Mechanochemical and Size Reduction Machines for Biorefining

Abstract

In recent years, we have witnessed an increasing interest in the application of mechanochemical methods for processing materials in biomass refining techniques. Grinding and mechanical pretreatment are very popular methods utilized to enhance the reactivity of polymers and plant raw materials; however, the choice of devices and their modes of action is often performed through trial and error. An inadequate choice of equipment often results in inefficient grinding, low reactivity of the product, excess energy expenditure, and significant wear of the equipment. In the present review, modern equipment employing various types of mechanical impacts, which show the highest promise for mechanochemical pretreatment of plant raw materials, is examined and compared—disc mills, attritors and bead mills, ball mills, planetary mills, vibration and vibrocentrifugal mills, roller and centrifugal roller mills, extruders, hammer mills, knife mills, pin mills, disintegrators, and jet mills. The properly chosen type of mechanochemical activation (and equipment) allows an energetically and economically sound enhancement of the reactivity of solid-phase polymers by increasing the effective surface area accessible to reagents, reducing the amount of crystalline regions and the diffusion coefficient, disordering the supramolecular structure of the material, and mechanochemically reacting with the target substances.

Action of Mechanical Forces on Polymerization and Polymers

“…The purpose of applied research was the development of technologies for the mechanochemical processing of natural polymer raw materials into products in demand on the market. To achieve these goals, the following important tasks are under implementation: Study of physico-chemical processes occurring in natural polymers, their supramolecular complexes and biological materials during mechanochemical processing in laboratory and industrial conditions [ 23 ]; Obtaining information about the influence of the chemical composition, surface properties, crystal and supramolecular structures of carbohydrate, protein and polyphenolic polymers on their reactivity in heterogeneous reactions, which follow mechanochemical processing [ 24 ]; Finding the conditions of mechanochemical processing of protein macromolecules, to ensure the stability of proteins and leading to the formation of reactive composites with carbohydrate polymers and vegetable raw materials in general [ 25 ]; Investigation into the behavior of nanocomposites and micro-composites based on polystyrene under conditions of rapid compression and identification of the role of mechanical action in the combined thermomechanical process [ 26 ]; Carrying out the mathematical modeling of vibration effects on the kinetics of solid-phase decomposition reactions in condensed media to develop models of the mechanism and reveal the role of mechanical action in the combined mechanochemical process [ 27 ]; Propose a mechanism revealing the role of mechanical action in the overall mechanochemical process, including mechanochromism [ 1 , 28 , 29 , 30 , 31 , 32 ]; Systematization of macroscopic manifestations of polymer mechanochemistry and evaluation of results in the framework of physical chemistry [ 5 ]. …”

“…Finding the conditions of mechanochemical processing of protein macromolecules, to ensure the stability of proteins and leading to the formation of reactive composites with carbohydrate polymers and vegetable raw materials in general [ 25 ];…”

Nonthermal Mechanochemical Destruction of POPs

“…Consequently, high energy mill is usually considered synonym of mechanochemical reactor. A large number of milling machine typologies is available on the market that can apply mechanical forces with different intensities and by diverse means [9]. Principally, these machines can be classified according to the main type of action in three groups [10]:…”

Concentrating rare earth elements in brown coal humic acids by mechanochemical treatment

“…10,11 Mechanochemical activation of coals has been used for solving various tasks for quite a long time. [12][13][14][15] Intense mechanical loading causes activation of the organic matter in coal and changes in its physicochemical properties. 16,17 Solidphase treatment in the presence of alkalis is the best-studied method for mechanochemical modication of brown coals.…”