Photosynthetic pigmentA photosynthetic pigment (accessory pigment; chloroplast pigment; antenna pigment) is a pigment that is present in chloroplasts or photosynthetic bacteria and captures the light energy necessary for photosynthesis. List of photosynthetic pigments (in order of increasing polarity): Carotene: an orange pigment Xanthophyll: a yellow pigment Phaeophytin a: a gray-brown pigment Phaeophytin b: a yellow-brown pigment Chlorophyll a: a blue-green pigment Chlorophyll b: a yellow-green pigment Chlorophyll a is the most common of the six, present in every plant that performs photosynthesis.
Formic acidFormic acid (), systematically named methanoic acid, is the simplest carboxylic acid, and has the chemical formula HCOOH and structure . It is an important intermediate in chemical synthesis and occurs naturally, most notably in some ants. Esters, salts and the anion derived from formic acid are called formates. Industrially, formic acid is produced from methanol. Insect defenses In nature, formic acid is found in most ants and in stingless bees of the genus Oxytrigona.
Sulfate-reducing microorganismSulfate-reducing microorganisms (SRM) or sulfate-reducing prokaryotes (SRP) are a group composed of sulfate-reducing bacteria (SRB) and sulfate-reducing archaea (SRA), both of which can perform anaerobic respiration utilizing sulfate (SO42-) as terminal electron acceptor, reducing it to hydrogen sulfide (H2S). Therefore, these sulfidogenic microorganisms "breathe" sulfate rather than molecular oxygen (O2), which is the terminal electron acceptor reduced to water (H2O) in aerobic respiration.
Amine gas treatingAmine gas treating, also known as amine scrubbing, gas sweetening and acid gas removal, refers to a group of processes that use aqueous solutions of various alkylamines (commonly referred to simply as amines) to remove hydrogen sulfide (H2S) and carbon dioxide (CO2) from gases. It is a common unit process used in refineries, and is also used in petrochemical plants, natural gas processing plants and other industries.
MethanethiolMethanethiol ˌmɛθ.eɪn.ˈθaɪ.ɒl (also known as methyl mercaptan) is an organosulfur compound with the chemical formula CH3SH. It is a colorless gas with a distinctive putrid smell. It is a natural substance found in the blood, brain and feces of animals (including humans), as well as in plant tissues. It also occurs naturally in certain foods, such as some nuts and cheese. It is one of the chemical compounds responsible for bad breath and the smell of flatus. Methanethiol is the simplest thiol and is sometimes abbreviated as MeSH.
Kraft processThe kraft process (also known as kraft pulping or sulfate process) is a process for conversion of wood into wood pulp, which consists of almost pure cellulose fibres, the main component of paper. The kraft process involves treatment of wood chips with a hot mixture of water, sodium hydroxide (NaOH), and sodium sulfide (Na2S), known as white liquor, that breaks the bonds that link lignin, hemicellulose, and cellulose. The technology entails several steps, both mechanical and chemical. It is the dominant method for producing paper.
Green sulfur bacteriaThe green sulfur bacteria, Chlorobiota, are a phylum of obligately anaerobic photoautotrophic bacteria that metabolize sulfur. Green sulfur bacteria are nonmotile (except Chloroherpeton thalassium, which may glide) and capable of anoxygenic photosynthesis. They live in anaerobic aquatic environments. In contrast to plants, green sulfur bacteria mainly use sulfide ions as electron donors. They are autotrophs that utilize the reverse tricarboxylic acid cycle to perform carbon fixation. They are also mixotrophs and reduce nitrogen.
Purple sulfur bacteriaThe purple sulfur bacteria (PSB) are part of a group of Pseudomonadota capable of photosynthesis, collectively referred to as purple bacteria. They are anaerobic or microaerophilic, and are often found in stratified water environments including hot springs, stagnant water bodies, as well as microbial mats in intertidal zones. Unlike plants, algae, and cyanobacteria, purple sulfur bacteria do not use water as their reducing agent, and therefore do not produce oxygen.
Reducing atmosphereA reducing atmosphere is an atmospheric condition in which oxidation is prevented by removal of oxygen and other oxidizing gases or vapours, and which may contain actively reducing gases such as hydrogen, carbon monoxide, and gases such as hydrogen sulfide that would be oxidized by any present oxygen. Although early in its history the Earth had a reducing atmosphere, about 2.5 billion years ago it transitioned to an oxidizing atmosphere with molecular oxygen (dioxygen, O2) as the primary oxidizing agent.
BisulfideBisulfide (or bisulphide in British English) is an inorganic anion with the chemical formula HS− (also written as SH−). It contributes no color to bisulfide salts, and its salts may have a distinctive putrid smell. It is a strong base. Bisulfide solutions are corrosive and attack the skin. It is an important chemical reagent and an industrial chemical, mainly used in paper pulp industry (Kraft process), textiles, synthetic flavors, coloring brasses, and iron control.
