Multi-functional forward osmosis draw solutes for seawater desalination

Forward osmosis(FO), as one of the emerging desalination technologies, has the potential to produce fresh water from a variety of water sources by utilizing the osmotic pressure gradient across a semi-permeable membrane.Draw solution, as an essential component of any FO process, can extract water molecules from seawater or wastewater. An ideal draw solution should meet three essential requirements, namely high osmotic pressure, low reverse flux, and facile regeneration mechanism. The selection of proper draw solutes is especially critical for an energy-efficient FO process since the energy consumption mostly arises from the separation or regeneration of the draw solution. Recently, we developed a few multi-functional FO draw solutes, mainly aiming to enhance the FO water flux and to explore facile re-concentration methods. This review summarizes these draw solutes,including Na^+_- functionalized carbon quantum dots, thermoresponsive copolymers, hydrophilic magnetic nanoparticles, and thermoresponsive magnetic nanoparticles.

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.

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.

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.