Cellulose Extraction from Spirulina Wastes (Spirulina platensis) and Isolation of Cellulose Nanofiber from it

The purpose of this study was to extract pure cellulose from the waste spirulina alga (Spirulina platensis) using a method of chemical treatment and then isolation of cellulose nanofibers by applying a mechanical process. For this purpose, purification of spirulina algae (separation of fat and protein) was carried out during three stages of chemical treatment using a 2% solution, followed by 3% sodium chloride solution, which was buffered by acetic acid. The extracted cellulose fibers were then subjected to 1% dry weight suspension and passed through a high pressure homogenizer in order to isolate the cellulose nanofibers. Before and after chemical treatment, the infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to study the chemical and structural properties of the samples. Also, the diameter and length of the prepared cellulose nanofibers were measured by atomic force microscopy (AFM). The FTIR results showed that the chemical and mechanical treatment could successfully isolated cellulose and nanocellulose fibers which are totally compatible with previously studies. The analysis of SEM images showed that pure cellulose fibers were extracted from spirulina algae. In addition, the XRD analysis illustrated that the cellulose and nanocellulose fibers had similar diffractogram to the cellulose I. AFM images demonstrated that the nanofibers had average diameter of 37 nm while their length was several microns. It can be concluded that the isolation of cellulose nanofibers by using the high pressure homogenizer could be possible from the chemically treated cellulose fibers.