Decrease In Separation Efficiency Research Articles

Extraction and enrichment of chlorinated phenols from surface waters for the determination by capillary-GC/FTIR-spectroscopy

A method is presented for the separation and substance-specific determination of chlorinated phenols at trace level in surface waters using capillary-GC/FTIR-spectroscopy. Since an injected amount of at least 100 ng is required to obtain well-structured IR spectra, the extraction and enrichment procedure must provide a concentration factor of 104 and simultaneously high recoveries. The separation of the complete range of chlorinated phenols is performed without derivatisation on a SE54 fused silica WCOT column; the degree of decrease in separation efficiency introduced by the FTIRS detection system is discussed. The applicability of an on-column injection technique using a thermodesorption- and cold trap injector with solvent removal is tested, which allows the injection of large volums of concentrate. Proceeding form 1 l water volume and a 10 ppb concentration level the chlorophenols are correctly identified by their IR spectra and the mean recovery is in the 90% range. Furthermore, the possibility is discussed to obtain information on the identity of matrix components based on IR data only.

Use of sodium sulphide in tanning

The high cost of primary materials and their limited resources, as well as the ever-increasing amount of waste, has magnified the need for recycling and resource recovery from lithium ion batteries (LIB). This need will only be exasperated in the future as personal electronic equipment and electric vehicles (EV) become more widespread. In this study, a simple process for the separation of the cathode materials from waste Apple iPhone 6 lithium batteries is proposed, consisting of thermal treatment followed by ultrasonication. The main advantages of the process are its simplicity and complete independence from all chemicals. Heating the cathode material to 550°C gradually increases the removal efficiency; however, further increase in temperature results in a sharp decline of removal due to changes in the Al foil structure. With limited aeration inside the muffle furnace the removal barely exceeded 60%, whereas under suitable aeration, removal efficiencies exceeding 90% were obtained. Ultrasonication aids the release of cathode powder by creating convective flow as well as intense cavitation. As ultrasonication time and power increase, so does the removal efficiency. However, by increasing the power from 50 W to 100 W, the cathode powder separation efficiency decreases. This is because the numerous cavitation bubbles create a barrier for the transmission of acoustic energy to other parts of the tank, meaning the physical vibration of the transducer is greater than the fluid's ability to stay in contact. The final obtained cathodic powder under optimum conditions (heating for 15 min at 550°C, followed by ultrasonic treatment at 45°C and 50 Watts for 1 min) was 45.5% Co, 4.9% Al, 13.7% Cu, 3.6% Li, and 13.7% Ni.