Potassium Release Kinetics and Water Retention of Controlled-Release Fertilizers Based on Chitosan Hydrogels

Controlled release fertilizer (CRF) hydrogels were prepared from poly(vinyl alcohol), poly(vinyl alcohol)/chitosan and chitosan using glutaraldehyde as a crosslinker. Intermolecular interactions of the CRF hydrogels were elucidated using FTIR. Water absorbency characteristics of the CRF hydrogels were also studied. It was found that the CRF hydrogels exhibited the equilibrium swelling ratio (SR) in the range 70–300%. The water retention of soil containing the CRF hydrogels was also examined. It was found that the CRF hydrogels increased the water retention of the soil. After 30 days, soil containing the PVA-, PVA/CS- and CS-hydrogels showed the water retention capacities of 25%, 10% and 4%, respectively. While the soil without the CRF hydrogel had already given off most of the water. The release behavior of potassium from the CRF hydrogels, both in deionized water and in soil, was investigated. In soil, the potassium release mechanism from the PVA- and PVA/CS-hydrogels were non-Fickian diffusion. On the other hand, the CS hydrogel showed, n value that was close to 1.0 corresponding to case II transport. In deionized water, all the CRF hydrogels showed small values of release exponent (n < 0.5) indicating a quasi-Fickian diffusion mechanism.     

Poly(Acrylic Acid) Grafted Sodium Alginate Di-Block Hydrogels as Efficient Biosorbents; Structure-Property Relevance

Naturally-based poly(acrylic acid) grafted sodium alginate di-block hydrogels were investigated as high efficiency biosorbents for copper(II) ion. The grafted di-block hydrogel was characterized using FTIR, TGA and SEM techniques. Blank and immobilized algal biosorbent beads formed via 2.0% (w/w) calcium ions were also investigated. Batch adsorption experiments revealed optimal pH dependence of copper(II) ion biosorption at pH 5.5 with high efficient copper(II) ion uptake of 98.5 mg/g. The dynamics studies showed that the high efficiency copper(II) ion biosorption followed pseudo-second order kinetics with significant contribution of intraparticle diffusion mechanism. The equilibrium data fitted to Langmuir, Freundlich, and Dubinin–Radushkevich (D–R) adsorption isotherm models. Thermodynamics parameters for copper(II) biosorption on blank and immobilized algal beads depicted the spontaneous nature of the biosorption process. Such high efficiency, feasibility, simplicity, and low cost properties adapt the di-block biosorbent to be the next generation promising biosorbents for water decontamination and to help in the recovery of the missing ecologic harmony.     

Preparation and Characterization of Hydrogel Based on Poly(vinyl alcohol) Cross-Linked by Different Cross-Linkers Used to Dry Organic Solvents

Poly(vinyl alcohol) (PVA) hydrogels were chemically cross-linked with/without different cross-linkers such as glutaraldehyde and epichlorohydrin, in the presence of a catalyst, or activator (potassium hydroxide) to produce three types of hydrogels. The structures of PVA and the prepared gel types were determined by FTIR spectroscopy, the mechanical and thermal properties, of these hydrogels were examined. The effects of different pH values and temperatures on the swelling properties of the prepared gels were examined. From the obtained results, it was found that, the low concentration of the cross-linker produced hydrogel with moderate properties, but in absence of the cross-linker, the obtained hydrogel exhibited good properties and can be used as friendly environmentally moisture absorbents from the organic solvents. The insolubility and swelling properties of gels were tested in these solvents. The results indicated that these hydrogels can be used as moisture absorbents and solvent dryers.     

Preparation and Properties of a Chitosan–Hyaluronic Acid-Polypyrrole Conductive Hydrogel Catalyzed by Laccase

Electro conductive hydrogels, consisting of chitosan (CS), hyaluronic acid (HA), and polypyrrole (PPy), were prepared via an in situ enzymic polymerization of pyrrole in the CS–HA hydrogel, using laccase as the catalyst. This CS–HA–PPy composite hydrogel showed good conductivity. The chemical structure and morphology of this conductive hydrogel were studied by Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction technique. For CS–HA–PPy and CH–HA hydrogel, the temperature at which fastest decomposition occurred was 260 and 244 °C, respectively. That means the thermal stability of CS–HA–PPy is better than CS–HA hydrogel. The conductive hydrogel also showed excellent swelling and deswelling behaviors.     

Fabrication and Characterization of Polyaniline Based Nano-Composite with Their Physico-Chemical and Environmental Applications

A series of organic–inorganic conducting nano polymer-matrix composite cation-exchanger have been synthesized via sol–gel method and characterized through FTIR, XRD, TGA-DTA, SEM, and TEM studies. The structural studies confirm the semi-crystalline nature of the material but the morphology of the exchanger gets changed after incorporation of inorganic moiety. The particle size of the nano-composite was found to be 19.2 nm. The observed band gap for the different samples was found to be in the range of 3.70–4.61 eV which shows that nano-composite material covers semiconducting range but the resistivity of samples is highly dependent on the percentage of inorganic part in the composite. Further the oxidative degradation of the polymer backbone begins after the removal of trapped water successively followed by dopant and low molecular weight oligomers. During the antimicrobial screening, the nano-composite was found to be active against different strains of bacteria and fungi. Gel electrophoresis and molecular docking studies were carried out to check the interaction and mechanism of inhibition of microbial growth, respectively by studying the effect of the nano-composite with DNA-Topoisomerase-1.     

聚乙烯亚胺改性UiO-66-NH2对水中U(Ⅵ)的吸附

采用聚乙烯亚胺(PEI)改性氨基化锆基金属有机骨架材料(UiO-66-NH₂)制备了UiO-66-NH₂/PEI,利用XRD、SEM和FTIR对产物进行了表征,并将其用于吸附水中的U(Ⅵ)。考察了UiO-66-NH₂/PEI吸附U(Ⅵ)的影响因素,并研究了吸附动力学和等温线。实验结果表明:UiO-66-NH₂/PEI对U(Ⅵ)具有良好的吸附效果,PEI与UiO-66-NH₂质量比为30%、溶液pH为6、吸附剂投加量为80 mg/L、吸附时间为120 min、初始U(Ⅵ)质量浓度为10 mg/L时,UiO-66-NH₂/PEI对U(Ⅵ)的去除率达98.2%(303 K下);UiO-66-NH₂/30%PEI对U(Ⅵ)的吸附在60 min内达到平衡,吸附过程符合准二级动力学模型和Langmuir模型,最大吸附量达452.49 mg/g。     

Nanocomposite Film Based on Gluten Modified with Heracleum persicum Essence/MgO/Polypyrrole: Investigation of Physicochemical and Electrical Properties

In this study, the wheat gluten film was prepared. Heracleum persicum essence, magnesium oxide nanoparticles and polypyrrole were used to modify the structure of the wheat gluten film. Physicochemical properties of the prepared films such as thickness, solubility, moisture absorption ability, antioxidant properties, and electrical conductivity of the films were investigated. Also, the mechanical, structural and thermal properties of the films were investigated by techniques such as SEM, FTIR, XRD, TGA, DTA and tissue analysis. SEM images showed that the essence and polypyrrole strengthened the gluten film structure and made it more resistant to the passage of gases. FTIR spectra confirmed the electrostatic interactions between gluten and essence and polypyrrole. XRD spectra showed the amorphous structure of gluten film and its composites. The results of thermal analysis showed that polypyrrole greatly increased the thermal resistance of the film and the nanoparticles had little effect on the thermal resistance. Thickness, solubility, moisture content and ability to absorb moisture were further affected by the essential oil. The antioxidant and electrical conductivity of the film was greatly increased in the presence of all three additives of essence, magnesium oxide nanoparticles and polypyrrole. The gluten–essence–MgO–PPy (Glu–E–MgO–PPy) composite film had the most antioxidant properties. Glu–E–MgO–PPy film with important electrical conductivity and antioxidant properties has the potential to be used as an active and intelligent film in the packaging of perishable food products.

     

α-Fe2O3/AC催化剂的制备及光Fenton反应降解双酚A

采用温和的无模板溶液反应合成了α-Fe₂O₃/AC复合催化剂,作为光Fenton降解双酚A反应的催化剂。通过XRD、SEM、FTIR、DRS、BET、XPS等方法对催化剂的形貌和理化特性进行了分析。结果表明：该催化剂晶型良好,为介孔材料,能够有效吸收和利用紫外光和可见光;该催化剂具有较高的催化活性,稳定性良好;在初始双酚A质量浓度为30 mg/L、溶液pH为4、H₂O₂加入量为320 mg/L、反应温度为40 ℃、催化剂加入量为1.33 g/L的条件下,双酚A降解率可达91.4%。     

Synthesis of Gum Acacia Capped Polyaniline-Based Nanocomposite Hydrogel for the Removal of Methylene Blue Dye

In this research work, a novel gum acacia capped polyaniline-based nanocomposite hydrogel (GPA NCHs) was developed and evaluated for the adsorptive removal of cationic methylene blue dye (MB) from aqueous solutions. Firstly, Gum acacia (GA) capped Polyaniline (PANI) dispersion was synthesized by using dispersion polymerization. Then, a water-swellable hydrogel network consisting of GA-PANI and acrylamide (AM) was obtained by using N,N′ -methylene-bisacrylamide (MBA) as a cross-linker, and ammonium persulphate/N,N,N′,N′-tetramethylethylenediamine (APS/TMEDA) as an initiating system. The developed materials were characterized by UV–visible, FTIR, XRD, SEM–EDX and TEM techniques. The microscopy studies revealed that GA-PANI nanoparticles have a granular morphological surface with an average size of?~?40–100 nm. Removal of MB dye from aqueous system was performed by adsorption studies in batch equilibrium mode with different dosage of GA-PANI, MB concentration, pH and temperatures. The adsorption data revealed that the absorption capacity of GPA NCHs highly depends on the dosage of GA-PANI, pH and concentration of the MB dye. The maximum percentage of MB removal onto GPA 1.0 NCHs was found to be 89% at pH 10 with a dye concentration of 10 mg L^?1. The equilibrium adsorption data were also analyzed by different models to understand the adsorption process. The results revealed that the adsorption process followed the pseudo-second-order kinetics and it fit well in Langmuir and Freundlich adsorption isotherms with a maximum adsorption capacity of 35.41 mg g^?1. These studies demonstrate that the GPA NCHs could be a promising adsorbent material for the removal of MB dye from contaminated aqueous systems.

     

A Study of Physicomechanical and Morphological Properties of Starch/Poly(vinylalcohol) Based Films

Starch/Poly(vinylalcohol) blends in two different ratios (60:40 and 50:50) were prepared with glycerol as a plasticizer. Films were cast by a solution casting method. One set of films were filled with 10 wt% of unmodified bentonite clay and another set of films were crosslinked with epichlorohydrin in an alkaline medium. The prepared film samples were subjected to X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), mechanical characterization and scanning electron microscope (SEM). Significant changes in the tensile properties were observed depending on the different chemical constituents of the films. The presence of clay and crosslinking with epichlorohydrin were both found to have considerable effect on the morphology and mechanical property of the films. The SEM investigations, XRD analysis and FTIR studies revealed the interaction between the various chemical components of the films.     

聚苯乙烯/CdS/TiO_2双壳层核壳纳米颗粒可见光催化降解甲基橙

采用溶胶-凝胶法,在聚苯乙烯(PS)/CdS核壳纳米颗粒表面包覆致密TiO_2层,制备出具有双壳层结构的PS/CdS/TiO_2纳米复合颗粒,考察了制备条件对材料结构的影响,并利用甲基橙溶液对其光催化性能进行了评价。SEM、TEM、XRD和FTIR分析结果表明,制得的微球单分散性良好,壳层包覆完整,厚度均匀。PS/CdS/TiO_2制备的适宜反应时间为12~18 h,适宜反应pH为7~9。PS/CdS/TiO_2较PS/CdS具有更为优异的可见光催化性能。     

Biodegradation of Poly(vinyl alcohol) and Bacterial Cellulose Composites by <Emphasis Type="Italic">Aspergillus niger</Emphasis>

The ability of fungal strains to attack a composite material obtained from poly(vinyl alcohol) (PVA) and bacterial cellulose (BC) is investigated. The fungal strain tested was Aspergillus niger. This fungal strain was able to change not only the polymer surface from smoother to rougher, but also to disrupt the polymer. The degradation results were confirmed by visual observations, scanning electron microscopy (SEM) analyses, X-ray diffraction analyses and FTIR spectra of the film samples. SEM micrographs confirmed the growth of fungi on the composite film surface. The degree of microbial degradation depends on culture medium and on composition of polymeric materials, especially on PVA content. The biodegradation process is accelerated by the presence of glucose in the culture medium as an easily available carbon source.     

Synthesis,Characterization and Environmental Applications of a New Bio-Composite Gelatin-Zr(IV) Phosphate

Gelatin-Zr(IV) phosphate composite (GT/ZPC) was synthesized by sol–gel method. Different techniques viz. Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray powdered diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for the characterisation of GT/ZPC composite ion exchanger. The ion exchange capacity (IEC) of GT/ZPC was observed to be better (1.04 meq g^?1) than its inorganic counterpart (0.64 meq g^?1). The pH studies revealed the monofunctional nature of GT/ZPC with one inflection point. The distribution studies showed that the GT/ZPC was highly selective for Cd²⁺ as compare to other metal ions. The environmental applicability of ion exchanger has been analysed for binary separations of metal ions using column method. Cd²⁺ was effectively removed from synthetic mixture of metal ions (Zn²⁺, Pb²⁺, Ni²⁺, Co²⁺ and Cu²⁺).     

磁性分子筛负载TiO2复合光催化剂的制备及性能

采用超声辅助水热法合成了磁性分子筛Fe₃O₄/SSZ-13,然后通过溶胶-凝胶法对其继续负载TiO₂制得复合光催化剂TiO₂-Fe₃O₄/SSZ-13。借助XRD,FTIR,SEM,TEM,VSM,UV-Vis,PL对其形貌、结构及性能进行了表征,并考察了其光催化性能。表征结果表明,Fe₃O₄的加入不会改变分子筛的原有结构,复合材料的光响应范围扩大,电荷分离效率提高。降解实验结果表明,光照40 min时活性艳红的去除率可达89.7%,光照60 min时活性艳红去除率可达最大（93.6%）,较TiO₂提高了5.7%。此外,这种材料还具有较强的磁性,饱和磁化强度为17.80 （A·m²）/kg,可通过外加磁场回收。     

聚乙烯亚胺改性聚苯胺/氧化石墨烯对Cr(Ⅵ)的吸附性能

采用聚乙烯亚胺(PEI)对聚苯胺/氧化石墨烯(PANI/GO)进行改性得到PEI-PANI/GO,通过XRD、FTIR、BET和SEM技术对PEI-PANI/GO进行表征,并考察了PEI-PANI/GO对溶液中Cr(Ⅵ)的吸附性能。表征结果显示,PEI-PANI/GO材料以介孔为主,比表面积为35.12 m²/g,孔体积为0.098 24 cm³/g。实验结果表明,在温度为20 ℃、体系pH为3、溶液中Cr(Ⅵ)初始质量浓度为400 mg/L的条件下,PEI-PANI/GO对Cr(Ⅵ)的平衡吸附量达117.63 mg/g。PEI-PANI/GO对溶液中Cr(Ⅵ)的吸附行为更符合准二级动力学模型和Langmuir等温吸附模型,表明吸附过程是单分子层吸附。经过循环吸附再生后第4次使用,PEI-PANI/GO对Cr(Ⅵ)的吸附量从117.63 mg/g降至84.27 mg/g,仍能保持71.64%的吸附量,说明其重复使用性能良好。     

Synthesis of Polyurethane and Characterization of its Composites Based on Alfa Cellulose Fibers

Polyurethane (PU) based on polycaprolactone (PCL) and 4,4′ diphenyl methylene diisocyanate (MDI) was synthesized using a two-step method. The PU obtained was then blended with various amounts of cellulose extracted from alfa stems to prepare composite materials. The influence of cellulose on the thermal and mechanical properties of different composites was demonstrated by means of several characterization techniques such as Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM)…     

Synthesis of mesoporous silica materials from municipal solid waste incinerator bottom ash

Incinerator bottom ash contains a large amount of silica and can hence be used as a silica source for the synthesis of mesoporous silica materials. In this study, the conditions for alkaline fusion to extract silica from incinerator bottom ash were investigated, and the resulting supernatant solution was used as the silica source for synthesizing mesoporous silica materials. The physical and chemical characteristics of the mesoporous silica materials were analyzed using BET, XRD, FTIR, SEM, and solid-state NMR. The results indicated that the BET surface area and pore size distribution of the synthesized silica materials were 992 m²/g and 2–3.8 nm, respectively. The XRD patterns showed that the synthesized materials exhibited a hexagonal pore structure with a smaller order. The NMR spectra of the synthesized materials exhibited three peaks, corresponding to Q² [Si(OSi)₂(OH)₂], Q³ [Si(OSi)₃(OH)], and Q⁴ [Si(OSi)₄]. The FTIR spectra confirmed the existence of a surface hydroxyl group and the occurrence of symmetric Si–O stretching. Thus, mesoporous silica was successfully synthesized from incinerator bottom ash. Finally, the effectiveness of the synthesized silica in removing heavy metals (Pb²⁺, Cu²⁺, Cd²⁺, and Cr²⁺) from aqueous solutions was also determined. The results showed that the silica materials synthesized from incinerator bottom ash have potential for use as an adsorbent for the removal of heavy metals from aqueous solutions.     

碱熔融活化固硫灰制备地聚合物

采用碱熔融活化法,由固硫灰制备地聚合物。在前期开展的单因素实验的基础上,采用正交实验,考察了NaOH和固硫灰的质量比、煅烧温度、煅烧时间3个因素对固硫灰基地聚合物的抗压强度的影响。采用XRD,SEM,IR等手段分析固硫灰碱熔融活化前后的物相、微观形貌以及硅铝化学键的变化。实验结果表明,以在NaOH与固硫灰的质量比为0.60、煅烧温度为550 ℃、煅烧时间为60 min的条件下制备的碱熔融固硫灰为原料,制备的固硫灰基地聚合物的抗压强度为38.00 MPa。表征结果显示：通过碱熔融活化固硫灰制备的地聚合物的XRD谱图中出现了地聚合物的特征衍射峰;碱熔融固硫灰的结构松散,在颗粒表面及内部存在大量孔隙;经碱熔融处理后固硫灰的硅酸盐和铝酸盐发生了解聚。     

锰锌铁氧体/SiO_2复合磁性材料的制备和表征

以正硅酸乙酯(TEOS)作为包覆材料,对锰锌铁氧体纳米颗粒进行SiO2包覆,制备出锰锌铁氧体/SiO_2复合磁性材料。利用FTIR,XRD,SEM等技术对其进行了表征,并研究了其对模拟亚甲基蓝废水的吸附脱色效果。实验结果表明:当SiO_2质量分数为40%1时,采用先将锰锌铁氧体在柠檬酸溶液中搅拌分散3 h后,加人氨水调节溶液pH,再继续搅拌分散3 h的分段分散方法制备的复合磁性材料对亚甲基蓝废水的处理效果更好,处理亚甲基蓝质量浓度为50 mg/L、COD为160 mg/L的废水,废水脱色率为97.2%,COD去除率为19.3%。表征结果显示:复合磁性材料锰锌铁氧体/SiO_2为球形颗粒,平均粒径为100 nm;SiO_2包覆前后锰锌铁氧体的晶型均为尖晶石型结构,在复合磁性材料中SiO_2以无定型的形态存在。