Synthesis and evaluation of a novel cationic konjac glucomannan-based flocculant

Effects of Glucomannan Supplementation on Type II Diabetes Mellitus in Humans: A Meta-Analysis

The hypoglycemic and lipid-lowering effects of glucomannan are widely known, and it is a potential effective treatment for type II diabetes. In this study, we evaluated the effects of glucomannan supplementation on blood-lipid-related indicators, blood-glucose-related indicators, blood pressure (BP), and body weight (BW) in patients suffering from type II diabetes. We searched databases including PubMed, Cochrane, the comprehensive biomedical research database (Embase), Web of Science, and China National Knowledge Infrastructure (CNKI) for literature on glucomannan and type II diabetes. Six randomized controlled trials (RCTs) were eligible (n = 440 participants) to be included in our analysis. Glucomannan not only reduced the total cholesterol (TC) (MD -0.38 [95% CI: -0.61, -0.15], p = 0.001) and low-density lipoprotein (LDL) levels (MD -0.35 [95% CI: -0.52, -0.17], p < 0.0001) compared with the control group, but also reduced the fasting blood glucose (FBG) (MD -1.08 [95% CI: -1.65, -0.50], p = 0.0002), 2 h postprandial blood glucose (P2hBG) (MD -1.92 [95% CI: -3.19, -0.65], p = 0.003), fasting insulin (FINS) (MD -1.59 [95% CI: -2.69, -0.50], p = 0.004), and serum fructosamine (SFRA) levels (SMD -1.19 [95% CI: -1.74, -0.64], p < 0.0001). Our analysis indicates that glucomannan is an effective nutritional intervention for type II diabetes.

Biopolymer-based flocculants: a review of recent technologies

Biopolymer-based flocculants have become a potential substitute for inorganic coagulants and synthetic organic flocculants due to their wide natural reserves, environmental friendliness, easy natural degradation, and high material safety. In recent years, with more and more attention to clean technologies, a lot of researches on the modification and application of biopolymer-based flocculants have been carried out. The present paper reviews the latest important information about the base materials of biopolymer-based flocculants, including chitosan, starch, cellulose, and lignin etc. This review also highlights the various modification methods of these base materials according to reaction types in detail. Via the recent researches, the flocculation mechanisms of biopolymer-based flocculants, such as adsorption, bridging, charge neutralization, net trapping, and sweeping, as well as, some other special mechanisms are comprehensively summarized. This paper also focuses on the water treatment conditions, the removal efficiency, and advantages of biopolymer-based flocculants in applications. Further, this review sheds light on the future perspectives of biopolymer-based flocculants, which may make progress in the sources of base materials, modification processes, multi-function, and deepening application researches. We believe that this review can guide the further researches and developments of biopolymer-based flocculants in the future, to develop them with a higher efficiency, a lower cost, more safety, and multi-function for more diversified applications. Graphical abstract.

Does polysaccharide quaternization improve biological activity?

The natural polysaccharides, due to their structural diversity, commonly present very distinct solubility and physical chemical properties and additionally have intrinsic biological activities that, gene-rally, reveal themselves in a light way. The chemical modification of the molecular structure can improve these parameters. In this review, original articles that approached the quaternization of polysaccharides for purposes of biological application were selected, without limitation of year of publication, in the databases Scopus, Web of Science and PubMed. The results obtained from the bibliographic survey indicate that the increase in positive charges caused by quaternization improves the interaction between modified polysaccharides and structures that have negative charges on their surface, such as the cell wall of microorganisms and some cells in the human body, such as the DNA. This greater interaction is reflected as an increase in the biological activity of all polysaccharides broached in this study. Another important data obtained was the fact that the chemical changes did not affect or irrelevantly affect the toxicity of almost all of the polysaccharides that were quaternized. Therefore, polysaccharide quaternization is a safe and effective way to obtain improvements in the biological behavior of these macromolecules.

Preparation and characterization of carboxymethyl chitosan/collagen peptide/oxidized konjac composite hydrogel

Medical dressings are used to protect damaged skin from external factors and provide a good healing environment. Hydrogels are aggregates of hydrophilic polymers and water that have a three-dimensional space and can absorb large amounts of water. It has been widely studied in the field of biomedical materials. In this study, we prepared a novel composite hydrogel combined carboxymethyl chitosan, collagen peptide and oxidized konjac, all three materials have been shown to be biocompatible. Then, we set up different hydrogels and tested hydrogels with different proportions. The structures of CMCS (carboxymethyl chitosan)/COP (collagen peptide)/OKGM (oxidized konjac) hydrogels were characterized by IR, NMR, X-ray diffraction and SEM. The effects of hydrogels on the growth of NS-FB and HS-FB cells were studied in vitro. The results of these tests show that the composite hydrogel has excellent mechanical properties and biological activity, and has potential application in wound dressing field.

Removal of the commercial pesticides Novadim Progress, Bordeaux mixture and Karate Zeon by pullulan derivatives based flocculants

Cationic pullulan derivatives have been synthesized and evaluated, for the first time, as flocculants for the separation of the commercial pesticides, Novadim Progress (organophosphoric type), Bordeax mixture and Karate Zeon (pyrethroid type) from synthetic wastewater. The investigated polymer samples contained either pendent tertiary amine or quaternary ammonium salts groups. The separation efficiency was followed by UV-Vis spectroscopy, while the information regarding the mechanism involved in the separation of pesticide particles have been obtained by zeta potential. UV-Vis spectroscopy data showed strong pesticide particles/polycation interactions in case of Novadim Progress and Bordeaux mixture (maximum pesticide removal between 90% and 98%). Good separation efficiency (around 80%) of Karate Zeon emulsion was also noticed. The zeta potential measurements indicated that the charge neutralization was the common flocculation mechanism for the removal of these pesticides. In addition, the hydrogen bondings and chelation of copper ions by amide and/or tertiary amino groups of the polycations had a noteworthy contribution to the pesticide removal.

The investigation of the specific behavior of a cationic block structure and its excellent flocculation performance in high-turbidity water treatment

The fabrication of a cationic polyacrylamide (CPAM) with high efficiency and economy has been highly desired in the field of high-turbidity water treatment. This study introduced an ultrasound (US)-initiated template polymerization (UTP) method to develop a novel cationic templated polyacrylamide (TPAA) with a microblock structure. TPAA was prepared using acrylamide (AM) and sodium (3-acrylamidopropyl)trimethylammonium chloride (ATAC) as the monomers and sodium polyacrylate (NaPAA) as the template. Factors that affected polymerization such as the ultrasound power, ultrasound time, initiator concentration, pH, and m_AM : m_ATAC and n_NaPAA : n_ATAC values were investigated. The properties of the polymers were characterized by Fourier transform infrared spectroscopy (FTIR), ¹H nuclear magnetic resonance spectroscopy (¹H NMR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The results indicated the successful formation of a cationic microblock structure in TPAA. In addition, TPAA displayed favorable thermal decomposition properties and a rough and coarse surface morphology, as shown by analyses using TGA and SEM, respectively. Moreover, a zip (type I) template polymerization mechanism was identified via analyses of the association constant (K_M), conversion (C_v) and polymerization rate (R_p). The flocculation performance of the templated copolymer TPAA was evaluated by treating high-turbidity water. According to the results for the zeta potentials and FTIR spectra of the generated flocs, it was indicated that the cationic microblocks in the templated copolymer could greatly enhance its charge neutralization, patching and bridging ability, and therefore excellent flocculation performance (residual turbidity: 5.8 NTU, D_f: 1.89, floc size d₅₀: 608.404 μm and floc kinetic: 15.86 × 10⁻⁴ s⁻¹) for treating high-turbidity water was achieved.

The fabrication of a cationic polyacrylamide (CPAM) with high efficiency and economy has been highly desired in the field of high-turbidity water treatment.

An efficiently sustainable dextran-based flocculant: Synthesis, characterization and flocculation

Polysaccharide-modified flocculant is a notable material in the field of wastewater treatment. Synthesis of biopolysaccharide derivatives as eco-friendly flocculants is remarkably desired for environmental protection. This work presents an efficient flocculant synthesized through copolymerization of acrylamide, sodium acrylate (AS), and dextran. Physicochemical properties of the flocculant were evaluated. Process parameters of coal-washing wastewater flocculation were tested using Response Surface Method. The application of graft polymers exhibited efficient flocculation performance at low level of flocculant dosage in alkalescent environment. The improved dextran contributes to handle industrial effluent and sanitary sewage.