Adsorption of 4-chlorphenol by brown coal activated by potassium hydroxide
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Дата
2021
Науковий керівник
Назва журналу
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Назва тому
Видавець
КПІ ім. Ігоря Сікорського; ТОВ «Українська водна спілка»
Анотація
The purpose of the work is to evaluate the 4-chlorophenol (CP) adsorption capacity of brown coal
activated carbons (ACs) prepared at different temperature of KOH activation. ACs were obtained in three
stages: 1) impregnation of coal with a KOH solution, 2) heating (4 deg/min) in argon to a given temperature
t (400-800C) and exposure for 1 h, 3) cooling, washing from KOH, drying. The samples are designated as
AC(t). Based on the N2 adsorption-desorption isotherms, the ACs total pore volume (Vt, cm3
/g) and specific
surface area (S, m2
/g) were determined. The ACs adsorption capacities were measured at 25С, CP
concentration 700 mg/L, АC dosage – 1 g/L. The alkaline activation temperature was found to be a key
factor in forming porosity of ACs and ability to adsorb CP. The CP maximum capacity (ACP(m), mg/g)
increases 6.6 times up to 307 mg/g for AC(800) having S=1142 m2
/g. The specific adsorption capacity
(ACP(S) = ACP(m)/S, mg/m2
) sharply decreases in a sample range from AC(400) to AC(550) and weakly
depends on temperature at 550-800C. The kinetics of CP adsorption is best described by a pseudo-second
order model. The rate determining stage is the interaction of CP molecules with AC surface. The CP
adsorption isotherms are best described by the Langmuir model. The dependence of the ACP(m) from S can be
approximated by three linear equations that probably correspond to the three regions of forming surface
adsorbtion centers (AdCs). The first (S370 m2
/g) is characterized by a small adsorption capacity increment
(kS=0.103 mg/m2
), but a significant (16.4 times) decrease in the specific capacity ACP(S). In the second region
(S=370-770 m2
/g, t=550-750C), capacity increment is 10 times more (kS=0.985 mg/m2
) and in the third
region (S770 m2
/g, t750C) the increase in CP capacity is the smallest (kS=0.067 mg/m2
). The
thermoinitiated formation of AdCs is assumed to be not proportional to the increase in surface area, and
their chemical structure and reactivity is determined by the alkaline activation temperature.
Опис
Ключові слова
activated carbon, adsorption, alkaline activation, brown coal, porous structure, 4-chlorophenol, адсорбція, активоване вугілля, буре вугілля, лужна активація, пориста структура, 4-хлорфенол
Бібліографічний опис
Таmarkina, Yu. V. Adsorption of 4-chlorphenol by brown coal activated by potassium hydroxide / Yu. V. Таmarkina, I. B. Frolova, V. O. Кucherenko // Вода і водоочисні технології. Науково-технічні вісті. – 2021. – № 1(29). – С. 36-78.