Chitin as a Sorbent Superior to Other Biopolymers: Features and Applications in Environmental Research, Energy Conversion, and Understanding Evolution of Animals

Abstract

Chitin is an effective sorbent which can be used in environmental monitoring, beyond obvious applications in withholding metal-containing pollutants from wastewater- or nuclear fuel reprocessing flows, since background levels in (purified) chitin are very low except for a few metals (Fe, Cu, Al, Ti, and Zn). Since retention of Mx+ and their complexes on chitin depend on an oxidation state, and to a lesser extent the presence of possible ligands or co-ligands, partition between chitin samples exposed to sediment and those exposed to water can be changed by environmental factors such as local biota producing or absorbing/metabolizing effective ligands such as citrate or oxalate and by changes of redox potential. Thermodynamics are studied via log P, using calibration functions log P vs. 1/r or log P vs. Σσ (sum of Hammett parameters of ligand donor groups) for di- and trivalent elements not involved in biochemical activity (not even indirectly) and thus measuring “deviations” from expected values. These “deviations” can be due to input as a pollutant, biochemical use of certain elements, precipitation or (bio-induced reduction of SO42− or CO2) dissolution of solids in sediment. Biochemical processes which occur deep in sediment can be detected due to this effect. Data from grafted chitin (saturation within ≤ 10 min) and from outer surfaces of arthropods caught at the same site do agree well. Log P is more telling than total amounts retrieved. Future applications of these features of chitin are outlined.

Biomining of ‘Heavy’ Metals and Lanthanides from Red Mud of a Former Lignite Mines by Sorption on Chitin

“…Based on previous research by the working group, it has been found that metals can be desorbed from chitin (Sigma-Aldrich) by using LiClO 4 -DMF solutions [9,19]. To achieve this, chitin samples were mixed at 300 rpm with 100 mL of a 1.0 M LiClO 4 -DMF solution for 24 h. The LiClO 4 solution was then decanted.…”

“…This implies that chitin may be a copolymer of D-glucosamine and acetyl-D-glucosamine, as illustrated in Figure 2), chitosan (ß-1→4 D-glucosamine), or 'modified' cellulose (ß-1→4 D-glucose) is a promising alternative to traditional mining processes. The utilization of biopolymers in biomining has been widely discussed in recent decades [8][9][10][11][12][13][14][15][16]. Chitin, for example, has been shown to bind a wide range of metals, mostly as Me 2+ -Ions [9,13,14,[17][18][19][20][21].…”

“…The utilization of biopolymers in biomining has been widely discussed in recent decades [8][9][10][11][12][13][14][15][16]. Chitin, for example, has been shown to bind a wide range of metals, mostly as Me 2+ -Ions [9,13,14,[17][18][19][20][21]. As illustrated in Figure 2, chitin is known to contain a variety of potential binding sites for metal ions like Fe 2+ .…”

“…As illustrated in Figure 2, chitin is known to contain a variety of potential binding sites for metal ions like Fe 2+ . Fränzle et al and others [9,[17][18][19] have mainly used chitin for biomonitoring as an alternative to moss monitoring. In this context, the authors have already demonstrated the high binding capability of chitin to various Me 2+ -ions [7][8][9]11,12,[17][18][19]22].…”

“…Fränzle et al and others [9,[17][18][19] have mainly used chitin for biomonitoring as an alternative to moss monitoring. In this context, the authors have already demonstrated the high binding capability of chitin to various Me 2+ -ions [7,8,9,11,12,[17][18][19]22]. Therefore, the application of chitin in biopolymers for different mining options or recycling metals from aqueous sources has been widely discussed over the past decade [7,8,11,12,20,[22][23][24].…”