Nitrogen-modified nanoporous activated carbon from eucalyptus leaves for ultrasound-assisted removal of basic dyes using derivative spectrophotometric method

Abstract

The nanoporous activated carbon (AC) was prepared from the euca­lyptus leaves via chemical activation with KOH, then treated with nitric acid/
/urea (NOAC) and finally used as a new adsorbent for simultaneous ultra­sound-assisted removal of basic red 46 (BR46) and basic yellow 13 (BY13) dyes from binary aqueous solutions. The NOAC nano-adsorbent was charac­terized with SEM, TEM, Raman, BET, FTIR, CHN, pH_pzc and Boehm titration analysis. Both of the AC and NOAC samples had superior BET surface area of 2222 and 1572 m² g^-1 with average micropore volume of 0.81 and 0.50 cm³ g^-1, respectively. First order derivative spectrophotometric method was used for analysis of BY13 in binary mixtures. Small amount of the adsorbent (30 mg) was capable to remove high percentage of dyes (>99 %) in a very short time (8 min). The adsorption of dyes follows the Langmuir isotherm and the pseudo-
-second-order kinetics. The adsorption capacities of NOAC for single solutions of BR46 and BY13 were 1111 and 1250 mg g^-1 as well as for binary solutions were 769 and 909 mg g^-1, respectively. The adsorption thermodynamics were also explored. Exhausted NOAC was regenerated using HCl (2 M) and reused for five adsorption-desorption cycles with high performance.