The present invention covers a novel method for creating an adsorbent and the resulting novel adsorbent. The method may be used to remove pollutants/unwanted chemicals from water, air, other gases, biological fluids (such as blood, urine, lipids, protein fluids), and other fluids (such as fuel). The adsorbent may be used to remove heavy metals (for example, lead), organic pollutants, inorganic non-meal pollutants (for example, nitrates and bromates). Accordingly, the current invention has many applications including but not limited to water treatment, wastewater treatment, biomedical fluid treatments, gas cleanup, and fuel (oil, gas) cleanup.

An ammonia-containing tail gas absorption system, comprising at least two sets of absorption devices, wherein at least two transport pipelines are provided at inlets of some of the absorption devices, and the transport pipelines are used to communicate the absorption devices with an ammonia-containing tail gas outlet of a reactor or other absorption devices. Valves are provided on the transport pipelines, and the valves are used to control the connection and disconnection of the transport pipelines so as to switch the series-parallel relationship between the sets of absorption devices.

An absorbent for selective removal of hydrogen sulfide over carbon dioxide from a fluid stream comprises an aqueous solution of a) a tertiary amine, b) a sterically hindered secondary amine of the general formula (I) ##STR00001##
in which R.sub.1 and R.sub.2 are each independently selected from C.sub.1-4-alkyl and C.sub.1-4-hydroxyalkyl; R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are each independently selected from hydrogen, C.sub.1-4-alkyl and C.sub.1-4-hydroxyalkyl, with the proviso that at least one R.sub.4 and/or R.sub.5 radical on the carbon atom bonded directly to the nitrogen atom is C.sub.1-4-alkyl or C.sub.1-4-hydroxyalkyl when R.sub.3 is hydrogen; x and y are integers from 2 to 4 and z is an integer from 1 to 4; where the molar ratio of b) to a) is in the range from 0.05 to 1.0, and c) an acid in an amount, calculated as neutralization equivalent relative to the protonatable nitrogen atoms in a) and b), of 0.05 to 15.0%. One preferred amine of the formula I is 2-(2-tert-butylaminoethoxy)ethanol. The absorbent allows a defined H.sub.2S selectivity to be set at pressures of the kind typical in natural gas processing.

A gas purifying filter includes a first gas permeable body having a gas inlet surface; a first adsorption layer disposed on the first gas permeable body and including activated carbon on which a phosphoric acid-based compound satisfying the following Formula 1 is supported; a second adsorption layer disposed on the first adsorption layer and including a hydrophobic zeolite having a SiO.sub.2/Al.sub.2O.sub.3 value of about 50 or more; and a second gas permeable body disposed on the second adsorption layer and having a gas outlet surface,

##STR00001##

where n is an integer greater than or equal to 1.

Systems and methods for producing nitrates, nitric acid, salts thereof, or a mixture thereof are disclosed. The systems may include a feed conduit configured for receiving a feed stream comprising molecular oxygen and molecular nitrogen; an inlet conduit configured for receiving an inlet stream; a plasma reactor fluidically coupled to the inlet conduit, the plasma reactor fluidically coupled to a reactor-outlet conduit configured for receiving the reactor-outlet stream, the plasma reactor configured to produce oxidized nitrogen species; and an absorber fluidically coupled to the reactor-outlet conduit, the absorber configured to receive the reactor outlet stream and to produce nitrates, nitrites, nitric acid, salts thereof, or a mixture thereof from the reactor outlet stream. A recycle conduit may be fluidically coupled to the absorber and the inlet conduit, wherein the recycle conduit is configured to receive the gas-phase stream from the absorber and provide the gas-phase stream to the inlet conduit.

A device for waste gas scrubbing in a urea plant may be configured such that a waste gas passes along a transportation direction in the duct. The duct may include a first region for removing urea dust particles from the waste gas and a second region for removing chemical compounds from the waste gas, which can be integrated by an acid-base reaction into an aqueous liquid phase. A cross-sectional area of the duct extending perpendicular to the transportation direction in the second region may be greater than a cross-sectional area extending perpendicular to the transportation direction in the first region. Further, the device may be configured such that the duct extends horizontally at least in sections and/or the transportation direction of the waste gas through the duct extends horizontally in an installed state.

An example article includes a substrate and a coating applied to the substrate. The coating includes a stabilizer and an organic phosphonic acid reactant. In an example article, the coating includes a water-soluble polymer and an organic phosphate or phosphonate reactant. An example coating configured to be applied to a basic gas filter substrate includes a water-soluble polymer and an organic phosphate or phosphonate reactant. An example technique includes applying a coating to a substrate and heating at least the coating to a temperature between about 100 C. and about 275 C. for about 1 minute to about 10 minutes. An example system includes a basic gas filter including a coating, and a sensor configured to sense an optical change in the coating.

Disclosed is an apparatus for separating amine gas from mixed gas, the apparatus including: a washer column through which mixed the gas passes; and a main adsorber column through which the mixed gas passing through the washer column passes. According to the present invention, the apparatus can remove amine gas more effectively and increase the lifetime of an adsorbent by allowing the mixed gas including the amine gas to pass through the washer column and the adsorber column.

A method, scrubbing solution and apparatus for removing a H.sub.2S scavenger, for example dithiazine, from a gas stream uses an acidic solution to convert the H.sub.2S scavenger to a salt. The acidic solution may be a phosphoric acid solution.

A method, scrubbing solution and apparatus for removing a H.sub.2S scavenger, for example dithiazine, from a gas stream uses an acidic solution to convert the H.sub.2S scavenger to a salt. The acidic solution may be a phosphoric acid solution.