M.S. Balathanigaimani

Preparation of powdered activated carbon from rice husk and its methane adsorption properties

Success of adsorbed natural gas (ANG) storage process is mainly based on the characteristics of the adsorbent, so various synthesized adsorbents were analyzed for methane adsorption on a thermodynamic basis. Activated carbon from rice husk (AC-RH) was synthesized and its methane adsorption capacities were compared with phenol based activated carbons (AC-PH2O and AC-PKOH). The adsorption experiments were conducted by volumetric method under various constant temperatures (293.15, 303.15, 313.15 and 323.15 K) and pressure up to 3.5MPa. Maximum methane adsorption was observed in AC-RH as its surface area is higher than the other two adsorbents. The experimental data were correlated well with Langmuir-Fruendlich isotherms. In addition, isosteric heat of adsorption was calculated by using Clausius-Clapeyron equation.

Adsorptive Removal of Nitrate and Phosphate Using MCM-48, SBA-15, Chitosan, and Volcanic Pumice

The nitrate and phosphate adsorption capacities of laboratory made and naturally available adsorbents were studied in this study. Two mesoporous silica materials, Mobil composition of matter no. 48 (MCM-48) and Santa Barbara Amorphous-15 (SBA-15), were hydrothermally synthesized, and chitosan was made by reacting crab shells with sodium hydroxide. Pumice powder was prepared by grinding volcanic rocks. All adsorbent powders were characterized by nitrogen adsorption/desorption, X-ray diffraction, Fourier transform infrared (FT-IR), scanning electron microscope (SEM), and high-resolution transmission electron microscopy (TEM) to check their physical properties and surface morphology as adsorbent materials. The adsorption isotherm data of nitrate and phosphate were described by both Langmuir and Freundlich isotherm models. In general, phosphate adsorption isotherms seem to be favorable while some of nitrate adsorption isotherms are slightly unfavorable and linear. Furthermore, the pseudo-second kinetic model is good in describing the batch adsorption rates. Among four adsorbent materials, MCM-48 shows the highest adsorption capacity for both nutrients while the adsorption capacity of SBA-15 is much lower than expected. It should be noted that pumice has considerably high adsorption ability for phosphate and chitosan has good capacity for nitrate even if they have much lower Brunauer, Emmett, and Teller (BET) surface area than mesoporous silica materials.

Nanostructured Biomass Based Carbon Materials from Beer Lees for Hydrogen Storage

The present work describes the preparation of carbon materials from beer lees and their hydrogen adsorption abilities. Activated carbons (ACs) from beer lees were prepared through chemical activation using potassium hydroxide as an activating agent. The low temperature nitrogen adsorption isotherm studies on prepared ACs were conducted at 77 K to determine their physical properties and adsorption energy distribution. The beer lees based carbons have energetically heterogeneous surfaces and high surface area ranging from 1927-2408 m2/g. ACs prepared in this study show the gravimetric hydrogen adsorption capacity of 2.43-2.92 wt% depending on their physical properties.