Shufen Zhang

Removal of cadmium(II) from aqueous solutions by chemically modified maize straw

A new regenerable adsorbent was successfully prepared by modifying maize straw (MS) with succinic anhydride in xylene. The succinylated-maize straw (S-MS) was characterized by FTIR, solid-state MAS (13)C NMR spectroscopy, SEM-EDX and point of zero charge analysis. NaS-MS was successfully obtained after deprotonating the carboxylic acid groups of S-MS by Na2CO3 solution. Batch experiments were carried out with NaS-MS for the removal of Cd(II). The effects of pH, adsorbent dosage, contact time, initial concentration and temperature were investigated. The experimental data were best described by a pseudo-second-order kinetics and Langmuir adsorption models. Thermodynamic parameters (ΔG, ΔH, and ΔS) were also calculated from data obtained from experiments performed to study the effect of temperatures. NaS-MS could be regenerated at least five times in saturated NaCl solution without any loss. Furthermore, ∼97% of adsorbed Cd(II) ions could be recovered as the metal oxide. Finally, the adsorption mechanism of NaS-MS was discussed.

Viscosity properties of acetylated carboxymethyl starch.

The viscosity properties of acetylated carboxymethyl starch (ACMS) aqueous solution with different DS (degree of substitution) at concentration of 2.0% (w/w) were investigated using Brookfield R/S+ Portable rheometer. All flow curves of ACMS are well fitted to Power law model. Arrhenius model was used to describe temperature sensitivity. Furthermore, the parameters, which influenced the viscosity properties of the solutions, including temperature, DS of carboxymethyl group (DScm), DS of acetyl group (DSac), presence of salt (NaCl) and shear rate were discussed in detail. Specifically, the viscosity-stability, salt-tolerance and shear-resistance of ACMS with DScm (0.76) and DSac (0.34) were compared with that of sodium alginate as thickener in food or non-food applications. The results indicate that the viscosity properties of ACMS (DScm=0.76, DSac=0.34) were similar to that of sodium alginate and ACMS with DScm (0.76) and DSac (0.34) may be considered as a substitute for sodium alginate in certain application.

Thermoresponsive cellulose ether and its flocculation behavior for organic dye removal

A thermoresponsive polymer, 2-hydroxy-3-butoxypropyl hydroxyethyl cellulose (HBPEC), was prepared by grafting butyl glycidyl ether (BGE) onto hydroxyethyl cellulose (HEC). The lower critical solution temperature (LCST) and critical flocculation temperature (CFT) of HBPEC were varied by changing the molar substitution (MS) and salt concentrations. Transmission electron microscopy (TEM) images and fluorescence spectroscopy showed that HBPEC can assemble into micelles. Additionally, using Nile Red as a model dye, the performance of HBPEC for the removing Nile Red from aqueous solutions via cloud point extraction procedures was investigated in detail. The encapsulation behavior of dye in the aqueous solution of HBPEC was studied by fluorescence spectroscopy and fluorescence microscope. The experimental results indicated that 99.4% of dye was removed from the aqueous solutions, and the HBPEC was recycled and reused easily, Furthermore, the recycle efficiency (RE) and maximum loading capacity portrayed little loss with the number of cycles.

Application of Tertiary Amine Cationic Polyacrylamide with High Cationic Degree in Salt-free Dyeing of Reactive Dyes

Abstract Tertiary amine cationic polyacrylamide with high cationization degree was used as a new cationic agent to pretreat cotton with dip-pad-bake method. The obtained cationic cotton was dyed with reactive dyes in the absence of electrolyte. The effects of the characteristics of the cationic agent and the pretreatment conditions on dyeability of reactive dye were investigated. The results showed that the fixation and K / S values of the reactive dyes on the cationic cotton were improved compared with those on the untreated one in the presence of salt. Tests on fastness properties of the dyed cotton and fabric quality of the pretreated cotton were carried out and the results showed that wash and rub fastness of the salt-free dyeing were both satisfactory. And anti-crease property, tensile and tear strength, and handling of the cationic cotton were also good compared with that of the untreated one.

Dyeability of Polylactide Fabric with Hydrophobic Anthraquinone Dyes

The dyeability of polylactide fabric has been investigated with the substituted aminoanthraquinone hydrophobic dyes. Their application to the polylactide fabric led to good exhaustion values and good wash fastness between 4 and 5. Microscopic assessment of cross-sections of the dyed polylactide fibres confirmed that these dyes could penetrate into the fibres. The nature of the substituted amino groups showed little influence on the wash fastness, but clearly influenced the exhaustion and light fastness.

Light–thermal conversion organic shape-stabilized phase-change materials with broadband harvesting for visible light of solar radiation

To achieve highly efficient utilization of sunlight, organic shape-stabilized phase change materials (OSPCMs) with light–thermal conversion and visible light (solar radiation) harvesting abilities were designed and synthesized through color matching (yellow, red, and blue) according to the solar irradiation energy density. These materials exhibited excellent rapid and broadband visible light-harvesting, light–thermal conversion, thermal energy storage, and form-stable (remained in the same state upon transition) effects. The chemical structures of OSPCMs were verified using Fourier transform infrared and proton nuclear magnetic resonance techniques. Differential scanning calorimetry results indicated that the melting temperatures and latent heats of the synthesized OSPCMs ranged from 48 °C to 64 °C and from 107.1 J g−1 to 138.5 J g−1, respectively. The novel materials show a reversible (more than 200 cycles) phase transition (crystalline state change) via ON/OFF switching of visible light irradiation. Colour matching showed that the light-to-heat conversion and thermal energy storage efficiency (η) of the OSPCMs significantly improved upon solar irradiation.

Novel pH- and temperature-responsive polymer: Tertiary amine starch ether

A novel double pH- and temperature-responsive tertiary amine starch ether (TAS) has been developed. Synthesis was performed by grafting dipropyl or dibutyl epoxypropylamine onto hydroxyethyl starch. The cloud point temperatures (TC) of TAS could be tuned to a wide range from 26 to 72.8°C by changing the alkyl chain length, their average molar substitution (MS), and pH value of the solution. The TC of TAS increases with decreasing the alkyl chain length, MS, and pH value of the solution. A linear relationship occurs between the TC and the pH, indicating well-tunable TC. These TAS also showed single pH-sensitive property due to the existence of tertiary amino and hydrophobic alkyl groups. The synthetic strategy presented here could be employed in the preparation of other novel biomaterials with dual pH- and temperature-responsive properties from a variety of polysaccharides.

Analysis of Sucrose Esters with Long Acyl Chain by Coupling of HPLC-ELSD with ESI-MS System

Abstract The analysis of sucrose esters with long acyl chain by improved high performance liquid chromatographic method with evaporative light scattering detection (HPLC-ELSD) and electrospray ionization mass spectrum (ESI-MS) is investigated. The improved HPLC-ELSD method for the separation and quantitation of commercial and synthesized sucrose esters is described. Samples are analyzed by means of a reversed-phase (RP) HPLC using a Hypersil C8 column (250 mm×4.6 mm, 5 μm particle size) with methanol-tetrahydrofuran (volume ratio of 90:10) and water under gradient condition as the mobile phase, in which the flow rate is 1.0 ml·min −1 and the column temperature is set at 40°C. This procedure provides a complete separation and determination of monoester, diester, triester and higher esters with different acyl chain lengths in each fraction by a single run, in combination with the ESI-MS technology. With this method, it is possible to determine the approximate compositions of mono- to polyesters in one analysis and quantitate pure positional isomers precisely using an external standard method. It is found that the method of ESI-MS coupling with HPLC system for the analysis of sucrose esters is straight forward, rapid and inexpensive, and can be readily applied in synthesis, puri?cation and structure studies.

Metal phthalocyanine catalyzed oxidation of 4-nitrotoluene-2-sulfonic acid to 4,4′-dinitrostilbene-2, 2′-disulfonic acid

Abstract The effects of catalyst, alkali concentration, 4-nitrotoluene-2-sulfonic acid concentration, reaction temperature, and time of preparation of 4,4′-dinitrostilbene-2,2′-disulfonic acid from 4-nitrotoluene-2-sulfonic acid was investigated. The results showed that the liquid-phase oxidation of 4-nitrotoluene-2-sulfonic acid under optimal conditions gives 4,4′-dinitrostilbene-2,2′-disulfonic acid in 81.8% yield and in 96.7% purity.

Thermoresponsive starch derivates with widely tuned LCSTs by introducing short oligo(ethylene glycol) spacers.

Water soluble, thermoresponsive 3-[2-butoxy(ethoxy)m]-2-hydroxypropyl starch ethers (BEmS) (m=0, 1, or 2) were prepared by reacting degraded waxy maize starch with n-butyl glycidyl ether, 3-(2-n-butoxyethyl) glycidyl ether, and 3-[2-(2-n-butoxyethoxy)ethyl] glycidyl ether, respectively. The lower critical solution temperatures (LCSTs) of BEmS could be tuned to a wide range from 17.5°C to 55.0°C by changing the side chain lengths of oligo(ethylene glycol) groups and their average molar substitution (MS). The LCSTs of BEmS increase with increasing side chain length of oligo(ethylene glycol) groups when BS, BES, and BE2S have similar MS values. By contrast, an increase in BEmS concentration and addition of NaCl to the BEmS solutions could lead to a decrease in the LCSTs of BEmS. In addition, the effects of NaCl and BEmS concentrations on the LCSTs become weaker when the side chain length of oligo(ethylene glycol) groups increase.