Search

BACKGROUND: Nanoscale tapioca starch (NTS) was successfully developed by high‐speed jet in our previous study. In this study, the adsorption capacity of Cu2+ onto NTS was further discussed. The optimal adsorption conditions (pH, contact time, contact temperature, initial Cu2+ concentration, and adsorbent concentration), adsorption kinetics, isotherms, and thermodynamic were also evaluated. RESULTS: The results showed that NTS exhibited excellent performance in adsorption of Cu2+, with adsorption capacities of 122.31 mg g−1 for Cu2+ (pH 7, 0.04 g L−1, 0.2 g L−1, 313.15 K and 10 min). The pseudo‐second‐order and Langmuir isotherms models could be used to explain the adsorption kinetics and adsorption equilibrium, respectively. The thermodynamic results showed that the adsorption process was spontaneous and endothermic with an increase in entropy. Cu2+ was adsorbed onto NTS, which was confirmed by energy dispersive spectrometry analysis. CONCLUSION: These findings indicated that NTS might be an effective, environment‐friendly and renewable bio‐resource adsorbent for removing heavy metals in industrial effluent. © 2021 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Highlights • Hydrogen bonds of cellulose might be cracked by two ways at different temperatures. • The O(3)H–O(5) bonds disruption could promote the dissolution at lower temperature. • The (O(2)H–O(6)) bonds might be responsible for dissolution at higher temperature. • Higher dissolving temperature might be a way to avoid cellulose degradation in ILs. Abstract Ionic liquids have been powerful solvents for cellulose. Mechanistic investigations of the dissolution processes have been extensively studied. In this paper, an experimental study has revealed that temperature also comes into play in cellulose dissolution. The supramolecular stuctrure of cellulose has been measured by X-ray diffraction, Fourier transform infrared spectroscopy, Solid-state CP/MAS 13C NMR, X-ray photoelectron spectroscopy and Gel permeation chromatography analysis, and the effects of temperature on hydrogen bonds of cellulose in ILs were investigated. These results indicated that hydrogen bonds of cellulose might be cracked by different ways at different temperature: The disruption of intramolecular hydrogen bonds (O(3) H-O (5)) could promote the dissolution process at lower temperature. And the disruption of intramolecular hydrogen bonds (O(2) H-O (6)) might be responsible for cellulose dissolution at higher temperature. It was suggested that higher dissolving temperature might be a way to avoid cellulose degradation with a high cellulose yield. [ABSTRACT FROM AUTHOR]

Tapioca starch-water suspension was subjected to high speed jet (HSJ) treatment and the physical properties were investigated by Particle size analysis, Differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscope (SEM). Particle size analysis revealed a significant increase in volume mean diameter from 17.00 to 40.35 μm. SEM studies showed that treated tapioca starch (TS) was prone to aggregate with each other and markedly damaged at starch granule surface which eventually disintegrated into gel-like structures at high pressure level. XRD patterns showed that all samples exhibited A-type and there was an evident loss of crystallinity after treated over 160 MPa. The TS showed similarity on FTIR spectral pattern but had different intensity in some peaks at increasing pressure. DSC analysis confirmed that TS was partly gelatinized after HSJ treatment, and the degree of gelatinization increased to 34.34 ± 1.0% when the pressure was 240 MPa. These results provided the basic information on the physical properties of TS treated at different pressures and indicated the potential possibility of HSJ for starch modification. [ABSTRACT FROM AUTHOR]

A novel biodegradable pH- and salinity-responsive cellulose copolymer was prepared by grafting 2-(Dimethylamino) ethylmethacrylate (DMAEMA) onto bagasse cellulose in ionic liquid. The grafting polymerization was achieved in 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) under microwave irradiation. Copolymers were then characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction and thermo gravimetric analysis measurements. The results revealed that polymer chains had been successfully bonded to the cellulose backbone. Furthermore, the self-assembly of cellulose-g-DMAEMA copolymers at various salt concentrations and pH solution were investigated by means of swelling behavior measurement. It indicated that the copolymers presented dual pH and salinity-responsive properties. The synthetic strategy showed great potential in the modification of other cellulosic biomass to afford new biomaterials with desired properties. [ABSTRACT FROM AUTHOR]

Dalbergia pinnata (Lour.) Prain (D. pinnata) is a plant widely distributed in tropical and subtropical regions of Asia, Africa, and the Americas. In humans, it is used in the prevention and treatment of diseases such as respiratory system, digestive system, cardiovascular and cerebrovascular diseases. This study was aim to evaluate chemical composition, antioxidant activities, antimicrobial, and anti-melanogenesis properties of Essential oils (EO) from D. pinnata. In this paper, the EO of D. pinnata were extracted using the supercritical CO 2 extraction method and purified by molecular distillation. The volatile compounds of EO were characterized using Gas Chromatography-Mass Spectrometer (GC-MS). The antioxidant activities were evaluated by the methods of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, 2, 2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging assays. And two Gram-positive bacteria, three Gram-negative bacteria and a fungus were employed to evaluate the antimicrobial activity. The zebrafish was used as experimental model to evaluate the anti-melanogenesis effect of the EO from D. pinnata. The EO of D. pinnata were obtained in a yield of 4.75% (v/w) calculated on dry weight basis. 14 volatile compounds could be detected and the predominant components include elemicin (91.06%), methyl eugenol (3.69%), 4-allyl-2,6-dimethoxyphenol (1.16%), and whiskey lactone (0.55%). The antioxidant assay showed that the EO could scavenge DPPH (IC50 values of 0.038 mg/mL) and ABTS (IC50 value of 0.032 mg/mL) free radical, indicating that the EO had strong antioxidant activity. The results of antimicrobial test showed that Staphylococcus aureus was most sensitive to EO with minimal inhibitory concentration (MIC) of 0.78 μL/mL, followed by Streptococcus pyogenes (6.25 μL/mL) and Candida albicans (12.5 μL/mL). Gram-negative strains, including Escherichia coli , Pseudomonas aeruginosa and Salmonella typhimurium , were slightly affected by the EO. Additionally, EO from D. pinnata could reduce tyrosinase activity and melanin synthesis of zebrafish embryos in dose-dependent manner. And EO exhibited the more obvious anti-melanogenic effect compared with the positive control arbutin at the same dose (30 mg/L). Our results validated the main activities attributed to D. pinnata for its antimicrobial and antioxidant. In addition, the potent inhibitory impacts of EO on the pigmentation provides a theoretical basis for the in-depth study of the EO from D. pinnata and their application in pharmaceutical and cosmetic industries. Image 1 [ABSTRACT FROM AUTHOR]