Electrowinning of Iron from Spent Leaching Solutions Using Novel Anion Exchange Membranes
MEMBRANES
Authors: Badenhorst, Wouter Dirk; Rossouw, Cloete; Cho, Hyeongrae; Kerres, Jochen; Bruinsma, Dolf; Krieg, Henning
Abstract
In the Pyror process, electrowinning (EW) is used to recover acid and iron from spent leaching solutions (SLS), where a porous Terylene membrane acts as a separator between the cathode and anode. In this study, a novel anion exchange membrane (AEM)-based EW process is benchmarked against a process without and with a porous Terylene membrane by comparing the current efficiency, specific energy consumption (SEC), and sulfuric acid generation using an in-house constructed EW flow cell. Using an FAP-PK-130 commercial AEM, it was shown that the AEM-based process was more efficient than the traditional processes. Subsequently, 11 novel polybenzimidazole (PBI)-based blend AEMs were compared with the commercial AEM. The best performing novel AEM (BM-5), yielded a current efficiency of 95% at an SEC of 3.53 kWh/kg Fe, which is a 10% increase in current efficiency and a 0.72 kWh/kg Fe decrease in SEC when compared to the existing Pyror process. Furthermore, the use of the novel BM-5 AEM resulted in a 0.22 kWh/kg Fe lower SEC than that obtained with the commercial AEM, also showing mechanical stability in the EW flow cell. Finally, it was shown that below 5 g/L Fe, side reactions at the cathode resulted in a decrease in process efficiency, while 40 g/L yielded the highest efficiency and lowest SECs.
D-FAP: Dual-Factor Authentication Protocol for Mobile Cloud Connected Devices
JOURNAL OF SENSOR AND ACTUATOR NETWORKS
Authors: Abuarqoub, Abdelrahman
Abstract
Emerging Mobile Cloud Computing (MCC) technologies offer a new world of promise by leveraging the quality of mobile services. With MCC, resource-constrained mobile devices could capitalize on the computation/storage resources of cloud servers via communication networks. While MCC adoption is growing significantly, several challenges need to be addressed to make MCC-based solutions scale and meet the ever-growing demand for more resource intensive applications. Security is a critical problem hindering the adoption of MCC. One of the most important aspects of MCC security is to establish authenticated communication sessions between mobile devices and cloud servers. The huge amount of data stored on mobile devices poses information security risks and privacy concerns for individuals, enterprises, and governments. The ability to establish authenticated communication sessions between mobile devices and cloud servers can resolve many security concerns. Limited computing and energy resources on mobile devices makes authentication and encryption a challenging task. In this paper, an overview of MCC authentication protocols is presented. Then, a Dual-Factor Authentication Protocol for MCC devices (D-FAP) is proposed. D-FAP aims at increasing authentication security by using multi-factors while offloading computation to the cloud to reduce battery consumption. The security of the protocol is formally verified and informal analysis is performed for various attacks. The results prove that the D-FAP is successful in mitigating various outsider and insider attacks.