•Removal of Cu(II) ions by m-ECCSB was studied.•m-ECCSB was characterized by X-RD, FTIR, SEM with EDS, TEM 1HNMR, and VSM analysis.•The pseudo-second-order model best described the sorption ...kinetics.•Langmuir model provided the best correlation for the experimental data.
Metal ions cause a serious public health problem. It is a great challenge to find an effective and efficient adsorbent to remove heavy metals from wastewater. Chitosan-based adsorbents are potential and effective for heavy metal ion removal. Hence a novel m-ECCSB was synthesized, characterized and utilized as an adsorbent for the removal of Cu(II) ions from aqueous solution. Various factors affecting the uptake behavior such as pH, adsorbent dosage, contact time, initial concentration of Cu(II) and temperature effect were investigated. Maximum adsorption capability (123.10mg/g) was obtained at pH=6, adsorbent dose of=250mg, rotational speed=200rpm, contact time=60min, and temperature of 323K. The result of the kinetic study shows that the adsorption of Cu(II) could be described by the pseudo-second-order equation. Equilibrium data were analysed with the Langmuir, Freundlich and Dubinin-Radushkevich isotherms and Langmuir model was found to provide the best fit of the experimental data. The thermodynamic parameters showed that the adsorption of Cu(II) onto m-ECCSB was spontaneous (ΔG°=−8.990, −10.00 and −10.593kJ/mol), endothermic (ΔH°=15.674, 15.478 and 15.699kJ/mol) and ΔS° (0.0814J/molK) suggests an increased randomness at the solid/solution interface under the studied conditions.
Polyamidoamine epichlorohydrin (PAAE) is the preeminent permanent wet strength additive used in papermaking. Wet strength additives are used to improve paper resistance to a rupture force in wet ...environments. The invention of PAAE in 1957 was an innovation, as it improved paper properties by giving superior wet strength in humid or wet conditions. It was rapidly adopted by the industry. Despite PAAE’s long history, the mechanism of PAAE interaction with fiber has not been fully understood. Therefore, fundamental understanding of PAAE mechanism needs to be investigated to improve its utilization in making sustainable paper products. These areas include an understanding of repulping methods and optimal PAAE dosages for better cost and performance. This paper investigates different generations of PAAE, the application method, and its impact on paper recyclability. Three generations of PAAE are currently on the market with at least two newer iterations under development. Critical application parameters that need to be understood include determination of the bonding mechanism, optimal dosage, and retention parameters. The main drawback of PAAE application is it makes paper recycling difficult. Several repulping methods are proposed for better recyclability and sustainability in the papermaking process.
Efforts to establish an asymmetric entry to hexanorlanostanes has resulted in a concise synthesis of 7,11-dideoxy-Δ
-lucidadone H from epichlorohydrin. By exploiting metallacycle-mediated annulative ...cross-coupling (to establish a functionalized hydrindane) and stereoselective formation of the steroidal C9-C10 bond to establish a stereodefined 9-alkyl estrane, 14 subsequent steps have been established to generate a hexanorlanostane system. Key transformations include formal inversion of the C13 quaternary center, oxidative dearomatization/group-selective Wagner-Meerwein rearrangement, and Lewis acid mediated semi-Pinacol rearrangement.
This study evaluates the feasibility of commercial chitosan (CQ) and modified chitosan (MQ) by epichlorohydrin to be used as a solid phase to remove fluorescein (FSC) from aqueous solutions by two ...different approaches: in batch and on a fixed column bed. For the batch study, all parameters that influence sorption capacity were evaluated, such as: pH, mass, ionic strength, temperature and time of contact. In the optimized condition, 75% removal was obtained for FSC using CQ, while the modification allowed an increase up to 99%, as well as an increase in the stability of the polymer. In the fixed column bed study, the influence of all the parameters was evaluated through breakthrough curves, and the thermodynamics parameters of each approach were obtained. The results of these studies demonstrate that the modification with epichlorohydrin enhanced the sorptive properties (from 35% to 95% in fixed bed experiments) and the polymer stability (making it insoluble), making it suitable to be used in wastewater treatment.
Chemical cross-linking using epichlorohydrin as cross-linking agent is the most straightforward method to produce water-insoluble β-cyclodextrin-based polymers. The numerous OH groups available on ...cyclodextrin (CD) molecules are active sites capable of forming a number of linkages. Although this cross-linking reaction has been known for 50 years and is well documented, and relatively easy to use for the preparation of CD-based networks, some basic questions concerning the reaction still continue to interest the scientific community. The main objectives of this review are (i) to describe the synthesis and characterization of insoluble CD–epichlorohydrin polymers, (ii) to provide useful information on their most important features, (iii) and to summarize the developments in the use of these materials for environmental purposes. In particular, the description of relevant environmental applications such as sorption-oriented processes, detoxification of wastewater, color removal, and concentration and purification of solutions is included. In this aim, an extensive pool of data from the literature, from 270 papers, reviews, patents and books, has been compiled. The various interactions occurring between pollutants and CD–epichlorohydrin polymer in the sorption processes are presented, and future research trends are discussed.
One-pot conversion of carbon dioxide into cyclic carbonate catalyzed by Zn2(C9H3O6)(C4H5N2)(C4H6N2)3 MOF.
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•98.93% conversion of epichlorohydrin and 98.32% selectivity to chloropropene ...carbonate was obtained.•Zn-BTC-2MeIm compound was stable in catalytic activity for CO2 conversion.•Zn-BTC-2MeIm also can enhance cycloaddition of CO2 with other epoxides.•The law of CO2 coupling with ECH was coincident with the first order kinetic.
Zn2(C9H3O6)(C4H5N2)(C4H6N2)3 (Zn-BTC-2MeIm) was hydrothermally synthesized and employed as a highly efficient catalyst for CO2 coupling with epichlorohydrin (ECH). Various techniques such as XRD, FT-IR, XPS, TG-DTG, NH3/CO2-TPD were employed for characterizing the compound. Interestingly, TG profile illustrated the Zn-BTC-2MeIm was stable above 200°C. The highest catalytic activity of 98.93% conversion of ECH and 98.32% selectivity to chloropropene carbonate was observed under the optimum conditions (100°C, 120mesh, 1000rpm, 3.0MPa, 6h, 0.75wt.% of ECH). Besides, the recyclability results exhibited Zn-BTC-2MeIm compound could be reused no less than three times with a slight reduction in its catalytic ability. Moreover, coupling results of CO2 with other epoxides showed this compound could efficiently convert various epoxides into cyclic carbonates. Finally, the investigation of the kinetic exhibited the law of CO2 coupling with ECH was coincident with the first order kinetic and the activation energy (Ea) was to be 113.38kJ/mol.
The substrate concentration and yield were shown to be very low in the production of (R)‐epichlorohydrin by hydrolysis of racemic epichlorohydrin using epoxide hydrolases in previous studies. In this ...work, we synthesized an epoxide hydrolase gene from Agrobacterium radiobacter and expressed it in Escherichia coli by the PCR assembly method. The recombinant A. radiobacter epoxide hydrolase (ArEH) was applied in the preparation of (R)‐epichlorohydrin and, a yield of 42.7% with ≥99% enantiomeric excess (ee) from 25.6 mM racemic epichlorohydrin was obtained. However, the ee of (R)‐epichlorohydrin was not able to reach 99% due to substrate and product inhibition when the substrate concentration was over 320 mM. Inhibition studies revealed that (S)‐3‐chloro‐1,2‐propanediol displayed non‐competitive inhibition in the conversion of (S)‐epichlorohydrin but non‐significant inhibition for (R)‐epichlorohydrin. Moreover, ArEH was successfully applied in the preparation of (R)‐epichlorohydrin at high substrate concentration by eliminating the substrate inhibition. The substrate concentration increased to 448 mM by intermittent feeding of the substrate and to 512 mM by using a two‐phase reaction system, with a high yield (>27%) and ee (>98%) of (R)‐epichlorohydrin. This is the first report of high‐yield production of (R)‐epichlorohydrin at high substrate concentration, laying the foundations for its application on the industrial scale.
Low-acrylonitrile nitrile butadiene rubbers (NBRs) are seriously degraded by No. 15 oil in the hydraulic system of aircraft. The present work aims to prepare rubber materials with excellent ...low-temperature and No. 15 aviation hydraulic oil resistance. Terpolymerization epichlorohydrin rubber (ECO) and low-acrylonitrile NBR were blended. The blends were vulcanized using peroxide. The effects of the ECO/NBR blending ratio on the oil resistance and low-temperature, physical and mechanical, hot air aging, and ozone aging properties were investigated using a multitechnique approach. The results showed that ECO had double bonds and could be vulcanized by peroxide. The percentage of volume swelling of ECO in No. 15 oil was about 1/7 of that of NBR. As the ECO content increased, the oil and ozone resistance and brittle temperature were gradually improved. The coefficient of cold resistance under compression and glass transition temperature peaked at a ratio of 50/50 due to the migration of dicumyl peroxide from ECO to NBR. Further, vulcanization, hot air aging, and other physical properties are also discussed. This work provides a reference for the development of ultra-low-temperature performance and No. 15 oil-resistant sealing rubber materials.
Wood plastic composites (WPCs) made from plant fibres and plastics have gained more and more attention. Studies have been focused on preparation and mechanical performance of WPCs. While mechanism of ...chemical modification of cereal straw has rarely been reported. In the present work, rice straw was etherified with epichlorohydrin (EPI) and the mechanism of etherification was investigated. Natural rice straw (NRS) was pretreated with NaOH to move most of hemicellulose and lignin. The alkali treated rice straw (ARS), whose dominant component being cellulose, was etherified with EPI at 120 °C for 1-8 h in toluene with NaOH as catalyst. NRS, ARS and etherified rice straw (ERS) were characterized and analyzed by FT-IR, solid CP/MAS
C-NMR, elemental analysis and neutral sugar analysis. The etherification reaction was finished within 5 h, and C
H
O units were introduced into the structure of cellulose, leading to the increase of contents of C and H in ERS. The etherification process of ARS in alkaline medium was divided into three stages, during which two hydroxyl groups were replaced by two ether bonds successively, and a new hydroxyl group was formed in the last step. The number of hydroxyl groups in ERS was reduced, and reduction of hydrophilicity of ERS could be expected.
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