Fundamental Study of Palladium Recycling Using “Dry Aqua Regia” Considering the Recovery from Spent Auto-catalyst

AbstractIn this research, a recycling process for palladium using “dry aqua regia,” which consists of iron(III) chloride–potassium chloride, was proposed. Palladium was dissolved in “dry aqua regia,” and the dissolved palladium was recovered by leaching with potassium chloride solution with added ammonium chloride and nitric acid. Palladium was almost completely dissolved in 3 h at 600 K, and the recovery ratio of dissolved palladium was up to 80%. In addition, the dissolution of palladium in coexistence with platinum and the dissolution of platinum-palladium alloy by “dry aqua regia” were also tested. The dissolved palladium and platinum were separated and recovered by solid–liquid separation technique using the difference in solubility of their compounds in potassium chloride and sodium chloride solutions. As a result, pure compounds of each element were recovered. This result suggested the possibility of using “dry aqua regia” for the separation of platinum-group metals. Graphical Abstract

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ACRYLAMIDE (CO)POLYMERS DISSOLUTION IN WATER-SALINE SOLUTIONS

Proceedings of the National Academy of Sciences of Belarus Chemical Series ◽

10.29235/1561-8331-2018-54-3-329-337 ◽

2018 ◽

Vol 54 (3) ◽

pp. 329-337 ◽

Cited By ~ 2

Author(s):

D. N. Davlyud ◽

P. D. Vorobiev ◽

Yu. V. Matrunchik ◽

E. V. Vorobieva ◽

N. P. Krutko

Keyword(s):

Sodium Chloride ◽

Potassium Chloride ◽

Solvent System ◽

Ionogenic Group ◽

Dissolution Time ◽

Chloride Solutions ◽

Sodium Chloride Solutions ◽

The Difference ◽

Capillary Viscosimetry ◽

Saline Solutions

Dissolution of acrylamide anionic (co)polymers in saline solutions (potassium and sodium chlorides) with concentration of 3.4 mol/l was studied by atomic absorption spectroscopy, optical microscopy, gel-test and capillary viscosimetry. It has been established that with increasing in the content of ionogenic groups and the transition from sodium chloride to potassium chloride solutions the dissolution rate of (co)polymer increases. The concentration of cations of low molecular weight electrolytes is higher in the swollen polymer phase than in the solution in the swelling stage of polymers, the difference in the counter ion content decreases with increasing dissolution time. Comparative analysis of the Huggins constant and the hydrodynamic radii of acrylamide (co)polymers has showed that increase in the interaction in polymer-solvent system is accompanied by the increase in size of macromolecular coils. The Kuhn segment of polymer macromolecules is higher in sodium chloride solutions than in potassium chloride solutions and increases with the decrease in ionogenic group content.

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Séparation solide-liquide : les membranes. / Solid-liquid separation : the membranes

Sciences Géologiques Bulletin ◽

10.3406/sgeol.1993.1903 ◽

1993 ◽

Vol 46 (1) ◽

pp. 175-182

Author(s):

Jean-Luc Bersillon

Keyword(s):

Liquid Separation ◽

Solid Liquid ◽

Solid Liquid Separation

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Nitrogen Removal in a Real-Time Controlled Sequencing Batch Membrane Bioreactor

Water Practice & Technology ◽

10.2166/wpt.2010.065 ◽

2010 ◽

Vol 5 (3) ◽

Author(s):

Cheng-Nan Chang ◽

Li-Ling Lee ◽

Han-Hsien Huang ◽

Ying-Chih Chiu

Keyword(s):

Real Time ◽

Nitrogen Removal ◽

Membrane Bioreactor ◽

Synthetic Wastewater ◽

Real Time Control ◽

Time Control ◽

Cake Layer ◽

On Line ◽

Solid Liquid ◽

Solid Liquid Separation

The performance of a real-time controlled Sequencing Batch Membrane Bioreactor (SBMBR) for removing organic matter and nitrogen from synthetic wastewater has been investigated in this study under two specific ammonia loadings of 0.0086 and 0.0045g NH4+-N gVSS−1 day−1. Laboratory results indicate that both COD and DOC removal are greater than 97.5% (w/w) but the major benefit of using membrane for solid-liquid separation is that the effluent can be decanted through the membrane while aeration is continued during the draw stage. With a continued aeration, the sludge cake layer is prevented from forming thus alleviating the membrane clogging problem in addition to significant nitrification activities observed in the draw stage. With adequate aeration in the oxic stage, the nitrogen removal efficiency exceeding 99% can be achieved with the SBMBR system. Furthermore, the SBMBR system has also been used to study the occurrence of ammonia valley and nitrate knee that can be used for real-time control of the biological process. Under appropriate ammonia loading rates, applicable ammonia valley and nitrate knee are detected. The real-time control of the SBMBR can be performed based on on-line ORP and pH measurements.

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Investigations on the filtration of natural aquatic suspensions supported by dosing small amounts of Fe(III)-salts (βFe ≤ 0.1 mg.L-1): mode of action and basic design criteria

Water Science & Technology Water Supply ◽

10.2166/ws.2002.0050 ◽

2002 ◽

Vol 2 (2) ◽

pp. 91-98

Author(s):

R. Winzenbacher ◽

R. Schick ◽

H.-H. Stabel ◽

M. Jekel

Keyword(s):

Large Scale ◽

Suspended Solids ◽

Iron Hydroxides ◽

Essential Step ◽

Iron Salts ◽

Alkaline Earths ◽

Co Precipitation ◽

Solid Liquid ◽

Solid Liquid Separation

Improved removal of particles during the treatment of natural aquatic suspensions has been achieved by pre-ozonation and the addition of small quantities of iron salts (βFe ≤ 0.1 mg.L-1; “Fe(III)-assisted filtration”) followed by rapid filtration. As shown by investigations on a large-scale installation at Lake Constance Water Supply, this procedure reliably reduces suspended solids by at least 2-3 powers of ten in long-term use. However, the high efficacy of Fe(III)-assisted filtration cannot be explained on the basis of known coagulation mechanisms (like adsorption-charge neutralization, co-precipitation). Instead, the essential step was found to be the conditioning of the filter medium by coating it with colloids containing Fe(OH)3, and this “Fe coating” process occurs only in the presence of alkaline earths (especially Ca2+). According to further experiments, the enhanced solid-liquid separation was ultimately traced to chemical interactions such as the formation of calcium-organic association structures between the iron hydroxides and other solids. For design of Fe(III)-assisted filtration steps, finally, a βCa/DOC ratio above 40 mg.mg-1 and pre-oxidation with ozone dosages not exceeding 2 mg O3/mg DOC was recommended.

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