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( Md Ishtiaq Hossain Khan ),( Masud Rana ),( Theoneste Nshizirungu ),( Jeong Hun Park ) 한국폐기물자원순환학회 2022 ISSE 초록집 Vol.2022 No.-
Many valuable metals may be found in waste Ni-Cd batteries. The leaching of valuable metals from waste Ni-Cd batteries has attracted tremendous attention in recent years. In spite of this, it remains difficult to develop a sustainable and efficient method. The purpose of this study was to investigate an efficient, convenient, and innovative way to recycle valuable metals from waste Ni-Cd batteries. Heavy metals from Ni-Cd batteries were leached in subcritical water using ferric chloride hexahydrate (FeCl<sub>3</sub>.6H<sub>2</sub>O). By releasing HCl in subcritical water, ferric chloride hexahydrate (FeCl<sub>3</sub>.6H<sub>2</sub>O) accelerates metals' leaching performance. Ni, Cd, and Co leaching efficiencies were also extensively studied using reaction parameters, such as temperature, time, solid-to-liquid ratio, and Ni-Cd powder-to-FeCl<sub>3</sub>.6H<sub>2</sub>O mass ratio. FT-IR, XRD, SEM-EDS, and XPS analyses were carried out on solid residues obtained after subcritical water leaching experiments. The leachate was analyzed by ICP-OES. In the optimized conditions, Ni, Cd, and Co leached with almost (93, 95, and 100) % efficiency; at 300°C, 120 minutes, 15g/L solids/liquids ratio, and 1:3 Ni-Cd-to-FeCl<sub>3</sub>.6H<sub>2</sub>O mass ratios. For the recovery of valuable metals from waste Ni-Cd batteries, the subcritical water leaching has been found to be efficient, environmentally friendly, and sustainable method.
Hossain, Shahdat,Rahaman, Asiqur,Nahar, Taslima,Basunia, Mafroz Ahmed,Mowsumi, Ferdousi Rahman,Uddin, Borhan,Shahriar, Masum,Mahmud, Ishtiaq 경희한의학연구센터 2012 Oriental Pharmacy and Experimental Medicine Vol.12 No.1
We investigated the effect of Syzygium cumini (L.) Skeels seed extract on the oxidative stress of brain cortical tissues of alcohol-treated rats. The in vitro antioxidative effect of methnolic S. cumini seed extract was initially compared with those of the buytylated hydroxyl toluene (BHT) and Vitamin C, by determining their DPPH-free radical scavenging activity. The S. cumini seed extract exhibited stronger free radical scavenging activity than those of the BHT and Vitamin C. Cortex homogenates were then directly incubated with 15% ethanol and/or Fenton's reagent ($H_2O_2+Fe_2SO_4$) to induce in vitro oxidative stress in the absence or presence of S. cumini seed extract. The S. cumini seed extract significantly reduced the levels of lipid peroxide (LPO) in the cortical homogenates. Twenty four rats were then divided into four groups: Control, S. cumini seed extract (SE)-administered, 15% ethanol-fed (EtOH) and EtOH+SE rats. The oral administration of the extract (400 mg/kg BW.day) for 8 weeks significantly (P<0.05) decreased the levels of LPO in the cortex of the EtOH+SE rats, suggesting that S. cumini seed not only scavenged the DPPH-free radicals and obstructed the ethanol/Fenton's reagents-induced in vitro oxidative stress of the cortical tissues but also reduced their in vivo formation. These results suggest that S. cumini seed could be used as a potential antioxidant therapy for alcoholics.
( Theoneste Nshizirungu ),( Masud Rana ),( Md Ishtiaq Hossain Khan ),( Young Tae Jo ),( Jeong-hun Park ) 한국폐기물자원순환학회 2022 ISSE 초록집 Vol.2022 No.-
Inadequate and inappropriate recycling technologies for e-waste have led to many environmental and economic problems, including the loss of strategic metals from spent cathode materials such as LiCoO<sub>2</sub>, high energy consumption, and the generation of hazardous materials. In this study, we proposed a novel and environmentally benign process for leaching, separating, and recovering strategic metals such as lithium (Li) and cobalt (Co) from spent lithium-ion batteries (LIBs) over hydrothermal reaction conditions assisted by dilute formic acid (DFA). The effects of experimental parameters such as (H<sub>2</sub>O: HCOOH) ratio (v/v), temperature, reaction time, and liquid-solid ratio on the extraction performance of Li and Co have been carefully evaluated. The findings revealed that DFA successfully leaches Li and Co from the spent LiCoO<sub>2</sub> cathode materials of Li-ion batteries without any assistance from reducing reagents. The solid materials were characterized by XRD, XPS, FT-IR, and SEM-EDS analyses. However, the leaching liquor was analyzed by ICP-OES. At 220°C, a reaction time of 25 min, an H<sub>2</sub>O: HCOOH ratio (v/v,) of 78:12, and a liquid-solid ratio of 25 mL/g, 99.89% for Li and 99.56% for Co were effectively leached from the spent LiCoO<sub>2</sub> powder. Further, the activation energy for Li was 24.15KJ/mol, while that for Co was 31KJ/mol. Finally, Co<sub>2</sub>O<sub>3</sub> nanoparticles and Li<sub>2</sub>CO<sub>3</sub> were successfully recovered from the leaching liquor by the precipitation and calcination methods after the separation steps. Therefore, this process could be an alternative method due to its low energy consumption, ease of use, and being environmentally friendly.