SYNTHESIS AND PROPERTIES OF ION EXCHANGERS DERIVED FROM NON-WOOD CELLULOSE

Abstract

A rational scheme for the processing of large-scale agro-industrial waste – walnut shells Juglans Regia L. and apricot kernels Prunus Armeniaca L. was proposed. At first stage, the raw material was delignificated using liquid ammonia to remove hemicelluloses and lignin. Isolated non-wood pulp is chemically modifying to increase sorption and ion exchange properties. For the synthesis of anion exchangers, cellulose was aminated using pyridine or trimethylamine after preliminary treatment consequentially with formalin and C2H5OH in HCl medium. As a result, we obtained high and weakly-basic ion exchangers with nitrogen content of 10.3–11.5% and high exchange capacity towards various classes of inorganic anions. For synthesis of cation exchangers, cellulose was treated with solution consisting of 20% H3PO4, 40% CO(NH2)2, and 40% H2O. Consequently, we obtained phosphorus-containing high-acidic cation exchangers with exchange capacity towards heavy metal of 5.5–8.6 mmol∙cm–3. Both types of ion exchangers have a high capacity towards uranium: anion exchanger – 4.25 mmol∙cm–3 and cation exchanger – 4.94 mmol∙cm–3, respectively. Average total yield of ion exchangers related to weight of air-dry feedstock was 90%. Synthesized ion exchangers characterized by IR spectroscopy. Presence of amine functional groups –NH2 in aminated cellulose and phosphate ester groups –OPO(OH)2 in phosphorylated cellulose was established. Specific surface area and total static exchange capacity of synthesized ion exchangers were established. An environmentally friendly method for the disposal of spent solutions from the synthesis of cation exchangers was proposed. It allows getting a liquid complex fertilizer containing 17% N and 13.9% P2O5. Usage of this fertilizer for grain crops feeding increases plants length by 40–75%, as well as overall biomass increase by 20–30%.