The extraction of cellulose in the paper industry primarily involves processing wood pulp. This process begins with logging and transporting trees to a mill where they are debarked and chipped into small pieces. These chips undergo thermal and chemical treatments to break down lignin (the substance that binds fibers together) and separate the cellulose fibers. Chemical pulping methods, such as the kraft process, use sodium hydroxide and sodium sulfide to dissolve lignin while preserving cellulose. Mechanical pulping, another method, physically grinds wood chips to release cellulose fibers without using chemicals. Post-processing includes washing, bleaching, and refining the pulp to enhance its properties for specific paper products. Cellulose extraction significantly impacts sustainability, prompting industries to adopt eco-friendly practices like using recycled materials and optimizing chemical usage.

Amino acids can be protonated or deprotonated depending on the pH of their environment. At low pH (acidic conditions), amino acids are more likely to be protonated. This is because, in an acidic environment, there is an abundance of H+ ions which increases the likelihood of the amino acids’ amine groups (NH2) accepting a proton to become NH3+. Similarly, the carboxyl group (COOH) tends to retain its proton, existing predominantly in its COOH form rather than deprotonating to COO-. The specific pH at which a given amino acid switches between protonated and deprotonated forms for its carboxyl and amino groups is defined by its pKa values. Each amino acid has specific pKa values that indicate the pH at which half of the molecules of that amino acid are protonated. For example, when the pH is below the pKa of the carboxyl group, the carboxyl group is predominantly protonated. Conversely, when the pH is above the pKa of the amino group, the amino group is predominantly deprotonated.

Polypropylene, a versatile thermoplastic polymer widely used in various applications, has a simple yet critical molecular structure that grants it unique properties such as strength, durability, and chemical resistance. The molecular formula for polypropylene is (C3H6)n, with "n" indicating the number of monomer units (propylene) in the polymer chain. This structure is the result of polymerization, wherein multiple propylene (C3H6) monomers undergo a chain-growth mechanism facilitated by catalysts to form long molecular chains. The specific arrangement and orientation of these chains (stereoregularity) can vary, giving rise to different forms of polypropylene, such as atactic, isotactic, and syndiotactic, each possessing distinct characteristics suitable for various applications, ranging from packaging materials to automotive components.