SORBENTS BASED ON NON-CARBONIZED VEGE­TABLE RAW MATERIALS

Abstract

A literature analysis was conducted with sources that describe non-carbonized plant materials (in particular, cellulose from various plants and its derivatives) as sorbents for toxic ions (Cr3+­, Cd2+­, Cu2+, Pb2+, Ni2+, etc.) and organic compounds, including oil products. The advantage of plant-based non-carbonized raw materials and sorption materials based on them is the ease of obtaining them from cheap and available plant materials (often from agricultural waste), while the absorbed oil pro­ducts can be separated from such sorbents by pressing, and the sorbents can be reused. The disadvantage is a different composition, depending on the region of growth. The use of inexpensive materials as a matrix for a composite sorbent makes it possible to widely use such material for post-cleaning and/or as the main method of cleaning aqueous solutions for consumer needs. In particular, the addition of finely dispersed inorganic compounds (in particular, graphene oxides) and organic modifiers to non-carbonized plant material for functionalization of its surface was analyzed. Surface modification gives the sorbent hyd­rophobic properties and/or results in a composite sorbent having a higher sorption capacity (compared to unmodified sorbents) in relation to target pollutants. The study authors suggest using fatty acids, zinc oxide, polysiloxa­nes, trimethylamine and other compounds as modifiers. The impact of the porous structure of cellulose on its properties as an element of a composite sorbent is also considered. The presence of functional groups in plant materials, in particular in biopolymers, allows them to be used as cheap anion exchangers. To increase the number of ion-exchange groups, the authors of the research suggest functionalizing the surface, which leads to an increase in the number, for example, of sulphatic groups, which in turn increases the ion-exchange capacity of such an ion-exchange material or a composite based on it. When using modified hydrophobic biosorbents to remove oil and oil products from water surfaces, it is possible to regenerate the sorbents mechanically, i.e. without reagents. This provides the possibility of multiple use of biosorbents on one side and the possible complete extraction of valuable products  sorbed hydrocarbons.