Biomaterials based on chitosan/orange peel as a controlled release matrix for KNO3: synthesis, characterization and their performance evaluation

Controlled release fertilizers are chemical products provided with a polymeric layer that offers control over the release rate as one of its main characteristics and are an alternative to traditional fertilization methods. The use of biopolymers like chitosan and food industry residues like orange peel is a viable for the development of biomaterials that can be used as a controlled release medium for fertilizers. Considering the current interest in the development of environmentally friendly materials, biomaterials based on chitosan and orange peel considered an agro-industrial waste were synthesized in this study, which can give added value to the biomaterial by reducing waste disposal and pollution. Biomaterials were synthesized using the ionic gelation method with different concentrations of sodium tripolyphosphate (TPP 1, 3 and 5% w/v) and tested as controlled release matrices of KNO 3 . Biomaterials were characterized by scanning electron microscopy (SEM), infrared spectroscopy (FTIR), surface charge distribution and zero charge point (PZC) and thermogravimetric analysis (TGA) to elucidate their structural properties and to know the release mechanisms. Biomaterials synthesized with 1% TPP showed a 27.3% load and a KNO 3 release yield of 12.28 mmol L −1 in a 12-day evaluation period. As a result of the increase in the concentration of TPP, the direct influence on the swelling, loading and release properties of KNO 3 was observed, for its part, the use of orange peel as mechanical support did not affect the performance of biomaterials.