Ggum-poly(Itaconic Acid) Based Superabsorbents Via Two-Step Free-Radical Aqueous Polymerization for Environmental and Antibacterial Applications

Ggum-based conducting hydrogels possessing dye removal and antibacterial property were developed by two-step free-radical aqueous polymerization method. Conductivity was introduced with polyaniline (PANI) chains incorporated within the crosslinked network of Ggum-poly(itaconic acid) superabsorbent. The material properties of the synthesized samples were characterized using FTIR spectroscopy, thermal analysis and scanning electron microscopy techniques. Results showed that synthesized samples exhibited the best antibacterial activity against Gram-positive bacteria. Synthesized samples were found to be effective in removal of toxic methylene blue (MB) dye from the waste water. The adsorption kinetics of superabsorbents has been described by using pseudo first and pseudo second order kinetics models. Furthermore, application of hydrogels to improve the water retention properties of different soils was also studied for agricultural purpose.     

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.

     

无机-有机复合絮凝剂PACSAM的制备及其脱色性能

以聚合氯化铝（PAC）和淀粉-丙烯酰胺接枝聚合物（ST-AM）为原料,合成了一种新型的无机-有机复合絮凝剂（PACSAM）。考察了PACSAM对活性染料、直接染料模拟印染废水及实际印染废水的脱色效果,并初步探讨了絮凝机理。实验结果表明：在很宽的pH范围内,PACSAM均表现出了良好的脱色性能;在PACSAM加入量为25m g/L时,PACSAM对实际印染废水的脱色率、COD去除率、浊度去除率分别为96.4%,92.1%,98.5%,废水处理效果明显好于壳聚糖和PAC。PACSAM的絮凝机理包括化学反应、分子间氢键、电中和及架桥作用等。     

Adsorption of Crystal Violet Dye from Aqueous Solution by Poly(Acrylamide-<Emphasis Type="Italic">co</Emphasis>-Maleic Acid)/Montmorillonite Nanocomposite

Poly(acrylamide-co-maleic acid)/montmorillonite nanocomposites, were synthesized via in situ polymerization with different maleic acid and MMT content. The capability of the hydrogel for adsorption of crystal violet (CV) was investigated in aqueous solutions at different pH values and temperatures. The pseudo-second-order kinetics model could fit successfully the adsorption kinetic data. The effects of maleic acid to acrylamide molar ratio (MA_R), weight percent of MMT (MMT%), the pH of medium and the solution temperature (T) on the CV adsorption capacity (q _e ) of adsorbents were studied by Taguchi experimental design approach. The results indicated that increasing the MMT% leads to a greater q _e . The q _e value of adsorbents increased also with increasing both MA_R and pH, while reduced when the temperature of medium increased. The relatively optimum conditions to achieve a maximum CV adsorption capacity for P(AAm/MA)/MMT adsorbents were found as: 0.06 for MA_R and 5 % of MMT%, medium pH = 7 and T = 20 °C.     

Design and Characterization of PVA–Methacrylic Acid Based Smart Polymeric System for Controlled Release of Metoprolol

In the present work covalently crosslinked smart polymeric system of hydrogel based on poly vinyl alcohol (PVA) and methacrylic acid (MA) was designed by free radical polymerization with different compositions using glyoxal (40 % water solution) as crosslinker. It was observed that swelling of hydrogel had a pronounced enhancing effect on increasing the concentration of MA due to availability of more ionized carboxylic groups of MA but produced an opposite effect on increasing the concentration of glyoxal owing to less porous structure. As far as PVA is concerned, swelling did not show significant effect on increasing the concentration of PVA. Hydrophilic polymer PVA rich in hydroxyl group pertained to be highly interactive with water. It was examined that the release of metoprolol tartrate decreased with increased concentration of glyoxal, but increased with increase in concentration of MA. PVA/MA hydrogel was characterized by Fourier transform infrared spectroscopy and X-ray diffraction to study the structure and crystallinity of hydrogel respectively. Morphology was studied through scanning electron microscopy. Furthermore differential scanning calorimetry and thermogravimetric analysis were also performed to characterize thermal stability. It may be concluded that the mechanism of drug release was mainly non-Fickian diffusion.     

A Novel Hyperbranched Polymeric Flocculant for Waste-Water Treatment

Cationic hyperbranched oligomer poly(N-acryloyl-1,2-diaminoethane hydrochloride) (HADE) was firstly synthesized by Michael addition reaction. And then, a series of cationic flocculants poly(acrylamide/N-acryloyl-1,2-diaminoethane hydrochlorides) (PAM-HADEs) with hyperbranched structure was prepared from HADE as macro-monomer and acrylamide (AM). The structures of PAM-HADEs were characterized by Fourier transform infrared spectrometry, ¹H and ¹³C nuclear magnetic resonance spectroscopy, gel permeation chromatography (GPC) and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF). And the properties were systematically evaluated by intrinsic viscosity, zeta potential and hydrodynamic radius. The mechanism of the cationic hyperbranched copolymer used in water treatment was extensively studied via a jar test in which the transmittance of the supernatant, settling time, and average floc size were used to evaluate the flocculability. Compared with the linear flocculant poly (acrylamide/liner-N-acryloyl-1,2-diaminoethane hydrochloride) (PAM-LADE), the novel hyperbranched polymeric flocculants exhibited outstanding flocculability which were reflected by shorter settlement time, high transmittance and large floc size. The primary cause that PAM-HADEs owned excellent flocculability is the more stretching configuration and less chains entanglement of PAM-HADEs in waste-water due to their hyperbranched structure compared with that of the linear PAM-LADE which exhibited curly coil configuration. On the other hand, abundant and exposed cationic terminal groups of PAM-HADEs originated from their hyperbranched structure also hint higher flocculation capacity. At optimum dosages of the polymer, the transmittance of the supernatant is less at low and high pH values, indicating that the natural pH (pH 7.29) of the suspension is the most appropriate pH for the flocculation.     

Enhancement of Sedimentation Velocity of Heavy Metals Loaded Hydroxyapatite Using Chitosan Extracted from Shrimp Waste

In this study, synthesize hydroxyapatite (HA) suspensions sedimentation was used after usual terms as support for adsorption of heavy metals ions. Thus, the effectiveness of chitosan, produced from shrimp waste, in the flocculation of turbid suspensions resulting from the treatment of water contaminated with heavy metals was studied by adsorption on HA. Different particles sizes of HA were mainly controlled in this work (an average of granule size ranging from 1.6 to 63 μm). The results of Cu²⁺ and Zn²⁺ adsorption on HA showed relatively fast kinetics, with removal extent of 88–95 % by varying the initial total metal concentration. High removal rates were obtained for Cu²⁺. Chitosan was found to be able to eliminate by flocculation more than 98 % of turbid suspensions generated by metals adsorption on HA after only 30 min of sedimentation. Effects of pH and dose of chitosan on the coagulation–flocculation process were also studied. The optimal dose of chitosan was found between 0.2 and 2 mg/L which corresponds to an optimal pH ranging from 6 to 7.     

Effective Removing of Remazol Black B by the Polyacrylamide Cryogels Modified with Polyethyleneimine

In this study, modified polyacrylamide (PAAm) cryogels with high dye holding capacity were synthesized with an easily and cheaply process and adsorption of Remazol Black B (RBB) with the synthesized materials was investigated. Firstly, PAAm cryogels were synthesized with free radical cryo-copolymerization method and they were modified with Hofmann reaction to form amine groups in the structure of the cyrogels. Then, to increase the removal efficiency of cryogels, polyethylenimine (PEI) molecules were crosslinked onto the cryogels via NH₂ groups present in the PAAm gels modified by the Hofmann reaction. The original and modified cryogels were characterized with fourier transformed infrared spectroscopy, ¹³C nuclear magnetic resonance spectroscopy, scanning electron microscopy and thermogravimetric analysis. The point of zero charge (pH_pzc) of the modified cryogels was found to be 7.13 and RBB removing capabilities of PEI-modified PAAm cryogels were investigated at pH between 2 and 7. In addition, the adsorption treatments were performed at different process time, incubation temperature, initial dye concentration and adsorbent amount to find maximum removal capacity of the adsorbent. The modified cryogels adsorbed maximum amount of RBB at pH 2 and the sorption process reached equilibrium in 6 h. It was observed that the adsorption efficiency did not change much with the increase in temperature. The maximum RBB removal capacity of the modified cyrogels was determined to be 201 mg/g when the initial RBB concentration was 200 mg/L, treatment time was 6 h at pH 2. Moreover, the adsorption of RBB dye with the modified cryogels takes place with a second order kinetic and RBB dye adsorption data showed compliance with the Langmuir isotherm. The findings of the study expose that the obtained PEI-modified PAAm cryogels are a hopeful material for RBB removal in aqueous environment.

     

Crosslinked Polyacrylamide Composite Hydrogels Impregnated with Fly Ash: Synthesis,Characterization and Their Application as Fractures Sealant for High Water Producing Zones in Oil and Gas Wells

Polymeric hydrogels are designed to serve many purposes in various fields of human endeavor. Herein, crosslinked polyacrylamide (PAM) composite hydrogels impregnated with coal fly ash (CFA) were synthesized, characterized and tested as fracture sealing agents in high water producing permeable zones in petroleum industry. The concept of utilizing CFA as an inorganic additive in the matrix of hydrogel emanates from the fact that CFA constitutes majorly alumina and silica. Both chemical oxides can induce the CFA to promote the inherent properties of hydrogel. Polyethyleneimine (PEI) was chosen as the crosslinking agent. Neat PAM/PEI hydrogel and PAM/PEI–CFA hydrogels at various CFA loadings (0.5, 1 and 2 wt%) were synthesized via a transamidation reaction pathway. The developed hydrogels were characterized by hybrid rheometer, FTIR, SEM and XRD instruments. Rheological results reveal that the PAM/PEI–CFA composite hydrogels embedded with various CFA quantities were more elastic than the neat PAM/PEI hydrogel, indicating the dispersion and reinforcing effect of CFA. The functional groups of these hydrogels were confirmed by the FTIR while SEM analysis show that the surface micrographs of neat PAM/PEI hydrogel and PAM/PEI–CFA1 hydrogel were porous in several regions. In contrast, the micrographs of PAM/PEI–CFA2 and PAM/PEI–CFA3 hydrogels demonstrated dense and “net-like” structural patterns. Further, XRD analysis revealed that CFA impregnation has a significant effect on the bulk structural properties of the fabricated hydrogels. The swelling rates of these hydrogels were determined by the gravimetric method and their diffusion parameters evaluated using Fickian diffusion and Schott-order kinetic models. Efficacy of the PAM/PEI–CFA composite hydrogel as fractures sealant in oil and gas wells was conducted at a typical reservoir temperature, 90 °C, and the outcome demonstrated considerable sealing potency.     

Statistical Optimization of Polyhydroxybutyrate Production by <Emphasis Type="Italic">Bacillus Pumilus</Emphasis> H9 Using Cow Dung as a Cheap Carbon Source by Response Surface Methodology

A gram positive bacterium (designated strain H9) found to be a potential polyhydroxybutyrate (biodegradable polymer) producer was isolated from the soil samples of a stress prone environment (municipal waste areas). This bacterium was identified as Bacillus pumilus H9 from its morphological, physiological and 16S rRNA gene sequence analysis. A four-factor central composite rotary design was employed to optimize the medium and to find out the interactive effects of four variables, viz. concentrations of cow dung, sucrose, peptone and pH on PHB production. Using response surface methodology, a second-order polynomial equation was obtained by multiple regression analysis and a yield of 2.47 g/L of PHB dry weight was achieved from the optimized medium at pH 7. Here, we report cow dung as a cheap carbon source for the production of PHB. Further, phbA, phbB and phbC genes were amplified by polymerase chain reaction which confirms the bacterium to be able to produce polyhydroxybutyrate.     

Use of slag for dye removal

Adsorption techniques employing activated carbon have been found to be reasonably effective in the removal of some of the ionic impurities in water. However, economic considerations may require the use of inexpensive sorbents which are either naturally available or available as waste products from manufacturing processes. Slag is one such waste product obtained during the manufacture of steel, and the present study investigates dye removal characteristics of slag from colored waters. Aqueous solutions prepared from commercial grade acid, basic, and disperse dyes were used in this study, and batch pH, kinetic, and isotherm studies were undertaken on a laboratory scale. The data were evaluated for applicability to the Langmuir, Freundlich, and BET isotherm models, and the removal capacity of slag was compared with that of granular activated carbon. Results indicated approximately 94% removal of the disperse dye by slag, compared with a removal of approximately 49% achieved by activated carbon. Removal of acid dyes (dyes containing anionic groups) was reasonably good (approximately 47 and 74%), though not as good as obtained using activated carbon (approximately 100%). Column studies were conducted with a disperse dye (nonionic, slightly soluble in water), and analysis of data showed a sorption capacity of 1.3 mg of disperse dye per gram of slag. However, effluent dye concentrations were found to be higher than the permissible levels for discharge to receiving waters.     

Soybean Oil-Based Photo-Crosslinked Polymer Networks

Novel soybean oil-based crosslinked polymer networks were prepared by UV photopolymerization and their mechanical properties were evaluated. Poly(ethylene glycol) diacrylate (PEGDA) and biodegradable poly(ε-caprolactone) diacrylate (PCLDA) were synthesized and used as crosslinking agent to form crosslinked polymer networks by UV-initiated free-radical polymerization with acrylated epoxidized soybean oil (AESO). The synthesis of acrylate end-capped macromers was confirmed using FT-IR and ¹H NMR spectroscopic techniques. Photopolymerization time, the composition of reaction mixture, and the type and length of crosslinking agent were changed to obtain crosslinked polymer networks with various mechanical properties. Polymers prepared from AESO and PCL degraded 6% of the initial weight in 24 days in phosphate buffer solution (pH 7.2) containing lipase enzyme. These potentially biodegradable and biocompatible polymers can be used as ecofriendly materials for biomedical and other applications to replace the existing petroleum-based polymers currently used.     

Evaluation of the Biosorption Characteristics of <Emphasis Type="Italic">Tremella fuciformis</Emphasis> for the Decolorization of Cationic Dye from Aqueous Solution

The present work reported on the evaluation of the methylene blue dye biosorption property of Tremella fuciformis under different experimental conditions. Batch mode experiments were carried out using different experimental parameters such as initial pH, dye concentration, biosorbent amount, contact time and temperature. Four widely used kinetic models were used to elucidate the biosorption kinetics. And the kinetic analysis illustrated that the experimental data best followed the pseudo-second-order kinetic model. Biosorption equilibrium was also investigated using four widely used isotherm models. The results indicated that the experimental equilibrium data fitted very well with Langmuir isotherm models. Thermodynamic analysis of biosorption processes was found to be feasibility, spontaneous and exothermic nature of MB biosorption. These results indicated that T. fuciformis would be a high effective and environmental friendly biosorbent for MB removal from aqueous solution.     

非离子型聚丙烯酰胺絮凝剂的制备及其絮凝性能

以丙烯酰胺（AM）和烷基酚聚醚（APAP）为单体,采用反相乳液聚合法制备了流动性好的非离子型聚丙烯酰胺絮凝剂（PAM-APAP）。考察了乳化剂和引发剂的种类、单体总质量分数、单体配比和反应温度等因素对聚合反应的影响。实验结果表明,制备PAM-APAP的最佳工艺条件为：单体总质量分数35%、m（AM）∶m（APAP）=9.0∶1.0、Span80+Tween80复配乳化剂加入量为油水总质量的7%、m（Span80）∶m（Tween80）=7.0∶1.5、V50加入量为单体总质量的1.5‰、反应温度50℃。PAM-APAP具有较好的絮凝效果,与其他絮凝剂相比用量较少,在加入量为100mg/L时,对聚合物驱油中产生的含聚合物污水的浊度去除率为87.9%,去油率为89.5%,且絮体不黏壁。     

Experimental and Modeling Studies for the Removal of Crystal Violet Dye from Aqueous Solutions using Eco-friendly <Emphasis Type="Italic">Gracilaria corticata</Emphasis> Seaweed Activated Carbon/Zn/Alginate Polymeric Composite Beads

This research article describes, an eco-friendly activated carbon prepared from the Gracilaria corticata seaweeds which was employed for the preparation of biodegradable polymeric beads for the efficient removal of crystal violet dye in an aqueous solution. The presence of chemical functional groups in the adsorbent material was detected using FTIR spectroscopy. The morphology and physical phases of the adsorbent materials were analyzed using SEM and XRD studies respectively. Batch mode dye adsorption behavior of the activated carbon/Zn/alginate polymeric beads was investigated as a function of dosage, solution pH, contact time, initial dye concentration and temperature. Maximum dye removal was observed at a pH of 5.0, 1 g of adsorbent dosage with 60 mg/L dye concentration, 50 min of contact time and at 30 °C. The equilibrium modeling studies were analyzed with Freundlich and Langmuir adsorption isotherms and the adsorption dynamics was predicted with Lagergren’s pseudo-first order, pseudo-second order equations and intra particle diffusion models. The process of dye removal followed a pseudo second-order kinetics rather than pseudo first order. The thermodynamic parameters like standard Gibbs free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) were determined and the results imply that the adsorption process was spontaneous, endothermic and increases the randomness between the adsorbent and adsorbate. The results from the experimental and correlation data reveal that the Gracilaria corticata activated carbon/Zn/alginate polymeric beads have proved to be an excellent adsorbent material for the removal of CV dye.     

蚀刻液水合肼还原除铜

将电路板厂废弃的蚀刻液,经氢氧化铜沉淀法回收大部分铜后,再采用水合肼还原,进一步除铜。反应温度为50℃,水合肼质量分数为3．0％,溶液pH为6．0,废液中铜的去除率可达98.5％,处理后废液中铜的质量浓度低于0．2g／L,可作为碱性蚀刻液重复利用。     

Assessment of Potential Capability of Water Bamboo Leaves on the Adsorption Removal Efficiency of Cationic Dye from Aqueous Solutions

Removal of toxic pollutants from water and wastewater is becoming an important process with the increase of industrial activities. The present study focused on assessing the suitability and efficiency of water bamboo leaves (WBL) for the removal of cationic dye from aqueous solutions. The effect of different variables in the batch method including solution pH (2–12), initial dye concentration (50–250 mg L^?1), adsorbent dose (0.05–0.30 g), contact time (5–180 min) and temperature (283–333 K) on the dye removal was investigated. The adsorption kinetics was discussed in view of four kinetics models. The results showed that the pseudo-second-order kinetics model described dye adsorption on WBL very well. The experimental equilibrium data were also tested by four isotherm models. It was found that adsorption of dye on WBL fitted well with the Langmuir isotherm model, implying the binding energy on the whole surface of the adsorbent was uniform and the dye molecules onto the surface of the adsorbent were monolayer coverage. Calculation of various thermodynamic parameters of the adsorption process indicated feasibility and exothermic nature of dye adsorption.     

絮凝沉淀-Fenton试剂氧化法处理含高浓度硫酸盐的洗涤剂生产废水

采用絮凝沉淀-Fenton试剂氧化法处理含高浓度硫酸盐的洗涤剂生产废水（简称废水）,考察了各种因素对COD去除率的影响。实验结果表明：根据实际废水的水质情况,选用聚合氯化铝（PAC）为絮凝剂,PAC最佳加入量为0．3g／L,经絮凝处理后COD去除率为42．3％;Fenton试剂氧化的最佳操作条件为：n（H2O2）：n（Fe^2＋）=0．5、H2O2加入量为7mmol／L、反应时间为2h,不调节废水初始pH,经Fenton试剂氧化处理后COD去除率为70％以上。经絮凝沉淀-Fenton试剂氧化法处理后,废水COD由1950mg／L降至240mg／L,总的COD去除率为87．7％,废水处理效果良好。     

Hydrolytic and enzymatic degradation of poly(γ-glutamic acid) hydrogels and their application in slow-release systems for proteins

The hydrolytic and enzymatic degradation of newly developed hydrogels, produced by cross-linking purified poly(-glutamic acid) (PGA) with dihaloalkane compounds, was studied and is reported in this paper. Analysis of hydrolysis of the hydrogel as a function of pH indicated that the hydrolysis occurred slowly at neutral pH, but fast in both acidic and alkaline solutions, while the polymer could be hydrolyzed rapidly only in acidic solutions. The ester bonds were more sensitive to hydrolysis than peptide bonds. The biodegradability of the hydrogel and polymer was further confirmed when enzymatic degradation was studied by three enzymes (cathepsin B, pronase E, and trypsin), which were able to cleave both ester and peptide bonds gradually. A slow-release system for porcine somatotropin (pST) formed by using the hydrogel as matrix to entrap the hormone was evaluatedin vitro andin vivo. Results demonstrated that the hydrogel was able to release the hormone for a period of 20–30 days and indicated its potential application in slow-release systems for bioactive materials, especially macromolecules, such as peptides and proteins.     

Optimized Removal of Acid Blue 62 from Textile Waste Water by SBA-15/PAMAM Dendrimer Hybrid Using Response Surface Methodology

SBA-15/PAMAM Nano adsorbent was synthesized by the proficiency of SBA-15 as an original compound, 3-chloropropyltrimethoxysilane as a bridge chemical compound and polyamidoamine dendrimer (PAMAM) in the role of a multifunctional amine end group for adsorption of acid blue 62 (AB62) from aqueous media. The synthesized adsorbent was characterized by transmission electron microscope, field emission scanning electron microscope and Fourier-transform infrared spectroscope. A response surface methodology was employed to evaluate the simple and amalgamated factors of the operating variables subtending initial pH (2–12), adsorbent dosage(0.01–0.03 g), contact time (5–120 min), initial dye concentration (40–600 ppm) and temperature (25–45?°C) to optimize the operating statues of the treatment method. These parameters were altered at five levels pursuant to the central composite design to appraise their effects on AB62 removal through analysis of variance. Analysis of variance represented a high coefficient of definition amount (R²?=?0.9999) and acceptable prediction quadratic polynomial model was concluded which ascertain the suitability of the model and a high correlation among the predicted and empirical amounts. Utmost color removal efficiency was auspicated and empirically accredited. The optimum conditions relied on acquired results for AB62 removal were at an initial pH of 2, adsorbent dosage of 0.03 g SBA-15/PAMAM, dye concentration of 40 mg l^?1, time contact of 60 min and temperature of 25?°C.