Experimental and theoretical study of recovery mechanism of impurity effect by the addition of EDTA

Abstract

The impurity effect by trivalent metal ion such as Al 3+ , Fe 3+ and Cr 3+ during crystal growth of KDP is reasonably well documented. If a metal ion is adsorbed onto the crystal surface, it prevents the step propagation relevant to the crystal growth rate. However, this impurity adsorption mechanism is still not well understood. Recently, in our work on the addition of chelate agents, a recovery effect of the metal ion adsorption was discovered. However, its recovery mechanism is not clearly understood both theoretically and phenomenally. In this research, ethylene-diamine-tetra-acetic acid, EDTA, which is the most common chelate agent, was used as a recovery agent. The recovery mechanism was considered from the correlation of experimental data and the interfacial distribution model that we proposed in our former study. Furthermore, quantum calculation of EDTA metal complex can explain the relaxation of impurity adsorption by the addition of EDTA.

The Role of an Impurity in Ceftriaxone Sodium Preparation for Injection in Determining Compatibility with Calcium-Containing Solutions

“…14) In a previous report, it has been shown that impurities attach to the crystal surface and thereby interrupt crystal growth. 7,[15][16][17][18] For example, it has been shown that many kinds of substances (metal ions, proteins, etc.) inhibit the nucleation and crystal growth of hydroxyapatite (HAP).…”

Electron paramagnetic resonance spectroscopy and first-principles calculations of Cr3+ doped KDP crystals

“…The measurements of the distribution of these impurities in the pyramidal and prismatic sectors of KDP agree well with Asakuma's theory. 6 The crystals were cut and oriented with high precision to obtain rectangular samples for EPR and optical absorption experiments. The EPR sample was rectangular with dimensions of 3 × 3 × 3.3 mm 3 along with the crystal a, b, and c axis.…”

“…[3][4][5] However, the behaviour of the impurity ions, once they have entered the crystal, is not yet completely clarified, even for divalent (e.g., Cu 2+ , Co 2+ , Ba 2+ , Fe 2+ ) and trivalent metal ions (e.g., Fe 3+ , Cr 3+ , Al 3+ ), which are currently considered to have the most significant influence. [6][7][8][9] The structure of the KDP crystals at room temperature belongs to the tetragonal crystal system, and the space group is I4 ¯2d. The cell parameters are a = b = 0.7453 nm and c = 0.6974 nm.…”

“…, Fe 3+ , Cr 3+ , Al 3+ ), which are currently considered to have the most significant influence. 6–9…”

Clarification of Impurity Colouring and Adsorption Mechanism for KDP Crystal Growth by Computational Chemistry

“…EDTA(ethylene-diamine-tetra-acetic acid, ) [6,7] (Sunset Yellow, Brilliant blue etc.) (100),(101) KDP [8][9][10]] KDP (Gaussian R 03W Ver.6, Gaussian Inc.) [11] (1)…”