• Journal of Korean Society on Water Environment
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• v.24 no.6
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• pp.670-675
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• 2008

Batch type adsorption and desorption tests were performed with different types (Powder, Granule) of Layered double hydroxides (LDHs) saturated with phosphate. The adsorption isotherm was approximated as a modified Langmuir type equation. The maximum adsorption capacity was 55 mg-P/g-LDH for powder type LDH, and 46 mg-P/g-LDH for granule type LDH. The highest phosphate desorption (79.6%) was obtained with 20% NaOH solution, whereas the desorption degrees were 4.8, 22.2% and 46.7% in the solutions of acidic condition (pH 4), 30% NaCl, and 3% NaOH, respectively. It was suggested that the optimal condition for the phosphate desorption from LDH was 30% NaCl + 3~6% NaOH solutions. The desorption characteristics of LDH was little influenced by adsorbent type.

• Korean Journal of Environmental Agriculture
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• v.25 no.4
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• pp.365-370
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• 2006

This study was performed to determine the adsorption-desorption characteristics of polyhexame-thyleneguanidine phosphate in three different soil types of textural classification. Adsorption and desorption studies is impotent for prediction their fate and generating essential information on the mobility of chemicals and their distribution in the soil, water and air of our biosphere. The detection limit of the test substance quantified by a spectroscopic method using Eosin indicator was $0.25{\mu}g/mL$. The reproducibility of analytical method was confirmed by the preliminary test. The concentrations of polyhexamethylenequanidine phosphate in aqueous solution were $1.36{\pm}0.09,\;2.45{\pm}0.01,\;and\;$4.25{\pm}0.05{\mu}g/mL$ by a spectroscopic method using Eosin indicator. The adsorption percents of polyhexamethylenequanidine phosphate in soil were greater than 95.2% for all three test soils. The desorption percents from the adsorbed soil were less than 4.5, 4.7 and 4.7%. Therefore, the adsorption coefficient (K) were greater than 110, 111 and 116. The adsorption coefficient calculated as a function of the organic carbon content (Koc) of the test soils were greater than 9,181, 11,100, and 8,942, respectively. Therefore, the test substance, polyhexamethylenequanidine phosphate could be concluded as medium or high adsorption (>25%) and poorly desorption (<75%) in soil media. Therefore, this chemical is likely to be retained in soil media and may not pose a risk in the aquatic environment.

• BMB Reports
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• v.30 no.5
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• pp.346-351
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• 1997

The maximum adsorption/desorption conditions and the adsorption mechanism of globular proteins to vaccine adjuvants were determined. The maximum adsorption ratio of protein to the $Al^{3+}$ content of aluminum oxyhydroxide and the optimal adsorption pH are 2:1 (${\mu}g:{\mu}g$) for bovine serum albumin (BSA) at pH 6.0 and 2.5:1 (${\mu}g:{\mu}g$) for immunoglobulin G (IgG) at pH 7.0, respectively. The maximum adsorption ratio onto aluminum phosphate gel was 1.5:1 (${\mu}g$ Protein:${\mu}g$ $Al^{3+}$) at pH 5.0 for both BSA and IgG. Adsorption of the native globular proteins, BSA and IgG, to aluminum oxyhydroxide and aluminum phosphate gel was reversible as a function of pH. Complete desorption of these proteins from aluminum phosphate gel was observed at alkaline pH, whereas only 80~90% removal from aluminum oxyhydroxide was achieved with alkaline pH and 50 mM phosphate buffer. We conclude that electrostatic and hydrogen bonding interactions between the native proteins and adjuvants are important binding mechanisms for adsorption, and that the surface charge of the protein and the colloid components control the maximum adsorption conditions.

• Journal of the Mineralogical Society of Korea
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• v.22 no.4
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• pp.289-295
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• 2009

The characteristics of phosphate desorption on kaolinite was studied by batch adsorptiondesorption experiments. Desorption procedure was carried out through sequential extraction method at pH 4. The phosphorous contents were measured using UV-VIS-IR spectrophotometer with 820 nm wavelength. The adsorption-desorption reaction of P on kaolinite was irreversible, and most of adsorbed P on kaolinite were not easily dissolved to aqueous solution, but may might be fixed on kaolinite surface. The desorption isotherms were well fitted with the Freundlich and Temkin equations in the case of short reaction and long reaction time, respectively. The desorption reaction was divided into the early fast reaction and the later slow reaction. The percentage of desorption generally decreased with increasing adsorbed P concentration and increasing desorption reaction time.

• Journal of the Mineralogical Society of Korea
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• v.21 no.2
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• pp.117-127
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• 2008

The characteristics of phosphate adsorption-desorption on kaolinite was studied by batch adsorption experiments and detailed adsorbed state of phosphate on kaolinite surface was investigated using ATR-FTIR (Attenuated Total Reflectance-Fourier Transform Infrared) spectroscopy. The phosphorous contents were measured using UV-VIS-IR spectrophotometer with 820 nm wavelength. The adsorbed P was generally increased with increasing pH value in the range of pH 4 to pH 9, however it is not distinct. Moreover the adsorbed P was significantly changed with different initial phosphate concentration. The adsorption isotherms were well fitted with the Langmuir equation, Temkin equation, and Freundlich equation in descending order. The maximum Langmuir adsorption capacity of kaolinite KGa-2 is 232.5 ($204.1{\sim}256.5$) mg/kg and has very higher value than that of kaolinite KGa-1b. Most of adsorbed phosphate on kaolinite were not easily desorbed to aqueous solution, but might fixed on kaolinite surface. However it needs further research about the exact desorption experiment. It was impossible to recognize phosphorous adsorption bands on kaolinite in ATR-FTIR spectrum from kaolinite bands themselves, because the absorption peaks of phosphorous have very similar positions with those of kaolinite, and the intensities of the former were very weak in comparison with those of the latter.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2019.10a
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• pp.134-134
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• 2019

Utilization of organic waste as a renewable energy source is promising for sustainability and mitigation of climate change. Pyrolysis converts organic waste to gas, oil, and biochar by incomplete biomass combustion. Biochar is widely used as a soil conditioner and adsorbent. Biochar adsorbs/desorbs metals and ions depending on the soil environment and condition to act as a nutrient buffer in soils. Biochar is also regarded as a carbon storage by fixation of organic carbon. Phosphorus (P) and nitrogen (N) are strictly controlled in many wastewater treatment plants because it causes eutrophication in water bodies. P and N is removed by biological and chemical methods in wastewater treatment plants and transferred to sludge for disposal. On the other hand, P is an irreplaceable essential element for all living organisms and its resource (phosphate rock) is estimated about 100 years of economical mining. Therefore, P and N recovery from waste and wastewater is a critical issue for sustainable human society. For the purpose, intensive researches have been carried out to remove and recover P and N from waste and wastewater. Previous studies have shown that biochars can adsorb and desorbed phosphates implying that biochars could be a complementary fertilizer. However, most of the conventional biochar have limited capacity to adsorb phosphates and nitrate. Recent studies have focused on biochar impregnated with metal salts to improve phosphates and nitrate adsorption by synthesizing biochars with novel structures and surface properties. Metal salts and metal oxides have been used for the surface modification of biochars. If P removal is the only concern, P adsorption kinetics and capacity are the only important factors. If both of P and N removal and the application of recovery are concerned, however, P and N desorption characteristics and bioavailability are also critical factors to be considered. Most of the researches on impregnated biochars have focused on P removal efficiency and kinetics. In this study, coffee waste is thermally treated to produce biochar and it was impregnated with Mg/Al to enhance phosphates and nitrate adsorption/desorption and P bioavailability to increase its value as a fertilizer. Kinetics of phosphates and nitrate adsorption/desorption and bioavailability analysis were carried out to estimate its potential as a P and N removal adsorbent in wasewater and a fertilizer in soil.

• Advances in environmental research
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• v.3 no.3
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• pp.231-251
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• 2014

The present study examines the phosphate adsorption potential and behavior of mixture of Ground Burnt Patties (GBP), a solid waste generated from cooking fuel used in earthen stoves and Red Soil (RS), a natural substance in fixed bed column mode operation. The characterization of adsorbent was done by Proton Induced X-ray Emission (PIXE), and Proton Induced ${\gamma}$-ray Emission (PIGE) methods. The FTIR spectroscopy of spent adsorbent reveals the presence of absorbance peak at $1127cm^{-1}$ which appears due to P = O stretching, thus confirming phosphate adsorption. The effects of bed height (10, 15 and 20 cm), flow rate (2.5, 5 and 7.5 mL/min) and initial phosphate concentration (5 and 15 mg/L) on breakthrough curves were explored. Both the breakthrough and exhaustion time increased with increase in bed depth, decrease in flow rate and influent concentration. Thomas model, Yoon-Nelson model and Modified Dose Response model were used to fit the column adsorption data using nonlinear regression analysis while Bed Depth Service Time model followed linear regression analysis under different experimental condition to evaluate model parameters that are useful in scale up of the process. The values of correlation coefficient ($R^2$) and the Sum of Square Error (SSE) revealed the Modified Dose Response model as the best fitted model to the experimental data. The adsorbent mixture responded effectively to the desorption and reusability experiment. The results of this finding advocated that mixture of GBP and RS can be used as a low cost, highly efficient adsorbent for phosphate removal from aqueous solution.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.2
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• pp.151-160
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• 2014

Capacitive deionization(CDI) has many advantages over other desalination technologies due to its low energy consumption, less environmental pollution and relative low fouling potential. The objectives of this study are evaluate the performance of CDI which can be used for dissolved salts removal from sewage. To identify ion selectivity of nitrate and phosphate in multiionic solutions and adsorption/desorption performance related to applied potential, a series of laboratory scale experiments were conducted using a CDI unit cell with activated carbon electrodes. The CDI process was able to achieve more than 75 % TDS and $NO_3{^-}$, $NH_4{^+}$ removals, while phosphate removal was 60.8 % and is inversely related in initial TDS and $HCO_3{^-}$ concentration. In continuous operation, increasing the inner cell pressure and reduction of TDS removal ability were investigated which are caused by inorganic scaling and biofouling. However a relative mild cleaning solution(5 % of citric acid for calcium scaling and 500 mg/L of NaOCl for organic fouling) restored the electrochemical adsorption capacity of the CDI unit to its initial level.

• Environmental Engineering Research
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• v.19 no.1
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• pp.37-40
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• 2014

This research investigates the quality changes during composting of bagasse and pig manure amended with 30% of surfactant-coated charcoal (SC). Two treatments, 30% uncoated charcoal (UC) amendment and no charcoal (NC) amendment, were done as control. Charcoal was coated with 0.37 mM tetradecyltrimethylammonium bromide (TDMA), a cationic surfactant, at the dosage of 10 g/L. At the end of the composting period, the carbon to nitrogen (C/N) ratio of SC amendment was 9.7; whereas, the C/N ratios of UC and NC amendment were 12.6 and 21.4, respectively. Plant nutrients contents of the compost produced from SC amendment were 20.7 mg $NH_4{^+}-N/g$, 42.8 mg $NO_3{^-}-N/g$, and 41.7 mg P/g. High nitrate and phosphate concentrations in SC amendment were due to the adsorption of these anions on the positive charge of TDMA. Desorption of plant nutrients retained in the compost pellets was also investigated. It was predicted that nitrate was fully desorbed from a pellet at 23 days for SC amendment, which was later than UC (14 days) and NC (10 days) amendment. A slow release of nitrate from the compost pellet will reduce the nitrate leaching into the environment. Thus, the adding of SC in the compost pile is one of the alternative methods to improve the quality of compost and plant nutrient retention.