scholarly journals Preparation and Characterization of Acid-Activated Bentonite with Binary Acid Solution and Its Use in Decreasing Electrical Conductivity of Tap Water

Minerals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 815
Author(s):  
Eri Nagahashi ◽  
Fumihiko Ogata ◽  
Chalermpong Saenjum ◽  
Takehiro Nakamura ◽  
Naohito Kawasaki
Keyword(s):  
Electrical Conductivity ◽  
Sulfuric Acid ◽  
Nitric Acid ◽  
Phosphoric Acid ◽  
Acid Solution ◽  
Tap Water ◽  
Acid Activation ◽  
Sodium Ions ◽  
Activated Bentonite ◽  
Adsorption Treatment

The characteristics of acid-activated raw bentonite (RB) activated with binary acid solutions sulfuric acid + nitric acid, nitric acid + phosphoric acid, and phosphoric acid + sulfuric acid, at a concentration of 5 mol/L (denoted as 5-SN, 5-NP, and 5-PS), were evaluated. Moreover, its application for improving the electrical conductivity in tap water was demonstrated. Acid activation induced the partial destruction of RB; subsequently, there was a significant release of sodium ions from the RB. In addition, the specific surface area and pore volume of 5-SN, 5-NP, and 5-PS were higher than those of RB. Next, the electrical conductivity when using RB increased with adsorption treatment because sodium ions were released from the RB. However, the electrical conductivity significantly decreased with adsorption treatment when using acid-activated RB. Specifically, magnesium ions, calcium ions, and potassium ions were removed into 5-SN, 5-NP, and 5-PS, and sodium ions were not released from the RB simultaneously. The removal percentage of the electrical conductivity using 5-SN, 5-NP, and 5-PS was approximately 31% to 36%. The results indicated that employing acid-activated RB with a binary acid solution is a useful method for decreasing the electrical conductivity in tap water.

scholarly journals A Study on the Leaching of Rare Earth Elements from Waste Phosphor Powder

2021 ◽  
Vol 59 (7) ◽  
pp. 459-468
Author(s):  
Gee Hun Lee ◽  
Chang Kwon Kim ◽  
Dong Hoon Lee ◽  
Young Jun Song
Keyword(s):  
Rare Earth ◽  
Sulfuric Acid ◽  
Nitric Acid ◽  
Hydrochloric Acid ◽  
Acid Solution ◽  
Rare Earth Elements ◽  
Nitric Acid Solution ◽  
Reaction Rate ◽  
Phosphor Powder ◽  
Leaching Reaction

This study was carried out to obtain data to design a process to recover rare earth elements, specifically Y(Yttrium), La(Lanthanum), Ce(Cerium), Eu(Europium), Tb(Terbium) from waste phosphor powder. For this purpose, we investigated the effect of temperature, concentration, time and acids on leaching of the rare earth elements. The effect of roasting temperature, roasting time, roasting agent and its dosage on the leaching of rare earth elements were also investigated. 92% of the Yttrium, 70% of the Europium and 8% of the Cerium contained in the waste phosphor powder was leached at the condition of 50 oC and 0.3N HCl solution for 3hours. However, Terbium and Lanthanum were never leached at this condition. The leaching ratio increased to 100% of Yttrium and Europium, 98% of Cerium, 92% of Terbium and 89% of Lanthanum by leaching after soda ash roasting. In the leaching experiment with unroasted phosphor at 80 oC, the initial leaching reaction rate of Yttrium was 0.035 mol/L·s in 0.3N sulfuric acid solution, 0.033 mol/L·s in nitric acid solution and 0.028 mol/L·s in 0.3N hydrochloric acid solution. And the initial leaching reaction rate of Europium was 0.0017 mol/L·s in 0.3N sulfuric acid solution, 0.00114 mol/L·s in nitric acid solution and 0.00113 mol/L·s in 0.3N hydrochloric acid solution. For Cerium, the initial leaching reaction rate was 0.00019 mol/L·s in 0.3N sulfuric acid solution, 0.00025 mol/L·s in nitric acid solution and 0.00014 mol/L·s in 0.3N hydrochloric acid solution.

Electrochemical Processing of Metal Wastes of Rhenium-Containing Heat-Resistant Nickel Alloys

2021 ◽  
Vol 316 ◽  
pp. 631-636
Author(s):  
L.Ya. Agapova ◽  
S.K. Kilibayeva ◽  
A.N. Zagorodnyaya
Keyword(s):  
Sulfuric Acid ◽  
Nitric Acid ◽  
Acid Solution ◽  
Sulfuric Acid Solution ◽  
Nickel Alloys ◽  
Anode Slime ◽  
Electrochemical Processing ◽  
Heat Resistant ◽  
Nickel Cobalt ◽  
Acid Addition

The paper presents the results of studies of electrochemical processing of large pieces of metal wastes of rhenium-containing heat-resistant nickel alloys (HRNA) with subsequent processing of the products of electrolysis. It shows the possibility of electrochemical processing of large (up to 2 kg) scrap pieces, without preliminary grinding, in sulfuric acid solution with nitric acid addition, under the current density of 500-1000 A/m2, with a temperature of 30-40о С. Up to 80-90% of rhenium and over 90% of nickel, cobalt, chrome and aluminum can be converted into the solution. Tungsten, tantalum and hafnium remain in the anode slime almost completely. Rhenium, nickel and cobalt remaining in the anode slime can be transferred to the solution, when the slime is chemically processed in sulfuric acid solution with nitric acid addition. The cake remaining after chemical decomposition of anode slimes represents a concentrate of refractory rare metals, containing up to 42% W; 18% Ta; 4% Hf. Rhenium is extracted from the combined solutions from anodic decomposition of HRNA wastes, and chemical dissolution of anode slimes, by the known extraction method in the form of the crude ammonium perrhenate (68,9 mас. % Re). After rhenium extraction the raffinate contains considerable quantities of nickel and cobalt, which can be precipitated by the alkali solution in the form of hydroxides to the nickel-cobalt concentrate, containing 31.5% Ni and 4.8% Co.

The Salt Makers

2019 ◽  
Author(s):  
Peter Wothers
Keyword(s):  
Organic Matter ◽  
Sulfuric Acid ◽  
Nitric Acid ◽  
Hydrochloric Acid ◽  
Acid Solution ◽  
Periodic Table ◽  
Dilute Hydrochloric Acid ◽  
Common Salt ◽  
Distilled Water ◽  
Metal Sulfate

This chapter looks at the elements from the penultimate group of the periodic table—the halogens (‘salt-formers’). We shall see that the first of these elements was discovered by Scheele during his investigations of the mineral pyrolusite. Lavoisier knew of the element but he failed to recognize it as such since he was convinced the gas had to contain oxygen and so must be a compound. It was left to Davy to prove that this was not so, which led to the English chemist naming this element that had been discovered (but not properly named) over thirty years before by the great Scheele. Davy’s choice was to influence the names given to all the members of this group, including the most recent member named in 2016. There are three common acids known as mineral acids, since they may all be obtained by heating combinations of certain minerals. Their modern names are nitric acid, sulfuric acid, and hydrochloric acid. Of these three, hydrochloric was probably the last to be discovered. Nitric and sulfuric acids were obtained in the thirteenth or early fourteenth centuries, but the earliest unambiguous preparation of relatively pure hydrochloric acid is from a hundred years later, in a manuscript from Bologna which translates as Secrets for Colour. It gives a curious recipe for a water to soften bones: ‘Take common salt and Roman vitriol in equal quantities, and grind them very well together; then distil them through an alembic, and keep the distilled water in a vessel well closed.’ As we saw in Chapter 3, ‘Roman vitriol’ is a hydrated metal sulfate, probably iron or copper sulfate; its mixture with salt, when heated, produces water and hydrogen chloride, which together form the acid solution. Later texts from the sixteenth and seventeenth centuries include similar methods to prepare this so-called spirit of salt, or ‘oyle of salt’. The first mentioned use, to soften bones, is indeed best achieved with hydrochloric acid, which readily dissolves the minerals from bone to leave only the organic matter largely intact. Leave a chicken bone in dilute hydrochloric acid for a few hours, and it may easily be bent without breaking.

scholarly journals Ammonia recovery from human urine as liquid fertilizers in hollow fiber membrane contactor: Effects of permeate chemistry

2020 ◽  
Vol 26 (1) ◽  
Author(s):  
Mekdimu Mezemir Damtie ◽  
Federico Volpin ◽  
Minwei Yao ◽  
Leonard Demegilio Tijing ◽  
Ruth Habte Hailemariam ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Nitric Acid ◽  
Phosphoric Acid ◽  
Acid Concentration ◽  
Hollow Fiber ◽  
Human Urine ◽  
Hollow Fiber Membrane ◽  
Membrane Contactor ◽  
Fiber Membrane ◽  
Acid Type

The production of the existing nitrogen fertilizer is costly and less environmental-friendly. Various green technologies are currently emerging toward providing alternative options. In this study, a liquid/liquid hydrophobic hollow-fiber membrane contactor was employed at ambient temperature and natural urine pH ~ 9.7 to recover ammonium fertilizers from human urine. Results showed that permeate side chemistry was one of the major factors affecting the ammonia mass transfer. The study on the ammonia capturing performance of diluted sulfuric acid, phosphoric acid, nitric acid, and DI water confirmed that acid type, acid concentration, and permeate side operating pH were the most important parameters affecting the ammonia capturing tendency. Sulfuric acid was slightly better in capturing more ammonia than other acid types. The study also identified increasing acid concentration didn’t necessarily increase ammonia mining tendency because there was always one optimum concentration value at which maximum ammonia extraction was possible. The best permeate side operating pH to extract ammonia for fertilizer purposes was selected based on the dissociation equilibrium of different types of acids. Accordingly, the analysis showed that the membrane process has to be operated at pH > 3 for sulfuric acid, between 3.5 to 11.5 for phosphoric acid, and above 0.5 for nitric acid so as to produce their respective high-quality liquid ammonium sulfate, ammonium monophosphate/diphosphate, and ammonium nitrate fertilizer. Therefore, permeate side acid concentration, pH, and acid type has to always be critically optimized before starting the ammonia mining experiment.

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