Disclosed are novel aqueous aluminum complex compositions and methods of making and using them. The novel compositions comprise very low halide content, even when made from aluminum chlorohydrate. The compositions find use in the production of zeolites, coatings, abrasives, binders, and refractories; and in the treatment of wastewater for example. The methods of making the novel compositions include passing a first aqueous aluminum complex composition through an anion exchange column or otherwise contacting the first composition with the anion exchange resin to provide a second aqueous aluminum complex composition that is different from the first aqueous aluminum complex composition. Also disclosed are methods of making zeolites and aqueous silica-alumina compositions from the novel aqueous aluminum complex compositions.

A method for producing an active silicic acid solution in which the existing amount of foreign matters as plate-like fine particles is reduced and a method for producing a silica sol in which such foreign matters are reduced. The method fulfills the following condition; the existing amount of plate-like fine particles having a length of one side of 0.2 to 4.0 m and a thickness of 1 to 100 nm is measured to be 0% to 30% in accordance with measuring method A, the method including the steps of: preparing an active silicic acid solution by subjecting an alkali silicate aqueous solution having a silica concentration of 0.5% by mass to 10.0% by mass to cation-exchange to remove alkaline components; and filtering the active silicic acid solution through a filter whose removal rate of particles having a primary particle size of 1.0 m is 50% or more.

A method for producing a silica sol containing a small amount of metal impurities and in which colloidal silica having an elongated particle shape dispersed in a solvent, includes: preparing a raw material liquid by adding a compound as an anion source selected from inorganic acids, organic acids, and their ammonium salts, and ammonia to a colloidal aqueous solution of activated silica having an SiO.sub.2 concentration of 1 to 6% by mass and a pH of 2 to 5 so that the mass ratio of the compound to SiO.sub.2 is 3.0 to 7.0%; and heating the raw material liquid at 80 to 200 C. for 0.5 to 20 hours. The elongated colloidal silica particles exhibit a D.sub.L/D.sub.B ratio of 2.5 or more. D.sub.L is an average particle diameter as measured by the dynamic light scattering method. D.sub.B is a primary particle diameter as measured by the nitrogen gas adsorption method.

An insulating composition containing silica particles, a resin, and a curing agent, wherein: when an aqueous solution of the silica particles having an SiO.sub.2 concentration of 3.8% by mass is heated at 121? C. for 20 hours, the amount of Na ions eluted from the silica particles is 40 ppm/SiO.sub.2 or less, especially, wherein the amount of Na ions eluted from the silica particles after the heating may be 5-38 ppm/SiO.sub.2, and, the silica particles may contain a polyvalent metal oxide so the ratio by mole of a polyvalent metal M to Si is 0.001-0.02; the mass ratio of Na.sub.2O/SiO.sub.2 in the silica particles may be 700-1,300 ppm; and the silica particles may have, on the surfaces thereof, a layer having a thickness of 0.1-1.5 nm and an Na.sub.2O/SiO.sub.2 mass ratio of 10-400 ppm, and may have an average particle diameter of 5-40 nm.

A method for producing an active silicic acid solution in which the existing amount of foreign matters as plate-like fine particles is reduced and a method for producing a silica sol in which such foreign matters are reduced. The method fulfills the following condition: the existing amount of plate-like fine particles having a length of one side of 0.2 to 4.0 m and a thickness of 1 to 100 nm is measured to be 0% to 30% in accordance with measuring method A, the method including the steps of: preparing an active silicic acid solution by subjecting an alkali silicate aqueous solution having a silica concentration of 0.5% by mass to 10.0% by mass to cation-exchange to remove alkaline components; and filtering the active silicic acid solution through a filter whose removal rate of particles having a primary particle size of 1.0 m is 50% or more.

A preparation method for a silica aerogel, comprising the following steps: A) raw material containing a solid silicon source and an alkaline solution is used to produce an aerogel precursor after mixing; and B) the aerogel precursor is dried to obtain a silica aerogel. An improved silica aerogel preparation method, comprising the following steps: A) a cation exchange resin and a silicate solution are used as raw materials and mixed; B) the mixed material is allowed to stand to obtain an aerogel precursor; and C) the aerogel precursor is dried to obtain a silica aerogel.

An exemplary embodiment of the present disclosure provides a method for manufacturing an aerogel. The method may include mixing a silicate salt with a solution to obtain a sol-gel. The method may include conditioning the sol-gel with one or more abradants to obtain an aerogel product.

There is provided a method for obtaining a purified aqueous solution of silicic acid containing less metal impurities such as Cu and Ni using water glass as a raw material with less number of purification steps than that in conventional methods without using any unnecessary additives. The method for producing a purified aqueous solution of silicic acid, the method comprising the steps of: (a) passing an aqueous solution of alkaline silicate having a silica concentration of 0.5% by mass or more and 10% by mass or less through a column filled with a polyamine-, iminodiacetic acid-, or aminophosphoric acid-type chelating resin, and (b) passing the aqueous solution passed in the step (a) through a column filled with a hydrogen-type cation exchange resin.

Provided is a silica-based polishing particle, particularly suitable for primary polishing, which provides a high polishing rate on the surface of a substrate and which prevents particle residues on the substrate after polishing, and an abrasive including the silica-based polishing particle. A silica-based polishing particle with a three-dimensional polycondensation structure containing an alkoxy group, wherein the particle has an average particle diameter (d) of 5 to 300 nm, an aspect ratio of more than 1.20 and 5.00 or less, and a carbon content of 0.005% by mass or more and less than 0.50% by mass.

Provided is a non-spherical silica sol containing non-spherical silica fine particles dispersed in a dispersion medium, the non-spherical silica fine particles having an average particle diameter in a range of 3 to 150 nm as measured by dynamic light scattering, a minor-diameter/major-diameter ratio in a range of 0.01 to 0.8, and a specific surface area in a range of 10 to 800 m.sup.2/g, and also having a plurality of wart-like projections on the surfaces thereof, and a process for producing the non-spherical silica sol. The non-spherical silica fine particles contained in the non-spherical silica sol have a unique structure different from the structure of ordinary non-spherical silica fine particles.