Abstract: A method of purifying cooling water used in nuclear reactors, which comprises contacting said cooling water with a hydrotalcite compound of the following formulaM.sub.1-x.sup.2+ M.sub.x.sup.3+ (OH).sub.2 A.sub.x/n.sup.n-. mH.sub.2 O (1)wherein M.sup.2+ represents a divalent metal cation, M.sup.3+ represents a trivalent metal cation, A.sup.n- represents an anion having a valence of n, and x and m satisfy the following expressions0<x<0.50.ltoreq.m<1or a calcined product thereof obtained by calcination at a temperature of up to about 900.degree. C.; and a purifying agent used therefor.

Abstract: A process for removing a halogen component from a halogen-containing organic compound, which comprises contacting an organic compound in the liquid state which is produced by using a halogen containing catalyst selected from the group consisting of Friedel-Crafts catalysts and Ziegler catalysts and contains the halogen component derived from said catalyst, with a hydrotalcite compound represented by the formulaM.sub.1-x.sup.2+ M.sub.x.sup.3+ (OH).sub.2+x-ny A.sub.y.sup.n-.mH.sub.2 OwhereinM.sup.2+ represents a divalent metal ion selected from the group consisting of Mg.sup.2+, Zn.sup.2+, Ca.sup.2+, Ni.sup.2+, Co.sup.2+, Mn.sup.2+ and Cu.sup.2+,M.sup.3+ represents a trivalent metal ion selected from the group consisting of Al.sup.3+, Fe.sup.3+ and Cr.sup.3+,A.sup.n- represents an anion having a valence of n selected from the group consisting of HCO.sub.3.sup.-, OH.sup.- and CO.sub.3.sup.2-, andx, y and m are each a positive number and satisfy the following conditions 0.1<x<0.5, 0.1<y<0.4, 0.ltoreq.

Abstract: A fire-retarding thermoplastic resin composition comprising (A) a thermoplastic resin, and (B) a fire-retarding amount of a hydrotalcite having a specific surface area, determined by the BET method, of not more than 30 m.sup.2 /g, the hydrotalcite being uncoated, or coated with an aqueous solution of an anionic surface active agent in a concentration of not more than 20 millimoles/liter in a thickness larger than a monolayer but up to a triple layer.