共查询到19条相似文献,搜索用时 78 毫秒
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以丙烯酸和腐植酸为原料,N,N-亚甲基双丙烯酰胺为交联剂,在水溶液中采用辉光放电电解等离子体引发聚合反应制备聚丙烯酸钠/腐植酸复合高吸水性树脂。 考察了放电电压、交联剂、丙烯酸中和度、后聚合温度、腐植酸钠和丙烯酸的含量对树脂吸水率的影响,讨论了树脂在0.9%氯化钠溶液中的溶胀速率和不同pH值溶液中的溶胀行为。 用红外光谱和热重分析分别对产物进行了结构表征和稳定性测试,结果表明,最佳的合成条件为:放电电压470 V、交联剂质量分数为0.6%、腐植酸钠质量分数为4%、丙烯酸质量分数为10%、中和度60%、后聚合温度70 ℃。 所得复合树脂对蒸馏水的吸水率为1152 g/g,对0.9%NaCl溶液的吸水率为89 g/g,800 ℃后复合树脂残留率为44.3%。 相似文献
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甲醇溶液辉光放电等离子体电解过程出现明显的非法拉第定律现象, 主要产物是氢气和甲醛, 还有少量一氧化碳、甲烷、乙烷、丙烷、1,3,5-三噁烷和水等, 产物和产量受放电极性和辅助电解质及放电电压等因素的影响. 在甲醇溶液电导率为11.40 mS·cm-1, 放电电压700 V 条件下, 阳极气体产量为55.90 mol/(mol electrons), 阴极气体产量为707.90 mol/(mol electrons), 阴极气体产量是阳极气体产量的12.66 倍, 气相产物中氢气含量在86%(molar fraction)以上. 在等离子体层中甲醇分解过程和其它类型的等离子体分解过程类似, 蒸汽鞘层中的加速电子是引发辉光放电过程非法拉第定律现象的决定因素. 阴极辉光放电过程中等离子体-溶液界面上的主要活性物种是中性粒子和电子,阳极辉光放电过程中等离子体鄄溶液界面上的主要活性物种是中性粒子和正离子. 辅助电解质对产物的影响主要是通过影响界面上发生的后续反应过程来表现. 相似文献
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辐射合成聚丙烯酰胺、聚丙烯酸钠及其共聚物水凝胶微观结构的扫描电镜研究 总被引:5,自引:0,他引:5
用60Co-γ射线辐射合成了低交联度的聚丙烯酰胺、聚丙烯酸钠及丙烯酰胺-丙烯酸钠共聚物水凝胶,用扫描电子显微镜研究了水凝胶经过丙酮脱水的干态试样的微观结构特征。发现聚合物中丙烯酰胺与丙烯酸钠单体单元的比例对其微观结构影响很大,并且从聚合物链段之间存在氢键和静电排斥这两种对立作用力相对强度的角度,定性地阐述了各水凝胶微观结构之间的差异。 相似文献
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辉光放电等离子体处理阳离子染料结晶紫废水 总被引:2,自引:0,他引:2
用辉光放电等离子体技术对结晶紫进行了降解脱色处理,考察了多种因素对结晶紫降解效果的影响。实验发现,提高电解质浓度和增加电压均可提高结晶紫的脱色效果,考虑到电极损耗,辉光放电最佳条件为:电解质浓度为2 g/L Na2SO4,电压为600 V。当改变溶液的初始pH值时,结晶紫的脱色率随溶液的初始pH值升高而增加,加入一定量H2O2能明显地提高结晶紫的脱色效率;若加入0.4 mmol/L Fe2 ,5 min时结晶紫的脱色率由原来的13.64%增加到91.36%。结果表明,辉光放电产生的.OH对结晶紫的降解起重要作用。最佳条件下,40 min内的脱色率达到93%,降解率为74%。 相似文献
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Jie Yu Yuanpei Pan Quanfang Lu Wu Yang Jinzhang Gao Yan Li 《Plasma Chemistry and Plasma Processing》2013,33(1):219-235
Highly swelling P(2-acrylamido-2-methyl-1-propanesulfonic acid- co-acrylic acid) (P(AMPS-co-AAc)) superabsorbent hydrogel was synthesized in aqueous solution by a simple one-step using glow-discharge electrolysis plasma technique, in which N,N’-methylenebisacrylamide was used as a crosslinking agent. The structure, thermal stability and morphology of P(AMPS-co-AAc) superabsorbent hydrogel were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. A mechanism for synthesis of P(AMPS-co-AAc) superabsorbent hydrogel was proposed. The reaction parameters affecting the equilibrium swelling (i.e., discharge voltage, discharge time, macroscopic temperature of the liquid phase, mass ratio of AMPS to AAc, and content of crosslinker) were systematically optimized to achieve a superabsorbent hydrogel with a maximum swelling capacity. The hydrogel formed which absorbed about 1,685 g H2O/g dry hydrogel of the optimized product was used to study the influence of various pH values and salts solutions (NaCl, KCl, MgCl2, and CaCl2) on the equilibrium swelling. In addition, swelling kinetics in distilled water and on–off switching behavior were preliminarily investigated. The results showed that superabsorbent hydrogel was responsive to the pH and salts. 相似文献
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Wei Yao Wenqi Zhang Liang Li Yingjie Li 《Journal of Dispersion Science and Technology》2013,34(5):714-722
In this study, thermo-sensitive magnetic cationic hydrogel (TSMCH) based on (3-acrylamidopropyl) trimethyl ammonium chloride (APTMACl) and N-isopropylacrylamide (NIPAm) was synthesized by free radical copolymerization. The TSMCH was characterized with Fourier transform infrared spectroscopy, thermal gravimetric analysis, x-ray diffraction, scanning electron microscope with energy dispersive x-ray, vibrating sample magnetometer, and zeta potential, and employed as adsorbent for adsorbing reactive red (RR) dye. Effects of molar ratios of APTMACl to NIPAm on the adsorption capacity of TSMCH were studied, and the results showed that a maximum adsorption capacity (1428.57 mg RR g?1 TSMCH) had been achieved when the molar ratio of APTMACl to NIPAm was 1:1. The adsorption isotherm of RR was well fitted by the Langmuir isotherm equation. TSMCH had good selectivity for adsorbing RR. Solution pH hardly affected the adsorption of RR on the TSMCH. The adsorption amount of RR increased with the increase of temperature. The adsorption–desorption of TSMCH was evaluated in three circles and a high regeneration rate was demonstrated. 相似文献
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Hydrogel beads based on the husk of agarwood fruit (HAF)/sodium alginate (SA), and based on the HAF/chitosan (CS) were developed for the removal of the dyes, crystal violet (CV) and reactive blue 4 (RB4), in aqueous solutions, respectively. The effects of the initial pH (2–10) of the dye solution, the adsorbent dosage (0.5–3.5 g/L), and contact time (0–540 min) were investigated in a batch system. The dynamic adsorption behavior of CV and RB4 can be represented well by the pseudo-second-order model and pseudo-first-order model, respectively. In addition, the adsorption isotherm data can be explained by the Langmuir isotherm model. Both hydrogel beads have acceptable adsorption selectivity and reusability for the study of selective adsorption and regeneration. Based on the effectiveness, selectivity, and reusability of these hydrogel beads, they can be treated as potential adsorbents for the removal of dyes in aqueous solutions. 相似文献
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Possessing three-dimensional porous structures and tunable mechanical strengths, cyclodextrin-containing polymeric hydrogels are one of the most promising water-based adsorbent materials due to their easy availability, simple chemical modification and environmental friendliness. In this work, two kinds of hydrogels were prepared via the copolymerization with acrylic acid and vinyl-derivatized β-cyclodextrins in water. These two gels have showed good adsorption performance towards cationic dyes through the noncovalent interactions with their anionic backbones and porous network. Meanwhile, pseudo-second-order model was selected to clarify the adsorption kinetics process. Moreover, nano-scaled TiO2 was doped into these resultant cyclodextrins-based hydrogels to achieve efficient degradation of dyes upon light irradiation. The obtained TiO2-loaded hydrogels could exhibit improved adsorption performance and make the adsorbed dyes photo-degraded with the decolorization rates above 95%. It can be envisioned that such cyclodextrin-based soft materials may find applications in dye clearance and water treatment. 相似文献
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A series of granular pH-sensitive semi-interpenetrating polymer network (semi-IPN) hydrogels based on chitosan (CTS), acrylic acid (AA) and gelatine (GE) were utilized for the adsorption and recycle of Pb(II) from aqueous solutions. The composite hydrogels have been characterized by FT-IR and TGA. The effects of contact time, pH value and initial Pb(II) concentration on the adsorption were investigated. Results indicated that the adsorption capacity of the hydrogel increased with increasing pH value and initial Pb(II) concentration, and a pH-sensitive adsorption characteristic was presented. The adsorption rate of the semi-IPN hydrogels on Pb(II) is fast with an adsorption rate constant of 14.9790 mg/(g·s), and adsorption equilibrium could be reached within 10 min. The adsorption isotherms of the hydrogels for Pb(II) could be described well by the Langmuir equation, rather than the Freundlich equation. The as-prepared hydrogels showed good reusability with 0.05 mol/l HNO3 solutions as the desorbing agent and 0.1 mol/l NaOH solutions as the regeneration agent, respectively. After five consecutive adsorption-desorption processes, the semi-IPN hydrogel with 20 wt% GE may reach 85.26% of its initial adsorption capacity. In addition, the adsorbed Pb(II) can be quantitatively recovered by simply eluting the hydrogel with dilute HNO3 solution, and a recovery ratio of 89.27% was reached for the semi-IPN hydrogel. The satisfactory adsorption amount is mainly derived from the chelating of functional groups (i.e. –COO? and –NH2) with Pb(II) ions. The hydrogel adsorbents exhibited excellent affinity for Pb(II), and can be applied to treat wastewater containing heavy metal ion and simultaneously recover the valuable metal sources. 相似文献
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在利用半胱氨酸修饰赖氨酸环二肽制备对称性四肽的过程中, 通过两种脱除Trt(三苯甲基)的方法分别得到含有Fmoc(芴甲氧羰基)的非环与大环四肽产物, 其结构得到了核磁、质谱、红外、元素分析等证实。 它们能使多种有机溶剂凝胶化, 且具有热可逆性, 由扫描电子显微镜(SEM)可观察到凝胶内部均为三维网络结构。 在体积分数低至0.1%的含氯有机溶剂/水两相体系中, 它们依然可以进行选择性凝胶化。 此外, 该有机凝胶干胶由于内部微纳米网络结构以及Fmoc基团的存在, 可以直接从水溶液中吸收多种染料分子, 且吸附能力随温度的升高而提高。 相似文献