Preparation Of Porous Mineral-based Chemical Sorbents And Removal Of H₂ S And So₂

The porous mineral materials can be used for the environment protection due to their environmental friendness, free-pollution and adsorptivities. There is a variety of mineral materials, for instance, diatomite, calcite, sepiolite, zeolite, medical stone, halloysite, and so on. For their abundant resource, high thermal stabilization, special constructions, better absorption capability, these minerals are often used for wastewater treatment and air purification after purification, grinding, modification, composite processing.Several chemosorbents from the porous mineral materials were prepared, mainly including: (1) the chemosorbents used for the removal of hydrogen sulfide and sulphur dioxide prepared by equivalent volume impregnation with potassium permanganate and porous mineral materials; (2) the chemosorbents used for the removal of hydrogen sulfide prepared by equivalent volume impregnation with potassium permanganate and porous clay heterostructures based on porous mineral materials; (3) the chemosorbents used for the removal of sulphur dioxide prepared with the porous mineral materials modified by metallic oxide.The samples prepared by impregnating with potassium permanganate and porous mineral materials, have low activity to remove H2S and SO2, due to the worse dispersion of potassium permanganate on carrieres caused by the lower specific surface area and higher bulk density of raw minerals. However, the porous clay heterostructures derived from porous mineral materials possess a higher specific surface area, larger pore volume and excellent absorption capability. When adding the suitable surfactant amount and calcinating at 550°C , the sample with a high specific surface area(672 m2/g) and large pore volume(1.04 cm3/g) can be obtained. After modified with potassium permanganate, its removal ability against hydrogen sulfide increased signifcantly, with a double breakthough time. For the difference of redox ability between hydrogen sulfide and sulphur dioxide, the chemosorbents modified by potassium permanganate have a higher removal efficiency of hydrogen sulfide but a lower removal efficiency of sulphur dioxide. In order to obtain the chemosorbents with better thermal stability and a higher sulphur dioxide removal capacity, we prepared the ZnO/attapulgite by a coprecipitation method. Due to the catalytic oxidation from nano-ZnO, the removal ability increased remarkably.In the practical use of chemosorbents, besides the cost and performance, no secondary pollution and easy recycling should be also considered. Because of their good plasticity, porous minerals can be extruded to particles after loading the potassium permanganate, ZnO and other active substances without any additive. In comparison with other materials, such as activated charcoal and activated alumina, the process is simpler and the particles after molding are stronger.