Rajesh Kumar Jyothi

The role of macrocyclic compounds in the extraction and possible separation of platinum and rhodium from chloride solutions.

Macrocyclic compounds (crown ethers), specifically 18-crown-6 (18-C-6), benzo-15-crown-5 (B-15-C-5), di-benzo-18-crown-6 (DB-18-C-6) and di-cyclohexano-18-crown-6 (DC-18C-6), are used as extractants as well as synergists with amine-group extractants. Platinum and rhodium belong to platinum-group metals (PGMs) and have very similar ionic radii and similar properties. The separation of PGMs is most useful for the preparation of functional materials. Macrocyclic compounds are tested for platinum and rhodium separation and are found to achieve marginal separation. Amines (used as extractants) are paired with macrocyclic compounds (used as synergists), and the separation factor between platinum and rhodium is increased with synergistic enhancement from a chloride solution. The present study discusses extraction chemistry, separation factors and the synergy between platinum and rhodium from chloride solutions. To ensure accurate data, the aqueous samples in this study are analyzed using an inductively coupled plasma optical emission spectrometer (ICP-OES).

Recovery of Tungsten from Spent V 2 O 5 –WO 3 /TiO 2 Catalyst

Currently, spent V2O5–WO3/TiO2 catalysts contribute significant amounts of solid waste following increasing levels of global demand. V2O5–WO3/TiO2 catalysts usually consist of TiO2 anatase as a supporting oxide, vanadium as a catalytic agent, and other promoters such as tungsten, silicon, and calcium. Although vanadium is the main catalytic agent, a relatively high content of tungsten (WO3, 7–10 wt%) typically exists compared to vanadium (0.5–1.5 wt%). Considering the irreplaceable properties and industrial importance of tungsten, a feasible method for the recycling of spent V2O5–WO3/TiO2 catalyst should be established to utilize it as a secondary source. This paper presents a process to recover tungsten from spent V2O5–WO3/TiO2 catalyst. The processes proposed here involving roasting, decomposition using HCl, ammonia leaching, and crystallization. Within the process, ammonium paratungstate (71 wt% as WO3) is obtained as a final product. The total yield rate of tungsten from feedstock was found to be 96.3%.

Diluents Role in Extraction and Possible Separation of Light Rare Earth Elements from Chloride Solutions by using Cyanex® 272 used as an Extractant

The present paper deals with liquid-liquid extraction studies and the possible separation of light rare earths (LREs) from chloride solutions. Aromatic diluents such as benzene, toluene and xylene were tested for LREs extraction and possible separation from chloride solutions. Bis(2,4,4-triethylpentyl)phosphinic acid (trade name Cyanex 272) was used as an extractant and dissolved in the diluents. Various experimental parameters such as time effect, influence of pH, extractant concentration variation and maximum loading capacity of the target LREs to Cyanex 272 were examined. Finally, the separation potential of each of the other LREs was calculated, and a suitable diluent system was proposed. The highest separation factors were found using the present systems. (Received July 18, 2018; Accepted September 3, 2018)

Status and Preparation Technology of Rare Earth Materials

The rare earths have an ever growing variety of applications in the modern technology. They provide many an industry with crucial materials and they provide many a customer with benefits. Rare earth materials utilization increasing day-by-day in the world wide, at the same time the resources are very limited in many countries like Korea. The recycling and recovery of the rare earth metals is much use full for future needs as well as high functional materials. The present general paper describes the status and preparation technologies for rare earth materials. The paper divides in to three parts, part one relates to overview and properties of rare earth metals and production as well as consumption ofp rare earth metals. Whereas part two having mineral processing and leaching studies of rare earth ore and separation and purification technologies of rare earths and preparation technologies of oxide and metals. The last part consist security of rare earth minerals and preparation technology and a security counter plans of rare earths materials.