Sorption Characteristics of Nitrogen Forms on Microporous Adsorbents for Novel Fertilizer Manikandan A.*, Subramanian K.S.1 Soil Microbiology Laboratory, Division of Crop Production, ICAR-Central Institute for Cotton Research, Nagpur, 440 010, Maharashtra 1Department of Nano Science and Technology, Tamil Nadu Agricultural University, Coimbatore-641 003, Tamil Nadu *Corresponding author (Email: poonamani223@gmail.com)
Online published on 24 August, 2017. Abstract Diffusion of nitrogen (N) on void pores determines the sorption capacity of microporous inorganic solid adsorbents. A laboratory study was undertaken to assess the sorption kinetics of N on adsorbents viz., zeolite, nano-zeolite, biochar and size reduced biochar in order to know the sorption efficiency and fabrication of novel N fertilizer. Adsorption and desorption pattern were examined using four forms of N viz., ammonium (NH4+), nitrate (NO3−), amide (NH2) and ammonium + nitrate (NH4++NO3−) were loaded at varying concentrations (100–700 mg L−1 (adsorption) and 20–200 mM (desorption)). Batch and contact time (0–8 h) experiments revealed that equilibrium time, equilibrium concentration and equilibrium percentage (NH4+-N; 5–7 h, 1.2–1.7 mg L−1, 46–73%) and (NO3−-N; 6–7 h, 0.9–1.6 mg L−1, 40–70%), respectively. Nanozeolite had the highest sorption capacity for 42.5, 40 mg g−1 after 6–7 h of shaking period of NH4+-N and NO3−-N, respectively. Theoretical Freundlich adsorption isotherm equations predicted adsorption of N as 35.0, 48.5, 31.3 and 43.8 mg g−1 (NH4+) and 17.5, 28.2, 14.3 and 19.2 mg g−1 (NO3−) for zeolite, nanozeolite, biochar and size-reduced biochar, respectively. Results of this study suggested that nano-zeolites are most suitable adsorbent to retain both forms of N which could be best adsorbent for fabrication of N fertilizer. Top Keywords Freundlich isotherm, zeolite, biochar, adsorption, desorption. Top |