No abstract

A forward osmosis (FO) membrane was developed from a mixture of chitosan and Dioscorea hispida starch, cross-linked using glutaraldehyde. The cross-linked chitosan/starch membrane was revealed to have high mechanical properties with an asymmetric structure. The prepared membrane’s performance was investigated as an FO filter assembled in a polypropylene water filter bag and aluminum foil plastic. In order to study the FO process, brackish water was used as a feed solution, drawn using three types of solution (fructose, sucrose, and fructose/sucrose mixture, each with 3 M concentration). The maximum water flux (5.75 L/m2 h) was achieved using 3 M sucrose. The cross-linked membrane restrained the ions in the feed with a rejection factor value close to 100%. The water quality parameters were evaluated for the physical, chemical, and biological criteria, such as pH, salinity, conductivity, total dissolved solids (TDS), heavy metals, and Escherichia coli content. The water quality parameters for the FO-processed water met that set by the World Health Organization for drinking water. FO filter bags with cross-linked chitosan/starch membranes can be an option to produce drinking water during an emergency.

Neat chitosan membranes have shortcomings in their application owing to weak mechanical properties, thus, requiring modification. In this study, a chitosan membrane was modified utilizing starch and cross-linking agent (citric acid) addition. The characterization of chitosan-starch membranes using Universal Testing Machine, Scanning Electron Microscope (SEM), Fourier Transform Infra-Red (FTIR), Differential Scanning Calorimetry (DSC), and Thermogravimetric Analysis (TGA) had proven the cross-linking formation. The cross-linked membrane had better tensile strength (11.07 kgf/mm2) than the uncross-linked membrane (66.07kgf/mm2). The DSC thermogram of uncross-linked and cross-linked membranes showed endothermic and exothermic peaks at different temperatures. In addition to the membranes’ thermal characteristics, the DTA thermogram showed the decomposition process on the uncross-linked membrane uncross-linking occurred at a temperature range of 277.74-363.27 °C, while the decomposition of the cross-linked membrane was observed at a range of 287.83-356.38 °C. The FT-IR spectra confirmed a decrease in the intensity of the absorption peak associated with cross-linking formation within the membrane.