A review of the existing and emerging technologies for wastewaters containing tetramethyl ammonium hydroxide (TMAH) and waste management systems in micro-chip microelectronic industries.

The present work aims to describe and review the available technologies and the recent advancements in treating industrial wastewater containing tetramethylammonium hydroxide (TMAH). It is a quaternary ammonium salt and widely used in the microelectronics industry; this kind of company produces large quantities of wastewater containing TMAH. The exhausted solutions must be treated appropriately since TMAH is corrosive, toxic to human health, and ecotoxic.

Effect of Acid Leaching Pre-Treatment on Gold Extraction from Printed Circuit Boards of Spent Mobile Phones.

The effect of a preliminary acid leaching for the recovery of gold by thiourea from printed circuit boards (PCBs) of spent mobile phones, was investigated. Preliminary leaching is aimed to recover copper in the leachate that would compete with gold in the successive leaching of the residue with thiourea, thus preventing the formation of the gold-thiourea complex. Two hydrometallurgical routes were tested for the recovery of copper first, and gold after.

Leaching test procedure for assessing the compliance of the chemical and environmental requirements of hardened woody biomass fly ash cement mixtures.

The compliance of the chemical and environmental requirements for using woody biomass fly ash (WBFA) as a mineral admixture in cement-based materials was studied in terms of the use of the cement-biomass fly ash concrete where the fluids surrounding and interacting with it renew themselves over time. The study was preceded by a preliminary characterization of WBFA whose results showed that the European chemical requirements (EN 450-1, 2012) established for the reuse of coal fly ash in cement-based materials (there is no normative for WBFA) were met except for the chloride content. A blend with a quite high content of WBFA (30%) and Portland cement (70%) was prepared to test the leaching behaviour of the cement-biomass fly ash concrete.

Removal of Mn and As from drinking water by red mud and pyrolusite.

Due to limited economic resources, which impede access to specific advanced technologies, many developing countries are still facing the challenge of reducing human exposure to heavy metals, which is primarily associated with the consumption of water contaminated through the discharge of poorly treated wastewater. In wastewater treatment technology, adsorption is sometime preferred to other approaches because of its high efficiency, easy handling, availability of different substrates and cost effectiveness. Moreover, increasing emphasis has recently been given to the use of low-cost adsorbents (generally solid wastes) for the treatment of polluted water, with a resulting double benefit for the environment.

A hydrometallurgical process for the recovery of terbium from fluorescent lamps: Experimental design, optimization of acid leaching process and process analysis.

Terbium and rare earths recovery from fluorescent powders of exhausted lamps by acid leaching with hydrochloric acid was the objective of this study. In order to investigate the factors affecting leaching a series of experiments was performed in according to a full factorial plan with four variables and two levels (4). The factors studied were temperature, concentration of acid, pulp density and leaching time.