Krízový manažment / Crisis Management

Krízový Manažment 2019, 18(1):12-20 | DOI: 10.26552/krm.C.2019.1.12-20

SORPTION OF TWO ORGANIC DYES AND THE MEASUREMENT OF SPECIFIC SURFACE AREA OF SORBENTS USED IN DISASTERS AND EMERGENCY SITUATIONS

Priscilla KECHE, Cyril S. DUBE, Roman TANDLICH

Division of Pharmaceutical Chemistry, Faculty of Pharmacy Rhodes University, Biotechnology Innovation Centre, P.O. Box 94, Grahamstown 6140, South Africa

The specific surface areas of kaolinite, activated charcoal and talc cover a wide range of values, which are extensively reported in literature. Therefore, these three adsorbents were used in this study for comparison of the specific surface area measurements using two molecular probes in the dye adsorption method, namely methylene blue and brilliant green. Both dyes were dissolved in MilliQ water and the batch-equilibration technique was used to measure the respective adsorption isotherms. The equilibrium data was analysed using the Langmuir isotherm and the specific surface areas were calculated using the maximum sorption capacities for methylene blue and brilliant green, as well as the literature/calculated molecular dimensions of methylene blue and brilliant green. Adsorption equilibrium of all three adsorbents was attained within the first 24 hours of contact time with both dyes, and the adsorption followed the Langmuir isotherm model which reflects the formation of a monolayer of both dyes on all three adsorbents. Use of NaOH to increase pH of methylene blue to a stable pH of 8.5 ± 0.2 was not achieved due to methylene blue exhibiting buffering properties within the first 2 hours of the adjustment. Preparation of methylene blue and brilliant green dilutions using MilliQ water only, resulted in a more stable acidic pH of 6±0.5 and 5±0.5 respectively. The pH of dye solutions ha s a significant effect on the adsorption process. The specific surface area values of talc (136.1 m2/g) and kaolinite (24.22 m2/g) determined using brilliant green dye are higher than those determined using methylene blue dye. Brilliant green was found to be more stable than methylene blue, and talc powder indicated to be a highly significant adsorbent in wastewater treatment containing brilliant green dye. Surface area results show that kaolinite and activated charcoal have high affinity for methylene blue.

Keywords: Methylene blue, Brilliant green, Sorption, Langmuir isotherm, Wastewater

Published: March 30, 2019  Show citation