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.

A zwitterionic polysulfone formed from an allyl-containing monomer, a phenol-containing monomer, and an aryl-halide-containing monomer. The zwitterionic polysulfone may be incorporated into a desalination membrane.

Embodiments described herein relate generally to durable graphene oxide membranes for fluid filtration. For example, the graphene oxide membranes can be durable under high temperatures non-neutral pH, and/or high pressures. One aspect of the present disclosure relates to a filtration apparatus comprising: a support substrate, and a graphene oxide membrane disposed on the support substrate. The graphene oxide membrane has a first lactose rejection rate of at least 50% with a first 1 wt % lactose solution at room temperature. The graphene oxide membrane has a second lactose rejection rate of at least 50% with a second 1 wt % lactose solution at room temperature after the graphene oxide membrane is contacted with a solution that is at least 80° C. for a period of time.

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.

A reverse osmosis desalination system has a combined displacement pump and displacement pressure recovery motor that propagate feed water with a structurally fixed recovery rate and structurally stabilized volume flow through continuously alternating discharging and recirculation intervals. Thereby enabled is an instantaneous discharge of the entire feed water concentrate and unmixed replacement with low salinity source water that intermittingly and effectively flushes the reverse osmosis membranes. This in turn provides for high recirculation peak salinity and recovery rate that are simple and reliably controlled without impairing membrane longevity.

This method, for regenerating a member used in a device that treats seawater, involves a cleaning step for removing deposits from the member. In the cleaning step, a first chemical solution containing an acid other than hydroxydicarboxylic acid and a second chemical solution containing hydrogen peroxide, a heavy metal compound and hydroxydicarboxylic acid are used.

A filtration apparatus includes a tubular casing having a longitudinal axis and first and second casing ends, a plurality of partition plates positioned in the casing and sealed thereto to thereby define a plurality of axially successive chambers within the casing, including an intake collection chamber between a first of the partition plates and the first casing end, a discharge collection chamber between a second of the partition plates and the second casing end, and a reject collection chamber opposite the second partition plate from the second casing end. A plurality of elongated filtration membrane stacks are positioned side-by-side in the casing generally parallel to the longitudinal axis. Each filtration membrane stack includes an intake end which is fluidly connected to the intake collection chamber, a discharge end which is fluidly connected to the reject collection chamber, and a permeate channel which extends between the intake and discharge ends and is fluidly connected to the discharge collection chamber, an end of the permeate channel located adjacent the intake end being sealed from the intake collection chamber. The filtration apparatus also includes an intake pipe having a first end fluidly connected to the intake collection chamber and a second end fluidly connected to a first connector located proximate the second casing end; a discharge pipe having a first end fluidly connected to the discharge collection chamber and a second end fluidly connected to a second connector located proximate the first connector; and a reject pipe having a first end fluidly connected to the reject collection chamber and a second end fluidly connected to a third connector located proximate the first and second connectors. Each filtration membrane stack includes a plurality of filtration membranes, and the plurality of filtration membrane stacks together define a plurality of axially successive sets of radially adjacent filtration membranes. Also, each filtration membrane of each of the sets of filtration membranes is sealed to a corresponding hole in a respective one of the partition plates.

A method of obtaining water from a liquid composition comprising water, the method comprising: (a) providing a sorbent material; (b) contacting the sorbent material with the liquid composition comprising water; (c) separating the sorbent material and the liquid composition comprising water; and (d) desorbing water from the sorbent material; wherein the sorbent material is a metal-organic material.