• Environmental Engineering Research
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• 제11권6호
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• pp.303-310
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• 2006

The aim of this study is to assess the applicability of sericite in wastewater treatment particularly the removal of two important heavy metal toxic ions viz., Cu(II) and Pb(II) from aqueous solutions. The batch type experiments showed that sericite is found to be one of useful natural sorbent for the removal of these two cations from aqueous solutions and it is also to be observed that with the increase in sorptive concentration amount of metal uptake increases and the concentration dependence data obtained are fitted well for the Langmuir adsorption isotherm rather than Freundlich adsorption model. Further, the Langmuir monolayer adsorption capacity is found to be $1.674\;mg\;g^{-1}$ for Cu(II) and $4.697\;mg\;g^{-1}$ for Pb(II). Kinetic studies enabled, an apparent equilibria can be achieved between soild/solution interface within ca 10 mins for Cu(II) and ca 90 mins for Pb(II). Moreover, the removal behavior of sericite for these two metal ions is greatly influenced by solution pH.

• Environmental Engineering Research
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• 제18권4호
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• pp.247-252
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• 2013

In this work, removal of phenol from aqueous solutions by activated red mud was investigated. Scanning electron microscopy and energy dispersive X-ray spectroscopy was used to observe the morphology and surface components of activated red mud, respectively. The effects of various parameters on the removal efficiency were studied, such as contact time, pH, initial phenol concentration, and adsorbent dosage. The removal percentage of phenol was initially increased, as the solution pH increased from 3 to 7, and then decreased above neutral pH. The removal percentage of phenol was decreased by increasing the initial phenol concentrations. Adsorption results show that equilibrium data follow the Freundlich isotherm, and kinetic data was well described by a pseudo-second-order kinetic model. Experimental results show that the activated red mud can be used to treat aqueous solutions containing phenol, as a low cost adsorbent with high efficiency.

• 산업기술연구
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• 제27권A호
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• pp.203-209
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• 2007

본 연구는 목재로서 활용가치가 적은 수피(bark)를 활용하여 수질오염물질을 제거할 수 있는 여과 시스템에 대한 기초연구로서 소나무의 일종인 loblolly pine(Pinus taeda L.) 수피의 인 ($PO_4-P$) 흡착특성을 연구하였다. 실험에 사용된 수피는 입상형태로서 polyallylamine hydrochloride로 전처리하여 회분식 등온 흡착실험을 수행하였다. 회분식 등온흡착실험은 수용액 pH 3~pH 8범위에서, 인의 농도별(10, 20, 30, 40 mg/L)로 수행하였다. pH 5에서 가장 높은 인 제거 효율을 나타냈으며, 수용액의 pH는 실험 후 pH 3으로 감소하였다. 이러한 감소는 수피에 의한 phosphate의 흡착이 Lewis acid-base 반응으로서 이 과정에서 $H^+$의 방출로 인하여 나타난 현상인 것으로 여겨지며, 주된 반응 메카니즘은 더 연구할 필요성이 있다. 인 흡착은 초기에 빠른 속도로 진행되었으며 대략 200분 이후에 평형에 도달하였고, 시간이 지날수록 흡착양이 증가하는 경향을 보였다. 인의 흡착특성 결과는 Langmuir 등온흡착식과 Freundlich 등온흡착식으로 설명될 수 있으며, 등온흡착식 적용결과, 흡착제에 대한 최대 흡착능은 7.14 mg/g 이며 다른 흡착제와 비교하여 더 높았다. 실험결과와 모델에 의한 흡착능을 비교하고자 pseudo second-order model을 적용하여 흡착 동역학 상수를 구하였다. 또한 EDXA분석으로 회분식 흡착실험 후 수피와 인이 결합되어있는 것을 확인할 수 있었다.

• 한국환경과학회지
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• 제14권7호
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• pp.691-697
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• 2005

Waste sludge may be used to recovery wastewater contaminated with heavy metals. The waste sludge is an inexpensive readily available source of biomass for biosorption with metal-bearing wastewater. The biosorption of heavy metals such as Pb(II), Cu(II), Cr(II), and Cd(II) onto waste sludge was investigated in batch ex­periments and waste sludge loaded heavy metals was separated by dissolved air flotation. The biosorption equi­bria of heavy metals could be described by Langmuir and Freundich isotherms. The adsorption capacity for waste sludge was in the sequence of Pb(II)>Cr(II)>Cu(II)>Cd(II). The system attained equilibrium about 20 min. The Langmuir and Freundlich adsorption model effectively described the biosorption equilibrium of Cu(II) and Cr(II) ions on waste sludge. Maximum adsorption capacity of Cu(II) and Cr(II) were 196.08 and 158.73 mg/g, respectively. Solid-liquid separation efficiencies were kept above $95\%$ on waste sludge loaded heavy metals, and were decreased with pH increasing.

• Advances in environmental research
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• 제4권1호
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• pp.49-68
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• 2015

Chemically activated and carbonized adsorbents were prepared from Moringa oleifera pod husks (MOP), characterized and evaluated for their ability to remove a common antibiotic - ofloxacin (OFX) from aqueous solution. The pulverized precursor was steeped in a saturated ammonium chloride solution for a day to give the chemically activated adsorbent (AMOP). A portion of AMOP was pyrolyzed in a muffle furnace at 623 K for 30 min to furnish its carbonized analogue (CMOP). The adsorbents showed favorable physicochemical attributes. The effects of operational parameters such as initial OFX solution pH and concentration, adsorbent dosage, temperature and contact time on OFX removal were investigated. At equilibrium, optimal removal efficiencies of 90.98% and 99.84% were achieved at solution pH 5 for AMOP and CMOP, respectively. The equilibrium adsorption data fitted into both the Langmuir and Freundlich isotherms. Gibbs free energy change (${\Delta}G^o$), enthalpy change (${\Delta}H^o$) and entropy change (${\Delta}S^o$) indicated that the adsorption of OFX was feasible, spontaneous, exothermic and occurred via the physisorption mode. Adsorption kinetics obeyed the Blanchard pseudo-second-order model. The results may find applications in the adsorptive removal of micro-contaminants of pharmaceutical origin from wastewater.

• Nuclear Engineering and Technology
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• 제49권1호
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• pp.172-177
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• 2017

A novel biosorbent, immobilized Saccharomyces cerevisiae in magnetic chitosan microspheres was prepared, characterized, and used for the removal of $Sr^{2+}$ from aqueous solution. The structure and morphology of immobilized S. cerevisiae before and after $Sr^{2+}$adsorption were observed using scanning electron microscopy with energy dispersive X-ray spectroscopy. The experimental results showed that the Langmuir and Freundlich isotherm models could be used to describe the $Sr^{2+}$ adsorption onto immobilized S. cerevisiae microspheres. The maximal adsorption capacity ($q_m$) was calculated to be 81.96 mg/g by the Langmuir model. Immobilized S. cerevisiae was an effective adsorbent for the $Sr^{2+}$ removal from aqueous solution.

• Environmental Engineering Research
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• 제19권3호
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• pp.205-214
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• 2014

Petroleum a vital commodity affecting every aspect of 21st century. Toxicity and adverse effects of sulphur as catalyst in petroleum products is of great concern required development of techniques for desulphurization in compliance with the International standards. Installation of desulphurizing units costs over $200 million per unit placing economic burden on developing countries like Pakistan. Present study analysis of commercial fuels (station petrol and jet fuel JP8) on gas chromatography-mass spectrometry (GC-MS) identified sulphur concentration of 19.94 mg/L and 21.75 mg/L, respectively. This scenario urged the researcher to attempt synthesis of material that is likely to offer good adsorption capacity for sulphur. Following protocol of sol-gel method, transition metals (Ni, Cu, Zn) solution is gelated with tetraethoxysilane (TEOS; silica precursor) using glycerol. Fourier transform infrared spectroscopy (FTIR) spectra revealed bonding of Zn-O, Cu-O, and Ni-O by stretching vibrations at $468cm^{-1}$, $617cm^{-1}$, and $468cm^{-1}$, respectively. Thiophene and Benzothiophene mixed in n-heptane and benzene (4:1) for preparation of Model Fuels I and II, respectively. Each of silica based metal was applied as adsorbent in batch mode to assess the removal efficiency. Results demonstrated optimal desulphurization of more than 90% following efficacy order as Si-Ni > Si-Zn > Si-Cu based adsorbents. Proposed multilayered (Freundlich) adsorption mechanism follows ${\pi}$-complexation with pseudo secnd order kinetics.

• 한국토양비료학회지
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• 제44권4호
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• pp.615-624
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• 2011

last few decades. In this study, the lyophilized cells of Pleurotus eryngii (mushroom) were used as an inexpensive biosorbent for Cd(II) and Pb(II) removal from aqueous solutions. The effect of various physicochemical factors on Cd(II) and Pb(II) biosorption such as pH (2.0-7.0), initial metal concentration ($0.0-300mg\;L^{-1}$), temperature, fungal biomass and contact time (0-120 min) were studied. Optimum pH for removal of Cd(II) and Pb(II) was 6.0, and the contact time was 45 min at room temperature. The nature of biosorbent and metal ion interaction was evaluated by Infrared (IR) spectroscopic technique. IR analysis of mushroom biomass revealed the presence of amino, carboxyl, hydroxyl and methyl groups, which are responsible for biosorption of Cd(II) and Pb(II). The maximum adsorption capacities of P. eryngii for Pb(II) and Cd(II) calculated using Langmuir adsorption isotherm were 82.0 and $16.13mg\;g^{-1}$, respectively. The adsorption isotherms for two biosorbed heavy metals were fitted well with Freundlich isotherm as well as Langmuir model with correlation coefficient ($r^2$>0.99). Thus, this study indicated that the P. eryngii is an efficient biosorbent for the removal of Cd(II) and Pb(II) from aqueous solutions.

• 한국물환경학회지
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• 제22권3호
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• pp.498-503
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• 2006

Adsorption features of $Cd^{2+}$ on waste tire particles have been investigated for the purpose of enhanced wastes recycling along with the development of an economic process for wastewater treatment. The isoelectric point of waste tire particles was found to be ca. pH 7 and the adsorbed amount of $Cd^{2+}$ was increased with pH under experimental conditions. The variation of the adsorption behavior of $Cd^{2+}$ with pH was well explained by the change of the electrokinetic potential of waste tire particles according to the pH. Adsorption of $Cd^{2+}$ was observed to reach its equilibrium within 45 minutes after the adsorption started under experimental conditions and followed the Freundlich model well. Kinetic analysis showed that the adsorption reaction of $Cd^{2+}$ was second order and thermodynamic estimation substantiated the endothermic behavior of $Cd^{2+}$ adsorption. As the amount of adsorbent increased, more adsorption of $Cd^{2+}$ was accomplished and the adsorption capacity of adsorbent was found to be enhanced by its pre-treatment with NaOH. Also, the adsorption of adsorbate was promoted as the ionic strength of wastewater was increased.

• 한국물환경학회지
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• 제23권2호
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• pp.222-227
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• 2007

The adsorption features of fluoride ion on the oyster shell have been investigated for the purpose of the employment of waste oyster shell as an adsorbent for the treatment of fluoride ion-containing wastewater. The major component of oyster shell was examined to be Ca with minor components of Na, Si, Mg, Al, and Fe. As the initial concentration of fluoride ion was raised, its absorbed amount was enhanced at equilibrium, however, the adsorption ratio of fluoride ion compared with its initial concentration was shown to be decreased. Also, adsorption of fluoride ion onto the oyster shell resulted in the formation of $CaF_2$ in the morphological structure of adsorbent. Kinetic analysis showed that the adsorption reaction of fluoride ion generally followed a second order reaction with decreasing rate constant with the initial concentration of adsorbate. Freundlich model agreed well with the adsorption behavior of fluoride ion at equilibrium and the adsorption reaction of fluoride ion was examined to be endothermic. Several thermodynamic parameters for the adsorption reaction were calculated based on thermodynamic equations and the activation energy for the adsorption of fluoride ion onto oyster shell was estimated to be ca. 13.589 kJ/mole.