Provided is a method for synthesizing TiO.sub.2 nanocrystal, comprising: adjusting the pH value of a colloidal suspension of tetratitanic acid nanosheet as a precursor to 5-13; and subjecting the precursor to a hydrothermal reaction to obtain the TiO.sub.2 nanocrystal. The TiO.sub.2 nanocrystal synthesized by the method is anatase-type, and the exposed crystal facet thereof is {010} crystal facet. The method has advantages of low cost, no pollution, simple synthesizing process, strong controllability, short production period and good reproducibility, and is suitable for industrial production.

Visible-light response hybrid aerogel and a preparation method and application thereof in waste gas processing are disclosed. Dicyandiamide is taken as a precursor and is calcined in two times to prepare a carbon nitride nanosheet; the carbon nitride nanosheet is dispersed in water, silver metavanadate quantum dots are subjected to in-situ growth to prepare a silver metavanadate quantum dot/carbon nitride nanosheet composite material; the silver metavanadate quantum dot/carbon nitride nanosheet composite material and graphene oxide carry out hydrothermal reaction, and are then frozen and dried to prepare silver metavanadate quantum dot/carbon nitride nanosheet/graphene hybrid aerogel which is the visible-light response hybrid aerogel. The problems of large reduction dosage, serious secondary pollution, complexity in operation and the like generated when waste gas is processed by a traditional flue gas denitration technology are overcome.

Visible-light response hybrid aerogel and a preparation method and application thereof in waste gas processing are disclosed. Dicyandiamide is taken as a precursor and is calcined in two times to prepare a carbon nitride nanosheet; the carbon nitride nanosheet is dispersed in water, silver metavanadate quantum dots are subjected to in-situ growth to prepare a silver metavanadate quantum dot/carbon nitride nanosheet composite material; the silver metavanadate quantum dot/carbon nitride nanosheet composite material and graphene oxide carry out hydrothermal reaction, and are then frozen and dried to prepare silver metavanadate quantum dot/carbon nitride nanosheet/graphene hybrid aerogel which is the visible-light response hybrid aerogel. The problems of large reduction dosage, serious secondary pollution, complexity in operation and the like generated when waste gas is processed by a traditional flue gas denitration technology are overcome.

A process for the manufacturing of 3D reduced graphene oxide/Fe.sub.2O.sub.3 material includes the following steps: (i) putting in contact a graphene oxide (GO) water dispersion with an aqueous solution of iron(II) sulfate; (ii) hydrothermal treatment; and (iii) freezing the reaction product obtained in step (ii) at a temperature ≤−5° C.; and (iv) lyophilisation. A 3D reduced graphene oxide/Fe.sub.2O.sub.3 material is obtainable by the process and further relates to electrodes for CDI devices having the material. A method for removing ions from a fluid, like saline water, using the capacitive deionization device includes applying a voltage to the electrodes while supplying said fluid into the capacitive deionization device.

A method for preparing a metal-free few-layer phosphorous nanomaterial. The method comprises an ice-assisted exfoliation process (or solvent ice-assisted exfoliation process). The method allows for the preparation of a few-layer phosphorous nanomaterial with improved yield and reduced duration and exfoliation power. The few-layer phosphorous nanomaterial is used in the preparation of a photocatalyst. The photocatalyst exhibits a long-term stability, high photocatalytic H.sub.2 evolution efficiency from water, and good stability under visible light irradiation.

A preparation method of a gradient long-effective catalytic membrane with high-strength and anti-deposition property is provided and includes: adding a nanometal oxide catalyst into an N, N-dimethylformamide solution of polyacrylonitrile or polystyrene, uniformly mixing, performing electrostatic spinning, keeping a receiver at −190° C. to −200° C. in the electrostatic spinning process, and performing freeze drying on a precursor membrane obtained after the electrostatic spinning is finished, so as to obtain the gradient long-effective catalytic membrane. According to the method, the gradient long-effective catalytic membrane with high-strength and anti-deposition property is obtained through a one-step method which adopts an ultralow-temperature-electrostatic spinning technology and combines with nanometal, the contradictory relation between the catalytic efficiency and the membrane stability in a traditional catalytic membrane is solved, the catalytic performance of the membrane is fully played, the organic polluted wastewater can be efficiently catalytically degraded, and the service life of the catalytic membrane is prolonged.

A preparation method of a gradient long-effective catalytic membrane with high-strength and anti-deposition property is provided and includes: adding a nanometal oxide catalyst into an N, N-dimethylformamide solution of polyacrylonitrile or polystyrene, uniformly mixing, performing electrostatic spinning, keeping a receiver at −190° C. to −200° C. in the electrostatic spinning process, and performing freeze drying on a precursor membrane obtained after the electrostatic spinning is finished, so as to obtain the gradient long-effective catalytic membrane. According to the method, the gradient long-effective catalytic membrane with high-strength and anti-deposition property is obtained through a one-step method which adopts an ultralow-temperature-electrostatic spinning technology and combines with nanometal, the contradictory relation between the catalytic efficiency and the membrane stability in a traditional catalytic membrane is solved, the catalytic performance of the membrane is fully played, the organic polluted wastewater can be efficiently catalytically degraded, and the service life of the catalytic membrane is prolonged.

A preparation method of a gradient long-effective catalytic membrane with high-strength and anti-deposition property is provided and includes: adding a nanometal oxide catalyst into an N, N-dimethylformamide solution of polyacrylonitrile or polystyrene, uniformly mixing, performing electrostatic spinning, keeping a receiver at −190° C. to −200° C. in the electrostatic spinning process, and performing freeze drying on a precursor membrane obtained after the electrostatic spinning is finished, so as to obtain the gradient long-effective catalytic membrane. According to the method, the gradient long-effective catalytic membrane with high-strength and anti-deposition property is obtained through a one-step method which adopts an ultralow-temperature-electrostatic spinning technology and combines with nanometal, the contradictory relation between the catalytic efficiency and the membrane stability in a traditional catalytic membrane is solved, the catalytic performance of the membrane is fully played, the organic polluted wastewater can be efficiently catalytically degraded, and the service life of the catalytic membrane is prolonged.

A preparation method of a gradient long-effective catalytic membrane with high-strength and anti-deposition property is provided and includes: adding a nanometal oxide catalyst into an N, N-dimethylformamide solution of polyacrylonitrile or polystyrene, uniformly mixing, performing electrostatic spinning, keeping a receiver at −190° C. to −200° C. in the electrostatic spinning process, and performing freeze drying on a precursor membrane obtained after the electrostatic spinning is finished, so as to obtain the gradient long-effective catalytic membrane. According to the method, the gradient long-effective catalytic membrane with high-strength and anti-deposition property is obtained through a one-step method which adopts an ultralow-temperature-electrostatic spinning technology and combines with nanometal, the contradictory relation between the catalytic efficiency and the membrane stability in a traditional catalytic membrane is solved, the catalytic performance of the membrane is fully played, the organic polluted wastewater can be efficiently catalytically degraded, and the service life of the catalytic membrane is prolonged.

The disclosure provides a porous manganese-containing Fenton catalytic material and a preparation method and use thereof. The porous manganese-containing Fenton catalytic material according to the disclosure includes particles with a cluster structure and the particles with the cluster structure include a porous-structure calcium oxide and two-dimensional nanosheets of a Mn—Ca compound on a surface of the porous-structure calcium oxide.