Sorption performance of light rare earth elements using zirconium titanate and polyacrylonitrile zirconium titanate ion exchangers

Lanthanum, cerium, neodymium, and samarium were sorption from aqueous solutions using zirconium titanate (ZrTi) and polyacrylonitrile zirconium titanate (PANZrTi) ion exchangers. The characterizations of prepared materials were performed using XRD, SEM, FTIR, TGA, and DTA techniques. The sorption behavior of various ions toward synthesized resin has been studied depending on reaction temperatures, pH values, and initial concentrations. The selectivity order found is Sm³⁺?>?Nd³⁺?>?Ce³⁺?>?La³⁺ on ZrTi-100, Ce³⁺?>?Sm³⁺?≈?Nd³⁺?>?La³⁺ on ZrTi-150, and Sm³⁺?≈?Ce³⁺?>?Nd³⁺?>?La³⁺ on PANZrTi depending on the condition of prepared ZrTi samples. The K_d for lanthanide ions was slightly decreased with temperature increased, which indicated the exothermic nature. The sorption data obtained for equilibrium conditions have been analyzed using the different isotherm models, and the applicability of these isotherm equations was compared by the correlation coefficients, R². It was established that the equilibrium isotherm models’ applicability follows the order: Langmuir?>?Dubinin– Radushkevich?>?Freundlich. It is found the Ce³⁺ has high adsorption capacity on each of ZrTi-100 and ZrTi-150, while Nd³⁺ has high adsorption capacity on PANZrTi.     

小分子烷烃在TON沸石上吸附性能

 采用蒙特卡罗(Monte Carlo)方法模拟计算了甲烷、乙烷和丙烷在TON沸石上的吸附等温线,计算结果与实验结果吻合较好。在此基础上,模拟了甲烷、乙烷和丙烷在TON中的吸附位、吸附能以及混合气体的吸附等温线。结果表明,3种短链烷烃在TON沸石的吸附位均在TON沸石的10-元氧环中。在273K时,丙烷在TON上的吸附能绝对值远大于甲烷和乙烷;在773K时,3种气体的吸附能绝对值相同。3种气体吸附能绝对值几乎均小于100 kJ/mol,说明它们在TON上的吸附是物理吸附。了解单组分气体以及混合气体在TON沸石上的吸附特性,对应用TON沸石分离气体的技术提供了有益参考。     

交联壳聚糖对酸性红B的吸附研究

实验以壳聚糖为原料,在碱性条件下以环氧氯丙烷对壳聚糖进行了化学改性,制得不溶于水的交联壳聚糖。研究了交联壳聚糖对偶氮染料酸性红B的吸附平衡规律,探讨了交联壳聚糖对酸性红B的吸附动力学规律以及初始浓度、pH值对吸附的影响,并且与壳聚糖在相同条件下做了对比实验。结果表明:交联壳聚糖对酸性红B的吸附性能优于壳聚糖。其吸附规律符合Langmuir吸附等温式,最大吸附容量为227.27 mg/g;其吸附动力学模型可以用准二级速率方程来描述,准二级动力学常数为4.06×10~(-4)g/(mg·min)。     

聚醚型螯合树脂的合成及其等温吸附性能

通过接枝反应制备了一系列以聚环氧氯丙烷为主链,侧链末端含吡咯配位基的HPnCP(n=6,4,2)螯合树脂,各步产物的化学结构经IR和1H NMR检测得以确认。静态吸附实验及等温吸附实验结果表明:该类树脂对Cu(Ⅱ)和Hg(Ⅱ)有着较好的吸附性能(大于1.0mmol/g);对Co(Ⅱ)和Cd(Ⅱ)达到饱和吸附时的平衡浓度约为0.06～0.07mol/l;HP_4CP对Co(Ⅱ)和Cd(Ⅱ)以及HP_2CP对Co(Ⅱ)的等温吸附既可用Langmuir方程描述也可用Freundlich方程描述;但HP_2CP对Cd(Ⅱ)的等温吸附不符合Langmuir方程,只可用Freundlich方程描述。     

电凝聚降低造纸工业废水的COD浓度并脱色

电凝聚是一种有效地处理制浆造纸工业废水的技术。对于处理制浆造纸工业废水的一些影响因素如电解时间、应用的电流辙、电解PH值及有利于提高电解效率的因素一直都研究着。从现在的实验结果可以看到,使用电凝聚处理废水的效果非常显著。有记录显示的低碳钢电极和铝电极最大的脱色率分别达到92％和84‰COD去除率分别为95％和89％。实验也指出用序列间歇反应器[Sequential Batch Reactor（SBR）]与电凝聚联合能增加生物降解能力,从而提高生物化学处理效率。电凝聚是用吸附等温线形式模拟,实验发现与朗缪尔（Langmuir）和雷德克一普劳斯尼茨（B＆dke-Prausnitz）预测的等温线模型完全匹配。     

Performance of TX-100 and TX-114 for the separation of chrysoidine dye using cloud point extraction

Cloud point extraction (CPE) is carried out to extract chrysoidine dye from aqueous solution using two different non-ionic surfactants, TX-100 and TX-114. The effects of different operating parameters, e.g., concentrations of surfactant, dye and salt, temperature, pH on extraction of both dye and surfactant have been studied in detail. The extraction of dye increases with temperature, surfactant concentration and salt concentration. Various design parameters of a CPE process have been estimated by developing correlations for dye solubilization and fractional coacervate phase volume with the operating conditions. The equilibrium solubilization data at four different temperatures follow Langmuir type isotherm. A method is presented to calculate the feed surfactant concentration required for the removal of dyes up to a level of 3.82x10(-6) M. The developed correlations may be useful to design a cloud point extractor of a desired efficiency.     

A comparison of low-cost biosorbents and commercial sorbents for the removal of copper from aqueous media

Three biosorbents, crab carapace, the macroalgae Fucus vesiculosus and peat were compared with two commercial materials, an activated-carbon and an ion-exchange resin for the removal of copper from aqueous media. Kinetic models of Lagergren first-order, pseudo-second order and intraparticular diffusion were used to model the data. The process for all materials is best represented by the pseudo-second order rate model. Langmuir and Freundlich isotherms were used to describe the sorption equilibrium data. Maximum uptake values were 79.4, 114.9 and 71.4 mg g(-1) for crab carapace, F. vesiculosus and ion-exchange resin, respectively. Langmuir and Freundlich isotherm models could not be fitted to the experimental data for peat and activated-carbon. Ion-exchange was calculated to contribute approximately 75%, 77% and 44% to the total biosorption by crab carapace, F. vesiculosus and peat, respectively. The removal efficiencies of crab carapace and F. vesiculosus were >95% and comparable with those achieved using ion-exchange resin. Results from this study suggest that both crab carapace and F. vesiculosus are efficient and effective biosorbent materials for the removal of copper from aqueous solutions and given that they are also low-cost, may be considered viable alternatives to activated-carbon and ion-exchange resin.     

硫酸钙处理含磷废水特性研究

研究工业石膏的主要成分硫酸钙对含磷废水的处理特性.讨论了废水pH、磷的初始含量、处理时间、投加量等参数对处理的影响,并对吸附等温特性进行了探讨.结果表明,硫酸钙对含磷废水具有良好的吸附作用,等温吸附特征与Langmuir方程和Temkin方程比较吻合,其吸附性能在碱性条件下较佳,初始含量对吸附影响明显,吸附规律为随着含量的增加,磷去除率逐渐减小,在磷的初始质量浓度低于20mg·L-1时,去除效果较好,可达到95%以上;随着吸附剂投加量的增加,磷去除率逐渐增大,而吸附容量逐渐减小.     

Removal of basic dyes from aqueous solutions using natural clay

Adsorption properties of natural clay (from Eski?ehir of Turkey) were investigated by depending on different adsorption conditions such as different initial dye concentrations and contact times. The chemical composition of the natural clay was analyzed by X-ray fluorescence spectrometry (XRF). The removal of basic dyes such as Nile Blue (NB) and Brilliant Cresyl Blue (BCB) from aqueous solutions using natural clay in this study was described. After the equilibrium adsorption time of 8 h, the adsorption capacities for NB and BCB reach about 25 mg/g and 42 mg/g, respectively. Lagergren kinetic equation was used to test the experimental data to examine the controlling mechanism of adsorption processes. Adsorption data of the BCB and NB onto natural clay were fitted well by the pseudo-first-order model. The adsorption isotherms data were correlated with the Freundlich equation and the Freundlich constants K_f (mg/g) and n (intensity of adsorption) were calculated. The r² (regression coefficients) values were 0.9835 and 0.9849 for NB and BCB, respectively. The adsorption capacities of natural clay for NB and BCB have the following order: BCB > NB.     

脱除硫酸锰溶液中杂质镁的研究

分别采用重结晶法和氟化沉淀法脱除硫酸锰溶液中的杂质镁。用Pitzer热力学模型对二元系MgSO4-H2O、MnSO4-H2O和三元系MgSO4-MnSO4-H2O的溶解度相图进行模拟预测,并结合溶解度相图对三元系的固溶体用重结晶法验证其分配比。同时采用氟化沉淀法进行对比试验。结果表明,由于固定分配比,重结晶法对镁锰分离作用十分有限,而加入MgF2晶种的氟化沉淀除镁新方法能够有效提高氟化沉淀法的效率,在95℃下,加入0.3g氟化镁晶种和250%理论用量的NH4F搅拌1h,能使镁的除去率达到94.3%。