A composite semipermeable membrane includes a porous support membrane, a separation functional layer containing a polyamide disposed on the porous support membrane, and a coating layer disposed on the separation functional layer, wherein a water contact angle of a surface of the coating layer is 40° or less, and a protein adsorption force of the surface of the coating layer is 0.4 nN or less.

Water permeable membranes and methods of preparation are described. The water permeable membrane can comprise a porous support, and a polyamide layer comprising a crosslinked polyamide on a surface of the porous support, wherein the polyamide layer further comprises nanoparticles and a hydrophilic additive, and wherein the hydrophilic additive covalently bonds to the crosslinked polyamide. The crosslinked polyamide can be interfacially polymerized on the porous support. Methods for desalinating water, performing dialysis, or performing pervaporation using the water permeable membranes are disclosed.

High energy consumption and the negative impacts of hyper saline brine are the two biggest hurdles to a widespread adoption of seawater desalination. Taking advantage of the principal that fluid pressure increases in direct proportion to depth, this invention reduces energy consumption by relocating the process of reverse osmosis at depths where the weight of the water produces the pressure required to drive the reverse osmosis process thereby eliminating the high costs normally associated with raising intake pressure and by simply varying pumping rates, the brine stream can be pre-diluted to levels slightly above the original thereby reducing environmental impact. The simplicity of the design also reduces the costs of building and installation thereby making it likely that seawater desalination will proliferate around the world.

A water recycling apparatus contains: a body, and inflow pipe, a reverse osmosis (RO) discharge pipe, and an outlet pipe. The body includes an accommodation chamber, a first receiving orifice, a second receiving orifice, and a third receiving orifice. The inflow pipe includes a first inlet, a first connection segment, and a first outlet. The RO discharge pipe includes a second inlet, a second connection segment, and a one-way check valve. The one-way check valve has a feeding segment and a discharging segment, such that the RO discharge pipe is connected with the feeding segment of the one-way check valve. The outlet pipe includes a guiding orifice, a third connection segment, and a leading orifice. The body further includes a first layer, a second layer, an inflatable layer, and an air nozzle communicating with the inflatable layer so as to inflate or deflate airs to the inflatable layer.

A proportioning valve for a reverse osmosis system that controls the production of product water by the differential pressure across the purification membrane. By sensing increasing tank pressure to actuate the proportioning valve, the flow of waste water is restricted. Placement of seals within the cavity of the valve, as well as placement of waste water inlet and outlet ports, protects tension components that provide reverse tank pressure from waste water exposure. A needle valve assembly responsive to an actuating assembly that senses tank pressure removes the need for an inlet tank water port while restricting water flow.

A method and system for reversibly converting water between an initial ionic strength and an increased ionic strength, using a switchable additive, is described. The disclosed method and system can be used, for example, in distillation-free removal of water from solvents, solutes, or solutions. Following extraction of a solute from a medium by dissolving it in water, the solute can then be isolated from the aqueous solution or “salted-out” by converting the water to a solution having an increased ionic strength. The solute then separates from the increased ionic strength solution as a separate phase. Once the solute is, for example, decanted off, the increased ionic strength aqueous solution can be converted back to water having its original ionic strength and reused. Switching from lower to higher ionic strength is readily achieved using low energy methods such as bubbling with CO.sub.2, CS.sub.2 or COS. Switching from higher to lower ionic strength is readily achieved using low energy methods such as bubbling with air, heating, agitating, introducing a vacuum or partial vacuum, or any combination or thereof.

A preparation method and use of a modified hydroxyethyl cellulose scale inhibitor for inhibiting silica scale are provided. The scale inhibitor is prepared by grafting reaction with hydroxyethyl cellulose as a raw material, ammonium persulfate as an initiator and N-(3-dimethylaminopropyl) methyl acrylamide as a graft monomer. The grafting reaction can introduce grafting chains containing amide group and tertiary amine group into a cellulose molecular chain, so that it can effectively disperse scale forming substances and obtain the efficient environment-friendly scale inhibitor. The scale inhibitor can effectively inhibit the generation of silica scale and prevent the increase of scale particle size, the scale inhibitor is used in a reverse osmosis system, which can effectively alleviate the decline of the membrane flux. The scale inhibitor has a good application prospect in controlling the silica scale on the surface of the reverse osmosis membrane.

Per- and polyfluoroalkyl substances (PFAS) are destroyed by oxidation in supercritical conditions. PFAS in water is concentrated in a reverse osmosis step and salt from the resulting solution is removed in supercritical conditions prior to destruction of PFAS in supercritical conditions.

A reverse osmosis apparatus for a seawater desalination system is provided. The reverse osmosis apparatus includes: a barrel in which a plurality of reverse osmosis membrane units with a reverse osmosis membrane wrapped in each reverse osmosis membrane unit are arranged; an inflow and outflow portion provided at a first end of the barrel and connected to a seawater inlet a high salinity water outlet; a partition wall configured to partition an inner space of the inflow and outflow portion into a first stage and a second stage; and a transport space portion provided in a second end of the barrel and configured to guide water being moved from a plurality of reverse osmosis membrane units arranged in the first stage to move to a plurality of reverse osmosis membrane units arranged at the second stage, wherein part of seawater fed to the inflow and outflow portion is fed around the tubes in the barrel and insulates the plurality of reverse osmosis membrane units in the barrel from external high temperature while being moved, and flows into the transport space portion.

A desalination performance restoration agent for a cellulose acetate membrane contains: a solvent; and a modified polyvinyl alcohol mixed in the solvent. The modified polyvinyl alcohol has an acetyl group structure in at least part of polyvinyl alcohol.