The purpose of the present invention is to provide: a separation film that consists primarily of a cellulose ester and has a high membrane strength and a high elongation degree; and a production method therefor. Provided is a separation film which has a structure comprising a cellulose ester phase and pores, wherein the average pore diameter R is 0.001-6 m, the value obtained from the expression: breaking strength (MPa)(100porosity (%))100 is 40 or greater, and the elongation degree is 10% or greater.

Problems that the invention is to solve is to provide a composite hollow fiber membrane being excellent in separation performance and permeation performance, having high membrane strength, and capable of being easily produced, and a method for producing the same. The present invention relates to a composite hollow fiber membrane including at least a layer (A) and a layer (B), in which the composite hollow fiber membrane has an outer diameter of 20 to 350 m and an inner diameter of 14 to 250 m, the tensile modulus of the composite hollow fiber membrane is from 1,000 to 6,500 MPa, the layer (A) contains a cellulose ester, the thickness of the layer (A) is from 0.01 to 5 m, and the open pore ratio H.sub.A of the layer (A) and the open pore ratio H.sub.B of the layer (B) satisfy H.sub.A<H.sub.B.

Problems that the invention is to solve is to provide a composite hollow fiber membrane being excellent in separation performance and permeation performance, having high membrane strength, and capable of being easily produced, and a method for producing the same. The present invention relates to a composite hollow fiber membrane including at least a layer (A) and a layer (B), in which the composite hollow fiber membrane has an outer diameter of 20 to 350 m and an inner diameter of 14 to 250 m, the tensile modulus of the composite hollow fiber membrane is from 1,000 to 6,500 MPa, the layer (A) contains a cellulose ester, the thickness of the layer (A) is from 0.01 to 5 m, and the open pore ratio H.sub.A of the layer (A) and the open pore ratio H.sub.B of the layer (B) satisfy H.sub.A<H.sub.B.

The present invention belongs to the membrane separation area, which provides an MXene material based composite nanofiltration membrane and corresponding method. The mentioned membrane is flat membrane, which has supporting layer and functional separation layer and supporting layer is under the functional separation layer. The functional separation layer is a kind of dense ultra-thin layer, no more than 50 ?m, prepared with MXene and crosslinking agent. This invention is about a flat composite nanofiltration membrane which has excellent separation performance, thermal resistance and chemical stability because of the novel MXene in the functional separation layer. It can be used in the treatment of the waste water with heavy metal ions, organic solvents or other highly oxidizing solution.

The present invention belongs to the membrane separation area, which provides an MXene material based composite nanofiltration membrane and corresponding method. The mentioned membrane is flat membrane, which has supporting layer and functional separation layer and supporting layer is under the functional separation layer. The functional separation layer is a kind of dense ultra-thin layer, no more than 50 ?m, prepared with MXene and crosslinking agent. This invention is about a flat composite nanofiltration membrane which has excellent separation performance, thermal resistance and chemical stability because of the novel MXene in the functional separation layer. It can be used in the treatment of the waste water with heavy metal ions, organic solvents or other highly oxidizing solution.

Presented herein are membranes for use in separating solids including salts from water. One application of such membranes is in a sub-surface irrigation system that that utilizes a saline or tainted water as a feed source. In various embodiments, the membranes operate on a solution diffusion principle. In other embodiments the membranes operate on an ultrafiltration principle and/or a solution diffusion principle. In any embodiment, the membranes operate similar to pervaporation membranes suitable for non-pressure driven systems. The membranes are designed to provide increased flux rate while separating solids such as salts from water.

Presented herein are membranes for use in separating solids including salts from water. One application of such membranes is in a sub-surface irrigation system that that utilizes a saline or tainted water as a feed source. In various embodiments, the membranes operate on a solution diffusion principle. In other embodiments the membranes operate on an ultrafiltration principle and/or a solution diffusion principle. In any embodiment, the membranes operate similar to pervaporation membranes suitable for non-pressure driven systems. The membranes are designed to provide increased flux rate while separating solids such as salts from water.

A cellulose ester, wherein, in a structural formula of the following general formula (I), a degree of substitution where X is an acyl group is from 2.91 to 3.0; the acyl group includes benzoyl group (A) optionally having a substituent, and benzoyl group (B) optionally having a substituent different from that of benzoyl group (A); and when the degree of substitution is 3.0, a degree of substitution of benzoyl group (A) is from 1.5 to 2.9, and a degree of substitution of benzoyl group (B) is from 0.1 to 1.5,

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wherein all or some of X represents an acyl group; when some of X represents an acyl group, the remainder represents a group selected from a hydrogen atom and an alkyl group; and n represents an integer of from 20 to 20,000.

Provided is a semipermeable membrane having a high chlorine resistance.

The semipermeable membrane is formed of a cellulose ester, the cellulose ester having an optionally substituted benzoyl group.

Provided is a semipermeable membrane having a high chlorine resistance.

The semipermeable membrane is formed of a cellulose ester, the cellulose ester having an optionally substituted benzoyl group.