Enhanced permeability and biofouling mitigation of forward osmosis membranes via grafting graphene quantum dots

In this paper,graphene oxide quantum dots with amino groups(NH_(2)-GOQDs)were tailored to the surface of a thin-film composite(TFC)membrane surface for optimizing forward osmosis(FO)membrane performance using the amide coupling reaction.The results jointly demonstrated hydrophilicity and surface roughness of the membrane enhanced after grafting NH_(2)-GOQDs,leading to the optimized affinity and the contact area between the membrane and water molecules.Therefore,grafting of the membrane with a concentration of 100 ppm(TFC-100)exhibited excellent permeability performance(58.32 L·m^(–2)·h^(–1))compared with TFC membrane(16.94 L·m^(–2)·h^(–1)).In the evaluation of static antibacterial properties of membranes,TFC-100 membrane destroyed the cell morphology of Escherichia coli(E.coli)and reduced the degree of bacterial adsorption.In the dynamic biofouling experiment,TFC-100 membrane showed a lower flux decline than TFC membrane.After the physical cleaning,the flux of TFC-100 membrane could recover to 96%of the initial flux,which was notably better than that of TFC membrane(63%).Additionally,the extended Derjaguin–Landau–Verwey–Overbeek analysis of the affinity between pollutants and membrane surface verified that NH_(2)-GOQDs alleviates E.coli contamination of membrane.This work highlights the potential applications of NH_(2)-GOQDs for optimizing permeability and biofouling mitigation of FO membranes.

Phenolic Based Porous Carbon Fibers with Superior Surface Area and Adsorption Efficiency for Radioactive Protection

Radioactive iodine element mainly in CH3I is a key fission product of concern in the nuclear fuel cycle,which directly threat-ens human health if released into the environment.Effective capture of the I element is essential for human health protection.The iodine filter,consisting of an activated carbon inner core and cotton filter,is the most common radioactive iodine pro-tection product.Currently,the activated carbon inside the iodine filter suffers from the weak adsorption efficiency and high cost.Herein,a process based on a strong alkali activation method was developed to significantly improve iodine absorption and reduce the cost.A series of flexible porous carbon fibers with a high specific surface area(up to about 1,500~2,200 m^(2)/g)were prepared by carbonation of the phenolic resin fibers(PF,prepared through melt spinning and crosslink)followed by activation via KOH treatment.Meanwhile,the nitrogen-doped sp^(2)-heterogeneous carbon atoms were prepared by add-ing nitrogen sources such as urea which led to a high surface area nano-porous fibers with an average pore size of~2.4 nm.The nitrogen-doped porous carbon fibers exhibit very high adsorption for liquid iodine and iodine vapor.The liquid iodine adsorption capacity of nitrogen-doped porous carbon NDAC-4 prepared under 800°C reaches 2,120 mg/g,which is 2.1 times higher than that of the commercial iodine filter,and for iodine vapor the capacity can reach 5,330 mg/g.Meanwhile,the CH_(3)I adsorption capacity is 510 mg/g,which is 3.4 times higher than that of commercial unmodified viscose fibers and has greater stability and circularity.Importantly,the research has met the requirements of industrial production,and the fabrication of phenolic-fibers-based protection equipment can be widely used in the nuclear radiation industry.

Color Prediction Model of Gray Hybrid Multifilament Fabric

To facilitate the product design of hybrid multifilament fabric prior to spinning,a color prediction model was proposed.The monofilaments in the multifilament were assumed to have a square cross-section and stacked vertically.The prediction model considered the refectance,transmittance and arrangement of the monofilaments in the fabric.To test the reflectance and transmittance of the monoflament with the Datacolor spectrophotometer,films with the same material and thickness as the monofilaments were made.Twenty kinds of multifilaments with different blending ratios and fineness were produced and woven into fabrics.The color difference between the fabric color tested by the spectrophotometer and predicted by the new model and classical Kubelka-Munk(K-M)theory was calculated and compared.The result shows that the average color difference obtained by the new model was 1.02 Color Measurement Committee(CMC)(2:1)units,which was less than that of 1.78 CMC(2:1)units obtained by the K-M theory.Through Spearman correlation analysis,the fabric lightness and the multifilament fineness had a significant infuence on calculated color difference,and the color difference decreased with increases of them.Finally,the surface color of a fabric was reproduced,indicating the model can be used to characterize the phenomenon of uneven color mixing on the fabric surface.