Preparation of novel magnetic nanoparticles as draw solutes in forward osmosis desalination

Novel magnetic nanoparticles(MNPs),Fe_(3)O_(4)@SiO_(2) and Fe_(3)O_(4)@SiO_(2)@PEG-(COOH)_(2),were prepared by loading different amounts of SiO_(2) or/and PEG-(COOH)_(2) onto Fe_(3)O_(4) nanoparticles,and their feasibility to be used as forward osmosis(FO)draw solutes was investigated.The characterization of the materials showed that,compared to normal Fe_(3)O_(4) nanoparticles,the modified MNPs exhibited enhanced dispersity and high osmotic pressure in aqueous solution.The FO experiment indicated that the synthesized draw solutes could obtain a water flux as high as 10 L·m^(-2)·h^(-1) with an aquaporin FO membrane.The optimal concentration of the added tetraethyl orthosilicate was 30%during the synthesis.The novel MNPs could be easily recovered from draw solutions by magnetic field,and the recovery rate of Fe_(3)O_(4)@SiO_(2) and Fe_(3)O_(4)@SiO_(2)@PEG-(COOH)_(2) was 83.95%and 63.37%,respectively.Moreover,after 5 recycles of reuse,the water flux of Fe_(3)O_(4)@SiO_(2) and Fe_(3)O_(4)@SiO_(2)@PEG-(COOH)_(2) as draw solutes still remained 64.36%and 85.26%,respectively.The experimental results demonstrated that the synthesized core–shell magnetic nanoparticles are promising draw solutes,and the Fe_(3)O_(4)@SiO_(2)@PEG-(COOH)_(2) was more suitable to be used as draw solute in FO process.

Lithium-based draw solute for forward osmosis to treat wastewater discharged from lithium-ion battery manufacturing

As draw solute is the core element of forward osmosis(FO)technology,here Li-Bet-Tf_(2)N synthesized from a customized ionic liquid betainium bis(trifluoromethylsulfonyl)imide([Hbet][Tf_(2)N])and Li2CO_(3) recovered from lithium-ion battery(LIB)wastes is proposed as a novel draw solute to treat Li+-containing wastewater from LIB manufacturing through FO filtration.Having high dissociation ability and an extended structure,Li-Bet-Tf_(2)N generates a sufficiently high osmotic pressure to drive the FO filtration efficiently along with insignificant reverse solute diffusion.Li-Bet-Tf_(2)N produces a water flux of 21.3 L·(m^(2)·h)–1 at 1.0 mol∙L^(-1) against deionized water,surpassing conventional NaCl and MgCl2 draw solutes with a higher water recovery efficiency and a smaller solute loss.Li-Bet-Tf_(2)N induces a more stable and higher water permeation flux with a 10.0%water flux decline than NaCl and MgCl_(2) for which the water fluxes decline 16.7%and 16.4%,respectively,during the treatment of 2000 mg∙L^(-1) Li+-containing wastewater for 12 h.More remarkably,unlike other draw solutes which require intensive energy input and complicated processes in recycling,Li-Bet-Tf_(2)N is easily separated from water via solvent extraction.Reproducible results are achieved with the recycled Li-Bet-Tf_(2)N.Li-Bet-Tf_(2)N thus demonstrates a novel class of draw solute with great potentials to treat wastewater economically.

THE CURVILINEARINTEGRAL PROBLEMS TO VELOCITY FIELD FOR DRAWING THROUGH PARABOLIC DIES

n this paper with Von Karmanis basic assumptions a kinematically admissible continuous velocity field has been established to drawing through parabolic dies (or called trumpet dies). Then by. using the curvilinear and the integral as a function of the upper limit an upper bound analytical solution of the drawing stress is obtained.

THE INTEGRAL AS A FUNCTION OF THE UPPER LIMIT AND AN ANALYTICAL SOLUTION TO PLANE STRAIN DRAWING AND EXTRUSION

A kinematically admissible velocity field which is different from Avitzur's is established in Cartesian Coordinates. An upper-bound analytical solution to strip drawing andextrusion is obtained by using the integral as a function of the upper limit in this paper.