• Journal of Environmental Health Sciences
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• v.21 no.1
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• pp.21-28
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• 1995

The removal of heavy metals from synthetic wastewater containing Pb, Cr, Cd using previously washed and dried exhausted coffee was studied varying cohcentration, pH and temperature. All the heavy metals were removed in 3.0 minutes and the removal efficiency was maximum 80~90% with different pH and temperature conditions. The differences in removal efficiency between exhausted coffee and activated carbon under the same conditions were not seen. The removal efficiency was slightly increased with increasing pH in Cd and increasing temperature in Cr, respectively. The batch adsorption kinetics and adsorption equilibrium were examined and described by a first order reversible reaction and Freundlich isotherm, respectively. And the removal of Pb was found to have the best removal efficiency.

• Korean Journal of Materials Research
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• v.27 no.3
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• pp.127-131
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• 2017

Isosteric heat of hydrogen adsorption is one of the most important parameters required to describe solid-state hydrogen storage systems. Typically, it is calculated from adsorption isotherms measured at 77K (liquid N2) and 87K (liquid Ar). This simple calculation, however, results in a high degree of uncertainty due to the small temperature range. Therefore, the original Sievert type setup is upgraded using a heating and cooling device to regulate the wide sample temperature. This upgraded setup allows a wide temperature range for isotherms (77K ~ 117K) providing a minimized uncertainty (error) of measurement for adsorption enthalpy calculation and yielding reliable results. To this end, we measure the isosteric heats of hydrogen adsorption of two prototypical samples: activated carbon and metal-organic frameworks (e.g. MIL-53), and compared the small temperature range (77~87K) to the wide one (77K ~ 117K).

• Proceedings of the KAIS Fall Conference
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• 2011.12a
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• pp.286-288
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• 2011

활성탄소섬유의 유해 미생물의 번식 억제력을 조사하기 위해 한천베지배양법을 이용하였다. 전이금속으로 코팅된 활성탄소섬유는 일부 유해 미생물에서 번식억제력이 나타났으며, 유해 미생물은 인간의 피부 부종을 야기시키는 미생물인 candida albicans이었다. 그리고 코팅 활성탄소섬유의 흡 탈착력은 코팅되지 않은 활성탄소섬유보다 약 5% 내외로 감소함을 알 수 있었다.

• Journal of the Korean Chemical Society
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• v.34 no.6
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• pp.569-581
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• 1990

It is generated in DMF by activated catalysts of superoxo cobalt(III) complex, such as [Co(III)(Schiff base)(L)]O$_2$ (Schiff base; SED, SOPD and o-BSDT, L; DMF and Py) which mole ratio of oxygen to metal is 1:1 that oxidation major product of 2,6-di-tert-butylphenol by homogeneous oxidatve catalysts of oxygen adducted tetradentate Schiff base cobalt(III) is 2,6-ditert-butylbenzoquinone (BQ). And oxidation product of 3,3',5,5'-tetra-tert-butyldiphenoquinone (DPQ) is generated by activated catalysts such as $\mu$-peroxo cobalt(III) complex; $[Co(III)(SND)(L)]_2$$O_2$ (L; DMF and Py) which mole ratio of oxygen to metal is 1:2. It is difficult to identify these homogeneous activated catalysts such as superoxo and $\mu$-peroxo cobalt(III) complexes in DMF and DMSO solvents. But we can identify by P.V.T method of the oxygen absorption in pyridine solvent and by the reduction process occurred to four steps including prewave of O$_2$- in 1:1 oxygen adducted superoxo cobalt(III) complexes and three steps not including prewave of O$_2$- in 1:2 oxygen adducted $\mu$-peroxo cobalt(III) complexes by the cyclic voltammetry with glassy carbon electrode in 0.1 M TEAP as supporting electrolyte solutidn.

• Bulletin of the Korean Chemical Society
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• v.27 no.9
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• pp.1423-1428
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• 2006

In this study, we have prepared pitch binded AC (activated carbon)/$AC/TiO_2$ composites photocatalysts through carbon tetrachloride solvent method. The developed samples were characterized with surface properties, structural crystallinity between AC and $AC/TiO_2$, elemental identification and photocatalytic activity. The results of the textural surface properties demonstrate that there are slight increases in the BET surface area and adsorbed volume from adsorption isotherm of composite samples with increasing of the amount of AC. The SEM results present to the characterization of porous texture on the pitch/AC/$AC/TiO_2$ composites and homogenous compositions in the particle for all the materials used. From XRD data, a weak and broad carbon peak of graphene remained rutile peaks kept with anatase structure were observed in the X-ray diffraction patterns for the pitch/AC/$AC/TiO_2$ composites. The EDX spectra show the presence of C, O and S with strong Ti peaks. Most of these samples are richer in carbon and major Ti metal than any other elements. Finally, the excellent photocatalytic activity of the pitch/AC/$AC/TiO_2$ composites between relative concentration ($c/c_o$) of MB and UV irradiation time could be attributed to the both effects between photocatalysis of the supported $AC/TiO_2$ and adsorptivity of the two kinds of carbons.

• Korean Journal of Materials Research
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• v.11 no.2
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• pp.120-125
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• 2001

Generally, hydroxyapatite(HAp), zeolite, carbon molecular sieve , activated carbon and alumina are used as heavy metal ions adsorption materials. Among those adsorption materials, HAp which has good positive ion-exchange ability with metal ion, and zeolite are utilized in wastewater treatment. Most of water pollutions are caused by hazardous heavy metals ions as well as bacteria in waste water. In this study, a adsorption materials (HAP and zeolite) are ion-exchanged with a well known antimicrobial metal ions, such as $Ag^+,\;Cu^{2+},\;and\;Zn^{2+}$, in order to give a adsorption of heavy metal ions and a killing effects of bacteria. The antimicrobial effects of adsorption materials are observed using by E. Coli. The results show that there is a complete antimicrobial effect in the adsorption materials with $Ag^+$ at the concentration of $1{\times}10^{-4}$cell/$m\ell$ of E. Coli until 24 hours. However, there is not good antimicrobial effects in the adsorption materials with $Cu^{2+},\;and\;Zn^{2+}$ substitution. Feng et. al. showed the denaturation effects of silver ions which induces the condensed DNA molecules and losing their replication abilities.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.584-591
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• 2017

Metal removal from water has not been explained clearly by either adsorption onto the surface of absorbents or precipitation as metal hydroxides because those occur simultaneously to a certain extent. For a better understanding of the metal removal mechanisms, batch experiments were performed using soil calcined at $850^{\circ}C$ under various pH conditions for Cu, Pb, Zn, Cd, and Cr. The results showed that the metal removal efficiency with the exception of Cr decreased abruptly, even within 5 min, showing more than 90% removal. The pH of each reactant increased gradually from around 7 to 9 with time. The increases in metal removal at higher pH appear to be associated with metal hydroxides precipitation. Comparative experiments, which were carried out changing the pH by reacting with commercial activated carbon (CAC), natural yellow soil (NYS), and calcined yellow soil (CYS), showed that the pH of the CYS only increased with time. Calcination processes might lead to a change in the physical properties of the soil matrix resulting in a high pH when reacted with water. Apart from adsorption onto the surface of the absorbents, these results show that the adsorption and/or precipitation of hydroxides onto the surface of adsorbents also play important roles in regulating the dissolved metals under alkaline conditions.

• Journal of Environmental Science International
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• v.13 no.4
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• pp.403-412
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• 2004

Waste water-soluble cutting oil was treated with WI type #1 and WI type #2. The properties of the original water-soluble cutting oil were pH=l0.4, viscosity=1.4cP, CODcr=44,750 ppm, and TOC=10,569 ppm. However, the properties of the oil used for more than 3 months were changed to pH=7.82, viscosity=2.1cP, CODcr=151,000 ppm, and TOC=74,556 ppm. It might be attributed to the fact that molecular chains were cut due to thermal oxidation and impurities such as metal chips were incorporated in to the oil during the operation processes. To prevent the putrefaction of oil, the sterilization effect of ozone and UV on the microorganism in the oil was investigated. Ozone treatment showed that 99.99% of the microorganism was annihilated with 30 minutes contact time and 60 minutes were necessary for the same effect when UV was used. Ozone treatment could cut molecular chains of the oil due to strong sterilization power, which was evidenced by the increase of TOC from 25,132 ppm at instantaneous contact to 28,888 ppm at 30 minutes contact time. However, UV treatment didn't show severe changes in TOC values and thus, seemed to cause of severe cut of molecular chains. When the activated carbon was used to treat the waste water-soluble cutting oil, TOC decreased to 25,417 ppm with 0.lg carbon and to 15,946 ppm with 5.0g carbon. This results indicated that the waste oil of small molecular chains could be eliminated by adsorption. From the results, it could be concluded that these treatment techniques could be proposed to remove the waste oil of small molecular chains resulting in the degradation of the oil properties. In addition, these experimental results could be used for the correlation with future works such as investigation of the molecular distribution according to the sizes, lengths, and molecular weight of the chains.

• Journal of Soil and Groundwater Environment
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• v.17 no.2
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• pp.47-53
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• 2012

In this study, the adsorption of $Cu^{2+}$ and $Cd^{2+}$ from aqueous solution on the biochar derived from used coffee grounds at different pyrolysis temperatures has been investigated as a potential low-cost treatment method for heavy metal-containing waters. Three biochar samples prepared by heating coffee sludge at temperature of $300^{\circ}C$ (B300), $500^{\circ}C$ (B500), and $700^{\circ}C$ (B700) were tested for the adsorption capacity and kinetics of Cd and Cu. Also the influencing factor of heavy metal removal by ion exchange in terms of cation exchange capacity (CEC) of each biochar was measured. Adsorption of Ca and Cu by biochar produced at higher pyrolysis temperature showed higher adsorption capacity but the optimal pyrolysis temperature based on performance and economy was known as $500^{\circ}C$. Sorption of Cu and Cd by biochar followed a Langmuir model at pH 6~6.5, attributing mainly to surface sorption. The biochar was more effective in Cu and Cd sorption than activated carbon (AC), with BC 500 being the most effective, which indicates that sorption of Cd and Cu by coffee sludge biochar is partly influenced by chemical sorption on surface functional group as well as physical sorption.

• Journal of Environmental Science International
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• v.27 no.9
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• pp.753-762
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• 2018

The present study set out to investigate the adsorption of Cd(II) ions in an aqueous solution by using Peanut Husk Biochar (PHB). An FT-IR analysis revealed that the PHB contained carboxylic and carbonyl groups, O-H carboxylic acids, and bonded-OH groups, such that it could easily adsorb heavy metals. The adsorption of Cd(II) using PHB proved to be a better fit to the Langmuir isotherm than to the Freundlich isotherm. The maximum Langmuir adsorption capacity was 33.89 mg/g for Cd(II). The negative value of ${\Delta}G^o$ confirm that the process whereby Cd(II) is adsorbed onto PHB is feasible and spontaneous in nature. In addition, the value of ${\Delta}G^o$ increase with the temperature, suggesting that a lower temperature is more favorable to the adsorption process. The negative value of ${\Delta}H^o$ indicates that the adsorption phenomenon is exothermic while the negative value of ${\Delta}S^o$ suggests that the process is enthalpy-driven. As an alternative to commercial activated carbon, PHB could be used as a low-cost and environmentally friendly adsorbent for removing Cd(II) from aqueous solutions.