Research on the coagulant aid effects of modified diatomite on coal microbial flocculation

Diatomite was modified by chitosan to prepare modified diatomite, and the modified diatomite in an optimized ratio was utilized in coal bio-flocculation. The interaction behavior and flocculation mechanism of modified diatomite on coal slurry water were investigated by single factor experiments, infrared spectroscopy, Brunauer-Emmett-Teller (BET) measurements, and zeta potential measurements. The single factor experiments showed that when the amount of microbial flocculant added was 1.5 ml, the temperature of coal slurry water was 39 °C, the pH was 5, and the amount of modified diatomite was 0.2 g, after 30 min of sedimentation, the flocculation transmittance of the coal slurry water reached 84.3%. The infrared spectra showed that the -NH2 and -OH of the chitosan molecule had a polar interaction with the Si-OH bond in diatomite. The BET measurements showed that the specific surface area of diatomite was not a decisive factor affecting the flocculation effect. Zeta potential measurements indicated that the amino protonation of chitosan increased the isoelectric point (IEP) of modified diatomite. These results showed that modified diatomite has a good effect on coal bio-flocculation.

The infrared spectroscopy of chitosan films doped with silver and gold nanoparticles

This work presents the dependences of the absorption intensity of the acid-soluble chitosan biopolymer films in the infrared (IR) region of the spectrum on the concentrations of silver and gold nanoparticles (NPs) of different morphologies. The interaction mechanisms in the vibrational spectra overlapping area of the silver NPs and chitosan molecules (2500–3500 cm−1) were observed. The influence of the metal NPs on the dipole moments of the OH-, NH3+- and CH-chitosan molecule group oscillations was established. This interaction leads to a linear increase of the IR absorption intensity with an increase of the silver nanoparticle concentration, synthesized by the citrate and borohydride methods. The presence of silver and gold ablative NPs in the chitosan films demonstrates the IR absorption intensity exponential decrease with the metal NPs’ concentrations.

KEMAMPUAN ADSORPSI KITOSAN UNTUK ION LOGAM TIMBAL (Pb2+) DAN KADMIUM (Cd2+)

ABSTRACT Chitosan is natural polymer that has been known to posses the capacity to adsorb various transition metals. This capacity of adsorption is resulted from the ability of chitosan to form complex compound with metal, especially Pb and Cd. The formation of chitosan-metal complex is enabled by the presence of active hydroxil group in chitosan molecule. The results of this study on adsorption of Pb2+ and Cd2+ revealed the existence of linear relationship between the amount of the metal adsorbed with concentration of the metal tested. It was found that for Pb2+, the maximum adsorption was 10.32 mg/g which was achieved for the metal concentration of 50 mg/L, and 24.998 mg/g for Cd2+ at metal concentration of 100 mg/L. The optimum contact time for adsorption was found to be 24 hours for both metals. The adsorption was found to take place with the adsorption energy of 29.82 kJ/mol for Pb2+ and 17.23 kJ/mol for Cd2+. Keywords: chitin, chitosan, adsorption, transition metal, and toxic metal

Chitosan-Grafted Copolymers and Chitosan-Ligand Conjugates as Matrices for Pulmonary Drug Delivery

Recently, much attention has been given to pulmonary drug delivery by means of nanosized systems to treat both local and systemic diseases. Among the different materials used for the production of nanocarriers, chitosan enjoys high popularity due to its inherent characteristics such as biocompatibility, biodegradability, and mucoadhesion, among others. Through the modification of chitosan chemical structure, either by the addition of new chemical groups or by the functionalization with ligands, it is possible to obtain derivatives with advantageous and specific characteristics for pulmonary administration. In this paper, we discuss the advantages of using chitosan for nanotechnology-based pulmonary delivery of drugs and summarize the most recent and promising modifications performed to the chitosan molecule in order to improve its characteristics.

A Biopolymer Chitosan and Its Derivatives as Promising Antimicrobial Agents against Plant Pathogens and Their Applications in Crop Protection

Recently, much attention has been paid to chitosan as a potential polysaccharide resource. Although several efforts have been reported to prepare functional derivatives of chitosan by chemical modifications, few attained their antimicrobial activity against plant pathogens. The present paper aims to present an overview of the antimicrobial effects, mechanisms, and applications of a biopolymer chitosan and its derivatives in crop protection. In addition, this paper takes a closer look at the physiochemical properties and chemical modifications of chitosan molecule. The recent growth in this field and the latest research papers published will be introduced and discussed.