Journal of Hazardous Materials B98 (2003) 117–126 Adsorption of ammonium dinitramide (ADN) from aqueous solutions 1. Adsorption on powdered activated charcoal G. Santhosh a , S. Venkatachalam a,∗ , K.N. Ninan a , R. Sadhana a , S. Alwan b , V. Abarna c , M.A. Joseph c a Propellants and Special Chemicals Group, Vikram Sarabhai Space Centre, Trivandrum 695022, India b Rocket Propellant Plant, Vikram Sarabhai Space Centre, Trivandrum 695022, India c Propellant Fuel Complex, Vikram Sarabhai Space Centre, Trivandrum 695022, India Received 28 June 2002; received in revised form 7 October 2002; accepted 8 October 2002 Abstract Investigations on the adsorption of ammonium dinitramide (NH 4 N(NO 2 ) 2 ) (ADN) from aqueous solutions on powdered activated charcoal (PAC) were carried out in order to find out an effective and easier method of separating ADN from aqueous solutions. The effectiveness of PAC in the selective adsorption of ADN from aqueous solutions of ADN (ADN-F) and ADN in presence of sulfate (SO 4 2- ) and nitrate (NO 3 - ) ions (ADN-PS) was examined and compared using batch and column methods. The adsorption process follows both Langmuir and Freundlich adsorption isotherms and the isotherm parameters for the models were determined. The observed data favor the formation of monolayer adsorption. The adsorption capacities were found to be 63.3, 119, 105.3 and 82 mg of ADN per g of PAC for ADN-F (batch), ADN-PS (batch), ADN-F (column) and ADN-PS (column), respectively. Break-through curves for ADN-F and ADN-PS were obtained for the optimization of separation of ADN from aqueous solutions. Elution curves were generated for the desorption of ADN from PAC using hot water as eluent. © 2002 Elsevier Science B.V. All rights reserved. Keywords: Adsorption; Ammonium dinitramide (ADN); Langmuir and Freundlich isotherms; Powdered activated charcoal 1. Introduction Ammonium dinitramide (NH 4 N(NO 2 ) 2 ) (ADN) is a powerful, environmental-friendly oxidizer developed in 1990s for use in composite solid rocket propellants [1,2]. It is an ∗ Corresponding author. Tel.: +91-471-565552; fax: +91-471-415236. E-mail address: valli@sancharnet.in (S. Venkatachalam). 0304-3894/02/$ – see front matter © 2002 Elsevier Science B.V. All rights reserved. PII:S0304-3894(02)00289-3