Methods are disclosed for treating water containing a target anion to remove the target anion. The methods can include preparing a treatment composition solution that contains a metal treatment agent, adjusting the treatment composition solution to a first pH that is alkaline and then to a second pH that is acidic, and contacting the treatment composition solution with the water that contains the target anion.

A filter media composition includes a ferrihydrite material having an average pore size (BJH) in a range from 1 to 3 nm and a surface area (BET) of at least 200 m.sup.2/g or at least 250 m.sup.2/g or at least 300 m.sup.2/g.

An atmospheric water harvesting material includes a deliquescent salt, a photothermal agent, and a polymeric hydrogel matrix containing the deliquescent salt and photothermal agent.

The ammonia adsorbent contains at least one substance selected from the group consisting of L-type zeolite, ferrierite, ZSM-5 type zeolite, strongly acidic cation exchange resin and Prussian blue type complex.

The present subject matter illustrates a method for accelerated in-situ chemical reduction of subsoil matter. The method comprises supplying a mixture comprising ferrous sulfide into soil pathways to biologically react with dissolved contaminates in the groundwater. Further, an organic hydrogen donor is supplied into the soil-pathways to produce anerobic-conditions to cause indigenous anaerobic bacteria to biodegrade residual concentrations of the contaminates.

Sensors for detecting analytes are disclosed. In various implementations, the sensing device may include a substrate and a sensor array. The sensor array may be arranged on the substrate, and may include a plurality of sensors. In some implementations, at least two of the sensors may include a first carbon-based sensing material disposed between a first pair of electrodes, and a second carbon-based sensing material disposed between a second pair of electrodes. The first carbon-based sensing material may be configured to detect a presence of each analyte of a group of analytes, and the second carbon-based sensing material may be configured to confirm the presence of each analyte of a subset of the group of analytes. In some instances, the group of analytes includes at least twice as many different analytes as the subset of analytes.

A magnetic adsorbent, including an admixture of an adsorbent and a magnetic material. A system for removing mercury from a fluid stream, the system including, a magnetic adsorbent injection unit for injecting an admixture of powdered activated carbon and magnetic material into the fluid stream; and a particulate removal unit. Also included are methods for removing mercury from a fluid stream and methods for producing a magnetic sorbent.

A sensing device for detecting analytes within a package or container is disclosed. In various implementations, the sensing device may include a substrate, one or more electrodes, and a sensor array. The sensor array may be disposed on the substrate, and may include a plurality of carbon-based sensors coupled to the one or more electrodes. The carbon-based sensors may be configured to react with unique groups of analytes in response to an electromagnetic signal received from an external device. In some instances, a first sensor may be configured to detect a presence of each analyte of a group of analytes, and a second sensor may be configured to confirm the presence of each analyte of a subset of the group of analytes.

A filter media composition includes a ferrihydrite material having an average pore size (BJH) in a range from 1 to 3 nm and a surface area (BET) of at least 200 m.sup.2/g or at least 250 m.sup.2/g or at least 300 m.sup.2/g.

Disclosed herein are embodiments of filtration systems and iron oxide nanowire-based filter meshes that can capture and inactivate pathogens in air. The filter meshes can include a porous lattice of iron metal and iron oxide nanowires radiating from the porous lattice of iron metal. The iron oxide nanowires radiating from the porous lattice of iron metal can be created by processing the filter mesh using the disclosed method. Pathogens can be inactivated by passing a sample containing the pathogens through the filter mesh and inactivating at least a portion of the pathogens as the sample passes through the filter mesh.