Abstract: An aqueous solution or solid substance contains divalent iron ions and L-ascorbic acid. The L-ascorbic acid is present in an amount of 2.0 parts by weight or more per 100 parts by weight of the divalent iron ions. The aqueous solution or solid substance can be used advantageously as deodorants, germicides, foods freshness preserving agents, water treatment agents or the like.

Abstract: A chemically active composition containing divalent iron ions, wherein an iron (II) compound, ascorbic acid and or citric acid and alum are contained and the ratio between the divalent iron ions in the iron (II) compound and ascorbic acid or citric acid is between 1:0.02 and 0.30 (in the case of ascorbic acid) or 1:0.01 and 0.80 (in the case of citric acid) by weight ratio. The composition is applied in the form of an aqueous solution or solid matter as a deodorant, freshness-preserving agent for foods, growth promoting agent for plants and flame retardant for burnable materials. Not only uni-functional materials can be obtained but also multi-functional materials.

Abstract: Magnesia particles obtained by calcining at a temperature of 500.degree.-700.degree. C. show excellent adsorbing properties.

Abstract: Magnesia particles obtained by calcining at a temperature of 500.degree. - 700.degree. C. show excellent adsorbing properties.

Abstract: An aqueous solution containing aluminum is mixed with an aqueous solution containing calcium and/or an aqueous solution containing magnesium and, if necessary, further with an aqueous solution containing iron and the pH of the resulting mixture is adjusted to cause insolubilization of the metallic elements present therein and consequently gives rise to a coprecipitation product. This coprecipitation product is dehydrated and dried and, as an adsorbent, brought into contact with waste water containing organic pollutants. The adsorbent adsorbs and removes said organic pollutants from said waste water.