• Environmental Engineering Research
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• 제14권3호
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• pp.153-157
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• 2009

Arsenic at abandoned mine sites has adversely affected human health in Korea. In this study, the feasibility of using cationic surfactant-modified activated carbon (MAC) to remove As(V) was evaluated in terms of adsorption kinetics, adsorption isotherms, and column experiments. The adsorption of As(V) onto MAC was satisfactorily simulated by the pseudo-second-order kinetics model and Langmuir isotherm model. In column experiments, the breakthrough point of AC was 28 bed volumes (BV), while that of MAC increased to 300 BV. The modification of AC using cationic surfactant increased the sorption rate and sorption capacity with regard to As(V). As a result, MAC is a promising adsorbent for treating As(V) in aqueous streams.

• Environmental Engineering Research
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• 제25권2호
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• pp.205-211
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• 2020

Chlorhexidine digluconate (CHD) in the aquatic environment causes irreversible change to microbes, making them resistant to biodegradation, which needs remediation other than biological process. Adsorption study was performed for the removal of CHD on fly ash (FA) as a function of pH and ionic strength. Experimental result has been validated by characterization using Scanning electron microscopy, Fourier Transform-Infrared Spectroscopy and Brunauer-Emmett-Teller. CHD adsorption with FA showed an increasing trend with an increase in pH. Variation in pH proved to be an influential parameter for the surface charge of adsorbent and the degree of ionization of the CHD molecules. The adsorption capacity of CHD decreased from 23.60 mg g-1 to 1.13 mg g-1, when ionic strength increased from to M. The adsorption isotherms were simulated well by the Freundlich isotherm model having R2 = 0.98. The Lagergren's model was incorporated to predict the system kinetics, while the mechanistic study was better explained by pseudo-second order for FA. On the basis of operational conditions and cost-effectiveness FA was found to be more economical as an adsorbent for the adsorption of CHD.

• 한국물환경학회지
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• 제32권3호
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• pp.291-296
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• 2016

This study investigated the potential use of soybean stover (SS) (0.1-0.5 g/100 mL)and rice hull (RH) (1.5-3.5 g/100 mL) derived biochars for removing methylene blue (100 mg/L) from wastewater compared to activated carbon (AC) (0.1-0.5 g/100 mL). The adsorption equilibrium data were best represented by Langmuir adsorption isotherm. The calculated maximum adsorption capacity was 71.42 mg/g for AC, 30.30 mg/g for SS, and 4.76 mg/g for RH. The adsorption kinetics was found to follow the pseudo-second order kinetics model. The rate constant was 0.0020-0.0065 g/mg.min for AC, 0.0069-0.5787 g/mg.min for SS, and 0.1370-0.3060 for RH. AC and SS biochars showed considerable potential for adsorption.

• 한국환경과학회지
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• 제22권10호
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• pp.1327-1335
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• 2013

Na-A zeolite (Z-Cl) was synthesized from coal fly ash, which is a byproduct of coal combustion for the generation of electricity. The adsorption of $Cu^{2+}$ and $Zn^{2+}ions$ onto Z-C1 was investigated via batch tests over a range of temperatures (303.15 to 323.15 K). The resultant experimental equilibrium data were compared to theoretical values calculated using model equations. With these results, the kinetics and equilibrium parameters of adsorption were calculated using Lagergren and Langmuir-Freundlich models. The adsorption kinetics revealed that the pseudo second-order kinetic mechanism is predominant. The maximum adsorption capacity ($q_{max}$) values were 139.0-197.9 mg $Zn^{2+}$/g and 75.0-105.1 mg $Cu^{2+}/g$. Calculation of the thermodynamic properties revealed that the absorption reactions for both $Cu^{2+}$ and $Zn^{2+}$ were spontaneous and endothermic. Collectively, these results suggest that the synthesized zeolite, Z-C1, can potentially be used as an adsorbent for metal ion recovery during the treatment of industrial wastewater at high temperatures.

• Journal of Microbiology and Biotechnology
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• 제33권2호
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• pp.251-259
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• 2023

Immobilizing microalgae cells in a hyphal matrix can simplify harvest while producing novel mycoalgae products with potential food, feed, biomaterial, and renewable energy applications; however, limited quantitative information to describe the process and its applicability under various conditions leads to difficulties in comparing across studies and scaling-up. Here, we demonstrate the immobilization of both active and heat-deactivated marine diatom Phaeodactylum tricornutum (UTEX 466) using different loadings of fungal pellets (Aspergillus sp.) and model the process through kinetics and equilibrium models. Active P. tricornutum cells were not required for the fungal-assisted immobilization process and the fungal isolate was able to immobilize more than its original mass of microalgae. The Freundlich isotherm model adequately described the equilibrium immobilization characteristics and indicated increased normalized algae immobilization (g algae removed/g fungi loaded) under low fungal pellet loadings. The kinetics of algae immobilization by the fungal pellets were found to be adequately modeled using both a pseudo-second order model and a model previously developed for fungal-assisted algae immobilization. These results provide new insights into the behavior and potential applications of fungal-assisted algae immobilization.

• 한국환경과학회지
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• 제24권9호
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• pp.1145-1153
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• 2015

PVC-Zeolite composite was prepared by immobilizing zeolite with polyvinyl chloride (PVC). The prepared PVC-Zeolite beads were characterized by using X-ray diffractometer (XRD), fourier transform infrared spectrometer (FTIR), thermo gravimetric analyzer (TGA), and scanning electron microscopy (SEM). The removal properties of Sr and Cs ions from aqueous solution were investigated in batch experiment. The removal efficiencies of Sr and Cs ions by the PVC-Zeolite beads were dependent on the initial pH of solution. The removal efficiencies sharply increased at below pH 4 and was kept constant at pH 4 or more. The adsorption kinetics of Sr and Cs ions by the PVC-Zeolite beads were fitted well by the pseudo-second-order model ($r^2$>0.99) more than pseudo-first-order model. The maximum adsorption capacities of Sr and Cs ions calculated from Langmuir isotherm model were 39.37 mg/g and 55.87 mg/g, respectively.

• Carbon letters
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• 제7권4호
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• pp.249-258
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• 2006

Treatment of water hyacinth with sulphuric acid produces carbonaceous materials that have been used to remove Cu(II) and Cd (II) ions from aqueous solutions. Untreated water hyacinth was also used for the subject of comparison. The textural properties of the carbonaceous materials were determined from nitrogen adsorption at 77 K. The optimum pH for the sorption of Cu (II) and Cd (II) ions on the investigated sorbents was determined. Dynamic adsorption measurements have been taken at 298 K whereas equilibrium measurements were carried out at 298, 313 and 323 K. The adsorption of nitrogen at 77 K on the untreated sample was too low and the surface areas of the treated samples 2, 3 and 4 were found between $70-208\;m^2/g$. The total pore volumes of these samples which were determined for the carbonaceous materials investigated were found to be 0.076-0.140 ml/g. The kinetic adsorption data of Cu (II) and Cd(II) were applicable to both pseudo - first and pseudo-second order but fit more the latter order. The equilibrium adsorption data were found to fit Freundlich and Langmiur equations. The values of DG, DH and DS are all negative indicating the feasibility and the spontaneous nature of the sorption of Cu (II) and Cd (II) ions by the sorbents investigated.

• Bulletin of the Korean Chemical Society
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• 제31권6호
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• pp.1638-1642
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• 2010

Mesoporous carbon CMK-3s with different textural properties have been used for the adsorption of phenol to understand the necessary physicochemical properties of carbon for the efficient removal of phenol from contaminated water. The kinetic constants (both pseudo-second order and pseudo-first-order kinetics) increase with increasing pore size of carbons. The maximum adsorption capacities correlate well with micropore volume compared with surface area or total pore volume even though large pore (meso or macropore) may contribute partly to the adsorption. The pore occupancies also explain the importance of micropore for the phenol adsorption. For efficient removal of phenol, carbon adsorbents should have large micropore volume and wide pore size for high uptake and rapid adsorption, respectively.

• 한국환경과학회지
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• 제30권9호
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• pp.719-726
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• 2021

In this study, zeolitic materials were synthesized from Jeju Volcanic Rocks (JVR) using a fusion/hydrothermal method at NaOH/JVR ratios of 0.6 and 1.2. The crystallinities of the zeolitic materials at NaOH/JVR ratios of 0.6 and 1.2 were 25.5% and 59.0%, respectively. It was confirmed through the SEM image that the zeolitic materials covered the zeolite particle with a cube-shaped crystals. The Co ions adsorption by the zeolitic materials were to reach the adsorption equilibrium at 120 min. It could be better simulated in the pseudo-second order adsorption kinetic equation than in the pseudo-first order adsorption kinetic equation. The adsorption capacities (q_m) of Co ions could be to estimate Langmuir isotherm better than Freundlich isotherm. The maximum adsorption capacities (q_m) at NaOH/JVR ratios of 0.6 and 1.2 were 55.3 mg/g and 68.7 mg/g, respectively. It was found that there was a high correlation between the crystallinity of zeolitic materials and the adsorption capacity of Co ions adsorption.

• Membrane and Water Treatment
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• 제15권1호
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• pp.41-50
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• 2024

Presence of hazardous dyes in water cause considerable risks to the human health and environment due to their potential toxicity and ecological disruptions. Therefore, in the present research, to suggest an alternative method for the retention of toxic Azocarmine G (ACG) dye from aqueous media, natural and H₂SO₄-modified acacia sawdust were performed for the first time as low-cost and efficient adsorbents. Based on batch experiments, it was determined that the best conditions for the developed dye retention process were an initial pH of 2.0 and an equilibrium time of 240 min. Analysis of the data using both pseudo-first order and pseudo-second order kinetic models showed that the retention of ACG onto the adsorbents predominantly occurred through chemical adsorption. Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models were employed to provide insights into the interaction between the adsorbate and adsorbent and the mechanism of the adsorption process. Maximum monolayer adsorption capacities of natural and H₂SO₄-modified acacia sawdust were determined as 28.01 and 64.90 mg g^-1, respectively by Langmuir isotherm model. Results of the study clearly indicated that the modification of acacia sawdust with H₂SO₄ leads to a substantial increase in the adsorption performance of anionic dyes.