• Journal of the Korean Ceramic Society
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• v.24 no.4
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• pp.343-348
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• 1987

The effects of salts such as aluminum sulfate as inorganic salt(2-4%), and sodium salts of citrate, tartrate, succinate, potassium tartrate and gelatin as organic salts(0.1%) on the formation of ${\alpha}$-calcium sulfate hemihydrate from by-product gypsum of phosphoric acid process under hydrothermal condition at 123$^{\circ}C$ and 133$^{\circ}C$ were investigated. Aluminum sulfate solution exhibited the catalystic effected on the crystallization of ${\alpha}$-calcium sulfate hemihydrate of which was assumed in the prismatic form, and organic salts solution exhibited little effect on the catalystic action to the crystallization, than inorganic salts. In the acidic solution with sulfuric acid(pH=2), needle like crystal of calcium sulfate hemihydrate was obtained. Hydrothermal process with aluminum sulfate solution also showed certain amounts of impurity removal such as phosphorus penataoxide from calcium sulfate hemihydrate.

• Journal of Korean Society of Water and Wastewater
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• v.33 no.6
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• pp.413-420
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• 2019

Pretreatment system of desalination process using seawater reverse osmosis(SWRO) membrane is the most critical step in order to prevent membrane fouling. One of the methods is coagulation-UF membrane process. Coagulation-UF membrane systems have been shown to be very efficient in removing turbidity and non-soluble and colloidal organics contained in the source water for SWRO pretreatment. Ferric salt coagulants are commonly applied in coagulation-UF process for pretreatment of SWRO process. But aluminum salts have not been applied in coagulation-UF pretreatment of SWRO process due to the SWRO membrane fouling by residual aluminum. This study was carried out to see the effect of residual matal salt on SWRO membrane followed by coagulation-UF pretreatment process. Experimental results showed that increased residual aluminum salts by coagulation-UF pretreatment process by using alum lead to the decreased SWRO membrane salt rejection and flux. As the salt rejection and flux of SWRO membrane decreased, the concentration of silica and residual aluminum decreased. However, when adjusting coagulation pH for coagulation-UF pretreatment process, the residual aluminum salt concentration was decreased and SWRO membrane flux was increased.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.3
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• pp.331-336
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• 2004

The correlation between polymeric aluminum species of coagulant and its coagulation efficiency was investigated using several commercial polymeric Al(III) inorganic coagulants (Poly Aluminum Hydroxy Chloro Sulfate 2020 (PAHCS2020), Poly Aluminum Hydroxy Chloro Sulfate 2500 (PAHCS2500) which was introduced in Korean water treatment plants. The poly aluminum chloride (PAC), Poly Aluminum Hydroxide Chloride Silicate (PACS)) and the aluminum salts ($AlCl_3$, Alum ($Al_2(SO_4)_3$)) were used for the purpose of comparison. The comparison of the coagulation efficiency of each coagulant was made by turbidity removal through the standard jar testing procedure and the determination of the hydrolytic Al(III) species was made by the ferron method which can differentiate the monomeric aluminum species from the polymeric aluminum species. Overall, PAHCS2020 and PAHCS2500 showed the better performance in turbidity removal than the aluminum salts. The performance of coagulation was even better without adjustment of pH during the coagulation experiment. The positive correlation between polymeric aluminum species of coagulant and coagulation efficiency was found.

• Journal of the Korean Ceramic Society
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• v.40 no.8
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• pp.720-724
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• 2003

Aluminum nitride (AlN) powders were synthesized by using a mixture of an aluminum nitrate or sulfate salt and carbon (mole ratio of $Al^{3+}$ to carbon=L : 30). The AlN was obtained by calcining the mixture under a flow of nitrogen in the temperature range 1100-1$600^{\circ}C$ and then burning out the residual carbon. The process of conversion of the salt to AlN was monitored by XRD and $^{27}$ Al magic-angle spinning (MAS) NMR spectroscopy. The salt decomposed to ${\gamma}$-alumina and then converted to AlN without phase transition from ${\gamma}$-to-$\alpha$-alumina. $^{27}$ Al MAS NMR spectroscopy shows that the formation of AlN commenced at 110$0^{\circ}C$. AlN powders obtained from the sulfate salt were superior to those from the nitrate salt in terms of homogeneity and crystallinity. A very small amount of AlN whiskers was obtained by calcining a mixture of an aluminum sulfate salt and carbon at 115$0^{\circ}C$ for 40 h, and the growth of the whiskers is well explained by the particle-to-particle self-assembly mechanism.

• Nutrition Research and Practice
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• v.7 no.6
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• pp.466-474
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• 2013

Despite the reports on safety concerns regarding the relationship between aluminum salts and neurological and bone disease, many countries continue to use aluminum as phosphate binders among patients with renal failure. In search for a diet supplement that could reduce aluminum toxicity related to renal failure, we carried out this prospective animal study in which the fenugreek seeds were assessed for their effects on rats nephrotoxicity induced by aluminum chloride ($AlCl_3$). Oral $AlCl_3$ administration during 5 months (500 mg/kg bw i.g for one month then 1600 ppm via drinking water) led to plasma biochemical changes, an inhibition of alkaline phosphatase (ALP), a decrease of total antioxidant status (TAS), and an induction of lipid peroxidation (LPO) in the blood and brain, in addition to kidney atrophy and morphological alterations at the level of Bowman's capsule, the glomerulus and different sorts of tubules, reminiscent of some known kidney disease. The treatment with the whole fenugreek seed powder (FSP) (5% in the diet) during the last 2 months showed its effectiveness in restoring normal plasma values of urea, creatinine, ALP and glucose, as well as re-increasing the TAS, inhibiting LPO and alleviating histopathological changes in the injured kidneys. This study highlights the induced nephrotoxicicity, as well as the related toxicity in the brain and bone, by chronic oral ingestion of the aluminum salts. However, the maintenance of a diet supplemented with fenugreek seeds could offer protection for the kidney, bone and brain, at the same time.

• Proceedings of the Korean Sanitation Conference
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• 2004.11a
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• pp.54-65
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• 2004

Use of aluminum salts as coagulants In water treatment may lead to increased concentrations of aluminum in finished water. Aluminum is a suspected causative agent of neurological disorders such as Alzheimer's disease. The objective of this study was to examine variation and minimizing in residual aluminum concentration during water treatment process. The aluminum sources at Bokjeong Water Plant were present naturally aluminum in the raw water and derived due to use of PACS as a coagulant. Much of the raw water total aluminum were in particulate and suspended aluminum. In this study was compared the optimize condition to minimize the concentration of residual aluminum using Jar-test with the various coagulants such as alum, PAC, PACS. The results indicated that PACS was more effective than alum, PAC and insufficient or excessive alum, PAC, PACS addition led to increase residual aluminum. Adjustment raw water pH $6.5\~7.0$ before coagulation using PACS was capable of minimizing total and dissolved aluminum. Thus it is important that the optimal dosage of coagulant and the optimal pH adjustment before coagulation can decided to minimize the concentration of residual aluminum in treated water.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.34 no.1
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• pp.85-97
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• 2024

Objectives: This study was intended to investigate the revision status of the occupational exposure standards for aluminum at home and abroad; to investigate worker exposure at domestic aluminum manufacturing and handling workplaces; to conduct social and economic evaluation for the revision of domestic aluminum exposure limits. Methods: We investigated the current status of occupational exposure limits for aluminum at home and abroad, and analyzed supporting data. An exposure survey was conducted targeting domestic aluminum manufacturing and handling workplaces. Based on these, revised aluminum occupational exposure limits were proposed. Results: The major aluminum exposure limits at home and abroad show a notable difference. The toxicity of aluminum, which was revealed through animal experiments and epidemiological investigations. The average concentration of aluminum in the air at 12 workplaces was 0.016 mg/m³, and the maximum was 0.0776 mg/m³. When total dust and respiratory dust were measured side by side and simultaneously for the same process, 12.1% of the total mass concentration of aluminum dust was respiratory dust. As a result of measuring and comparing the size distribution of dust with an optical particle counter in real time, 48.1% of the total dust in the form of welding fume and pyro-powder was respiratory dust. Based on the literature review and workplace survey, three proposals for changing the aluminum exposure limit were proposed. Proposal (1): For all types, 10 mg/m³ is unified as the exposure limit except for soluble salts and alkyls. Proposal (2): 1(R) mg/m³ as the exposure limit for all forms except soluble salts and alkyl. Proposal (3): 1(R) mg/m³ for pyro-powder and welding fume, and 10 mg/m³ for metal dust, aluminum oxide, and insoluble compounds as exposure standards. A pyro-powder was defined as dry aluminum powder of 200 mesh size (74 ㎛) or smaller (larger size classified as metal dust). Reason for setting: In the workplace survey, the ratio of respiratory dust to total dust was analyzed to be about 1:10, so it was judged that the domestic standard and the ACGIH standard were compatible. Conclusions: In all scenarios according to the revision of the exposure standard, the B/C ratio was greater than 1 or only benefits existed, so it was evaluated as sufficiently reasonable as a result of the socio-economic evaluation.

• Journal of the Korean Ceramic Society
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• v.26 no.1
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• pp.132-138
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• 1989

High purity(99.99%) spherical particles of hydrated Basic Aluminum Salts(BAS) were prepared by a homogeneous precipitation process utilizing the urea decomposition reaction and characterized by XRD, SEM, TG-DTA, IR and PSA methods. Amorphous hydrated BAS was precipitated in the range of pH 4~6. The molar ratio [Al3+]/[SO42-] for the precipitate particles was about 3.7. With increasing the concentration of aluminum sulfate the precipitation of the hydrated BAS occurred slowly and the precipitate particles with a narrow size distribution were fine(1-2${\mu}{\textrm}{m}$ in diameter). At temperatures in the range 400$^{\circ}$to 95$0^{\circ}C$, desulfurization and dehydroxylization resulted in weight loss with 22%. When the precipitate particles were thermally treated, the crystlline ${\gamma}$-Al2O3 was identifited by XRD at 50$0^{\circ}C$ and ${\gamma}$-Al2O3 particles were transformed into $\alpha$-Al2O3 at 100$0^{\circ}C$. A vermicular network was produced by calcining at 125$0^{\circ}C$ for 30min.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.3
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• pp.249-255
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• 2020

Objective: The purpose of this study was to provide technical information about the management of occupational exposure limits(OELs) for substances with completely revised ACGIH TLVs. Methods: The history of ACGIH TLVs for aluminum compounds, the reason for the complete revision of the related ACGIH TLV in 2008, and OELs for them in respective countries were reviewed. In addition, the results of a 2019 work environment assessment for aluminum compounds in Korea were reviewed. Results: In 1979, the ACGIH set up the TLVs for aluminum compounds considering types of compounds such as metal dust, pyro powders, welding fumes, soluble salts, alkyls, and aluminum oxide. However, in 2008 the ACGIH withdrew the TLVs for all types of aluminum and its compounds and adopted new TLVs for aluminum metal and insoluble compounds. This can cause confusion in many countries in the management of exposure to aluminum compounds because they adopt or refer to the ACGIH TLVs. Conclusion: Although Korea is setting occupational exposure limits by referring to the ACGIH's TLVs, it is necessary to sufficiently review whether it is necessary to accept the TLVs as they are if a TLV is completely changed, like took place with the revision of aluminum compounds in 2008.

• Resources Recycling
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• v.26 no.5
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• pp.77-84
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• 2017

White and black dross are resulted from the recycling of aluminum. There are no established processes to recover valuable materials from black dross. Hydrometallurgical processes seem to be suitable for the treatment of aluminum dross. The salts in the black dross are recovered by dissolving with water. The residues are treated by either alkaline or acid leaching. Although the leaching rate of alumina by NaOH is lower than that by acid, its intermediates are more suitable to the production of alumina-based materials. The future direction for the treatment and recovery of valuable materials from aluminum dross is discussed.