The use of a membrane electrode to study the crystallisation of calcium sulphate from aqueous solution. II. The influence of organic additives on the crystallisation of calcium sulphate

2007 ◽  
Vol 23 (6) ◽  
pp. 451-455 ◽  
Author(s):  
William Ching ◽  
Eric R. McCartney
Keyword(s):  
Aqueous Solution ◽  
Calcium Sulphate ◽  
Membrane Electrode ◽  
Organic Additives

Formation of Membrane Electrode Assembly for High Temperature Methanol Fuel Cells

2015 ◽  
Vol 645-646 ◽  
pp. 1175-1180 ◽  
Author(s):  
Da Zhi Wang ◽  
Xiao Hu Zhu ◽  
Wen Zha ◽  
Tong Qun Ren ◽  
Ming Qiang Li ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
High Temperature ◽  
Flow Rate ◽  
Proton Exchange Membrane ◽  
Membrane Electrode Assembly ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Membrane Electrode ◽  
Layer By Layer ◽  
Catalyst Layers

In this work, a quaternized polysulfone/PTFE/H3PO4composite membrane was prepared and used to a high temperature sustainable proton exchange membrane (HTPEM). This HTPEM was prepared based on a porous PTFE membrane, which can sustainable for 200 °C. Pt/C nano-suspension was prepared and deposited layer-by-layer on the gas diffusion layer (GDL) using electrohydrodynamic atomization (EHDA) deposition technique for the formation of cathode and anode catalyst layers (CLs). The CLs presented well packed and porous features. This EHDA deposited cathode and anode CLs, GDL and HTPEM were assembled to a membrane electrode assembly (MEA) and high temperature methanol fuel cell (HTMFC). The results showed that low concentration and high flow rate of methanol aqueous solution led to the loss of phosphoric acid on HTPEM, which resulted in the decline of the HTPEM. When the concentration and the flow rate of the methanol aqueous solution was increased and reduced, respectively, the cell can work properly at a temperature of 170 °C.

The affinity of crystal growth and dissolution in aqueous solution with special reference to calcium sulphate dihydrate

1979 ◽  
Vol 47 (5-6) ◽  
pp. 607-612 ◽  
Author(s):  
J. Christoffersen ◽  
M.R. Christoffersen ◽  
G.M. Van Rosmalen ◽  
W.G.J. Marchée
Keyword(s):  
Aqueous Solution ◽  
Crystal Growth ◽  
Special Reference ◽  
Calcium Sulphate

scholarly journals Factors Affecting Precipitation of Calcium Lactate from Fermentation Broths and from Aqueous Solution

2019 ◽  
Author(s):  
Aladár Vidra ◽  
Áron Németh ◽  
András Salgó
Keyword(s):  
Aqueous Solution ◽  
Lactic Acid ◽  
Fermentation Broth ◽  
Calcium Sulphate ◽  
Calcium Lactate ◽  
Precipitation Process ◽  
Factors Affecting ◽  
Traditional Procedure ◽  
Statistical Designs ◽  
Fermentation Broths

Lactic acid is one of the most important organic acids which is being extensively used around the globe in a range of industrial and biotechnological applications. Lactic acid can be produced either by fermentation or by chemical synthesis but the biotechnological fermentation process has several advantages compared to the other one. However fermentation broth contains a number of impurities which must be removed from the broth in order to achieve more pure lactic acid. Efficiency of recovery is crucial to the economy of the whole process as well since the costs of separation and recovery are responsible for more than half of the entire cost of production. In the traditional procedure, the heated and filtered fermentation broth is concentrated to allow crystallization or precipitation of calcium lactate, followed by addition of sulphuric acid to remove the calcium in form of calcium sulphate. The disadvantage of this procedure is the relatively high solubility of calcium lactate which causes product loss in the crystallization step. Therefore we investigated the effects of four operating parameters of the crystallization/precipitation process from two different fermentation broths and from an aqueous solution. Thus we applied three central composite statistical designs, in which the examined parameters were the temperature of the solution, the duration of the process, the effect of ethanol addition to the solution as well as the effect of multi-cycle precipitation after separation of the precipitated calcium lactate. According to the results, more than 50 percent calcium lactate precipitation increase can be obtained from fermentation broth by adding sufficient amount of ethanol and adjusting the proper temperature of the process.

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