A Review of Pectin-Based Material for Applications in Water Treatment

Abstract

Climate change and water are inseparably connected. Extreme weather events cause water to become more scarce, polluted, and erratic than ever. Therefore, we urgently need to develop solutions to reduce water contamination. This review intends to demonstrate that pectin-based materials are an excellent route to detect and mitigate pollutants from water, with several benefits. Pectin is a biodegradable polymer, extractable from vegetables, and contains several hydroxyl and carboxyl groups that can easily interact with the contaminant ions. In addition, pectin-based materials can be prepared in different forms (films, hydrogels, or beads) and cross-linked with several agents to change their molecular structure. Consequently, the pectin-based adsorbents can be tuned to remove diverse pollutants. Here, we will summarize the existing water remediation technologies highlighting adsorption as the ideal method. Then, the focus will be on the chemical structure of pectin and, from a historical perspective, on its structure after applying different cross-linking methods. Finally, we will review the application of pectin as an adsorbent of water pollutants considering the pectin of low degree methoxylation.

Fractionation and physicochemical characterization of dietary fiber of kenaf (Hibiscus cannabinus L.) seed

“…Prior studies reported LM pectin extracted from cashew apple pomace (28–46% DE), potato pulp (21.51–37.5%) and sunflower head (36.4–39.2%), 38,50 whereas pectic polysaccharides isolated from dragon fruit peel fractions exhibited higher DE values (51.71–63.74%) 51 . Low methoxy pectin implies that less than 50% of the galacturonic acid residues are methoxylated 52 . The mechanism for gel formation varies between high‐methoxy (HM) and LM pectin.…”

“…51 Low methoxy pectin implies that less than 50% of the galacturonic acid residues are methoxylated. 52 The mechanism for gel formation varies between high-methoxy (HM) and LM pectin. HM pectin forms a gel at pH 3.5 and high sugar concentrations (>55%), whereas LM pectin gels form in the presence of divalent cations such as Ca 2+ , at pH values between 2 and 6, as well as without the need for sugar for gel formation.…”

Reviewing twenty years of patents on ultrasonic-assisted pectin extraction from food and food waste

“…Pectin is the complex polysaccharide group contained in the primary cell wall and intercellular regions of the plants, affecting their flexibility and mechanical strength [31]. As depicted in Figure 2, pectin-based products demonstrate various applications such as food [82], agriculture [121,122], pharmacy and health promotion [13,83], packaging [1,123], water treatment [124] and 3Dprinting [125].…”

Dual Crosslinking of Low-Methoxyl Pectin by Calcium and Europium for the Simultaneous Removal of Pharmaceuticals and Divalent Heavy Metals

“…Crosslinking with calcium ions is common to achieve this, although other metal ions have also been used. Divalent metal ions, such as Ca 2+ , promote the gelation of pectin [7]. The crosslinks are established between the carboxylate groups (COO − , i.e., non-methyl-esterified residues) of neighboring pectin chains via the Ca 2+ ions, which replace the hydrogen bonds in neat pectin.…”

“…Later [12,13], it was suggested that Ca 2+ ions could also establish mono-complexes; that is, Ca 2+ ions can interact with single carboxylate groups. Some reviews have summarized the formation of the "egg-box" model or other possible structures in pectin [7,14]. In addition to Ca 2+ , pectin can also be reticulated by cations such as Zn 2+ .…”