{'fraction_non_alphanumeric': 0.024946543121881683, 'fraction_numerical': 0.022808267997148968, 'mean_word_length': 5.185022026431718, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Acid Dye Adsorption Properties of Ethylenediamine-Modified Magnetic Chitosan Nanoparticles

Ethylenediamine-modified magnetic chitosan nanoparticles (EMCN) were prepared and used for the adsorption of Acid Orange 7 (AO7) and Acid Orange 10 (AO10) from aqueous solutions. Magnetic chitosan nanoparticles were prepared by adding a basic precipitant NaOH solution to a W/O microemulsion system containing cyclohexane/n-hexanol, chitosan and ferrous salt. This was then modified with ethylenediamine to increase the amine content and to improve the adsorption capacity. Transmission electron microscopy showed that the EMCN was essentially monodispersed and had a main particle size distribution of 15-40 nm. Adsorption experiments indicated that the maximum adsorption capacity was at a pH of 4.0 for AO7 and a pH of 3.0 for AO10. Because of the small diameter and the high surface reactivity of EMCN, the adsorption equilibrium for both dyes was reached very quickly. The equilibrium experiments fitted the Langmuir isotherm model well and the maximum adsorption capacities of 3.47 and 2.25 mmol·g - 1 were obtained for AO7 and AO10, respectively. We estimated the thermodynamic parameters and accordingly the adsorption process was found to be spontaneous and exothermic. Additionally, we regenerated EMCN with an NH4OH/NH4Cl solution (pH 10.0) and the regenerated material was used to readsorb the dyes.