• Resources Recycling
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• v.26 no.3
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• pp.79-91
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• 2017

The core of Hydrogen Fuel Cell Vehicles (FCV) is polymer solid fuel cell (PEFC), and the core material that generates electrochemical electricity in the cell is platinum catalyst. Platinum is localized in South Africa and Russia, and the world production of Pt is about 178 tons per year, which is expensive and recycled. At present, the amount of Pt used in PEFC is $0.2{\sim}0.1mg/cm^2$. In order to reduce the price of the battery and increase the FCV supply, the target is to reduce the amount of Pt used to $0.05{\sim}0.03mg/cm^2$. $Pt-Pd/Al_2O_3$, Pt/C, Pt/GCB, Pt/Au/C, PtCo/C, PtPd/C, etc. by using polyol method using nano Pt, improved Cu-UPD/Pt substitution method and nano-capsule method, Have been researched and developed, and there have been reported techniques for improving the activity of Pt catalysts and stabilizing them. This paper investigates the production technology of nano-Pt and nano-Pt catalysts, recycling of spent Pt catalysts and application trends of Pt catalysts.

• Resources Recycling
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• v.31 no.4
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• pp.40-48
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• 2022

In waste lithium iron phosphate (LFP) batteries, the cathode material contains approximately 4% lithium. Recycling the constituent elements of batteries is important for resource circulation and for mitigating the environmental pollution. Li contained in the waste LFP cathode powder was selectively leached using persulfate-based oxidizing agents, such as sodium persulfate, potassium persulfate, and ammonium persulfate. Leaching efficiency and waste LFP powder properties were compared and analyzed. Pulp density was used as a variable during leaching, which was performed for 3 h under each condition. The leaching efficiency was calculated using the inductively coupled plasma (ICP) analysis of the leachate. All types of persulfate-based oxidizing agents used in this study showed a Li leaching efficiency over 92%. In particular, when leaching was performed using (NH₄)₂S₂O₈, the highest Li leaching percentage of 93.3% was observed, under the conditions of 50 g/L pulp density and an oxidizing agent concentration of 1.1 molar ratio.

• Resources Recycling
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• v.30 no.1
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• pp.44-52
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• 2021

This study investigated the effect of the type of alkaline precipitant used on the synthesis of lithium hydroxide by examining the behavior of lithium hydroxide produced using lithium sulfate recovered from a waste lithium secondary battery as a raw material. The double-replacement reaction (DRR) process was used to remove the impurities contained in the lithium salt precursor of lithium sulfate and to improve the efficiency of the synthesis of lithium hydroxide. The experiment was conducted by control the molar ratio of the precursor ([Li]/[OH]), the reaction temperature, and the composition of the alkaline precipitant (KOH, Ca(OH)2, Ba(OH)2) used for the production of highly-crystalline lithium hydroxide. A secondary solid-liquid separation was performed following the reaction to remove the impurities generated, and the purified aqueous solution of lithium hydroxide was evaporated to remove the moisture and obtain the product as a powder. The crystallinity and synthesis behavior of the product were examined.

• Resources Recycling
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• v.28 no.4
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• pp.30-36
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• 2019

In this study, Li powder was recovered from the by-product of LNO ($Li_2NiO_2$) process, which is the positive electrode active material of waste lithium ion battery, through the $CO_2$ thermal reaction process. In the process of recovering Li powder, the $CO_2$ injection amount is 300 cc/min. The $Li_2NiO_2$ award was phase-separated into the $Li_2CO_3$ phase and the NiO phase by holding at $600^{\circ}C$ for 1 min. After this, the collected sample:distilled water = 1:50 weight ratio, and after leaching, the solution was subjected to vacuum filtration to recover $Li_2CO_3$ from the solution, and the NiO powder was recovered. In order to increase the purity of Ni, it was maintained in $H_2$ atmosphere for 3 hours to reduce NiO to Ni. Through the above-mentioned steps, the purity of Li was 2290 ppm and the recovery was 92.74% from the solution, and Ni was finally produced 90.1% purity, 92.6% recovery.

• Clean Technology
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• v.27 no.1
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• pp.33-38
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• 2021

Demand for lithium-based secondary batteries is greatly increasing with the explosive growth of related industries, such as mobile devices and electric vehicles. In Korea, there are several top-rated global lithium-ion battery manufacturers accounting for 40% of the global secondary battery business. Most discarded lithium secondary batteries are recycled as scrap to recover valuable metals, such as Nickel and Cobalt, but residual wastes are disposed of according to the residual lithium-ion concentration. Furthermore, there has not been an attempt on the possibility of water discharge system contamination due to the concentration of lithium ions, and the effluent water quality standards of public sewage treatment facilities are becoming stricter year after year. In this study, the as-received waste water generated from the cathode electrode coating process in the manufacturing of high-nickel-based NCM cathode material used for high-performance and long-term purposes was analyzed. We suggested a facile recycling process chart for waste water treatment. We revealed a correlation between lithium-ion concentration and pH effect according to the proposed waste water of each recycling process through analyzing standard water quality tests and daphnia ecological toxicity. We proposed a realistic waste water treatment plan for lithium electrode manufacturing plants via comparison with other industries' ecotoxicology.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.1
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• pp.19-33
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• 2023

Objectives: The purpose of this study is to systematically identify situations where exposure levels are expected to be high by structuring domestic lead measurement data according to exposure processes and activities. Methods: Occupational exposure data on lead was collected from the results of the Evaluation of Reliability of Working Environment Measurement conducted by the government from 2019 to 2020. Lead exposure characteristics were analyzed by PROC (process category) and activity. The Risk Characterization Ratios (RCRs) of five PROCs according to ventilation type and lead content were evaluated using the MEASE (Metal's EASE) model. Results: The exposure data on lead (n=250) was classified into 12 PROCs and 12 activities, with an average concentration of 0.040 mg/m³ and about 14% exceeding the occupational exposure limit of 0.05 mg/m³. Processes with high exposure levels were PROC 7 (industrial spraying), 23 (open processing and transfer operations of molten metal), 24 (mechanical treatment), 25 (welding), and 26 (handling of powder containing lead). The results of evaluating RCR for the five PROCs were greater than 1 or close to 1 even if local exhaust ventilation was used. Conclusions: There is a possibility that the concentration of exposure is high in the casting and tapping of molten metal containing lead, mechanical treatment such as fracturing and abrasion, handling of powder, spraying, battery manufacturing, and waste battery recycling processes. It is necessary to implement chemical management policies for workplaces with such processes.

• Applied Chemistry for Engineering
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• v.35 no.1
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• pp.37-41
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• 2024

The coconut shell, a by-product of popular tropical fruit, is a promising material due to its interesting properties. The preparation of the composite consisted of conducting polymer and coconut shell using a simple wet method, and subsequent carbonization produced a carbonized material under a controlled carbonization cycle. In addition, its electrochemical performance as an anode in lithium-ion batteries was also investigated. The appearance of the obtained materials was observed with a scanning electron microscope. The internal structure of the carbon derived from the coconut shell under a controlled heating profile was analyzed using a Raman spectroscope. A simple electrical measurement based on the ohmic relationship showed that the carbonized product has a significant electrical conductivity. The application of the carbonized product as anode in a lithium-ion battery was tested using half-cell charge/discharge experiments. This article provides important information for future research regarding the recycling of fruit shells and food waste.

• Clean Technology
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• v.23 no.3
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• pp.248-255
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• 2017

In dismantling factories for recycling, it is important to input actual working data to a personal computer (PC) in order to monitor the work results and related recycling rate of the inputs. This should be performed with a keyboard, a mouse, or other devices. But when a worker is working in the factory, it could be bothersome or time consuming to go to the PC. Especially, workers who works at dismantling factories have a generally low education level are scared to use a PC, which could be used as a pretext for not using the PC. In some cases, data input is performed by a worker after the day's job. In this case, it could take additional time, the worker can make more mistakes, and the data could be unreliable. In this study, we developed a man-machine interface (MMI) device using a safety helmet. A joystick-like device, pushbuttons, and a radio frequency (RF) device for wireless communication is equipped in a safety helmet. This MMI device has functions similar to a PC mouse, and it has a long communication distance. RF is used because it consumes less battery power than Bluetooth. With this MMI device, workers need not go to a PC to input data or to control the PC, and they can control the PC from a long distance. The efficiency of PCs in a factory could be increased by using the developed MMI system, and workers at the dismantling factories could have less reluctance in using the PC.

• Resources Recycling
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• v.17 no.5
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• pp.44-51
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• 2008

The removal of minor elements such as Na, Ca and Fe has been performed from domestic aluminum hydroxide of 99.7% purity with organic acids. Oxalic and citric acid were used as the leaching agent, respectively and aluminum hydroxides of different particle size were also employed for the purification with organic acid leaching. Fine grinding of aluminum hydroxide has been tested using ball mills and leaching characteristics of each element have also been examined in terms of leaching parameters such as temperature, acid concentration, and solid density. As a result, it was found that oxalic acid showed higher leaching efficiency than citric acid in the concentration range of 0.1 to 1.0 mole/l and leaching amount of each element was also increased with the acid concentration and reaction temperature. It was observed that about 45% of Na was leached out during ball milling process which implied that the majority of Na contained in aluminum hydroxide was water soluble compound.

• Resources Recycling
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• v.17 no.4
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• pp.30-36
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• 2008

The preparation of porous lightweight materials as well as the measurement of physical properties has been performed by using SSA(sewage sludge ash) as the raw material. For this aim, two types of lightweight filler, that is, perlite and silica sphere were employed respectively and bentonite was also used as an inorganic binder. The properties of lightweight specimen calcined at 1,000 were measured in terms of density, compressive strength, thermal conductivity and sound absorption to examine the effect of material composition as well as the preparation condition on the properties of lightweight material. As a result, the density of specimen prepared with perlite was ranged from 1.23 to $1.37g/cm^3$ and the compressive strength was ranged from 242.3 to $370.5kg/cm^2$. In case of specimen prepared with silica sphere, it was found that the compressive strength was less than $100kg/cm^2$ even though density was lower than that of specimen with perlite. As far as the thermal conductivity of specimen was concerned, it was ranged from 0.3 to $0.5W/m^{\circ}K$ depending on material composition so that the insulation effect was superior to conventional concrete.