• Membrane and Water Treatment
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• 제7권5호
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• pp.403-416
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• 2016

The possibility of using carica papaya leaf powder for removal of copper from wastewater as a low cost adsorbent was explored. Different parameters that affect the adsorption process like initial concentration of metal ion, time of contact, adsorbent quantity and pH were evaluated and the outcome of the study was tested using adsorption isotherm models. A maximum of 90%-94.1% copper removal was possible from wastewater having low concentration of the metal using papaya leaf powder under optimum conditions by conducting experimental studies. The biosorption of copper ion was influenced by pH and outcome of experimental results indicate the optimum pH as 7.0 for maximum copper removal. Copper distribution between the solid and liquid phases in batch studies was described by isotherms like Langmuir adsorption and Freundlich models. The adsorption process was better represented by the Freundlich isotherm model. The maximum adsorption capacity of copper was measured to be 24.51 mg/g through the Langmuir model. Pseudo-second order rate equation was better suited for the adsorption process. A dynamic mode study was also conducted to analyse the ability of papaya leaf powder to remove copper (II) ions from aqueous solution and the breakthrough curve was described by an S profile. Present study revealed that papaya leaf powder can be used for the removal of copper from the wastewater and low cost water treatment techniques can be developed using this adsorbent.

• 자원리싸이클링
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• 제8권1호
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• pp.37-43
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• 1999

본 연구는 망간단괴와 그로부터 유가금속을 침출한 잔사를 카드뮴 폐수의 흡착제로 이용하는 기초실험으로 초기 카드뮴 농도에 따른 흡착성을 살펴보았다. 또한 이를 Freundlich, Langmuir, Temkin 등온흡착식에 적용하여 각 흡착계를 설명하였다. 카드뮴 이온의 초기농도가 증가함에 따라 흡착량은 증가하였으나 흡착성은 점차로 감소하는 경향을 보였다. 이를 Freundlich, Langmuir 식에 적용한 결과, 선형성을 나타내었다. 그리고 Freundlich 식에서 흡착제의 흡착능력을 평가하는 k값은 망간단괴가 11.72로 제일 컸다. 망간단괴의 경우는 Langmuirtlr의 단분자층을 형성하여 흡착되는 흡착질의 최대흡착량인 $X_m$값또한 0.16으로 침출잔사, 잔사-생단괴 혼합, 활성탄에 비해 큼을 알 수 있었다.

• 한국환경보건학회지
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• 제21권3호
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• pp.77-86
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• 1995

Lead(II) removal efficiency by natural kaolinite was investigated through laboratory experiments. This study was conducted in two phases-sorption and desorption. In the adsorption study, the influence of sorption kinetics and sorption isotherm and various parameters such as pH, temperature, coexisting other heavy metal ions on the lead adsorption was investigated. And desorption study was carried out in order to find the re-usability of kaolinite as an adsorbent. The results of the study are as follows. 1. Sorption kinetics was investigated under the condition of 2.5 mg/l adsorbent concentration, pH 6.5$\pm$0.05, temperature $30\pm 0.5\circ$C, initial lead(II) concentration 25 mg/l. Adsorption rate was initially rapid and the extent of adsorption arrived at adsorption equilibrium with 73% adsorption efficiency in an hour. 2. The sorption isotherm experiment was made with different initial lead(II) concentration. A linearized Freundlich equation was used to fit the acquired experimental data. As a result, Freundlich constants, the sorption intensity (1/n) was 0.47 and the measure of sorption (k) was 2.44. So, it was concluded that sorption of lead(II) by kaolinite is effective. 3. The effect of pH on lead(II) sorption by kaolinite shows that at a pH of 3, only 6% of the total lead(II) was adsorbed and at a pH 9, 97% of the lead(II) was removed. And the effect of temperature on lead(II) sorption by kaolinite shows that as the temperature increased, the amount of lead(II) sorption per unit weight of kaolinite increased. But the effect was minor (p<0.05). 4. Sorption isotherm of lead coexisting cadmium (II) or zinc (II) was lower than that of lead itself. It was caused by the result of competitive sorption to adsorption site. And there was no difference between the sorption isotherm of cadmium and zinc. 5. In desorption studies, only 5.12% desorption took place in distilled water, while 52.08% in 0.1 N hydrochloric acid. Consequently used kaolinite could be regenerated by hydrochoric acid.

• Macromolecular Research
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• 제16권6호
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• pp.492-502
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• 2008

This study examined the adsorption of a synthetic cutting fluid and cutting fluid effluent on chitosan and SDS-modified chitosan, Chitosan and SDS-modified chitosan were prepared in form of beads and fibers. A series of batch experiments were carried out as a function of the initial concentration of cutting fluid, contact time and pH of the fluid. The contact angle study suggested that the SDS-modified chitosan was more hydrophobic than chitosan. The Zeta potential study showed that chitosan, SDS-modified chitosan and synthetic cutting fluid had a point of zero charge (PZC) at pH 7.8, 9 and 3.2, respectively. SDS-modified chitosan has a greater adsorption capacity than chitosan. The experimental results show that adsorption capacity of the cutting fluid on 1.0 g of SDS-modified chitosan at pH 3 and for a contact time of 120 min was approximately 2,500 g/kg. The adsorption capacity of chitosan and SDS-modified chitosan increased with decreasing pH. The Langmuir, Freundlich, and Brunauer Emmett and Teller (BET) adsorption models were used to explain the adsorption isotherm. The Langmuir isotherm fitted well with the experimental data of chitosan while the BET isotherm fitted well with the SDS-modified chitosan data. Pseudo first- and second-order kinetic models and intraparticle diffusion model were used to examine the kinetic data. The experimental data was fitted well to a pseudo second-order kinetic model. The significant uptake of cutting fluid on chitosan and SDS-modified chitosan were demonstrated by FT-IR spectroscopy, SEM and heat of combustion.

• 상하수도학회지
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• 제28권4호
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• pp.453-459
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• 2014

The excessive concentration of phosphorus in the river and reservoir is a deteriorating factor for the eutrophication. The converter slag was used to remove the phosphate from the synthetic wastewater. Influencing factors were studied to remove soluble orthophosphate with the different particle sizes through the batch and the column experiments by continuous flow. Freundlich and Langmuir adsorption isotherm constants were obtained from batch experiments with $PS_A$ and $PS_B$. Freundlich isotherm was fitted better than Langmuir isotherm. Regression coefficient of Freundlich isotherm was 0.95 for $PS_A$ and 0.92 for $PS_B$, respectively. The adsorption kinetics from the batch experiment were revealed that bigger size of convert slag, $PS_A$ can be applied for the higher than 3.5 mg/L of phosphate concentration. The pilot plant of continuous flow was applied in order to evaluate the pH variation, breakthrough points and breakthrough adsorption capacity of phosphate. The variation of pH was decreased through the experimental hours. The breakthrough time was 1,432 and 312 hours to 10 mg/L and 50 mg/L for the influent concentration, respectively. The breakthrough adsorption capacity was 3.54 g/kg for 10 mg/L, and 1.72 g/kg for 50 mg/L as influent phosphate concentration.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권2호
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• pp.110-115
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• 2006

We conducted a sensitivity analysis of the simulated moving bed (SMB) chromatography with the case model of the separation of two amino acids phenylalanine and tryptophan. We consider a four-zone SMB chromatography where the triangle theory is used to determine the operating conditions. Competitive Langmuir isotherm model was used to determine the adsorption isotherm. The finite difference method is used to solve nonlinear partial differential equation (PDE) systems numerically. We examined the effects of alterations in the operating conditions(feed-extract, feed-raffinate, eluent-extract, eluent-raffinate, recycle, and switching time) and the adsorption isotherm parameters (Langmuir isotherm parameters a and b) on SMB efficiency. The variation range of operating conditions and Langmuir isotherm a was between -50 and 50% of original value and the variation range of the Langmuir isotherm b was between $2.25^{-5}$ and $2.25^5$ times of original value.

• 상하수도학회지
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• 제19권4호
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• pp.404-410
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• 2005

A series of batch type adsorption experiments were performed to remove aquatic phosphorus, where the layered double hydroxide (HTAL-CI) was used as an powdered adsorbent. It showed high adsorption capacity (T-P removal: 99.9%) in the range of pH 5.5 to 8.8 in spite of providing low adsorption characteristics (pH<4). The adsorption isotherm was approximated as a modified Langmuir type equation, where the maximum adsorption amount (50.5mg-P/g) was obtained at around 80mg-P/L of phosphorus concentration. A phosphate ion can occupy three adsorption sites with a chloride ion considering the result that 1 mol of phosphate ion adsorbed corresponded to the 3 moles of chloride ion released. Although the chloride ion at less than 1,000mg-CI/L did not significantly affect the adsorption capacity of phosphate, carbonate ion inhibited the adsorption property.

• Environmental Engineering Research
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• 제13권2호
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• pp.79-84
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• 2008

Adsorption of heavy metals by sawdust was investigated to evaluate the effectiveness of using sawdust to remove heavy metals from aqueous solutions. Kinetic and isotherm studies were carried out by considering the effects of initial concentration and pH. The adsorption isotherms of heavy metals fitted the Langmuir or Freundlich model reasonably well. The adsorption capacity of metal was in the order $Pb^{2+}$ > $Cu^{2+}$ > $Zn^{2+}$. A high concentration of co-existing ions such as $Ca^{2+}$ and $Mg^{2+}$ depressed the adsorption of heavy metal. Adsorption data showed that metal adsorption on sawdust follows a pseudo-second-order reaction. Kinetic studies also indicated that both surface adsorption and intraparticle diffusion were involved in metal adsorption on sawdust. Column studies prove that sawdust could be effective biosorbent for the removal of heavy metals from aqueous phase.

• 분석과학
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• 제13권4호
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• pp.433-439
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• 2000

무정형 알루미나를 흡착제로 사용하여 니켈(II) 이온의 흡착거동을 조사하였다. 흡착반응속도에 관하여 실험한 결과, 두 단계 흡착, 즉 한 시간 이내 빠르게 진행되는 흡착과 그 이후에는 느리게 진행되는 흡착으로 구분되었다. 흡착등은 실험에서는 Langmuir-Freundlich 흡착식을 만족하였으며 PH가 높을수록 최대흡착량이 증가함을 보였다. 이온강도의 변화에 따른 흡착량의 변화를 조사한 결과 어떤 뚜렷한 경향성을 보이지 않은 것으로 보아 니켈(II) 이온의 흡착은 정전기적 상호작용이라기 보다는 표면착물형성으로 이루어짐을 추정할 수 있었다. 일정한 이온강도에서 세 가지의 니켈(II) 이온 농도에서 pH를 변화시키면서 흡착량을 측정한 결과 니켈(II) 이온의 농도가 높을수록 흡착률은 감소했으며 흡착변곡점은 보다 높은 pH쪽으로 이동하였다.

• 한국지반공학회논문집
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• 제26권9호
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• pp.37-45
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• 2010

본 연구에서는 지하수에 존재하는 비소를 산업 폐기물인 제강 슬래그를 이용하여 제거하고자, 제강 슬래그에 대한 비소의 흡착특성을 규명하였다. 이를 위해 등온흡착 실험과 동적흡착 실험을 수행하였고, 흡착반응 후 용액의 화학적 특성을 분석하였다. 실험 결과, 흡착 실험을 수행한 모든 용액은 염기 상태로 존재하였으며(pH 9이상), 칼슘의 농도가 가장 높았다(30~50mg/L). 등온흡착 실험결과는 Langmuir 모델보다Freundlich 모델에 적용하는 젓이 더 합리적이였으며, 제강 슬래그에 As(V)가 As(III)보다 약 87% 더 많이 흡착되는 것으로 확인됐다. 동적흡착 실험결과의 경우, 유사일차모델보다 유사이차모델을 통해 해석하는 것이 더 적합하였다. 비소의 초기농도가 높을수록 평형 흡착량($q_e$)과 완화시간($t_r$) 이 모두 증가하였으며, As(V)는 As(III)보다 평형 흡착량이 많고 완화시간은 짧은 것을 확인할 수 있었다. 또한, 유사이차모델을 통해 예측된 평형 흡착량이 등온흡착 실험에서 구한 평형 흡착량과 유사해 동적흡착 실험결과로 등온흡착 실험결과를 예측하는 것이 가능함을 확인하였다.