Provided herein phosphorous-boron bonded compounds which are configured for capturing CO.sub.2 with high affinity and tunability to specific CO.sub.2 capture needs and related products, compositions, methods and systems for capturing storing and/or utilizing carbon dioxide.

Provided is a carbon dioxide absorbent including an ionic liquid including an imidazole-based anion and an aliphatic alcohol. Since an alcohol solvent included in the carbon dioxide absorbent according to one embodiment has low toxicity and a very high boiling point, the carbon dioxide absorbent has no problem of release into the atmosphere and consequent environmental pollution, and is chemically stable to significantly lower the possibility of release of decomposition products into the atmosphere. In addition, the carbon dioxide absorbent is also effective, since it may absorb carbon dioxide with a higher equivalent than an absorbent input equivalent, and has low regeneration energy so that carbon dioxide is easily desorbed.

Methods of dewatering viscous materials are provided. The method comprises contacting the viscous material with pressurized carbon dioxide at a temperature and for a time wherein at least a fraction of water is expressed from the viscous material. Then the pressure is released, and the water expressed from the viscous material is removed to yield a dewatered product. Exemplary viscous materials that can be dewatered by the method include black liquor from wood pulping operations, wet lignin, wet super water absorbent polymers and sugar solutions. The pressurized carbon dioxide is present in subcritical or supercritical form. The method provides dewatering at reduced cost.

A solid amino acid salt sorbent for removing CO.sub.2 from a CO.sub.2 containing gas comprises an amino acid constituent and an alkali metal constituent. The solid amino acid salt sorbent comprises one or more of potassium taurine salt, sodium proline salt, sodium taurine salt, sodium lysine salt, potassium lysine salt, lithium lysine salt, potassium glycine salt, sodium glycine salt, lithium glycine salt, histidine sodium salt, taurine sodium salt, aspartic acid sodium salt, asparagine sodium salt, alanine sodium salt, or leucine sodium salt. The sorbent may further comprise a support component arranged in a structural relationship with the amino acid and alkali metal constituents.

The agent for selective metal recovery of the present invention includes a material derived from an alga belonging to the order Cyanidiales, which is dead cells or a cell surface layer of an alga belonging to the order Cyanidiales, or an artificial material produced by simulating the cell surface layer, or includes a porphyrin. The metal recovery method of the present invention includes an addition step of adding a material derived from an alga belonging to the order Cyanidiales, which is dead cells or a cell surface layer of an alga belonging to the order Cyanidiales, or an artificial material produced by simulating the cell surface layer, or adding a porphyrin, to a metal solution; and a recovery step of recovering a metal from the metal solution by the material derived from an alga belonging to the order Cyanidiales or the porphyrin.

Processes and apparatuses for degrading PFAS into calcium fluoride, carbon dioxide, and water. PFAS are heated and introduced to a calcium base which will degrade the PFAS. The PFAS may be in a stream that is a PFAS enriched stream formed by desorbing the PFAS from an adsorbent which removed the PFAS from a contaminant stream. The PFAS may be desorbed in the presence of the calcium base. The calcium base may be calcium hydroxide, calcium oxide, calcium carbonate, or combinations thereof.

The present disclosure provides an agent for selective metal recovery, a metal recovery method, and a metal elution method.