Technologies are generally described for gas filtration and detection devices. Example devices may include a graphene membrane and a sensing device. The graphene membrane may be perforated with a plurality of discrete pores having a size-selective to enable one or more molecules to pass through the pores. A sensing device may be attached to a supporting permeable substrate and coupled with the graphene membrane. A fluid mixture including two or more molecules may be exposed to the graphene membrane. Molecules having a smaller diameter than the discrete pores may be directed through the graphene pores, and may be detected by the sensing device. Molecules having a larger size than the discrete pores may be prevented from crossing the graphene membrane. The sensing device may be configured to identify a presence of a selected molecule within the mixture without interference from contaminating factors.

A method which distinctly characterizes and quantifies the pyritic sulfur and the organic sulfur of a sedimentary rock sample. A rock sample is subjected to a heating sequence in an inert atmosphere which produces effluents resulting which are continuously oxidized. SO.sub.2 is continuously measured, and a pyrolysis sulfur content and a pyrolysis pyritic sulfur content are deduced therefrom. The residue from heating in an inert atmosphere is then heated in an oxidizing atmosphere. Released SO.sub.2 is continuously measured and at least an oxidation sulfur content is deduced therefrom. The pyritic sulfur content is determined from pyrolysis, a weighting function, a second parameter representing the impact of the mineral matrix and a third parameter representing the impact of the organic matrix.

Processes for sensing a variety of toxic chemicals and/or processes for determining the residual life of a filter or filtration system are provided. Exemplary process for sensing a toxic chemical include contacting a toxic chemical, or byproduct thereof, with a sorbent that includes a porous metal hydroxide and a transition metal reactant suitable to react with a toxic chemical or byproduct thereof. The sorbent is contacted with the toxic chemical or byproduct thereof for a sampling time. A difference between a post-exposure colorimetric state of the sorbent and a pre-exposure colorimetric state of the sorbent or control is determined to thereby sense exposure to, or the presence of, the toxic chemical or byproduct thereof.

Method for distinctly characterizing and quantifying the pyritic sulfur and the organic sulfur of a sedimentary rock sample.

A rock sample is subjected to a heating sequence in an inert atmosphere, the effluents resulting from this heating in an inert atmosphere are continuously oxidized, the SO.sub.2 released is continuously measured, and a pyrolysis sulfur content and a pyrolysis pyritic sulfur content are deduced therefrom. The residue from heating in an inert atmosphere is then heated in an oxidizing atmosphere, the SO.sub.2 released is continuously measured and at least an oxidation sulfur content is deduced therefrom. The pyritic sulfur content is determined from the pyrolysis pyritic sulfur content and from a weighting function taking account of a first parameter representing a pyrite thermal degradation rate, a second parameter representing the impact of the mineral matrix and a third parameter representing the impact of the organic matrix. The organic sulfur content can further be determined from at least the oxidation sulfur content, the pyrolysis sulfur content and the pyritic sulfur content.

Application: notably petroleum exploration and exploitation.

Processes for sensing a variety of toxic chemicals and/or processes for determining the residual life of a filter or filtration system are provided. Exemplary process for sensing a toxic chemical include contacting a toxic chemical, or byproduct thereof, with a sorbent that includes a porous metal hydroxide and a transition metal reactant suitable to react with a toxic chemical or byproduct thereof. The sorbent is contacted with the toxic chemical or byproduct thereof for a sampling time. A difference between a post-exposure colorimetric state of the sorbent and a pre-exposure colorimetric state of the sorbent or control is determined to thereby sense exposure to, or the presence of, the toxic chemical or byproduct thereof.