In the paper the chemical modification of activated carbon was presented. The activated carbon was modified by nitric acid. For the tested activated carbons, the following physical and chemical properties were determined: bulk density, pH of the water extract, and effective diameter of the grains. Elemental and technical analyses were performed. The pore distribution was determined using mercury porosimetry. Low-temperature nitrogen isotherms were used to analyze the microporous structure. The chemical properties of the surfaces of the tested adsorbents were interpreted by means of the Boehm method. The water vapor adsorption isotherms at 303 K were determined and the adsorption capacity towards methanol was tested using the desiccator method. Thermogravimetric tests were used and, at the same time, the released oxidizing gases from the tested samples were analyzed using a mass spectrometer. As a result of the modification, activated carbon enriched with acidic oxygen functional groups was obtained. The resulting modified activated carbon showed worse structural parameters (when compred to umodified activated carbon), however it was characterized by a higher adsorption capacity in relation to polar adsorbates such as water and methanol, especially in the low pressure range.

The paper presents a numerical approach to the analysis of the statistical effect of functional groups on the sorption of methanol and water on hard coal samples. The material used for the analysis was obtained from numerous samples of hard subbituminous and bituminous coals up to anthracite from different Polish coal mines and includes sorption isotherms of water and methanol vapors, as well as carbon dioxide and methane on these samples. Measurements were made of the sorption isotherms of water and methanol vapors and the data set has been supplemented with the sorption isotherms of water, methane and carbon dioxide taken from the literature for the precise estimation of the model parameters. More precise estimation is reached by using a strong setting of the coal structure parameters for a bigger number of sorption system, and in each case the same parameters of coal geometry are constant with an exact fitting of sorption isotherm. The adsorption-absorption model of the sorption in coal (Multiple Sorption Model-MSM) is used in the numerical experiments and the parameters of hard coal structure and the sorption systems are estimated. It has been stated that water as a polar substance together with methanol, as well as carbon dioxide and methane give good estimates of coal structure and let us quantify the polar effect of surface groups present in hard coal. The polar effect is introduced in the model in the range of adsorption and expansion sub-processes. The presence of oxygen groups in the bulk of coal matter has no significant effect and can be neglected. A weak decreasing tendency of polar factors ratio for water and methanol is discovered.

The objective of the experimental work was to determine the removal efficiency of selected dyes from aqueous solutions using an adsorption process. Studies of adsorption from aqueous solution on a laboratory scale were performed for the two dyes, bromocresol green and methyl orange. Activated carbon from coconut shell, lignite from Bełchatów mine and biosorbent from orange peel as an alternative adsorbent were used. For the study were selected grain fractions of ϕ=1.0-1.5 mm. The experiment was carried out at constant room temperature for 30 minutes in static conditions of contact. The influence of both dye concentration in the solution, and the dosage of sorbent to the dye sorption capacity is stated. The results are presented as isotherms. Biosorbent preparation process should be modified in order to avoid its decay under dye sorption from an aqueous solution. Biosorbent is comparable porous material to active carbon AC1 for bromocresol green when they have adsorption capacity am [mmol•g-1] 0.0199 and 0.0209, respectively. In the case of methyl orange adsorption capacity is 0.2061for AC1 and 0.0135 for biosorbent. It means that in second case biosorbent is weak adsorbent for water cleaning, even worse than lignite Be (am=0.0399 [mmol•g-1]. Finally, this kind of biosorbent is not suitable for adsorption cleaning of water for methyl orange at this stage of processing because maceration of material and freeing of natural dye occur.

E3S Web of Conferences, open access proceedings in environment, energy and earth sciences

E3S Web of Conferences, open access proceedings in environment, energy and earth sciences