Titanium dioxide/sulfonated graphene oxide/silver nanoparticle composite membrane and its preparation method and application are disclosed. Mixing graphene oxide, sodium chloroethanesulfonate, and sodium hydroxide uniformly in the water, and then adding concentrated nitric acid to obtain sulfonated graphene oxide; mixing the aqueous solution of said sulfonated graphene oxide with the aqueous solution of silver nitrate, stirring in the dark, then adding ascorbic acid, and continuing to stir to obtain a silver nanoparticle/sulfonated graphene oxide composite material; dispersing said silver nanoparticle/sulfonated graphene oxide composite material in water, and then deposited on said titanium dioxide nanorods arrays by vacuum deposition, and vacuum dried to obtain titanium dioxide/sulfonated graphene oxide/silver nanoparticle composite membrane. The membrane possessed photocatalytic effect under UV light and special wettability: super-hydrophobic oil under water/super-hydrophobic under oil, which could in situ separation and degradation of oil/water emulsion.

Titanium dioxide/sulfonated graphene oxide/silver nanoparticle composite membrane and its preparation method and application are disclosed. Mixing graphene oxide, sodium chloroethanesulfonate, and sodium hydroxide uniformly in the water, and then adding concentrated nitric acid to obtain sulfonated graphene oxide; mixing the aqueous solution of said sulfonated graphene oxide with the aqueous solution of silver nitrate, stirring in the dark, then adding ascorbic acid, and continuing to stir to obtain a silver nanoparticle/sulfonated graphene oxide composite material; dispersing said silver nanoparticle/sulfonated graphene oxide composite material in water, and then deposited on said titanium dioxide nanorods arrays by vacuum deposition, and vacuum dried to obtain titanium dioxide/sulfonated graphene oxide/silver nanoparticle composite membrane. The membrane possessed photocatalytic effect under UV light and special wettability: super-hydrophobic oil under water/super-hydrophobic under oil, which could in situ separation and degradation of oil/water emulsion.

Metal nanoparticles and compositions derived therefrom can be used in a number of different applications. Methods for making metal nanoparticles can include providing a first metal salt in a solvent; converting the first metal salt into an insoluble compound that constitutes a plurality of nanoparticle seeds; and after forming the plurality of nanoparticle seeds, reacting a reducing agent with at least a portion of a second metal salt in the presence of at least one surfactant and the plurality of nanoparticle seeds to form a plurality of metal nanoparticles. Each metal nanoparticle can include a metal shell formed around a nucleus derived from a nanoparticle seed, and the metal shell can include a metal from the second metal salt. The methods can be readily scaled to produce bulk quantities of metal nanoparticles.

Metal nanoparticles and compositions derived therefrom can be used in a number of different applications. Methods for making metal nanoparticles can include providing a first metal salt in a solvent; converting the first metal salt into an insoluble compound that constitutes a plurality of nanoparticle seeds; and after forming the plurality of nanoparticle seeds, reacting a reducing agent with at least a portion of a second metal salt in the presence of at least one surfactant and the plurality of nanoparticle seeds to form a plurality of metal nanoparticles. Each metal nanoparticle can include a metal shell formed around a nucleus derived from a nanoparticle seed, and the metal shell can include a metal from the second metal salt. The methods can be readily scaled to produce bulk quantities of metal nanoparticles.

A powder bed material can include from 80 wt % to 100 wt % metal particles having a D50 particle size distribution value from 4 ?m to 150 ?m. From 10 wt % to 100 wt % of the metal particles can be surface-activated metal particles having in intact inner volume and an outer volume with structural defects. The structural defects can exhibit an average surface grain density of 50,000 to 5,000,000 per mm.sup.2.

A powder bed material can include from 80 wt % to 100 wt % metal particles having a D50 particle size distribution value from 4 ?m to 150 ?m. From 10 wt % to 100 wt % of the metal particles can be surface-activated metal particles having in intact inner volume and an outer volume with structural defects. The structural defects can exhibit an average surface grain density of 50,000 to 5,000,000 per mm.sup.2.

Methods for reducing a concentration of hexavalent chromium within a first aluminum slurry by adding a reducing agent to form a second aluminum slurry are provided. The reducing agent causes a chemical reduction reaction with the hexavalent chromium compound of the first aluminum slurry to form a trivalent chromium compound within the second aluminum slurry such that a first weight ratio of hexavalent chromium to trivalent chromium in the first aluminum slurry is decreased to a second weight ratio of hexavalent chromium to trivalent chromium in the second aluminum slurry, with the second weight ratio being less than the first weight ratio.

Methods for reducing a concentration of hexavalent chromium within a first aluminum slurry by adding a reducing agent to form a second aluminum slurry are provided. The reducing agent causes a chemical reduction reaction with the hexavalent chromium compound of the first aluminum slurry to form a trivalent chromium compound within the second aluminum slurry such that a first weight ratio of hexavalent chromium to trivalent chromium in the first aluminum slurry is decreased to a second weight ratio of hexavalent chromium to trivalent chromium in the second aluminum slurry, with the second weight ratio being less than the first weight ratio.

Methods for reducing a concentration of hexavalent chromium within a first aluminum slurry by adding a reducing agent to form a second aluminum slurry are provided. The reducing agent causes a chemical reduction reaction with the hexavalent chromium compound of the first aluminum slurry to form a trivalent chromium compound within the second aluminum slurry such that a first weight ratio of hexavalent chromium to trivalent chromium in the first aluminum slurry is decreased to a second weight ratio of hexavalent chromium to trivalent chromium in the second aluminum slurry, with the second weight ratio being less than the first weight ratio.

Methods for reducing a concentration of hexavalent chromium within a first aluminum slurry by adding a reducing agent to form a second aluminum slurry are provided. The reducing agent causes a chemical reduction reaction with the hexavalent chromium compound of the first aluminum slurry to form a trivalent chromium compound within the second aluminum slurry such that a first weight ratio of hexavalent chromium to trivalent chromium in the first aluminum slurry is decreased to a second weight ratio of hexavalent chromium to trivalent chromium in the second aluminum slurry, with the second weight ratio being less than the first weight ratio.