• 공업화학
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• 제34권4호
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• pp.412-420
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• 2023

본 연구는 red mud와 fly ash 기반 geopolymer 흡착제(RFGPA)를 소성 온도 변화(200, 400, 600 ℃)에 따라 제조하고 소성 온도가 methylene blue (MB)의 흡착에 미치는 영향을 조사하였다. 또한, X-ray fluorescence (XRF), scanning electron microscopy (SEM), X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FT-IR), 및 Brunauer-Emmett-Teller (BET) 분석을 통해 제조한 RFGPA의 특성을 조사하였다. MB를 이용한 소성 온도에 따른 RFGPA의 흡착 kinetics 결과 약 72시간에 MB 흡착 평형에 도달하였고, 흡착 isotherm 결과 MB 농도가 증가함에 따라 흡착 정도가 증가하는 경향을 보였다. 또한, RFGPA에 대해 소성 온도가 증가할수록 MB 흡착량이 감소하는 것을 확인하였다. RFGPA의 MB 흡착메커니즘을 확인하기 위해 수학적 모델식에 적용한 결과 상대적으로 Freundlich와 Sips 모델이 Langmuir 모델 보다 더 적합한 것을 확인하였다. 제조한 RFGPA 내에 존재하는 Fe₂O₃에 대한 MB의 광분해 효과를 확인하기 위해 dark condition 및 visible condition에서 MB 분해 정도를 분석한 결과 visible condition에서 분해속도가 dark condition보다 약 3배 빠른 것을 확인하였다.

• Bulletin of the Korean Chemical Society
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• 제33권10호
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• pp.3184-3190
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• 2012

Color impurity in industrial effluents pose a significant risk to human health and the environment, so much effort has been expended to degrade them using various methods, including the use of clay minerals as adsorbent. The purpose of this study was to advance understanding of the mechanisms for the removal of methylene blue (MB) from aqueous solutions onto montmorillonite as an adsorbent. Preliminary experiments showed that montmorillonite was effective for this purpose and adsorption equilibrium could be reached in about 24 h. Adsorption capacity of the clay decreased with increase in temperature and ionic strength, and increased with in pH. The fitness of equilibrium data to common isotherm equations such as the Langmuir, Freundlich, Elovich, Temkin and Dubinin-Radushkevich were tested. The Langmuir equation fitted to equilibrium data better than all tested isotherm models. Thermodynamic activation parameters such as ${\Delta}G^0$, ${\Delta}S^0$ and ${\Delta}H^0$ were also calculated and results were evaluated. As result montmorillonite clay was found as effective low cost adsorbent for removal of cationic dyes from waste waters.

• 약학회지
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• 제32권3호
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• pp.187-193
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• 1988

An activated carbon which showed big adsorption capacities of iodine, potassium permanganate and phenol was prepared from the Korean ricechaff. By scanning electron micrographs and IR spectra, it was observed that the organic components in the rice-chaff were decomposed to carbon dioxide and vapor by the pyrolysis and the activation, that activated carbon particles had carbon-carbon structures with a lot of microporosity. The adsorption capacities of iodine, potassium permanganate and phenol were determined. The adsorption isotherm of phenol was well fitted in Freundlich's equation.

• 청정기술
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• 제18권3호
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• pp.312-319
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• 2012

말라카이트 그린은 염료로 사용되지만 유해한 독성 물질이다. 본 연구에서는 제올라이트에 의한 말라카이트 그린의 흡착특성을 조사하였다. 일정한 양의 제올라이트에 대해 초기농도, 접촉시간, pH 및 흡착온도 등이 말라카이트 그린의 흡착에 미치는 영향을 회분식 및 칼럼흡착실험을 통하여 연구하였다. 회분식흡착실험을 통해 흡착등온선을 구한 결과 말라카이트 그린의 흡착평형관계는 $25{\sim}45^{\circ}C$ 범위에서 Freundlich 식이 잘 적용되었다. 흡착등온식으로 부터 평가된 k와 ${\beta}$ 값은 각각 23.60~46.88, 0.225~0.347이었다. 입자내 확산모델을 사용하여 흡착기구를 결정하였다. 고정층의 운전조건이 파과곡선에 미치는 영향을 조사하였다. 말라카이트 그린의 유입농도와 초기유속이 증가함에 따라 파과시간은 감소하였다. 층높이가 증가함에 따라 파과시간이 증가하였는데, 흡착대의 길이는 비슷한 양상을 나타냈다.

• 한국토양비료학회지
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• 제49권6호
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• pp.789-794
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• 2016

Continuous excessive application of phosphorus (P) fertilizer and manure in plastic film house soils can lead to an accumulation of P in soils. The understanding of P sorption by soils is important for fertilizer management. In this study, 9 samples were collected for acidic and calcareous soils as non-cultivated soil and plastic film house soils as cultivated soil Phosphorus sorption data of acidic soils fit the Langmuir equations, Freundlich equations in calcareous and plastic film house soils. In calcareous and plastic film house soils, the slope of isotherm adsorption changed abruptly, which could be caused P precipitation with $CaCO_3$. The calculated Langmuir adsorption maximum ($S_{max}$) varied from 217 to 1,250, 139 to 1,429, and $714mg\;kg^{-1}$ for acidic soils, calcareous soils, and plastic film house soils with low available phosphate concentration, respectively. From this result, maximum P adsorption by the Langmuir equation could be regarded as threshold of P concentration to induce the phosphate precipitation in soil. Phosphate-sorption values estimated from one-point isotherm for acidic and calcareous soils as non-cultivated soils were comparable with the $S_{max}$ values calculated from the Langmuir isotherm.

• Advances in environmental research
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• 제6권2호
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• pp.113-125
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• 2017

Santa Barbara Amorphous-15(SBA-15) nanoparticles were utilized as the inexpensive and effective adsorbents to remove methylene blue dye from the aqueous solution.SBA-15 was created by Zhao et al method. Infrared spectroscopy, X-ray diffraction and scanning electron microscopy (SEM) were used for the evaluated physical properties of SBA-15. The results of diffraction X-ray indicated that was the crystalline structure for it. Also IR spectroscopy indicated was a silica the whole structure of the groups and SEM image verify the structure of relatively identical particles size of SBA-15. Factors affecting adsorption including the amounts of adsorbent, pH and contact time were investigated by a SBA-15 nanomaterial design. The extent of dye removal enhanced with increasing initial dye concentration and pH from 4 to 10. The higher percentage adsorption were obtained under optimum conditions of variables (sorbent dose of 200 mg/liter, initial MB concentration 10 mg/liter, initial pH of 10 and temperature of $25^{\circ}C$). Maximum adsorption happened after the 2 hour and the kinetic processes of the dyes adsorption were described by applying the pseudo-first-order and the pseudo-second-order and the relatively High correlation with the kinetic Ellovich models. It was found that the pseudo-second-order models kinetic equation described the data of dye adsorption with a good correlation (R2>0.999) which indicated chemisorption mechanism. Freundlich and Langmuir adsorption models were investigated in conditions of variables (adsorbent dose 0.01 gr/liter, MB concentration 10, 20, 30 mg/liter, pH of 4, 7, 10, contact time 90 min and temperature of $27^{\circ}C$). The adsorption data were represented by Langmuir isotherm model. These values are higher than the adsorption capacities of some other adsorbents that have recently been published in the literature.

• Korean Chemical Engineering Research
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• 제58권4호
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• pp.624-634
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• 2020

The ability of natural and modified clay to adsorb phenol was studied. The clay samples were analyzed by different technical instruments, such as X-ray fluorescence (XRF), X-ray diffraction (XRD) and FT-IR spectroscopy. Surface area, pore volume and average pore diameter were also determined using B.E.T method. Up to 73 and 99% of phenol was successfully adsorbed by natural and activated clay, respectively, from the aqueous solution. The experiments carried out show that the time required to reach the equilibrium of phenol adsorption on all the samples is very close to 60 min. The amount of phenol adsorbed shows a declining trend with higher pH as well as with lower pH, with most extreme elimination of phenol at pH 4. The adsorption of phenol increases proportionally with the initial phenol concentration. The maximum adsorption capacity at 25 ℃ and pH 4 was 29.661 mg/g for modified clay (NaMt). However, the effect of temperature on phenol adsorption was not significant. The simple modification causes the formation of smaller pores in the solid particles, resulting in a higher surface area of NaMt. The equilibrium results in aqueous systems were well fitted by the Freundlich isotherm equation (R² > 0.98). Kinetic studies showed that the adsorption process is best described by the pseudo-second-order kinetics (R² > 0.99). The adsorption of phenol on natural and modified clay was spontaneous and exothermal.

• 한국환경과학회지
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• 제27권11호
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• pp.975-982
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• 2018

In this study, zeolite (Z-C1) was synthesized using a fusion/hydrothermal method from coal fly ash. The morphological structures of Z-C1 were confirmed to be highly crystalline with a cubic crystal structure. Exchange capacities of $Ca^{2+}$ and $Mg^{2+}$ ions in a single and a mixed solution reached equilibrium within 120 min. The exchange kinetics of these ions were well predicted by the pseudo-second-order rate equation. The exchange isotherms of the $Ca^{2+}$ and $Mg^{2+}$ ions matched the Langmuir isotherm better than the Freundlich isotherm. The maximum cation exchange capacities ($q_m$) obtained by the Langmuir isotherm model were 2.11 mmol/g (84.52 mg/L) and 1.13 mmol/g (27.39 mg/L) for the $Ca^{2+}$ and $Mg^{2+}$ ions, respectively.

• 한국환경보건학회지
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• 제27권1호
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• pp.63-68
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• 2001

A laboratory experiment was performed to invstigate the nitrate removal using FeCl$_3$ -treated activated carbon. Iron chloride(III) was coated onto the surface of activated carbon. The removal efficiency of nitrate was increased with increasing of FeCl$_3$ was used for coating material. About 22~26mg of Fe per unit g of activated carbon was adsorbed. The nitrate removal was not affected by the pH under the experiment range of pH, but the pH value in solution decrease to 3.5~4.0 after reaction. The removal efficiency of nitrate was increased with increasing of dosage of adsorbents. Ammonia was not detected and the Fe concentration as low as 0.22mg/$\ell$ was desorbed from the adsorbents. The adsorbents was regenerated using KCl solution, and recovery was 76.6% at 1 M of KCl. The adsorption of nitrate by FeCl$_3$-treated activated carbon followed the Freundlich isotherm equation and the Freundlich constant, 1/n, was 0.346. These results showed that the FeCl$_3$-treated activated carbon could serve as the basis of a useful nitrate removal.

• 자원환경지질
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• 제36권5호
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• pp.381-385
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• 2003

본 연구는 폐산화철을 이용한 폐수 중금속 제거 가능성을 알아보고자 시도되었다. 실제 폐수와 폐산화철을 적용하기에 앞서 상업적으로 구입가능한 Mn-ferrite를 이용하여 실내 회분식 시험을 통한 흡착실험을 실시하여 pH, 접촉시간, 중금속 농도 및 온도 등과 같은 다양한 흡착 조절인자들을 이용하여 페라이트에 의한 Cd과 Pb의 흡착 및 제거특성을 알아보았다. 접촉시간을 1에서 360분까지 변화하여 흡착속도를 측정하였으며 일정온도에서 Cd와 Pb의 농도를 변화시켜 흡착등온선을 구하였다. 또한 온도(15∼35$^{\circ}$)와 pH(4∼10) 변화에 따른 흡착특성 변화를 고찰하였다. Cd과 Pb는 Freundlich 식에 잘 맞았으며 Cd에 비하여 Pb가 더 흡착이 잘 되었다. pH가 높을수록 Cd와 Pb가 더 잘 흡착되었으며 이는 pH증가에 따라 수소이온 농도가 감소하고 결과적으로 표면의 흡착가용 장소가 증가하기 때문인 것으로 생각된다. 같은 pH에서 원소의 농도가 증가할 때 흡착이 더 잘 일어났다. 온도 역시 Pb와 Cd의 흡착능에 영향을 미쳤으며 Pb의 경우 온도가 증가할수록 흡착정도가 높아지는 반면 Cd의 경우 덜 흡착이 되었다. Cd는 Pb에 비하여 더 온도에 영향을 받으며 이러한 Cd와 Pb의 흡착특성 차이는 Cd에 비하여 Pb가 더 hard한 특성 때문인 것으로 생각된다. 본 연구는 폐산화철을 이용하여 각종 폐수 중금속을 제거하는 공정에 사용될 수 있음을 시사한다.