Kipal Kim

Adsorption characteristics of phenol and chlorophenols on granular activated carbons (GAC)

The adsorption of phenol and chlorophenols on four commercial granular activated carbons (GAC) was investigated by batch experiment to correlate with the structure of activated carbons. Physical properties including surface area, average pore diameter and micropore volume and chemical structure of the activated carbons were characterized by N2 adsorption experiment, scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, elemental analysis, X-ray photoelectron spectroscopy (XPS) and FT-IR spectroscopy. To calculate the adsorption parameters, adsorption isotherm data were fitted to the Freundlich equation. From the correlation between the characterization and the Freundlich parameters, it is concluded that the adsorption behavior of phenol and chlorophenols on activated carbons is controlled by the dispersion force between the π-electrons in activated carbons and those in phenol molecules.

Evaluation on the adsorption capabilities of new chemically modified polymeric adsorbents with protoporphyrin IX.

A chemically modified polymeric adsorbent was synthesized to evaluate the availability as an adsorbent for solid-phase extraction (SPE) of phenol and chlorophenols. Commercially available Amberlite XAD-2 and XAD-4 resins were modified with macrocyclic protoporphyrin IX (PPIX) through the ketone linkage. Adsorption isotherms were obtained by batch experiments and the data were fitted to the Freundlich equation to calculate the adsorption parameters. Breakthrough volumes were measured by column experiments. Physical properties such as surface area, average pore diameter and micropore volume of resins were measured to correlate with the adsorption characteristics. As a result, adsorption capacity was increased for the chemically modified resins and it can be concluded that the increase of pi-pi interaction due to the introduction of the porphyrin molecule is the major factor for the increase of the adsorption capacity.

Phosphate adsorption ability of biochar/Mg-Al assembled nanocomposites prepared by aluminum-electrode based electro-assisted modification method with MgCl₂ as electrolyte.

In this work, the textural properties and phosphate adsorption capability of modified-biochar containing Mg-Al assembled nanocomposites prepared by an effective electro-assisted modification method with MgCl2 as an electrolyte have been determined. Structure and chemical analyses of the modified-biochar showed that nano-sized stonelike or flowerlike Mg-Al assembled composites, MgO, spinel MgAl2O4, AlOOH, and Al2O3, were densely grown and uniformly dispersed on the biochar surface. The adsorption isotherm and kinetics data suggested that the biochar/Mg-Al assembled nanocomposites have an energetically heterogeneous surface and that phosphate adsorption could be controlled by multiple processes. The maximum phosphate adsorption capacity was as high as 887 mg g(-1), as fitted by the Langmuir-Freundlich model, and is the highest value ever reported. It was concluded that this novel electro-assisted modification is a very attractive method and the biochar/Mg-Al assembled nanocomposites provide an excellent adsorbent that can effectively remove phosphate from aqueous solutions.

Influence of pyrolysis temperature on characteristics and phosphate adsorption capability of biochar derived from waste-marine macroalgae (Undaria pinnatifida roots).

The collected roots of Undaria pinnatifida, the main waste in farming sites, accounting for 40-60% of annual production, was pyrolyzed under temperature ranging from 200 to 800°C to evaluate the influence of pyrolysis temperature on biochar properties and phosphate adsorption capacity. It was confirmed that an increase in the pyrolysis temperature led to a decrease of the yield of biochar, while ash content remained almost due to carbonization followed by mineralization. Elemental analysis results indicated an increase in aromaticity and decreased polarity at a high pyrolysis temperature. When the pyrolysis temperature was increased up to 400°C, the phosphate adsorption capacity was enhanced, while a further increase in the pyrolysis temperature lowered the adsorption capacity due to blocked pores in the biochar during pyrolysis. Finally, a pot experiment revealed that biochar derived from waste-marine macroalgae is a potent and eco-friendly alternative material for fertilizer after phosphate adsorption.

Selective Solid-Phase Extraction of Polycyclic Aromatic Hydrocarbons by the Chemically Modified Polymeric Adsorbents with Protoporphyrin IX

SummaryThe chemically modified polymeric adsorbents were evaluated for selective solid-phase extraction of polycyclic aromatic hydrocarbons. Commercially available Amberlite XAD-2 and XAD-4 resins were modified with macrocyclic protoporphyrin IX or tetrakis(p-carboxyphenyl)-porphyrin through the ketone linkage. The variables that influence the selectivity and recovery of the solid-phase extraction were optimized. The best result was obtained with XAD-4 resins modified with macrocyclic protoporphyrin IX. After preconcentration and clean-up step, the polycyclic aromatic hydrocarbons were determined by gas chromatography with mass spectrometric detection. The method was used to determine polycyclic cromatic hydrocarbons in soil, and the recovery was in the range of 79.6% to 94.1%.