• Journal of Navigation and Port Research
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• v.39 no.6
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• pp.523-528
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• 2015

In this study, we investigated the effects of sulfuric acid on the synthesis of calcium borate in the artificial boron-containing brine (bittern) saturated with calcium hydroxide. For the study, we attempted to synthesize calcium borate under various conditions such as reaction temperature, reaction time, and cooling temperature after heating, and then to examine the recovery and purity of the calcium borate according to the presence or absence of sulfuric acid at each condition. The XRD analysis confirmed that, regardless of the presence of sulfuric acid, the calcium borate ($Ca_2B_2O_5{\cdot}H_2O$) was synthesized, while, in the presence of sulfuric acid, the calcium sulfate ($CaSO_4{\cdot}0.5H_2O$) was produced as a by-product. In all the experiments performed by varying the reaction temperature and time, the recovery and purity of the calcium borate without sulfuric acid were observed higher than those with it. The results indicated that the addition of sulfuric acid increased the solubility of the calcium hydroxide, but the calcium sulfate produced as a by-product could decrease the recovery and purity of the calcium borate by preventing the synthesis. In this study, the artificial boron-containing brine (bittern) (500 mg-B/L) was saturated with calcium hydroxide in the absence of sulfuric acid, and then the solution was heated at $80-105^{\circ}C$ for less than 10 minutes to synthesize the calcium borate. The recovery and purity of calcium borate were measured as high as 80 % and 96 %, respectively.

• Corrosion Science and Technology
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• v.18 no.3
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• pp.78-85
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• 2019

The International Maritime Organization (IMO) will administer a new 0.5% global sulfur cap on fuel content from 1 January 2020, lowering from the present 3.5% limit. Seawater $SO_x$ (sulfur oxide) scrubbing is especially spray scrubbing and a promising alternative to complying with the IMO regulation. However, the ionization of $SO_2$ (sulfur dioxide) and the $H_2SO_4$ (sulfuric acid) formed from $SO_3$ (sulfur trioxide) is proposed to accelerate corrosion of the internal seawater pipe. Apparently, the corrosion of the scrubber seawater piping system occurs in a severe and frequent manner. Hence, in this study, electrochemical measurement and weight loss of carbon steel (used as seawater pipe in most of the ships) in diluted sulfuric acid solution were investigated to determine corrosion rate, corrosion current density, corrosion potential, electrochemical behavior, and impressed-current density. Accordingly, the corrosion rate of carbon steel sheet in various diluted sulfuric acid solutions was observed to be greater than that in natural seawater, thus suggesting the fundamental data to deal with corrosion problems in scrubber seawater pipe.

• Bulletin of the Korean Chemical Society
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• v.31 no.7
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• pp.1927-1930
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• 2010

A fast, efficient, and high yielding method for the preparation of amines by reductive amination of aldehydes and ketones using sodium borohydride in the presence of cellulose sulfuric acid in EtOH and under solvent-free conditions at room temperature is described.

• Journal of the Korean Ceramic Society
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• v.26 no.1
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• pp.81-90
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• 1989

High purity alumina and amorphous silica were prepared from Ha-dong kaolin by means of appliance of sulfuric acid. The effect of sulfuric acid concentration, reaction temperature and reaction time on the formation of aluminum sulfate was investigated. The precipitation conditions ofaluminum sulfate from the sulfuric acid solution with ethanol and ammonium hydroxide were deteremined. In the optimum condition, the conversion of aluminum oxide in kaolin to aluminum oxide powder was 85.0 percent. Alumina powder was prepared by calcination of the precipitates, and its purity was 99.0 percent.

• Bulletin of the Korean Chemical Society
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• v.25 no.6
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• pp.865-868
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• 2004

Aldehydes and ketones were converted to their corresponding acetals in the presence of silica-bound sulfuric acid in n-hexane under mild and heterogeneous conditions with excellent yields.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.981-983
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• 2010

The condensation of several aromatic/heteroaromatic aldehydes with 2-aminothiophenol catalyzed by silica sulfuric acid under microwave irradiation afforded 2-arylbenzothiazoles in high yields and short reaction times under solvent-free conditions. The major advantages of the present method are good yields, ecofriendly, reusable catalyst, mild and solvent-free reaction conditions.

• Bulletin of the Korean Chemical Society
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• v.33 no.7
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• pp.2149-2155
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• 2012

A metal-free and efficient procedure for the oxidation of alcohols into the corresponding carbonyl compounds has been described using ammonium nitrate in the presence of silica sulfuric acid under mild and heterogeneous conditions. The use of non-toxic and inexpensive materials, simple and clean work-up, short reaction times and good yields of the products are among the advantages of this method.

• Structural Engineering and Mechanics
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• v.64 no.2
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• pp.243-257
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• 2017

Investigating the properties and durability of high-strength concrete exposed to sulfuric acid attack for the purpose of its application in structures exposed to this acid is of outmost importance. In this research, the resistance and durability of high-strength concrete containing macro-polymeric or steel fibers together with the pozzolans of silica fume or nano-silica against sulfuric acid attack are explored. To accomplish this goal, in total, 108 high-strength concrete specimens were made with 9 different mix designs containing macro-polymeric and steel fibers at the volume fractions of 0.5, 0.75, and 1.0%, as well as the pozzolans of silica fume and nano-silica with the replacement levels of 10 and 2%, respectively. After placing the specimens inside a 5% sulfuric acid solution in the periods of 7, 21, and 63 days of immersion, the effect of adding the fibers and pozzolans on the compressive properties, ultrasonic pulse velocity (UPV), and weight loss of high-strength concrete was investigated and the respective results were compared with those of the reference specimens. The obtained results suggest the dependency of the resistance and durability loss of high-strength concrete against sulfuric acid attack to the properties of fibers as well as their fraction in concrete volume. Moreover, compared with using nano-silica, using silica fume in the fibrous concrete mix leads to more durable specimens against sulfuric acid attack. Finally, an optimum solution for the design parameters where the crushing load of high-strength fibrous concrete is maximized was found using response surface method (RSM).

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.281-286
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• 2003

This study presents the results of investigations with the object to determine the resistance to sulfuric acid for some kinds of cements containing 0%-70% of slag powder. The specimen is immersed 5% H$_2$SO$_4$ solution after the 28th days, is measured chemical analysis, XRD, SEM and etc after the immersed 35th days and is measured the erosion depth after the immersed 168th days. The results of experiment are founded out that alumina cement containing slag power was excellent at a point of view for the sulfuric acid resistance and the erosion depth was suitable to the evaluated method of the sulfuric acid resistance in the stead of the evaluated method of weight loss.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.719-722
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• 2004

Resins using recycled PET offer the possibility of a lower source cost of materials for making useful polymer concrete products. The purposed of this paper is to form a part of reducing the damage of sulfuric acid, through investigating recycled PET polymer concrete, . immersed at sulfuric acid solution for 84 days. Recycled PET PC is excellent chemical resistance, resulting in the role of unsaturated polyester resin which consists of polymer chain structure accomplishes bond of aggregates and filler strongly. Also, Recycled PET PC, used fly-ash as filler, is stronger resistance of sulfuric acid corrosion than $CaCO_3$, because it is composed of $SiO_2$ and very strong glassy crystal structure. Therefore, Recycled PET PC, used fly-ash as filler, is available under corrosion circumstances like sewer pipe or waste disposal plant.