixed-Anion Hydrotalcite-Like Compounds
متن کامل
Anion-exchange Properties of Hydrotalcite-like Compounds
-Ion-exchange isotherms between hydrotalcite-like compounds (HT) of the NO3-, CI-, and SO4forms and F , 0% Br , I , OH-, SO42-, CO3 z-, and Naphthol Yellow S (NYS 2-) ions were determined, and the spacing and the width of the 003 reflection were measured as a function of HT composition. The ion-exchange equilibrium constant for HTs of monovalent anions are in the sequence OH> F > Cl > Br> NO3> ...
متن کاملPhotostability enhancement of anionic natural dye by intercalation into hydrotalcite.
The aim of this study is the improvement of the photostability of several natural anionic dyes, carmine (CM), carthamus yellow (CY), and annatto dye (ANA), by complexation with hydrotalcite. The composite of the dyes and hydrotalcite is prepared by the coprecipitation method. CM is successfully intercalated in the hydrotalcite layer when the amount of introduced CM is large. The photostability ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Journal of colloid and interface science
دوره 384 1 شماره
صفحات -
تاریخ انتشار 2012