Adsorption thermodynamics and kinetic investigation of aromatic amphoteric compounds onto different polymeric adsorbents

The adsorption behavior ofp-aminobenzoic acid and o-aminobenzoic acid onto the different polymeric adsorbents was systematically investigated as a function of the solution concentration and temperature. Experimental results indicated that the equilibrium adsorption data of the four polymeric adsorbents fitted well in the Freundlich isotherm. The adsorption capacity of multi-functional polymeric adsorbent NJ-99 was the highest, which might be attributed to the strong hydrogen-bonding interaction between the amino groups on the resin and the carboxyl group of aminobenzoic acid. The adsorption capacity of o-aminobenzoic acid onto any adsorbent was higher than p-aminobenzoic acid. Thermodynamic studies suggested the exothermic, spontaneous physical adsorption process. Adsorption kinetics results showed that the adsorption followed the pseudo-second-order kinetics model and the intraparticle mass transfer process was the rate-controlling step.

Divalent nitrogen-rich cationic salts with great gas production capacities

Monocyclic nitrogen-rich 3-(aminomethyl)-4,5-diamine-1,2,4-triazole(1)and fused cyclic 3,7-diamine-6-(aminomethyl)-[1,2,4]triazolo[4,3-b][1,2,4]triazole(9)were synthesized through the convenient cyclization reaction from the readily available reactant.Their energetic salts with high nitrogen content were proved to be rare examples of divalent monocyclic/fused cyclic cationic salts according to the single crystal analyses.The structure of intermediate B was also identified and verified by its trivalent cation crystal 17.5H_2O indirectly.Energetic compounds 2-8 and 10-17 were fully characterized by NMR spectroscopy,infrared spectroscopy,differential scanning calorimetry,elemental analysis.These energetic salts exhibit good thermal stability with decomposition temperatures ranged from 182℃to 245℃.The sensitivity of compounds 2,6,10 and 14 is similar or superior to that of RDX while the others were much more insensitive to mechanical stimulate.Furthermore,detonation velocity of 10(8843 m/s)surpass that of RDX(D=8795 m/s).Considering the high gas production volume(≥808 L/kg)of 2,4,10and 12,constant-volume combustion experiments were conduct to evaluate their gas production capacities specifically.These compounds possess much higher maximum gas-production pressures(P_(max):7.88-10.08 MPa)than the commonly used reagent guanidine nitrate(GN:P_(max)=4.20 MPa),which indicate their strong gas production capacity.

Effect of cationic monomer structure on the aggregation behavior of amphoteric acrylic polymer around isoelectric point

Amphoteric polymer can be used as retanning agent in leather manufacture.It is particularly useful in chrome-free tanning systems since it can regulate the charge properties of chrome-free leather and enhance the fixation of anionic post-tanning chemicals in leather.However,the aggregation and precipitation of amphoteric polymer retanning agents around the isoelectric point(pl)hinder their wide application.Herein,we synthesized five amphoteric acrylic polymers(AAPs)by free radical copolymerization with acrylic acid and five different cationic acrylic monomers.The effect of cationic monomer structure on the aggregation behavior of AAPs was investigated.The aggregation of AAPs in aqueous solution showed pH and concentration dependence.Light scattering analysis showed that Poly(AAA-co-MAPTAC)and Poly(AA-co-DMAPMA)were in the shape of coiled linear flexible chains with small particle size(R_(g)7.6 nm and 14.8 nm,respectively)near the pl.However,Poly(AA-co-DAC),Poly(AA-co-DMC)and Poly(AA-co-DMAEMA)were in the shape of hollow spheres and exhibited serious aggregation.Quantum chemical calculations suggested that the amide groups in the cationic monomers MAPTAC and DMAPMA enhanced the nucleophilicity of AAPs.Thus the corresponding AAPs could carry a large number of cationic charges to slow their aggregation when the pH just climbed over the pl.The results are expected to provide theoretical reference for the synthesis and wide-spread application of AAPs.

Decomposition of a β-O-4 lignin model compound over solid Cs-substituted polyoxometalates in anhydrous ethanol: acidity or redox property dependence?

Production o f aromatics from lignin has attracted much attention. Because of the coexistence of C-O and C-C bonds and their complex combinations in the lignin macromolecular network, a plausible roadmap for developing a lignin catalytic decomposition process could be developed by exploring the transformation mechanisms of various model compounds. Herein, decomposition of a lignin model compound, 2-phenoxyacetophenone （2-PAP）, was investigated over several ce-sium-exchanged polyoxometalate （Cs-POM） catalysts. Decomposition of 2-PAP can follow two dif-ferent mechanisms： an active hydrogen transfer mechanism or an oxonium cation mechanism. The mechanism for most reactions depends on the competition between the acidity and redox proper-ties of the catalysts. The catalysts of POMs perform the following functions： promoting active hy-drogen liberated from ethanol and causing formation of and then temporarily stabilizing oxonium cations from 2-PAP. The use of Cs-PMo, which with strong redox ability, enhances hydrogen libera-tion and promotes liberated hydrogen transfer to the reaction intermediates. As a consequence, complete conversion of 2-PAP （〉99%） with excellent selectivities to the desired products （98.6% for phenol and 91.1% for acetophenone） can be achieved.

两性纤维素多孔凝胶球的制备及其动态吸附性能

用于废水处理的多孔凝胶球存在制备工艺繁琐,吸附种类单一,吸附效率低等不足;为提高多孔凝胶球的性能,采用滴入相分离、酯化反应引入羧基及希夫碱反应引入氨基的化学改性方法,制备得到兼具高孔隙率、高力学性能和羧基/氨基活性基团的两性纤维素多孔凝胶球(ACM),并构建动态吸附柱装置以探究不同条件下ACM对染料的动态吸附性能。结果表明:通过降低染料初始质量浓度,增加填料高度和减慢进液流速的方式可有效提高吸附柱的动态吸附效率;0.8 g的ACM可处理7.5 L含染料的废水;对ACM的动态吸附过程进行动态模型拟合,其与Thomas和Yoon-Nelson模型的拟合程度高,表明吸附是均匀表面的单分子层吸附,动态吸附过程中存在2个或多个速率控制步骤,内部扩散和外部扩散均不是吸附过程中的限速步骤。基于ACM优异的分级孔结构、丰富的活性位点和低传质阻力等优势,认为ACM展现出良好的动态吸附性能,在印染废水处理方面有较大应用潜力。

河北省某钼尾矿土壤化改良及种植实验研究

以河北省某钼尾矿为研究对象,采用低成本添加剂与机械混合方法对钼尾矿进行土壤化改良。针对钼尾矿的保水性、酸碱性及阳离子交换能力,开展了单因素改良实验及复合改良实验。结果表明,利用农家肥、蒙脱土、聚丙烯酰胺及柠檬酸复合改良剂对钼尾矿进行改良,钼尾矿的饱和吸水率提高至61.1%,水分挥发速率和渗滤速率明显降低;阳离子交换能力达到了10.15 cmol/kg,pH值降低至8.08,达到了适宜种植的水平。此外,通过盆栽实验验证了复合改良后钼尾矿的植物生长效应,与原始钼尾矿相比,复合改良后钼尾矿中的小白菜生长状态良好,植株的高度和质量分别提高了77.4%和98.1%。经过15 d的小白菜种植后,改良钼尾矿的保水性、pH值及阳离子交换能力达到了正常土壤的水平,实现了钼尾矿向可种植土壤的转化。

Effect of background electrolytes on the adsorption of nitroaromatic compounds onto bentonite

To further elucidate interaction of nitroaromatic compounds with mineral surface, the sorption of m-dinitrobenzene （m-DNB） and nitrobenzene to original bentonite in aqueous solution containing different electrolytes （i.e., KCl, NH4Cl, CaCl2 and Tetramethylammonium bromide （TMAB）） was studied. The sorption of m-DNB was greatly enhanced with the presence of KCl and NH4Cl, while little influence was observed with CaCl2 and TMAB, following the order of KCl 〉 NH4Cl 〉〉 TMAB, CaCl2, or DI water. For nitrobenzene, sorption enhancement only occurred at high nitrobenzene concentrations in the presence of KCl, and the solute equilibrium concentration at inflexion point was lowered with increasing KCl concentration. These sorption enhancements were significantly promoted with the increase of electrolyte concentration. The salting-out effect is insufficient to account for the sorption enhancement by original bentonite with increasing KCI or NH4Cl concentration. X-ray diffraction patterns of bentonite suspensions indicated that the sorption enhancement of m-DNB was attributed to the intercalation of K^＋ or NH4^＋ into bentonite interlayer and then dehydration with m-DNB to form inner-sphere complexes, which caused previously expanded bentonite interlayers to collapse in aqueous suspension, thus further enhanced the interaction of phenyl with siloxane surface. In comparison, the sorption enhancement of NB is attributed to the formation of outer-sphere complexes with K^＋ at high solute-loadings （〉 20（0-400 mg/kg）. The sorption of m-DNB to initially modified TMA^＋-bentonite and K^＋-bentonite was almost the same as respective sorption to original bentonite in solution containing TMA^＋ and K^＋.

Effect of cationic monomer structure on the aggregation behavior of amphoteric acrylic polymer around isoelectric point

Amphoteric polymer can be used as retanning agent in leather manufacture. It is particularly useful in chrome-free tanning systems since it can regulate the charge properties of chrome-free leather and enhance the fixation of anionic post-tanning chemicals in leather. However, the aggregation and precipitation of amphoteric polymer retanning agents around the isoelectric point (pI) hinder their wide application. Herein, we synthesized five amphoteric acrylic polymers (AAPs) by free radical copolymerization with acrylic acid and five different cationic acrylic monomers. The effect of cationic monomer structure on the aggregation behavior of AAPs was investigated. The aggregation of AAPs in aqueous solution showed pH and concentration dependence. Light scattering analysis showed that Poly (AA-co-MAPTAC) and Poly (AA-co-DMAPMA) were in the shape of coiled linear flexible chains with small particle size (Rg 7.6 nm and 14.8 nm, respectively) near the pI. However, Poly (AA-co-DAC), Poly (AA-co-DMC) and Poly (AA-co- DMAEMA) were in the shape of hollow spheres and exhibited serious aggregation. Quantum chemical calculations suggested that the amide groups in the cationic monomers MAPTAC and DMAPMA enhanced the nucleophilicity of AAPs. Thus the corresponding AAPs could carry a large number of cationic charges to slow their aggregation when the pH just climbed over the pI. The results are expected to provide theoretical reference for the synthesis and widespread application of AAPs.

Two Polymorphs of the Inclusion Compound [(n-C_4H_9)_4N]^+·(C_(13)H_9O_3)^-·H_2O

Two polymorphs of the inclusion compound [（n-C4H9）4N]＋＇（C13H903）H2O have been prepared and characterized by X-ray crystallography. Polymorph 1： triclinic P1, a = 13.4982（2）, b = 13.5743（2）, c = 17.1996（2） A, at = 67.045（1）,β = 77.845（1）, γ= 88.762（1）°, V = 2830.43（7） A3, Z = 4, R = 0.0491, wR= 0.1276; Polymorph 2： tetragonal P43, a = b = 13.53690（1） A, c = 30.8491（8） A, V = 5653.02（16） A3, Z = 8, R = 0.0448, wR = 0.0984. In these two crystal structures, the hydrogen-bonded ribbons built of 4,4＇-dihydroxybenzophenone （DHBP, C13H1003） anions and water molecules are orderly arranged to generate two-dimensional host layers, with tetrabutylammonium cations contained between the layers to form the sandwich-like inclusion compounds. The structures of 1 and 2, which exist as two polymorphs, both display the similar packing pattern and hydrogen-bond linking model.

聚醚废浓缩液中固体悬浮物的复合絮凝去除

采用复合絮凝法处理聚醚废浓缩液,考察了絮凝剂种类、复配比、水力条件等因素对絮凝效果的影响,并探讨了絮凝剂与固体悬浮物的作用机制。实验结果表明:与单独使用聚合氯化铝(PAC)和阳离子型聚丙烯酰胺(CPAM)相比,二者复配使用时可得到更高的浊度去除率和液体回收率;在PAC与CPAM的复配比(质量比)10.0∶1、絮凝剂总用量600 mg/L、先加PAC后加CPAM、慢速搅拌转速60 r/min、慢速搅拌时间15 min、沉淀时间1.5 h的最佳絮凝条件下,浊度去除率高达97.36%,上清液固体悬浮物质量浓度降至34.82 mg/L,液体回收率为95.20%。絮体的微观结构和Zeta电位分析表明:PAC和CPAM复配使用时,形成的絮团粒径大,密实性高,在黏度较大的聚醚废浓缩液中沉降性好,且形成的沉淀层紧密。

Thixotropy of Aqueous Suspensions Containing Mg-AI Hydrotalcite-like Compound and Low-substituted Cationic Starch： Comparison between Oscillatory Shear and Thixotropic Loop Measurements

The rheological properties of aqueous suspensions consisting of positively charged aluminum magnesium hydrotalcite-like compound （HTlc） and low-substituted cationic starch （LCS） were investigated. Special emphasis was placed on the thixotropic phenomenon. Thixotropic behavior was investigated by two thixotropic methods： thixotropic loop and oscillatory shear measurements. LCS molecules could be adsorbed onto HTlc particles due to the hydrogen bonding between ether groups or hydroxyl groups of LCS and hydroxyl groups of HTlc. The elastic dynamic response of the HTlc/LCS suspension increased with increasing mass ratio （R） of HTlc and a three-dimensional network structure could be formed in the suspension with higher R value. The thixotropic type of the HTlc/LCS suspension transformed from negative to positive and then to complex thixotropy when R changed from 0 to 0.5. By comparing between the thixotropic results obtained by thixotropic loop and oscillatory shear measurements, it was validated that the thixotropic loop for the suspension showing complex thixotropy had a crossover point.

牛仔经纱阳离子复配改性工艺优化及染色效果分析

基于目前牛仔纱靛蓝上染的生产情况,选择阳离子改性剂提高棉纱线与靛蓝染料的亲和性,提高上染率和匀染率。选用分子量不同的两种改性剂CHPTAC(3-氯-2-羟丙基三甲基氯化铵)和聚环氧氯丙烷二甲胺进行复配改性,利用单因子试验探究单独使用两种改性剂的改性剂质量浓度、NaOH质量浓度、渗透剂ZD质量浓度、温度对改性效果的影响;利用正交试验探究最佳复配改性工艺;利用Minitab建立二次回归模型响应预测;最后对复配改性染色效果进行分析。结果表明:两种改性剂单独使用时,CHPTAC匀染效果优良,聚环氧氯丙烷二甲胺增深效果显著;将两者复配改性,最优复配比例1∶4,氢氧化钠质量浓度2 g/L,渗透剂ZD质量浓度为3 g/L;采用复配改性工艺,以染纱10000 m测算,合计节约用水约14 t,节电约53.33 kW;通过10组实验验证Minitab建立的二次回归响应预测模型,结果均在预测区间内,较能反映实际情况。对改性前后棉纱线的上染效果(色光、耐摩擦色牢度、染料分布)分析可知,改性剂不会对染色色光造成影响;复配改性上染棉纱线的耐干湿摩擦色牢度下降0.5级;改性后棉纱线表面染色深度增加,其中复配改性上染棉纱线深度最大,且纵向色深分布均匀,无露白情况,染料渗透效果得当。

阳离子淀粉-聚硅酸复合絮凝剂制备及污水处理性能

针对传统无机絮凝剂投药量大、絮凝效果不佳的问题,提出一种高效的阳离子淀粉-聚硅酸复合絮凝剂的制备,并对其絮凝性能进行测试。实验结果表明,絮凝剂优化配比为:水溶剂用量为10m L,3-氯2-羟丙基三甲基氯化铵(CHPTMA)用量为4m L,紫外光强度为32.5m W·cm^(-2),阳离子改性淀粉与聚硅酸的质量比为4∶2,紫外光引发时间为2h,m_(阳离子改性淀粉)∶m_(醚化剂)=4∶4.5,醚化3h。以此条件制备的复合絮凝剂在投加量为5mg·L^(-1)时对污水除浊效果最好,除浊率达到了98.6%。

两性淀粉的制备及性能

选用三聚磷酸钠作为磷酸化试剂与阳离子淀粉干热反应制备两性淀粉，用正交试验方法研究了磷酸化试剂用量、ｐＨ、反应温度、反应时间及其它因素对阴离子取代度和反应效率的影响，并对两性淀粉结合磷含量、阴离子对阳离子基团比率、粘度、电导率和Ｚｅｔａ电位进行测试．结果表明，在同一淀粉分子链上接上阳、阴两种离子基因是可能的．在影响合成反应的诸因素中，磷酸化试剂用量最重要．加入１％的尿素可大大提高阴离子取代度和反应效率．阴离子对阳离子基团比率与两性淀粉表面活性密切相关．

两性-阳离子复配修饰塿土对苯酚的吸附

研究了采用两性表面修饰剂十二烷基二甲基甜菜碱(BS-12)和阳离子表面修饰剂十六烷基三甲基溴化铵(CTMAB)复配修饰塿土后对苯酚的吸附反应和热力学特征,并探讨其吸附机理.结果表明,复配修饰后的土样对苯酚的吸附能力明显增强.20℃时表现为CK(原土)<50BS(50%BS-12)<100BS(100%BS-12)<50BS+25CT(50%BS-12+25%CTMAB)<100BS+25CT(100%BS-12+25%CTMAB)<50BS+50CT(50%BS-12+50%CTMAB)<100BS+50CT(100%BS-12+50%CTMAB),40℃时表现为CK(原土)<50BS(50%BS-12)<100BS(100%BS-12)<50BS+25CT(50%BS-12+25%CTMAB)<50BS+50CT(50%BS-12+50%CTMAB)<100BS+25CT(100%BS-12+25%CTMAB)<100BS+50CT(100%BS-12+50%CTMAB).其吸附等温线可用Henry模型描述.供试土样对苯酚的吸附呈现放热焓减反应特征,属于焓减控制的自发性过程.

BS-CTMAB复配修饰膨润土对苯酚的吸附

采用两性表面修饰剂十二烷基二甲基甜菜碱（BS-12）和阳离子表面修饰剂十六烷基三甲基溴化铵（CTMAB）复配修饰膨润土，通过批处理法研究了不同修饰比例、温度、pH和离子强度等条件下，复配修饰膨润土对苯酚的吸附规律和热力学特征，并探讨了其吸附机制。结果表明，CTMAB复配修饰显著增强了两性修饰膨润土对苯酚的吸附能力，30℃时吸附量呈现100BS＋100CT（100％BS-12＋100％CTMAB）〉100BS＋50CT（100％BS-12＋50％CTMAB）〉50BS＋100CT（50％BS-12＋100％CTMAB）〉100BS＋150CT（100％BS-12＋150％CTMAB）〉50BS＋50CT（50％BS-12＋50％CTMAB）〉100BS＋25CT（100％BS-12＋25％CTMAB）〉50BS＋150CT（50％BS-12＋150％CTMAB）〉50BS＋25CT（50％BS-12＋25％CTMAB）〉100BS（100％BS-12）〉50BS（50％BS-12）〉CK（原土）的顺序。当CTMAB复配修饰比例在0~100％CEC时，两性复配修饰土样对苯酚的吸附量随着修饰比例的增大而升高，而在100％~150％CEC阶段，吸附量则随CTMAB修饰比例的增大有所降低；修饰土样对苯酚吸附量随着温度、pH的升高而降低，在低浓度范围内，随着离子强度的增大而升高。Henry模型适用于描述苯酚在供试土样的吸附，供试土样对苯酚的吸附属于自发的物理吸附过程，吸附呈现焓减、熵增特征。

两性聚丙烯酰胺的制备及其絮凝性能

开发了一种对非离子聚丙烯酰胺进行改性制备两性聚丙烯酰胺(APAM)絮凝剂的新方法。以硅藻土悬浮液为絮凝对象,考察了改性反应中影响APAM絮凝效果的因素。结果表明,采用无水乙酸与三甲胺、环氧氯丙烷合成季胺盐型阳离子剂的方法优于采用盐酸的方法;在10mL质量分数为10%、相对分子质量为3×106的非离子型聚丙烯酰胺水溶液中加入8mL浓度为2.6mol/L的阳离子剂,同时控制V(NaOH)∶V(NaClO)为0.44,改性得到的APAM絮凝性能最佳,在pH3～9的较宽范围内对硅藻土悬浮液有较好的絮凝效果。在pH为3、APAM加入量为1.8mg/L时,硅藻土悬浮液的絮凝率可达100%。

淀粉基两性天然高分子改性絮凝剂的合成

以淀粉-丙烯酰胺接枝共聚物为原料,通过Mannich反应和水解反应,合成了同时具有阴、阳离子基团的两性高分子絮凝剂.最佳反应条件为:接枝物、甲醛与二甲胺的摩尔配比为1∶1.1∶1.5,接枝物浓度在2.5%,胺甲基反应温度50℃,反应时间2.5h,阳离子度达50%以上;碳酸钠与氢氧化钠的质量比为1.4∶1,水解剂与接枝物的摩尔配比为1∶1,水解温度为65℃,水解时间3h,阴离子度达23%以上.产物对印染和造纸污水的浊度和化学耗氧量(COD)去除率优于部分水解聚丙烯酰胺(HPAM).

CTMAB对BS-12修饰膨润土的复配修饰模式

研究了十六烷基三甲基溴化铵(CTMA)在十二烷基二甲基甜菜碱(BS-12)修饰膨润土表面的复配模式,通过BS-12膨润土表面Ca2+/2和CTMA总浓度(SCC)变化及20℃和40℃条件下CTMA吸附量的变化可知:存在离子交换和疏水键合模式。CTMA在25%、50%、100%BS-12修饰(25BS、50BS和100BS)膨润土表面出现疏水键的临界比例(RC)分别为20.30%、11.56%和2.00%,且疏水比例随CTMA复配比例(R)及其摩尔分数的增大而增大,疏水键合模式占绝对优势的临界比例(RC′)分别为200%、150%和100%。对于BS-12单一修饰及BS-12+CTMA复配修饰比例之和,50%及200%分别是膨润土表面出现疏水键合及其占绝对优势的转折点。R<RC,离子交换模式;RC≤R≤RC′,离子交换与疏水键合共存;R>RC′,疏水键合占绝对优势。RC、RC′及CTMA最大吸附量(qm)呈现25BS>50BS>100BS特点,升温使qm减小。

离子型层状化合物制备及应用研究

简单介绍离子型和非离子型两类层状化合物的结构和性能,重点概括了以 LDH为代表的阴离子型层状化合物和以α 磷酸盐为代表的阳离子型层状化合物的制备以及研究进展。