Radiation-induced cross-linking:a novel avenue to permanent 3D modification of polymeric membranes

Membrane fouling is always the biggest problem in the practice of membrane separation technologies,which strongly impacts their applicability,separation efficiency,cost effectiveness,and service lifespan.Herein,a simple but effective 3D modification approach was designed for permanently functionalizing polymeric membranes by directly cross-linking polyvinyl alcohol(PVA)under gamma-ray irradiation at room temperature without any additives.After the modification,a PVA layer was constructed on the membrane surface and the pore inner surface of polyvinylidene fluoride(PVDF)membranes.This endowed them with good hydrophilicity,low adsorption of protein model foulants,and easy recoverability properties.In addition,the pore size and distribution were customized by controlling the PVA concentration,which enhanced the rejection ability of the resultant membranes and converted them from microfiltration to ultrafiltration.The crosslinked PVA layer was equipped with the resultant membranes with good resistance to chemical cleaning by acidic,alkaline,and oxidative reagents,which could greatly prolong the membrane service lifetime.Furthermore,this approach was demonstrated as a universal method to modify PVDF membranes with other hydrophilic macromolecular modifiers,including polyethylene glycol,sodium alginate,and polyvinyl pyrrolidone.This modification of the membranes effectively endowed them with good hydrophilicity and antifouling properties,as expected.

Stability study of Disperse Blue 79 under ionizing radiation

Ionizing radiation is a promising method for dye degradation or textile coloration using commercial azo dyes and small molecular weight organic dyes. Thus, the stability of the molecular structure of an azo dye is important under ionizing radiation. Disperse Blue 79, as an example azo dyes, was irradiated with gamma rays or electron beam (EB) to investigate the radiation-induced effects on the molecular structure. Ultraviolet visible spectroscopy (UV Vis), nuclear magnetic resonance (NMR) spectra analysis, and mass spectrometry (MS) studies indicated that acetoxy and methoxyl were easily cleaved on the irradiation of the aqueous dye solution but retained a stable structure on the irradiation of the powder form. Gamma rays and EB showed similar effects on the decomposition process. Chromaticity changes using the Lab* method showed that the dye turned to dark yellow and the value of b* of the irradiated dyes increased with the increasing absorbed dose, which indicated that Disperse Blue 79 could be partly decomposed in an aqueous solution This work was nancially supported by the National Natural Science Foundation of China (Nos. 11875313, 11605274, and 11575277). Xiao-Jun Ding and Ming Yu contributed equally to this work. & Jing-Ye Li jyli@shnu.edu.cn 1 Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China 2 University of Chinese Academy of Sciences, Beijing 100049, China 3 The Education Ministry Key Lab of Resource Chemistry, Shanghai Key Lab of Rare Earth Functional Materials, College of Chemistry and Materials Science, Shanghai Normal University, Shanghai 200234, China with an absorbed dose of 10 kGy. Furthermore, the results demonstrated that the chemical stability of the Disperse Blue 79 under ionizing radiation are different in its powder form with the dye in the aqueous solution.

Fabrication of stable MWCNT bucky paper for solar-driven interfacial evaporation by coupling c-ray irradiation with borate crosslinking

Herein,we report a facile solution process for preparing multi-walled carbon nanotube(MWCNT)bucky paper for solar-driven interfacial water evaporation.This process involves vacuum filtrating a dispersion of MWCNTs that was modified by polyvinyl alcohol(PVA)under c-ray irradiation on a cellulose acetate microporous membrane,followed by borate crosslinking.Fourier transform infrared spectroscopy,Raman spectroscopy,and thermogravimetry confirmed the success of PVA grafting onto MWCNTs and borate crosslinking between modified MWCNT nanoyarns.The as-prepared crosslinked MWCNT bucky papers(BBP membranes)were used as a solar absorber,by placing them on a paper-wrapped floating platform,for interfacial water evaporation under simulated solar irradiation.The BBP membranes showed good water tolerance and mechanical stability,with an evaporation rate of 0.79 kg m^(-2)h^(-1)and an evaporation efficiency of 56%under 1 sun illumination in deionized water.Additionally,the BBP membranes achieved an evaporation rate of 0.76 kg m^(-2)h^(-1)in both NaCl solution(3.5 wt%)and sulfuric acid solution(1 mol L-1),demonstrating their impressive applicability for water reclamation from brine and acidic conditions.An evaporation rate of 0.70 kg m-2 h-1(very close to that from deionized water)was obtained from the solar evaporation of saturated NaCl solution,and the BBP membrane exhibited unexpected stability without the inference of salt accumulation on the membrane surface during long-term continuous solar evaporation.