Nanoman vs

The morphology and structure of as-obtained composites were characterized by scanning electron microscope (SEM, FEI Nova NanoSEM 230, FEI company, Hillsboro, OR, USA), scanning transmission electron microscope (STEM-EDS, JEM-2100F, Japan Electronics Co., Ltd. (JEOL), Tokyo, Japan), atomic force microscope (AFM, NanoMan VS, Bruker, Germany), X-ray powder diffraction patterns (XRD, D/max 2550 VB + XX diffractometer, Rigaku International Corp, Tokyo, Japan), X-ray photoelectron spectroscopy (XPS, K-Alpha 1063, Thermo Scientific, Waltham, MA, USA), Raman scattering spectra (532 nm, Renishaw inVia, Renishaw, London, England), and Fourier transformed infrared spectra (FT-IR, Nicolet IS10, Thermo Scientific, Waltham, MA, USA). The contact angles were measured using a Date Physics JY-82C goniometer (Dingsheng testing machine testing equipment Co., Ltd, Jinan, China). Zeta potentials were recorded using a Malvern Nano-ZS Zetasizer. The N₂ adsorption-deposition isotherms were measured by bjbuilder KUBO-X1000 (Beijing Builder Electronic Technology Co., Ltd., Beijing, China).

It should be noted that the material of Duracid NF membrane was not provided by the manufacturer and previous study. With limited information, it is difficult to compare and select the most appropriate membrane for extracting lithium from the lepidolite leaching solution. Therefore, four NF membranes need to be comprehensively characterized by FT-IR (Nicolet iS5, Thermo Fisher, Waltham, USA), hydrophobicity (JY-82, Chengde Dingsheng, Chengde, China), zeta potential (Supass, Anton Paar, Graz, Austria), microcosmic morphology (SU8010, Hitachi, Tokyo, Japan), roughness (NanoManVS, Bruker, Karlsruhe, Germany), pore size and hydraulic permeability. All membrane samples were first cut to a suitable size, and then washed three times in an ultrasonic bath of pure water for 10 min each time to prepare for the following measurements.

For AFM sample preparation, protein samples (10 μL) were pipetted on freshly cleaved mica (Beijing Zhongxingbairui Technology Co., Ltd.) and dried at room temperature. The AFM images were collected using a Nanoman VS (Bruker) with tapping mode at a resolution of 256 lines per image and a scan rate of 1 Hz. The AFM images were processed using NanoScope Analysis.