Two-Layer Functional Coatings of Chitosan Particles with Embedded Catechin and Pomegranate Extracts for Potential Active Packaging

Two-layer functional coatings for polyethylene (PE) and polypropylene (PP) films were developed for the active packaging concept. Prior to coating, the polymer films were activated by O2 and NH3 plasma to increase their surface free energy and to improve the binding capacity and stability of the coatings. The first layer was prepared from a macromolecular chitosan solution, while the second (upper) layer contained chitosan particles with embedded catechin or pomegranate extract. Functionalized films were analyzed physico-chemically to elemental composition using ATR-FTIR spectroscopy and XPS. Further, oxygen permeability and wettability (Contact Angle) were examined. The antimicrobial properties were analyzed by the standard ISO 22196 method, while the antioxidative properties were determined with an ABTS assay. Functionalized films show excellent antioxidative and antimicrobial efficacy. A huge decrease in oxygen permeability was achieved in addition. Moreover, a desorption experiment was also performed, confirming that the migration profile of a compound from the surfaces was in accordance with the required overall migration limit. All these properties indicate the great potential of the developed active films/foils for end-uses in food packaging.

Numerical Analysis of an Isovolumetric Thermal Desorption Experiment

Our research group is currently investigating a new kind of thermal desorption experiment (TDE), which uses a hydrogen isotope by loading-unloading process yielding transport parameters. Safety issues are limiting the hydrogen loading content to 3 % at 105 Pa, while former experiments are using pure hydrogen for the loading process at nearly same pressure e. g. [1]. Especially the thermal elongation coefficient (TDE operating conditions 300° to 500 °C compatibility to stainless steel) forces to think about an alternative material of boron silicate glass for specimen containment, in this paper copper will be discussed. The analysis of TDE concerns the amount of hydrogen stored in the specimen, stored in the time variable gas phase as well as stored in the containment material. These three phases are coupled by phase equilibrium. The here developed analysis procedure can currently only be performed numerically for a two dimensional geometry. However a two dimensional analytical solution regarding the same boundary condition is currently under investigation. One part of the solution results of this problem can be compared to an additional analytical solution with simpler boundary conditions, e.g. a vanishing hydrogen amount inside the specimen containment observed in steady state. The numerical results will be used to check the suitability of several experimental scenarios, for example the usability of a copper based specimen containment. The approach currently practiced in many experiments is to simply subtract the zero rate of hydrogen without considering the phase equilibrium between the three mentioned phases. The main goal of this analysis procedure consists in the solution of the inverse problem, namely the extraction of the transport parameters like Sieverts ́-and diffusion-constant from a measured time dependent desorption pressure increase.

Immobilization of Dithizone on Natural Bentonite as Adsorbent of Cd(II) Ion

Research on the adsorption of Cd (II) ion in dithizone-immobilized natural bentonite has been carried out. The aims of this research were focused on the preparation of dithizone-immobilized natural bentonite (BA-D) as adsorbent and desorption experiment of Cd(II) ion. The BA-D was prepared by adding dithizone (dissolved in toluene) into the activated natural bentonite. The adsorbents were characterized by FTIR and X-Ray Diffraction (XRD). This research showed that adsorption capacities of BA-A and BA-D were 1.70×10‒5 and 2.77×10‒5 mol g‒1 (46% of increasing). According to desorption experiment, interaction between activated natural bentonite and Cd(II) ionwere performed by electrostatic interaction, formation of hydrogen bond and complex formation.

Adsorption characteristics of cadmium ions from aqueous solution onto pine sawdust biomass and biochar

The adsorption capacity of cadmium ions by pine sawdust biomass and biochar was evaluated in batch experiments. Pine sawdust biochars were pyrolyzed at 500 °C and 700 °C and obtained in the absence of oxygen. The adsorption capacity of biochar was higher than the raw biomass (3.47 mg/g). Biochars produced at 700 °C showed better adsorption efficiency (6.09 mg/g) than that produced at 500 °C (4.78 mg/g). Also, the adsorption kinetics and adsorption isotherms were studied. The adsorption behavior of cadmium by pine sawdust biomass and biochar fitted Langmuir isotherms and pseudo-second order kinetics. In addition, the desorption experiment by different solutions (neutral, acidic, and alkaline) were conducted. The desorption of cadmium ions in neutral and alkaline environments was not obvious, while the desorption in an acidic environment was. Pine sawdust biochar, pyrolyzed at 700 °C, is a potential adsorbent for cadmium removal in neutral and alkaline environments.

Characterization and mechanism of lead and zinc biosorption by growing Verticillium insectorum J3

Verticillium insectorum J3 was isolated from a local lead-zinc deposit tailing, and its biosorption characteristics and reaction to the toxicities of different Pb(II) and Zn(II) concentrations were investigated. SEM, FTIR, a pH test and a desorption experiment were carried out to identify a possible mechanism. The biosorption of J3 presented an inhibition trend at low concentrations (25-75 mg L-1) and promotion at high concentrations (100-300 mg L-1). J3 absorbed Pb(II) prior to Zn(II) and produced alkaline substances, while mycelial and pellet morphology modifications were important for the removal of Pb(II) and Zn(II) under different stressful conditions (SEM results). Both intracellular accumulation and extracellular absorption may contribute to the removal of Pb(II) at lower concentrations (25-50 mg L-1), although mainly extracellular biosorption occurred at higher concentrations (75-300 mg L-1). However, Zn(II) bioaccumulation occurred at all concentrations assayed. Verticillium insectorum J3 may have evolved active defenses to alleviate the toxicity of heavy metals and proved to be a highly efficient biosorbent, especially for Pb(II) at high concentrations. This study is a useful reference for the development of biotreatment technologies to mitigate heavy metal waste.

Research on Desorption of Suspended Sediments to TN and TP in Waizhou Reach

The physical and chemical characteristics of suspended sediment in Waizhou reach are studied.The particle size is between 0.005-0.75mm.The pH value of sediment sample is 7.1.The desorption experiment after adsorbing total nitrogen(TN) and total phosphorus(TP) saturated was carried out.The experimental results show the desorption of sediment on TN and TP reaches basic equilibrium about 8h.Desorption capacity decreases with the increase of sediment concentration.Desorption process is completed by two steps.The first step is physical desorption process quickly.The second step is chemical desorption and belongs to the process of slow response.Using the Langmuir model can better simulate the process of desorbing.The correlation coefficients of fitting with TN and TP are above 0.8 and 0.75 respectively.The higher the sediment concentration, the better fitting effect.

Experimental Study on Coal Sample's Methane Desorption Law in Different Adsorption Balance Pressures

Taking 7 group anthracite coal samples which size is 1¡«3mm from different coal mines of the same mine field as research objects, there carried coal samples' methane adsorption and desorption experiment under the condition of about 1Mpa¡¢2Mpa¡¢3Mpa¡¢4Mpa adsorption equilibrium pressures and adsorption equilibrium temperature 20¡æ. The coal samples' cumulative methane desorption volume of each minute were measured in the initial 30 minutes time, and there obtained the desorption data. Based on experimental data analysis found that the methane desorption law between cumulative methane desorption volume and desorption time is fit to SUN Chong-xu Formulate (Q=ati). Then aimed to the same coal sample, the desorption eigenvalues of different adsorption equilibrium pressures were studied using SUN Chong-xu Formulate based on the experiment data. The study results show that the coal sample's desorption eigenvalues of different adsorption equilibrium pressures keeps a constant, and the average eigenvalues is 0.237 for these experiment samples. Then 1~3mm size coal samples can be used to determent methane content when the loss time less than 8 minutes.

Impacts of pH and Electrolyte on Cadmium Desorption Characteristics in Contaminated Soil

In this paper, two kinds of different pollution degree soils denoted as L1 and L2 were used as test soils. Desorption experiment was carried out to study the impacts of pH and electrolyte on desorption characteristics of cadmium (Cd) in soils. The results showed that the variation trends of Cd desorption rates with increase in pH were similar. In other words, it decreased as pH increased. In acidic region, desorption rate of heavy metal Cd decreased rapidly as pH increased. When pH = 4, Cd desorption rate was largest; in neutral and alkaline regions (pH = 7-10), desorption rate of heavy metal Cd decreased slowly as pH increases. Cd desorption behavior was closely related to type and concentration of electrolyte. Under the same concentration, Cd desorption capabilities of three electrolytes in soils L1 and L2 could be expressed in following order: CaCl2> Ca (NO3)2> NaCl.