Immobilization of hexavalent chromium in contaminated soils using biochar supported nanoscale iron sulfide composite.

See more Iron products. Iron (atomic symbol: Fe, atomic number: 26) is a Block D, Group 8, Period 4 element with an atomic weight of 55.845. The number of electrons in each of Iron's shells is 2, 8, 14, 2 and its electron configuration is [Ar] 3d⁶ 4s². The iron atom has a radius of 126 pm and a Van der Waals radius of 194 pm. Iron was discovered by humans before 5000 BC. In its elemental form, iron has a lustrous grayish metallic appearance. Iron is the fourth most common element in the Earth's crust and the most common element by mass forming the earth as a whole. Iron is rarely found as a free element, since it tends to oxidize easily; it is usually found in minerals such as magnetite, hematite, goethite, limonite, or siderite. Though pure iron is typically soft, the addition of carbon creates the alloy known as steel, which is significantly stronger.

See more Sulfur products. Sulfur (or Sulphur) (atomic symbol: S, atomic number: 16) is a Block P, Group 16, Period 3 element with an atomic radius of 32.066. The number of electrons in each of Sulfur's shells is 2, 8, 6 and its electron configuration is [Ne] 3s² 3p⁴. In its elemental form, sulfur has a light yellow appearance. The sulfur atom has a covalent radius of 105 pm and a Van der Waals radius of 180 pm. In nature, sulfur can be found in hot springs, meteorites, volcanoes, and as galena, gypsum, and epsom salts. Sulfur has been known since ancient times but was not accepted as an element until 1777, when Antoine Lavoisier helped to convince the scientific community that it was an element and not a compound.

See more Chromium products. Chromium (atomic symbol: Cr, atomic number: 24) is a Block D, Group 6, Period 4 element with an atomic weight of 51.9961. The number of electrons in each of Chromium's shells is 2, 8, 13, 1 and its electron configuration is [Ar] 3d⁵ 4s¹. Louis Nicolas Vauquelin first discovered chromium in 1797 and first isolated it the following year. The chromium atom has a radius of 128 pm and a Van der Waals radius of 189 pm. In its elemental form, chromium has a lustrous steel-gray appearance. Chromium is the hardest metallic element in the periodic table and the only element that exhibits antiferromagnetic ordering at room temperature, above which it transforms into a paramagnetic solid. The most common source of chromium is chromite ore (FeCr₂O₄). Due to its various colorful compounds, Chromium was named after the Greek word 'chroma.' meaning color.