Author(s):
1. Branko Škundrić, Akademija nauka i umjetnosti Republike Srpske, Republic of Srpska, Bosnia and Herzegovina
2. Rada Petrovic, Republic of Srpska, Bosnia and Herzegovina
3. Jelena Penavin-Škundrić, Prirodno-matematički fakultet Banja Luka, Republic of Srpska, Bosnia and Herzegovina
4. Dragana Gajić, Prirodno-matematički fakultet Banja Luka, Republic of Srpska, Bosnia and Herzegovina
5. Darko Bodroža, Faculty of Technology Banja Luka, Republic of Srpska, Bosnia and Herzegovina

Abstract:
This paper studies adsorption of hexavalent chromium, Cr(VI), from aqueous solution onto natural clay kaolinite (kaolinite mine “Motajica”, Kobaš, Srbac). The effect of adsorbent weight, contact time, pH value of solution and temperature on efficiency of adsorption was examined. Optimal parameters were: adsorbent weight m=0,5 g; contact time t=1 hour; pH=3,0 and temperature t=35ºC, while the efficiency, based on these parameters, was 31,12%. Adsorption of hexavalent chromium, Cr(VI), from aqueous solution onto natural clay kaolinite is the result of electrostatic interactions. Experimental data were analyzed using three linearized adsorption models: Freundlich, Langmuir and Temkin. In this adsorption process of hexavalent chromium, Cr(VI), onto kaolinite, the Freundlich isotherm model has the highest value of correlation coefficient (R2=0,961) and therefore best describes equilibrium phenomena of Cr(VI) adsorption onto this adsorbent. Based on the value of Freundlich constant, KF (=0,0416 (mgg-1)(mgL-1)1/n), which is in the correlation with adsorbent capacity, it is concluded that kaolinite has relatively low adsorption capacity for hexavalent chromium, Cr(VI). The second Freundlich constant, n, is related to adsorption intensity of adsorbent and surface heterogeneity. Obtained value for n, is greater than one (n=1,2516) and indicates that it is favored adsorption. Based on obtained and analyzed data of adsorption process, it can be concluded that natural clay kaolinite showed sufficient removal efficiency to be used as an adsorbent for hexavalent chromium, Cr(VI), removal from aqueous solutions.

Key words:
adsorption, kaolinite, hexavalent chromium, Cr(VI), Freundlich isotherm, Langmuir isotherm, Temkin isotherm

Thematic field:
SYMPOSIUM A - Science of matter, condensed matter and physics of solid states

Date of abstract submission:
06.07.2020.

Conference:
Contemporary Materials 2020 - Savremeni materijali