The present invention provides a safe and highly efficient method for producing graphite oxide. The present invention relates to a method for producing graphite oxide by oxidizing graphite, the method including the step of oxidizing graphite by adding a permanganate to a liquid mixture containing graphite and sulfuric acid while maintaining the concentration of heptavalent manganese at 1% by mass or less in 100% by mass of the liquid mixture.

A water-based wellbore fluid may include an aqueous base fluid and a modified graphene shale inhibitor that comprises one or more substituents that are covalently bonded to graphene via a linking group. One of the one or more substituents may be a hydrocarbon group that has a number of carbon atoms in the range from 8 to 14.

A water-based wellbore fluid may include an aqueous base fluid and a modified graphene shale inhibitor that comprises one or more substituents that are covalently bonded to graphene via a linking group. One of the one or more substituents may be a hydrocarbon group that has a number of carbon atoms in the range from 8 to 14.

Since a surface of the artificial graphite of the negative electrode active material according to the present invention is modified with nitrogen, dispersibility in an aqueous system may be improved and accordingly, affinity between a binder and the negative electrode active material is increased to increase the adhesive strength of an electrode. Also, since the surface of the artificial graphite is modified with nitrogen, there is an effect of maintaining a high battery capacity. Furthermore, in the method of preparing a negative electrode active material according to the present invention, since an oxygen-containing functional group is connected to the artificial graphite by a mild oxidation process, the nitrogen may be easily attached to the artificial graphite so that the negative electrode active material becomes an electrical conductor by maintaining original crystallinity while having a hydrophilic property. Thus, excellent battery efficiency may be achieved.

Since a surface of the artificial graphite of the negative electrode active material according to the present invention is modified with nitrogen, dispersibility in an aqueous system may be improved and accordingly, affinity between a binder and the negative electrode active material is increased to increase the adhesive strength of an electrode. Also, since the surface of the artificial graphite is modified with nitrogen, there is an effect of maintaining a high battery capacity. Furthermore, in the method of preparing a negative electrode active material according to the present invention, since an oxygen-containing functional group is connected to the artificial graphite by a mild oxidation process, the nitrogen may be easily attached to the artificial graphite so that the negative electrode active material becomes an electrical conductor by maintaining original crystallinity while having a hydrophilic property. Thus, excellent battery efficiency may be achieved.

Provided is filtration member for use in a filtration device, said filtration member comprising a layer of woven or nonwoven fabric having two primary surfaces and a layer of chemically functionalized graphite flakes deposited on at least one of the two primary surfaces or embedded in the layer of woven or nonwoven fabric, wherein said graphite flakes comprise chemical function contain 1%-50% by weight of a non-carbon element selected from O, N, H, F, Cl, Br, I, or a combination thereof. Also provided is a face mask comprising: (a) a mask body configured to cover at least wearer's mouth and nose; and (b) a fastener to hold the mask in place on the wearer's face; wherein the mask body includes (i) an air-permeable outer layer, (ii) an inner layer located on a wearer's side when the mask is worn, and (iii) the filtration member comprising graphite flakes.

Provided is an face mask comprising: (a) a mask body configured to cover at least wearer's mouth and nose; and (b) a fastener to hold the mask in place on the wearer; wherein the mask body includes (i) an air-permeable outer layer preferably comprising a hydrophobic material (e.g. water-repelling fibers), (ii) an inner layer located on a wearer's side when the mask is worn, and (iii) a graphene foam layer disposed in the mask body between the outer layer and the inner layer or embedded (totally or partially) in the outer layer or the inner layer. The foam pore wall graphene surfaces may be deposited with an antiviral or anti-bacteria compound.

A material that can be used in a wide temperature range is provided. A graphene compound includes graphene or graphene oxide and a substituted or unsubstituted chain group, the chain group includes two or more ether bonds, and the chain group is bonded to the above graphene or graphene oxide through a Si atom. Alternatively, a method for forming a graphene compound includes a first step and a second step after the first step. In the first step, graphene oxide and a base are stirred under a nitrogen stream. In the second step, the mixture is cooled to room temperature, a silylating agent that has a group having two or more ether bonds is introduced into the mixture, and the obtained mixture is stirred. The base is butylamine, pentylamine, hexylamine, diethylamine, dipropylamine, dibutylamine, triethylamine, tripropylamine, or pyridine.

A material that can be used in a wide temperature range is provided. A graphene compound includes graphene or graphene oxide and a substituted or unsubstituted chain group, the chain group includes two or more ether bonds, and the chain group is bonded to the above graphene or graphene oxide through a Si atom. Alternatively, a method for forming a graphene compound includes a first step and a second step after the first step. In the first step, graphene oxide and a base are stirred under a nitrogen stream. In the second step, the mixture is cooled to room temperature, a silylating agent that has a group having two or more ether bonds is introduced into the mixture, and the obtained mixture is stirred. The base is butylamine, pentylamine, hexylamine, diethylamine, dipropylamine, dibutylamine, triethylamine, tripropylamine, or pyridine.

The invention relates to an exfoliation method according to which a fluid loaded with particles flows at a first flow rate into a first (2), and then into a second, section of a pipe (1), the first flow rate being suitable for generating shear stresses and cavitation bubbles in the fluid as it passes through the first section (2) of the pipe (1), the second section (3) having a hydraulic diameter suitable for bringing about an implosion of cavitation bubbles as soon as the fluid exits the first section (2) and flows into the second section (3), so that an exfoliation of the particles is brought about under the combined action of the shear stresses and a shock wave generated by the implosion of the cavitation bubbles, the first section (2) having a hydraulic diameter less than 300 μm.