- Cellulose fibers are insoluble in most conventional solvents, including water.
- On the basis of the cross-linking method, the hydrogels can be divided into chemical gels and physical gels.
- Hemicellulose and cellulose follow the same biosynthetic routes.
- The mechanisms by which the heat may flow are three: conduction, convection, and radiation.
- Biochemical pretreatment is mainly used to overcome recalcitrant material and increase surface area to optimize cellulose accessibility to cellulases.
- The visually observable “wood grain”, which results from the higher order arrangement and directionality of various cell types,
- One of a class of substances that cannot be separated into simpler substances by chemical means are known as elements.
- The crystallinities of cellulose nanocrystals samples produced from bleached pulp fibers using strong acid hydrolysis were not substantially greater than that of the original fibers.
- Whether the raw material is vegetable oil or beef tallow, the bio-diesel producers refer to this main ingredient as feedstock.
- In general, crystallization may be analyzed from the standpoint of purity, yield, energy requirements, and rates of formation and growth of crystals.
- In the paper making process, the first step is refining.
- Natural rubber comes from the milky sap of a tropical tree.
- Alkanes are unsaturated hydrocarbons.
- The most common cellulase groups produced by T. reesei that cleave the β-1,4- glycosidic bonds are β-glucosidase, endoglucanases and exoglucanases.
- In the process of liquid-liquid extraction, the liquid-mixture feed and solvent are miscible.
- In some cases, momentum, heat, and mass transfer all occur simultaneously.
- Hydrothermal was first used by the British geologist Sir Roderick Murchison (1792-1871) to describe the action of water at elevated temperature and pressure, in bringing about changes in the earth’s crust leading to the formation of various rocks and minerals.
- All matter is made from some kinds of chemicals.
- Additional cleaning and conditioning steps may be required to remove other contaminants such as ammonia, sulfur, and carbon dioxide.
- Hardwood is always harder than softwood.
- The degree of association between lignin molecules decreased with decreasing ionization of the carboxylic group in the lignin.
- Wood cells transport and store water and nutrients throughout the organism.
- When heating a liquid in a test-tube, we need point the test-tube away from other people.
- Before entering the paper machine, water is added to the pulp slurry to make a thin mixture normally containing less than 5 percent fiber.
- Sulfite pulping can proceed both in alkaline, pH-neutral, or acidic conditions.
- The pills and medicine we use are all made from chemicals, that are there to make our body stronger and to kill viruses and bacteria.
- Activated carbon can only absorb odors.
- All elements are symbolized by abbreviations derived from their modern names.
- A primary alcohol can be oxidized to an aldehyde, and it can't further oxidation yields a carboxylic acid.
- Filtration is a process used to separate solids from liquids using a filter medium that allows the fluid to pass through but not the solid.
- Flavonoids generally occur in plants as glycosylated derivatives.
- Pulping is the process by which the bonds within the cellulosic fibers in the cell walls are ruptured either mechanically or chemically.
- Concentrated acids must be neutralized with NaHCO3 before disposing them down the sink.
- Modifications on hydroxyl groups can lead to the formation of polyol derivatives of lignin.
- The standardization and quality aspect of herbal medicine becomes a high profile issue.
- The separation operation called distillation utilizes vapor and liquid phases at essentially the same temperature and pressure for the coexisting zones.
- Approximately 80% of the global oil and fat production is animal origin, whereas 20% is of vegetable oil.
- A secondary alcohol can be oxidized to a ketone.
- Safety goggles and laboratory coat has to be worn at all time in a laboratory.
- In wood, the natural state of cellulose, called cellulose II.
- Extraction and characterization of several active phyto-compounds from these green factories have given birth to some high activity profile drugs.
- Active carbon is carbon that has been treated with oxygen.
- Depending on the nature of cellulosic materials, cellulose aerogels include cellulose derivative-based ones, regenerated cellulose-based ones, and nanocellulose-based ones.
- Cellulose hydrogels can be prepared from a cellulose solution through physical cross-linking.
- Phosphoric acid cannot be used to prepare crystalline cellulose nanoparticles.
- O2 is a compound.
- Generally, thermal energy, chemical treatment are the main strategy for depolymerizing lignin.
- There are three common states of matter: gaseous, liquid, and solid.
- The basic flavonoid structure is the flavan nucleus, which consists of 15 carbon atoms arranged in three rings (C6-C3-C6).
- Plant oils are triglycerides, tri-esters of glycerol with long chain fatty acids, with varying composition of fatty acids depending on the plant, the crop, the season, and the growing conditions.
- The bleaching step is necessary in the pulping and papermaking process.
- Furfural is exclusively produced from lignocellulosic biomass by dehydrating pentose.
- Polyphenols are generally water-insoluble compounds.
- The cellulose microfibrils only have crystalline regions.
- Typically photosynthesis converts 10% of the available sunlight to stored, chemical energy.
- The radical polymerization of vinylic monomers onto lignin has been used to prepare lignin-graft copolymers by a ‘‘grafting from” procedure.
- The two atoms of an oxygen molecule are joined together by an ionic bond.
- Pretreatment with dilute acid has little effect on lignin.
- Modification of lignin prior to resin synthesis has typically been performed by reacting lignin with phenol in the presence of organic solvents such as methanol or ethanol.
- In the laboratory, the most basic form of filtration is using gravity to filter a mixture.
- Evaporation is the removal of solvent as vapor from a solution, slurry or suspension.
- As the mix travels up a conveyer, an electromagnet removes any metal contaminates.
- Even if highly volatile solvents are exposed to a source of fire, they will not cause a fire.
- Dilute acid hydrolysis (1-3%) can destroy cellulose crystals at room temperature.
- In a falling film evaporator, the liquid is fed at the bottom of the tubes in a vertical tube bundle.
- The degree of unsaturation, which can be expressed by the iodine value (amount of iodine in g that can react with double bonds present in 100 g of sample under specified conditions).
- Heartwood is often darker than the sapwood.
- The term "chemical engineer" implies that the person is primarily an engineer whose first professional concern is with manufacturing processes-making something, or making some process work.
- The Tg and viscosity of the copolymer can be increased by increasing the length of the graft chain.
- The lignin content was estimated by the gravimetric Klason procedure.
- Biochemical approaches include three unit-operations namely, pretreatment, hydrolysis, and distillation.
- Chemical activation is usually carried out at lower temperatures (from 400 to 700℃) with activating agents like phosphoric acid, potassium hydroxide, sodium hydroxide and zinc chloride.
- When the paper is dry it may be treated with stabilizing materials and surface finishes to improve durability or printability.
- The traditional techniques of solvent extraction of plant materials are mostly based on the correct choice of solvents and the use of heat or/and agitation to increase the solubility of the desired compounds and improve the mass transfer.
- Generally, the cellulosic cell wall from nearly any plant or trees can be used for pulp.
- Biomass is mostly made up of carbon, hydrogen, compounds did not burn called ash.
- A worm screw supply the mixture to a press roll, a constant spray of water keeps the mixture from sticking to it.
- Furfural can be produced by a one-step or a two-step process. The advantage of the one-step process is that a higher quantity of furfural is produced when compared to the two-step process.
- They spray the rubber cubes with a mix of calcium carbonate and solvent the mixture forms the film on the cubes that prevents mold and keeps them from sticking together during transport.
- If the feed is introduced at one point along the column shell, the column is divided into an upper section, which is often called the stripping section, and a lower section, which is often referred to as the rectifying section.
- Filter cakes are formed late in the fluid flow.
- Hot air blows into this dryer to bring the sugars humidity level down to 0.05 percent, that standard for table sugar.
- Heat fluxes may then be based either on the inside area or the outside area of the choice is arbitrary.
- Extraction may be used to separate more than two components; and mixtures of solvents, instead of a single solvent, are needed in some applications.
- Sodium hydroxide and calcium hydroxide can be used instead of potassium hydroxide to neutralize the acid.
- Drying is an absolute term that means a certain value.
- The main resistance to the flow of heat or mass to a surface lies within the laminar sublayer.
- Any evaporator that uses pump to ensure higher circulation velocity is called a forced circulation evaporator.
- Polyphenols also characteristically possess a significant binding affinity for proteins, which can lead to the formation of soluble and insoluble protein-polyphenol complexes
- Terpene is derive from a 5C compound, isoprene.
- There are two different types of polysaccharide hydrolysis, involving acidic (sulfuric acid) or enzymatic reactions.
- Lignin mainly has two types of linkages including C-C and C-O-C.
- The non-bonded orbital interactions (π-π interactions) of the aromatic groups could caused the association of lignin molecules.
- The aromatic moieties present in the lignin structure will improve the mechanical and thermal properties of epoxy resins.
- Cardanol double bond may be epoxidised or undergo olefin-metathesis reaction which may act as modified monomer for the formation of different set of polymers.
- The reactivity of lignin has nothing to do with its solubility.
- In addition to glucomannan, minor amounts of miscellaneous polysaccharides are present in hardwoods.
- The softening temperature (Ts) of lignins in dry state is higher than that in moist lignins.
- Highly porous aerogels usually tend to show higher oil-sorption capacities
- The relative distribution of phenolic nuclei in lignin strongly differs between plant species.
- The role of hemicellulose is to modify and crosslink the basic fibrils and promote the interaction between other biopolymers.
- The outer layer (S1) is thicker than The middle layer (S2).
- Fossilised biomass has been exploited as coal and oil.
- Cellulose has many hydroxyl groups which can form hydrogen bonding linked network easily.
- Softwoods are mainly vessel members, fibres, and parenchyma, and hardwoods are mainly made of made of tracheids and parenchyma.
- Klason lignin is a standard analytical method to measure the lignin content of lignocellulosic biomass.
- Starch only has one forms, i.e. amylose.
- For esterification reaction of cellulose, the conversion was low and for silynation reaction, the conversion is good but with a high cost.
- In the case of fire alarm, we need stop all of your ongoing work, turn off gas and electric devices.
- If you work with flammable solvent, make sure there is no source of ignition close by.
- If a liquid gets into your eyes, the eye should be washed immediately with clean running water for at least 10min.
- We can eat or drink in laboratories
- There is no need to label glass or flask filled with solution.
- If one or both of the hydrogen atoms on the amide nitrogen atom are replaced by hydrocarbon groups, the structure is named as an N-substituted amide.
- By doing research in chemistry, we can find new cures for diseases as well as better chemicals to use in our natural environment.
- In either case, the position of the multiple bond is indicated by numbering from the end of the chain, starting at the end that will assign the lower number to the first carbon atom of the multiple bond.
- Elements with similar chemical properties generally fall into the same group in the periodic table.
- Calcium oxide is an inorganic compounds.
- Any chemical species capable of binding to electron pairs is called a Lewis acid; any molecule that tends to donate an electron pair is referred to as a Lewis base.
- A pure substance always has the same physical and chemical properties and is either an element or a compound.
- Ethers tend to be reactive, and low molecular mass ethers are often used as solvents.
- Trace elements are essential to life.
- Generally, gum rosin is produced by chemical processing of woody raw material.
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