Isolation and characterization of cellulose from date palm waste using rejected brine solution

•Isolation of cellulose from date palm fibers using rejected brine.•Needle-shaped cellulose fibers were obtained.•Cellulose fibers with higher thermal stability were produced.•Diffusion models were best-fit to determine activation energies for date leaves (79.39 kJ/mol) and isolated cellulose (103.27 kJ/mol).