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산업의 발달 및 국민소득 증대에 따라 유가 금속(귀금속)의 수요는 지속적으로 증가하였고 유가금속 추출 및 제련공정이 광범위하게 연구 되었다. 각 공정에서는 다량의 폐수 및 폐기물이 발생하고 있으며 대부분의 경우 폐수 내에 상당한 양의 귀금속이 함유되어 있는 것으로 보고되고 있다. 탄닌(Tannin)은 많은 hydroxyl group(-OH)을 가지고 있어 금속에대한 흡착력이 뛰어나다고 보고된 바 있다. 밤껍질은 25%의 탄닌을 함유하고 있어 유가금속의 흡착이 뛰어날 것으로 판단되며 또한 우리 나라는 세계 제1위의 밤 생산국가로 연간 12만톤의 밤을 생산하는 것으로 보고되고 있다. 이중 약 6만 톤은 밤껍질로 특별한 재활용 없이 폐기되고 있는 실정이다. 이에 본 연구에서는 기존의 귀금속 회수공정에 이용되는 이온교환수지법의 단점인 경제성과 효율성을 보안할 수있고, 버려지는 밤껍질을 이용한 친환경적 유가금속 회수기술을 개발하고자 하였다. 밤껍질은 밤 가공 공정에서 발생되는 속껍질인 율피를 이용하였다. 귀금속 폐액은 팔라듐(Pd), 금(Au), 백금(Pt) 각각의 1000ppm 표준용액을 다양한 농도로 조절하여 이용하였으며 pH는2.0으로 조절하여 등온흡착실험을 수행하였다. 실험결과 율피의 최대흡착량은 팔라듐(Pd)의경우는 9.01 mg g-1으로 나타났으며 금(Au)의경우 500 mg g-1으로 기존에 알려진 흡착제(해조류: 78 mg g-1, 잔나비버섯속 carnea:94.3 mg g-1 등)에 비해 흡착능이 매우 뛰어난 것으로 판단되었다. 백금의 경우는 기존의 흡착제에 비해 낮은 것으로 조사되었다.
The problem of load flow analysis by computer method is to reduce the computing time and memory requirement. In load flow analysis, the Newton-Raphson method has most widely used, because the method has advantage that has the best convergence characteristcs and requires the least computing time, but the method has disadvantage that requires too much memory space. In this paper, the method and programming are presented for reducing memory requirement of computer with the approximate computing time as compared with Newton-Raphson method. In this paper, to reduce the memory requirement and computing time the following method is performed. ① Only non-zero elements of admittance matrix and Jacobian matrix are stored in computer by one dimension with index of each element. ② Voltage magnitude and phase angle corrections are decoupled by neglecting submatrix ??, ?? in Jacobian matrix. ③ The optimmally ordered sparsity triangular Factorization method in Jacobian is employed, and programming for the method is developped. The method of load flow analysis presented in this paper can considerably reduce the memory requirement approximately to the extent of Ward-Hale method and take the approximate computing time as compared with Newton-Raphson method.
Precious metals have been used to make accessories and decorations for a long time, but since their physiochemical properties have been revealed, they have continuously increased as materials for industrial use, and as a result, the need for studies on the recovery process of precious metals has surfaced, leading to active studies in Korea and overseas on the topic. Therefore, the aim of this study was to develop bisorption recovery technology that can supplement disadvantages of existing precious metals recovery process such as chemical precipitation, solvent extraction and ion exchange. Materials used as biosorbents were found through documentary research, and chestnut shells, evaluated to be accessible and mass produced and have great metals adsorption capacity, were selected for the study. The maximum adsorption capacity for gold (Au) was 500 mg/kg and determined by a batch-type adsorption experiment using chestnut shell. Langmuir and Freundlich model showed a correlation coefficient (R2) value of 0.996 and 0.963, respectively. As a result of using chestnut shell in a powder form and producing with beads, a type of shell, a bead with a tail form rather than a perfect shape was made, but it had gold adsorption characteristics. The results indicate possibility of development of a more economic, efficient and environment-friendly previous metals recovery technology that can substitute high priced ion exchange resin that is currently being used.
The objective of this research was to evaluate the feasibility of waste chestnut as a new biosorbent to recover platinum from industrial wastewater. This study is a part of a larger project to develop precious metal recovery process using agricultural by-product produced in Korea. Batch-type adsorption experiment was carried out to determine platinum adsorption in an aqueous solution by chestnut shell. Result showed that Freundlich isotherms adequately described platinum adsorption with R 2 of 0.930. The mechanism of platinum adsorption by chestnut shell was evaluated by characterizing surface properties, functional group and chemical composition of chestnut shell using SEM-EDS and FT-IR analyses.
Biosorption has emerged as an innovative and economical method to recover base metals from aqueous wastes. The objective of this research was to evaluate the feasibility of waste chestnut as a new biosorbent to recover palladium from industrial wastewater. This study is a part of a larger project to develop precious metal recovery process using agricultural by-product produced in Korea. Batch-type adsorption experiment was carried out to determine palladium adsorption in an aqueous solution by chestnut shell. Result showed that Langmuir isotherms adequately described palladium adsorption with R2 of 0.999. The maximum adsorption capacity using Langmuir model revealed that chestnut shell can remove palladium in an aqueous solution up to 9.09 mg g-1. The mechanism of palladium adsorption by chestnut shell was evaluated by characterizing surface properties, functional group and chemical composition of chestnut shell using SEM-EDS and FT-IR analyses. The overall experimental results suggest that waste chestnut can be used for palladium biosorption from industrial wastewater.