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

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, pHpzc 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.