3 Effect of reaction temperature on the formation of calcium borate using a saturated solution of calcium hydroxide ··· 16 Fig. the rate of formation of calcium borate using a saturated solution of calcium hydroxide ··· 21 Fig.
7 Effect of cooling temperature on the calcium borate formation using a saturated solution of calcium hydroxide ··· 22. 4 Effect of sulfuric acid on the recovery of calcium borate according to reaction time ··· 36 Fig. 5 Effect of sulfuric acid on the purity of calcium borate according to reaction time ··· 37 Fig.
General Introduction
Background
However, parts of the borates that precipitate in the country have been used in industry. Therefore, before drilling that is buried in the country runs out, we need to extract drilling elsewhere. In another study, it was put into the solid calcium hydroxide in the waste water and heated at 60℃ for 8 hours. 2005) stated that the hydrothermal treatment using Ca(OH)2 as a mineralizer was found to effectively convert boron in the aqueous media to calcium borate, Ca2B2O5·H2O.
In the optimal hydrothermal condition, more than 99% boron was recovered from the 500 ppm synthetic wastewater. In the last study, the initial pH was changed by adding sulfuric acid to the artificial boron wastewater to find the effect of the initial pH on the recovery of calcium borate. The optimal conditions for the experiment in the previous study were located and summarized in the following Table 2.
Objective
The initial pH was adjusted to 1.0 using sulfuric acid and the solution was heated to 80℃ after adding solid calcium hydroxide, the recovery of the resulting calcium borate [inyoite, CaB3O3(OH)5·4H2O] was about 96% (Yilmaz et al., 2012). Boron removal and recovery from concentrated wastewater using a microwave hydrothermal method, Journal of Hazardous Materials, 186, pp.
Optimum conditions for the calcium borate formation reaction of boron recovery from wastewater, KSWST Jour.
Introduction
Most previous studies have been conducted in a direction to remove borate precipitated in wastewater with boron because boron has been considered a target for removal, not recovery and reuse. Studies that solid calcium hydroxide is added to boron-containing wastewater from precipitation as calcium borates have been published several times in the country. 2005) said that solid calcium hydroxide and phosphoric acid were added to artificial wastewater and then heated at 130℃ for 14 hours. As a result, boron was recovered about 99% and precipitated from calcium borate (Ca2B2O5·H2O). 2011) explained that crushed oyster shells were added to wastewater instead of solid calcium hydroxide by heating the reaction at 130℃ for 10 minutes.
In another study, it was placed in solid calcium hydroxide in wastewater and heated at 60℃ for 8 hours. Tsai and Lo (2015) reported that boron was removed by boron precipitation in wastewater using submicron calcium hydroxide synthesized with calcium chloride and calcium nitrate. Boron recovery was 67.2% using commercially available calcium hydroxide in this study, this value was lower than using submicron calcium hydroxide.
That is, the recovery of calcium borate was higher when calcium hydroxide particle size was small (Tsai & Lo, 2015). In previous studies, this was considered the recovery of calcium borate, not the purity of calcium borate, because the solid calcium hydroxide was always added to wastewater to remove boron and they obtained the insoluble solid, calcium borate. 99 % of wastewater, but the purity of the calcium borate dropped significantly due to the residual solid calcium hydroxide, which was excessively added to increase the recovery of calcium borate.
In this study, we used a saturated solution of calcium hydroxide instead of the solid calcium hydroxide to find a way to increase the purity of calcium borate and optimal conditions while maintaining a high recovery of calcium borate.
Materials and Methods
- Effect of the state (saturated solution, solid) of the calcium
- Using a saturated solution of calcium hydroxide
- Using solid calcium hydroxide
- The optimum conditions for generating the calcium borate with
- Reaction temperature
- The amount of solid calcium hydroxide
- Reaction time
- Stirring speed
- Cooling temperature after the reaction
The solution was stirred at 250 rpm for 6 hours to dissolve as much calcium hydroxide as possible. While the filtrate was heated at 100℃ for 80 minutes (150 rpm), white solids formed during the reaction. After the reaction was completed, the solution was cooled until the temperature of the solution in the reaction vessel was 70 ℃, and the solid was filtered through 0.45 μm filter paper.
The solid was dried using a dryer heated to 105.5℃ for 12 hours after washing with ultrapure water. Boron concentration was measured by dissolving 0.1 g of the dried solid with 50 mL of 1 M nitric acid to calculate the purity of calcium borate. The recovery of calcium borate was calculated as follows by measuring the residual boron concentration of the filtrate (2).
In this experiment, solid calcium hydroxide was used instead of saturated calcium hydroxide solution. Then 2.57 g of solid calcium hydroxide was added to the solution and stirred for 6 hours (250 rpm). Boron artificial wastewater with undissolved solid calcium borate was heated at 100℃ for 80 minutes (150 rpm).
The following experiment was divided into five to derive the optimal conditions for calcium borate formation. After stirring each suspension, the undissolved solid calcium hydroxide was removed using a 0.45 m filter paper.μ.
Results and Discussion
- Effect of the state (saturated solution, solid) of the calcium
- Reaction temperature
- The amount of solid calcium hydroxide
- Reaction time
- Stirring speed
- Cooling temperature after the reaction
2, It was compared with the recovery and purity of calcium borate produced by each reaction with a saturated solution of calcium hydroxide and solid calcium borate. Effect of reaction temperature on the formation of calcium borate using a saturated solution of calcium hydroxide (B: 500 ppm, dose of solid calcium hydroxide: 2.57 g, reaction time: 80 min, speed of stirring: 150 rpm and cooling temperature: 70. The effect of the dose of solid calcium hydroxide on the formation of calcium borate using a saturated solution of calcium hydroxide (B: 500 ppm, reaction temperature: 100 , time reaction time: 80 min, stirring speed: 150 rpm ℃ and cooling temperature: 70.
When varying the amount of solid calcium hydroxide while fixing the amount of boric acid to produce calcium borate, there was a change in solution pH and recovery of calcium borate in Fig. That is, the greater the amount of solid calcium hydroxide, the recovery of calcium borate and the pH increased. According to the experimental results, calcium borate was produced when a certain amount of solid calcium hydroxide was added and the pH of the reaction solution was more than pH 12.
The recovery rate was 64% or more under the conditions, although the amount of solid calcium hydroxide increased, the recovery of calcium borate was kept constant. In this study, when the solid calcium hydroxide was added more than 1.71 g, the recovery of calcium borate was increased up to 13. Although the recovery of calcium borate was lower in 38% when the reaction time was 10 min.
The effect of stirring speed on the formation of calcium borate using a saturated solution of calcium hydroxide (B: 500 ppm, reaction temperature: .100 ℃, reaction time: 80 min, dosage of solid calcium hydroxide: 2.57 g and cooling temperature: 70. yield of calcium borate was almost constant at 71–77% despite varying the stirring speed from 0–400 rpm. Effect of cooling temperature on calcium borate formation using saturated calcium hydroxide solution (B: 500 ppm, reaction temperature: 100 °C, reaction time: 80 min, dosage of solid calcium hydroxide: ℃ 2.57 g and stirring speed: 150 rpm).
If heat is trapped in the reaction process of calcium hydroxide and boric acid, the mineralization process to produce calcium borate is interrupted.
Conclusions
But it was allowed to cool rapidly using an ice bath after the production of calcium borate to prevent remelting of the product. Use of pretreated oyster shells and waste oysters and microwave hydrothermal treatment to recover boron from concentrated wastewater, Bioresource Technology, 102, pp. Recovery of boron from high boron wastewater using modified submicron Ca(OH)2 particles, International Journal of Environmental Science and Technology, 12, p.
Effects of sulfuric acid on the synthesis of high-purity calcium borate in boron-containing brine.
Effects of sulfuric acid on the synthesis of highly pure
- Reaction temperature
- The presence of sulfuric acid
- The absence of sulfuric acid
- Reaction time
- Cooling temperature after the reaction
- Reaction temperature
- Reaction time
- Cooling temperature after the reaction
- Effect of sulfuric acid on the synthesis mechanism of calcium
At this time, we investigated the effect of the recovery and the purity of the resulting calcium borate according to the presence or absence of sulfuric acid. The recovery of calcium borate was calculated as follows by measuring the residual boron concentration of the filtrate (1). In previous studies, the solid calcium hydroxide was added in excess to improve the recovery of calcium borate.
The calcium borate [Ca2B2O5∙H2O] peak was confirmed regardless of its presence or absence. In the absence of sulfuric acid, the only calcium borate peak was visible. When changing the reaction temperature to 50-105℃, the results of calcium borate recovery and purity were compared between the presence and absence of sulfuric acid in Fig.
Regardless of the presence and absence of sulfuric acid, the higher the reaction temperature, the recovery of calcium borate was significantly increased. On the other hand, the purity of calcium borate showed a significant difference in accordance with the presence or absence of sulfuric acid at each temperature. In the absence of sulfuric acid, the purity of calcium borate was almost constant regardless of the reaction temperature.
While the reaction time was varied, it showed the results of investigating the effect of the recovery and purity of calcium borate in accordance with the presence of sulfuric acid in fig. The purity of calcium borate in accordance with the reaction time showed different trends, each other. 5, When sulfuric acid was not added, the purity of calcium borate was constant at 85-95% regardless of the reaction time.
But the reaction time should be kept for at least 60 minutes to increase the recovery and purity of calcium borate when sulfuric acid is added. When sulfuric acid was not added, the recovery of calcium borate was essentially constant as a function of cooling temperature. 6 Effect of sulfuric acid on the recovery of calcium borate according to cooling temperature after heating.
