Improved negative charge of tight ceramic ultrafiltration membranes for protein-resistant and easy-cleaning performance

•A negative tight ceramic ultrafiltration membrane was constructed by grafting PAA.•PAA modification with a lower molecular weight has little effect on the membrane pores.•PAA modification enhanced the permeance of ceramic membrane in protein filtration.•The flux recovery ratio of modified membrane was over 90% cleaning with pure water.•The performance of modified membranes was sensitive to the pore sizes of original membranes.