• Journal of Life Science
• /
• v.11 no.3
• /
• pp.197-202
• /
• 2001

This study was conducted to investigate the effect of simulated acid solution(SAS) on acid buffering capacity, chlorophyll content and butrient leacking in 4 herb species(Petunia hybrida Vilm, Gomphrena globosa L. Celosia cristat L. Salvia officinallis L) . The acid buffering capacity in the leves was increased in the treatment of pH 3.0 in Celosia L., whereas it was increased at pH 4.0 in Petunia Petunia hybrida Vilm. and Gomprean globosa L.. But, the acid buffering capacity of the leaves did not work at ph 2.0 treatment in 4 herb species. With decreasing pH level, the chlorophyll content of Petunia hybrida Vilm. and Gomphrena globosa L. Was markedly decreased than that of Gelosia cristata L. and Savia officinalis L. As the pH levels decreased from 5.6 to 2.0 the nutrient leaching from leaves was significantly increased in 4 herb species. In pH 4.0 and 5.6, the concentrations of nutrient leaching from leaves were higher in Perunia hybrida Vilm. and Gomphrean globosa L. than Gelosia cristata L. and Salvia officinalis L., Based on the results, there was a great differences in response to SAS among the 4 herb species. Im general, Gelosia cristata L. and Salvia officinalis L. represented a higher tolerance to SAS Petunia hybrida Vilm, and Gomphrena globosa L..

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.10 no.2
• /
• pp.84-88
• /
• 1990

This experiment was conducted to evaluate the effect of cutting frequency and nitrogen fertilization on $(NO_3$-N leaching losses under 12 years mixture permanent meadow, The results of this study were summarized as follows: 1. There was no difference in the $(NO_3$-N content of soil water within 1 m soil depth during the whole experimental period. It means that the content of $(NO_3$-N leaching losses was not influenced by botanical composition, cutting frequency and nitrogen fertilization in this experiment. 2. The level of $(NO_3$-N content during the whole experimental period was not in excess of 0.5 ppm level.

• Journal of the Korean Chemical Society
• /
• v.11 no.1
• /
• pp.28-32
• /
• 1967

The direct acid leaching of domestic Marmatite concentrate at elevated temperatures and pressures was investigated. Almost 100 percent of zinc was extracted from the concentrate liberating free sulfur in 4 hours at $100^{\circ}C$ when the oxygen partial pressure was 5 atm. in sulfuric acid solution. By applying the Arrhenius equation to leach reaction in the range of $60^{circ}$ to $100^{\circ}C$ at the same oxygen partial pressure, 15.7 kcal per mole of activation energy was calculated. At the initial stage of leaching, the rate of reaction increased linearly by increasing temperature and pressure. The concentration of sulfuric acid gave minor effect to leaching velocity in the range of 5 to 20 percent. The particle size should be under 270 mesh for 100 percent extraction of zinc.

• Proceedings of the Korean Institute of Resources Recycling Conference
• /
• 2005.10a
• /
• pp.304-307
• /
• 2005

Printed circuit boards (PCBs) of the printer are composed of various organic and inorganic compounds as well as metals and alloys. This study was conducted to recover valuable metals from used PCBS by physical separation and leaching. The PCBs was crushed, sieved, classified by zig zag classifier and magnetic constituents were removed by the magnetic separation. The non-magnetic constituents of sizes between 1.2 and 0.6 mm especially containing high quantity of Cu (e.g. 83% on metal base and 31% on total base) were used for the leaching experiment. The effect of the nature and concentration of acids and reaction temperature were investigated. The Cu leaching rate to 98.5% in 2M nitric acid, pulp density 100g/L, $90^{\circ}C$, 300rpm, 1hr leaching.

• Economic and Environmental Geology
• /
• v.32 no.1
• /
• pp.53-62
• /
• 1999

The possibility of heavy metal pollution by contaminated roadside soils was studied under controlled conditions. The soil samples from roadside and those from a retention pond consisting of settling particles were characterized by the XRD analyses and the sequential extraction experiments. Characterization by sequential extraction, for roadside soil indicates elevate total concentrations of heavy metals. The leaching behavior of the samples under different pH and time conditions were also studied. Differences between both types of samples result mainly from the buffering effect of carbonates, present in roadside soils and lacking from settling particles. Acid leaching of the settling particles is equivalent to the sum of FI+FII+FIII, while the amounts leached from roadside soil are lower probably from kinetic reasons. The buffering effects of carbonates were found to greatly delay the onset of the leaching reactions and the extent of dissolution in most metals except for Ca and Mn. The study of leaching kinetics at pH of 6.5 and 5 showed that Cd and Zn reached the maximum possible concentration within 3 days, while Pb did not show any sign of dissolution at both ph values. The absolute amounts of dissolved Cd and Zn increased by 7 to 9 times by decreasing the pH from 6.5 to 5, indicating slightly acidified rain may result in significant metal dissolution. As deduced from both sequential extraction and leaching experiments, the relative mobility of heavy metals is found to be : Mn=Cd>Zn>>Pb>Fe, in spite of large differences in heavy metal contents and localizations.

• Journal of Powder Materials
• /
• v.30 no.3
• /
• pp.233-241
• /
• 2023

In this study, we evaluated the effects of acid leaching on the properties of Cr powder synthesized using self-propagating high-temperature synthesis (SHS). Cr powder was synthesized from a mixture of Cr2O3 and magnesium (Mg) powders using the SHS Process, and the byproducts after the reaction were removed using acid leaching. The properties of the recovered Cr powder were analyzed via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), particle size analysis (PSA), and oxygen content analysis. The results show that perfect selective leaching of Cr is challenging because of various factors such as incomplete reaction, reaction kinetics, the presence of impurities, and incompatibility between the acid and metal mixture. Therefore, this study provides essential information on the properties under acidic conditions during the production of high-quality Cr powder using a self-propagating high-temperature synthesis method.

• Resources Recycling
• /
• v.22 no.3
• /
• pp.43-49
• /
• 2013

A study on the recovery of lithium and leaching behavior of NCM powder by hydrogen reduction for NCM system Li-ion battery scraps was investigated. The reductive rate was about 93% at $800^{\circ}C$ by hydrogen treatment. The lithium carbonate with 99% purity was manufactured by using $CO_2$ gas and washing method with water for NCM powder after hydrogen reduction. As a result of comparing the powders before and after the hydrogen reduction treatment for acid leaching behavior we obtained 32% enhanced leaching rate of cobalt, 45% enhanced leaching rate of nickel and the 90% leaching effect for manganese by hydrogen reduction at 2M $H_2SO_4$ concentration condition.

• Nuclear Engineering and Technology
• /
• v.55 no.2
• /
• pp.523-529
• /
• 2023

Cemented uranium tailings backfill created from alkali-activated slag (CUTB) is an effective method of disposing of uranium tailings. Using some environmental functional minerals with ion exchange, adsorption, and solidification abilities as backfill modified materials may improve the leaching resistance of the CUTB. Natural zeolite, which has good ion exchange and adsorption characteristics, is selected as the backfill modified material, and it is added to the backfill materials with cementitious material proportions of 4%, 8%, 12%, and 16% to prepare CUTB mixtures with environmental functional minerals. After the addition of natural zeolite, the uniaxial compressive strength (UCS) of the CUTB decreases, but the leaching resistance of the CUTB increases. When the natural zeolite content is 12%, the UCS reaches the minimum value of 8.95 MPa, and the concentration of uranium in the leaching solution is 0.28-8.07 mg/L, the leaching rate R₄₂ is 9.61×10^-7 cm/d, and cumulative leaching fraction P₄₂ is 8.53×10^-4 cm, which shows that the alkali-activated slag cementitious material has a good curing effect on the CUTB, and the addition of environmental functional minerals helps to further improve the leaching resistance of the CUTB, but it reduces the UCS to an extent.

• Journal of Korea Soil Environment Society
• /
• v.3 no.3
• /
• pp.21-31
• /
• 1998

A study on the acid leaching and precipitation has been conducted to remove arsenic from the closed-mine tailings. HCI and H$_2$SO$_4$were used as the leach liquor of arsenic and the tailing obtained from the Da-Duck Mine, which was already closed several decades ago, was also used as the source of arsenic. The effect of the concentration of acid, leaching time and the slurry density on the leaching efficiency of arsenic has been examined. In addition, pH controls and the addition of sodium sulfide were also attempted to remove the arsenic compound as the precipitation from the leachate. After 1 hr leaching by HCI, 40 to 86% of arsenic was leached out depending on the concentration of acid or the slurry density while 47 to 77% of it was leached out by $H_2$$SO_4$. The leaching of arsenic by both acids was almost accomplished within 10 min. and after that only a slight increase in leaching efficiency was observed with leaching time. When the leach liquor was used repeatedly for the leaching of arsenic, the concentration of arsenic in the leach liquor was found to increase continuously although the leaching efficiency was diminished. As far as the precipitation of arsenic in the leachate was concerned, more than 99% of arsenic could be precipitated through the addition of sodium sulfide as the precipitator while the pH controls resulted in the precipitation of up to 84%.

• Asian Journal of Turfgrass Science
• /
• v.20 no.1
• /
• pp.47-55
• /
• 2006

Golf course community has always been concerned about water quality regarding to pesticide and fertilizer managements. This study conducted to investigate sorption and leaching behavior of common pesticides used for golf course in granular activated carbon I (GAC 1), granular activated carbon II(GAC II), and charcoal. We used batch study to investigate the influence of concentrations of Smithion and Folicur and particle sizes of GAC I, GAC II, and charcoal on sorption. Also, column study was used to investigate the leaching effect of Smithion in GAC I and charcoal. We found that sorption of Smithion and Folicur were higher in less $45{\mu}m$ of particle size for GAC I, GAC II, and charcoal compared to $1.7{\sim}2.0mm$ size, and the sorption of Smithion and Folicur in less $45{\mu}m$ of particle size ranged from 90 to 99%. In the column study, there was no difference in leaching effect between GAC I and charcoal. Overall, we found that charcoal might offer a cost effective adsorbent as a pesticides in leachate.