• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2001.09a
• /
• pp.19-22
• /
• 2001

The effects of pH on the sequential sorption/desorption of chlorinated phenols (2-chlorophenol, 2.4-dichlorophenol and 2,4,5-trichlorophenol) in HDTMA-montmorillonite were investigated by maintaining pH 4.85 or 9.15 in the sequential batch sorption and desorption experiments. The chlorinated phenols are hydrophobic ionizable orginic compounds; they can exist as either neutral (pH << pKa) or anionic (pH >> pKa) forms. Among the tested chlorinated phenols, 2,4,5-trichlorophenol showed the highest sorption affinity at pH 4.85 as expected by the $K_{ow}$ . Neutral speciation at pH 4.85 exhibited higher sorption affinity than anionic speciation at pH 9.15. Our results indicates that desorption of chlorinated phenols is strongly dependent on pH of the aqueous phase. Freundlich model was used to analyze the single-solute sorption/desorption results. The ideal adsorbed solution theory(IAST) was employed to predict the hi-solute sorption/desorption equilibria.

• Journal of Environmental Science International
• /
• v.20 no.2
• /
• pp.215-222
• /
• 2011

The adsorption behavior of nitrate nitrogen was investigated from aqueous solution using char prepared from oak chip. The removal rate of nitrate nitrogen was found to be dependent on temperature and it is increased as the temperature increase. Adsorption equilibrium data of nitrate nitrogen on oak char. reasonably fitted Langmuir and Freundlich isotherm models. The adsorption energy obtained from D-R model was 12.5 kJ/mole at $20^{\circ}C$ indicating an ion exchange process as primary adsorption mechanism. Thermodynamic parameters such as ${\Delta}G^o$, ${\Delta}H^o$, and ${\Delta}S^o$ were -23.76 kJ/mole, 26.1 kJ/mole and 89.7 J/K mole at $20^{\circ}C$, respectively, indicated that the nature of nitrate nitrogen adsorption is spontaneous and endothermic.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.7
• /
• pp.2217-2221
• /
• 2011

We investigated the selective deoxyribonucleic acid (DNA) adsorption on layered double hydroxide (LDH) nanoparticles via studying the interaction between positively charged LDH nanoparticle as adsorbent and negatively charged adsorbates such as methyl orange (MO), fluorescein (FL), and DNA strands. The size controlled LDH $(Mg_{0.78}Al_{0.22}(OH)_2(CO_3)_{0.11}{\cdot}mH_2O)$ was prepared by conventional coprecipitation method, followed by the hydrothermal treatment. According to the adsorption isotherms, the adsorbed amounts of MO and FL were similar, however, that of DNA were much larger. The adsorption behaviors were well fitted to Freundlich adsorption model. The concentration dependent adsorption behavior on LDH surface was described in order to verify the selective DNA separation ability. The result showed that the LDH has advantages in selective adsorption of DNA competing with single molecular anions.

• Journal of Korean Society on Water Environment
• /
• v.21 no.1
• /
• pp.14-20
• /
• 2005

A feasibility study has been conducted regarding the application of waste coffee grounds as an adsorbent for the treatment of nickel ion containing wastewater. The major variables which considered to influence the adsorbability of nickel ion were its initial concentration, reaction temperature, pH, and coexisting ion. The specific surface area of coffee grounds used in the experiment was found to be ca. $39.67m^2/g$, which suggesting its potential applicability as an adsorbent due to its relatively high surface area. In the experimental conditions, more than 90% of the initial amount of nickel ion was shown to adsorb within 15 minutes and equilibrium in adsorption was attained after 3 hours. The adsorption behavior of nickel ion was well explained by Freundlich model and kinetics study showed that the adsorption reaction was second-order. Adsorption was reduced with temperature and its change of enthalpy in standard state was estimated to be -807.05 kJ/mol. Arrhenius equation was employed for the calculation of the activation energy of adsorption and nickel ion was observed to adsorb on coffee grounds exoentropically based on thermodynamic estimations. As pH rose, the adsorption of nickel ion was diminished presumably due to the formation of cuboidal complex with hydroxide ion and the coexistence of cadmium ion was found to decrease the amount of nickel ion adsorption, which was proportional to the concentration of cadmium ion.

• Carbon letters
• /
• v.15 no.2
• /
• pp.105-112
• /
• 2014

Wastewater from textile industries is a major cause of water pollution in most developing countries. In order to address the issues of water pollution and high cost for treatment processes, the use of an inexpensive and environmentally benign adsorbents has been studied. The objective was to find a better alternative to the conventional methods. Lemon grass waste (ash) collected from a lemon grass stream distillation subunit in Bhutan was tested for dye removal from aqueous solutions. The study investigated the removal of methylene blue using the following operational parameters: initial concentration (100-600 mg/L), contact time, adsorbent dose (0.1-0.55 gm/100 mL), and pH (3-10). It was found that the percentage removal of dye increased with a decrease of the initial concentration and increased contact time and dose of adsorbent. The basic pH solution of dye showed better adsorption capacity as compared to the acidic dye solution. Langmuir and Freundlich adsorption isotherms were fitted to the data well. Data fitted better to Lagergren pseudo 2nd order kinetics than a 1st order kinetic model. Surface morphology was also examined via scanning electron microscopy. An elemental analysis was also carried out and the chemical composition and functional groups were analyzed using energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy techniques, respectively. The obtained results indicate that lemon grass ash could be employed as a low cost alternative to commercial activated carbon in wastewater treatment for the removal of dyes.

• Environmental Engineering Research
• /
• v.25 no.4
• /
• pp.605-613
• /
• 2020

This study is to investigate the possibility of using activated carbon prepared from Iraqi date-pits (ADP) which are produced from palm trees (Phoenix dactylifera L.) as low-cost reactive material in the permeable reactive barrier (PRB) for treating lead (Pb⁺²) from the contaminated groundwater, and then compare the results experimentally with other common reactive materials such as commercial activated carbon (CAC), zeolite pellets (ZP). Factors influencing sorption such as contact time, initial pH of the solution, sorbent dosage, agitation speed, and initial lead concentration has been studied. Two isotherm models were used for the description of sorption data (Langmuir and Freundlich). The maximum lead sorption capacities were measured for ADP, CAC, and ZP and were found to be 24.5, 12.125, and 4.45 mg/g, respectively. The kinetic data were analyzed using various kinetic models particularly pseudo-first-order, pseudo-second-order, and intraparticle diffusion. COMSOL Multiphysics 3.5a depend on finite element procedure was applied to formulate transmit of lead (Pb⁺²) in the two-dimensional numerical (2D) model under an equilibrium condition. The numerical solution shows that the contaminant plume is hindered by PRB.

• Journal of Korean Society of Water and Wastewater
• /
• v.10 no.4
• /
• pp.103-110
• /
• 1996

Excessive phosphorus (P as orthophosphate) is one of the major pollutants in natural water that are responsible for algal blooms and eutrophication. P removal by slag is an attractive solution if the P sorption capacity of the slag is significant. To design an efficient land treatment facility, basic information on the behaviour of P in the media-water environment is required. In this study, detailed column experiments were conducted to study the P transport under dynamic condition, and mathematical models were developed to describe this process. The column experiments conducted with dust and cake waste products (slag) from BHP steel industry in Australia as adsorbing media indicated that they had higher sorption capacity of P than that of a sandy loam soil from North Sydney, Australia. P transport in the dust and cake columns exhibited characteristics S-shaped or curvilinear breakthrough curves. The simulated results from a dynamic physical non-equilibrium sorption model (DPNSM) and Freundlich isotherm constants satisfactorily matched the corresponding experimental breakthrough data. The mobility of P is restricted proportionally to the adsorbent's sorption capacity.

• Journal of Korean Society of Water and Wastewater
• /
• v.30 no.1
• /
• pp.105-111
• /
• 2016

This paper presents the applicability of natural zeolite (Clinoptilolite) for recovery of ammonium nitrogen from high-strength wastewater stream. Isotherm experiments showed the ammonium exchange Clinoptilolite followed Freundlich isotherm and its maximum exchange capacity was $18.13mg\;NH_4{^+}-N/g$ zeolite. The X-ray photoelectron spectroscopy (XPS) analysis indicated that a significant amount of nitrogen was adsorbed to the Clinoptilolite. Optimal flowrate for recovery of high concentration ammonium nitrogen was determined at 16 BV/d (=19.2 L/min) throughout the lab-scale column studies operated under various flowrate conditions. This study also provided a method to determine the recovery rate of final product of nitrogen fertilizer based on the model application to the lab-scale continuous data.

• Applied Chemistry for Engineering
• /
• v.31 no.5
• /
• pp.495-501
• /
• 2020

In this study, zirconium fumarate of metal-organic framework (MOF-801) was solvothermally synthesized at 130 ℃ and characterized through powder X-ray diffraction (PXRD) analyses and porosity measurements from N₂ sorption isotherms at 77 K. The ability of MOF-801 to act as an adsorbent for the phosphate removal from aqueous solutions at 25 ℃ was investigated. The phosphate removal efficiency (PRE) obtained by 0.05 g/L adsorbent dose at an initial phosphate concentration of 60 ppm after 3 h was 72.47%, whereas at 5 and 20 ppm, the PRE was determined to be 100% and 89.88%, respectively, after 30 min for the same adsorbent dose. Brunauer-Emmett-Teller (BET) surface area and pore volume of the bare MOF-801 sample were 478.25 ㎡/g and 0.52 ㎤/g, respectively, whereas after phosphate adsorption (at an initial concentration of 60 ppm, 3 h), the BET surface area and pore volume were reduced to 331.66 ㎡/g and 0.39 ㎤/g, respectively. The experimental data of kinetic (measured at initial concentrations of 5, 20 and 60 ppm) and isotherm measurements followed the pseudo-second-order kinetic equation and the Freundlich isotherm model, respectively. This study demonstrates that MOF-801 is a promising material for the removal of phosphate from aqueous solutions.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.38 no.3
• /
• pp.153-157
• /
• 2005

The biosorption of Pb and Cr by Sargassum thunbergii was investigated in a batch conditions. The Pb and Cr uptake capacity of Sargassum thunbergii was 232.5 mg Pb/g biomass and 91.6 mg Cr/g biomass, respectively. An adsorption equilibria was reached within about 0.5 hr for both the Pb and the Cr. The adsorption parameters for both the Pb and the Cr were determined according to the Langmuir and Freundlich model. With increasing pH values, more negative sites are becoming available for the adsorption of Pb and Cr. The selectivity of mixture solution showed an uptake order of Pb>Cu>Cr>Cd. Pb and Cr adsorbed by S. thunbergii could be recovered ken 0.1 M HCl, 0.1 M $HNO_3$ and 0.1M EDTA by a desorption process, and the efficiency of Pb desorption was above $95.8\%$, whereas the efficiency of the Cr desorption was below $50.7\%$.