Electrospun preparation of polylactic acid nanoporous fiber membranes via thermal-nonsolvent induced phase separation

•Fiber membranes with nanoporous structures were obtained via thermal-nonsolvent induced phase separation.•PLLA nanoporous fiber membranes were prepared by electrospinning a single solvent system.•A water bath was used to obtain the PLLA nanoporous fiber membranes regardless of humidity.•This kind of PLLA nanoporous fiber membranes possessed high specific surface area and water flux.•The nanopore structures endow membranes excellent performance in oil adsorption and organic dye filtration.