用丙二醇碳酸酯对膨润土进行活化的研究

膨润土及其产品GCL正广泛应用于城市垃圾填埋场的防渗系统中。但是膨润土的膨胀性能在成分复杂的液体(如渗滤液)中会大幅下降，从而直接影响防渗效果。在分析中，利用丙二醇碳酸酯对钠基膨润土进行活化，提高其耐化学性，并分析了其性能改善的机理。     

改性膨润土作为垃圾渗透液防渗层的实验研究

本文以天然钠基膨润土为原料，采用水溶液聚合法，在室温条件下，通过改性聚丙烯酰胺对膨润土进行直接插层改性，制备了一种新型聚丙烯酰胺改性膨润土防渗材料。以此防渗材料作为防渗层，选用沈阳大辛填埋场的垃圾渗透液为处理对象，在动态实验下，就其对实际垃圾渗滤液中主要污染物去除的有效性和控制垃圾渗滤液渗透的可行性进行研究。抗渗性能测试结果表明，改性膨润土防渗性能较好，渗透系数为1．0×10^-7cm/s，达到固体废物填埋场的防渗材料国家标准1．0×10^-7cm／s的使用要求。改性膨润土防渗层对COD、氨氮、重金属离子去除效果较好，吸附作用较强，COD和氨氮最大去除率分别达到81％和91％，TFe、Zn^2＋和TCr的最大去除率分别达到71％、58％和73％。实验结果验证了本研究所制备的改性膨润土防渗材料具有优良的抗渗、截污性能。     

成型膨润土和钛柱撑膨润土对水中Pb2+和氯乙酸吸附及再生

针对水中微量铅离子和氯乙酸的脱除,考察了成型膨润土及成型钛柱撑膨润土的吸附性能,得出对铅离子的吸附,成型膨润土、成型钛柱撑膨润土与粉末状活性炭性能相当,而对氯乙酸的吸附前两者要比粉末状活性炭低好多.确定了成型膨润土吸附氯乙酸后可用沸水煮沸30 min的方法再生,成型钛柱撑膨润土吸附氯乙酸后,可用500℃焙烧3 h的方法再生,再生的膨润土循环使用3次后性能降低明显.此外,还测得了成型的膨润土及成型的钛柱撑膨润土吸附铅离子和氯乙酸的等温线,计算出其对铅的最大吸附量分别为24.33 mg/g和15.47 mg/g.     

成型膨润土和钛柱撑膨润土对水中Pb2+和氯乙酸吸附及再生

针对水中微量铅离子和氯乙酸的脱除，考察了成型膨润土及成型钛柱撑膨润土的吸附性能，得出对铅离子的吸附，成型膨润土、成型钛柱撑膨润土与粉末状活性炭性能相当，而对氯乙酸的吸附前两者要比粉末状活性炭低好多。确定了成型膨润土吸附氯乙酸后可用沸水煮沸30 min的方法再生，成型钛柱撑膨润土吸附氯乙酸后，可用500℃焙烧3 h的方法再生，再生的膨润土循环使用3次后性能降低明显。此外，还测得了成型的膨润土及成型的钛柱撑膨润土吸附铅离子和氯乙酸的等温线，计算出其对铅的最大吸附量分别为24.33 mg/g和15.47 mg/g。     

改性土-膨润土阻隔墙阻控离子型稀土矿氨氮污染

以土-膨润土为阻隔材料,使用硅灰及水泥对其进行固化改性,研究改性后阻隔墙对离子型稀土矿原地浸矿氨氮污染的阻控效果。通过了解阻隔墙材料的渗透性能、力学性能,并结合阻隔材料对氨氮的吸附效果、穿透效果和数值模拟结果,探讨改性土-膨润土阻隔材料对氨氮污染的阻控性能。结果表明:硅灰改性土-膨润土阻隔材料,最佳质量配比为硅灰∶土=1∶10,最佳含水率为67.80%;改性阻隔材料生成的铝硅酸盐提高了阻隔墙防渗性能,渗透系数为2.36×10~(-9) m·s~(-1);CaCO_3提高了材料的力学性能,使抗压强度达到0.896 MPa;改性阻隔材料对氨氮的吸附过程符合准二级动力学模型及Langmuir等温模型。这说明该吸附过程以化学吸附为主,并且该吸附是放热过程。在不同氨氮浓度的穿透下,渗透系数呈逐渐减小的趋势,实验期间并未达到穿透浓度。利用Visual MODFLOW数值模型对阻隔墙的阻控效果进行模拟发现,7 300 d后NH_4~+扩散范围小,未穿透阻隔墙。硅灰改性土-膨润土阻隔墙用于对离子型稀土矿氨氮污染阻控的效果较好。     

巯基化改性膨润土对重金属的吸附性能

以钙基膨润土为基本材料,制备了巯基化改性膨润土,并对比研究了此材料与其他17种改性膨润土和原材料对重金属的吸附性能.结果表明,巯基化膨润土对镉的吸附能力显著优于其他材料,在本实验条件下,其对镉的吸附率高于其他材料30％以上,对镉的吸附量可达52.1 mg/g.巯基化膨润土对铅的吸附能力在重金属竞争吸附条件下优于其他材料,而其对镍的吸附能力在所有材料中处于中等水平;另外,巯基化膨润土对3种重金属的吸附受重金属竞争吸附影响较小.因此,在所研究的材料中,巯基化膨润土材料是一种最理想的重金属吸附材料.     

有机膨润土在废水处理中的应用及其进展

本文简单介绍了膨润土的基本性质，膨润土及改性膨润土在废水处理中的应用；重点综述了有机膨润土的制备方法，吸附水中有机物的性能、机理、规律及影响因素，有机膨润土在废水处理中的应用及其进展。     

不同膨润土对含镉废水的吸附性能

研究了不同投加量和吸附时间时,钠基膨润土、钙基膨润土和高胶质价钙基膨润土对含镉废水中Cd~(2+)的吸附特性。研究结果表明,在相同投加量时钙基膨润土对Cd~(2+)的吸附性能最佳,吸附可在30 min达到平衡。3种膨润土-Cd~(2+)吸附体系中,Freundlich模型对钠基膨润土-Cd~(2+)吸附体系的拟合较好。由膨润土对Cd~(2+)的吸附动力学可知,该吸附过程符合准二级动力学。     

CTAB改性膨润土制备及其对海洋溢油的吸附

利用室内吸附实验,以钙基膨润土和改性后的CTAB-膨润土为研究对象,研究了改性前后的膨润土在海洋环境条件下对石油的吸附性能。结果表明,CTAB已经成功地插层到钙基膨润土层间,使其表面形貌更加蓬松,层间距增大为2.04 nm,改性后膨润土由亲水性变为疏水性。改性前后的膨润土对海洋溢油的吸附率均随着膨润土浓度的增加及粒径的减小而增加,改性后膨润土的吸油率比改性前提高了13.1%,最高达到59.5%。临界颗粒物浓度为1 000 mg·L~(-1),最佳颗粒物粒径范围为100μm。CTAB-膨润土对委内瑞拉原油的吸附过程较好地符合准二级动力学模型和Freundlich吸附等温线模型,吸附的最佳时间为240 min,最佳温度为30℃,饱和吸附量约为526 mg·g~(-1)。改性前后的膨润土在海洋环境条件下对石油的吸附性能有明显变化,CTAB-膨润土对海洋溢油的吸附优势较为显著。     

酸性膨润土处理含重金属废水初探

比较了膨润土及酸性膨润土处理重金属离子的性能;着重探讨了酸性膨润土去除废水中铅、镉、镍、铜、铬、锌的适宜条件;将它用于电镀废水中重金属离子的处理,效果较好。     

Adsorption of phenol by bentonite

The potential of bentonite for phenol adsorption from aqueous solutions was studied. Batch kinetics and isotherm studies were carried out to evaluate the effect of contact time, initial concentration, pH, presence of solvent, and the desorption characteristics of bentonite. The adsorption of phenol increases with increasing initial phenol concentration and decreases with increasing the solution pH value. The adsorption process was significantly influenced by the solvent type in which phenol was dissolved. The affinity of phenol to bentonite in the presence of cyclohexane was greater than that in water and was lowest in the presence of methanol. Methanol was used to extract phenol from bentonite. The degree of extraction was dependent on the amount of phenol adsorbed by bentonite. X-ray diffraction analysis showed that the crystalline structure of bentonite was destroyed when cyclohexane was used. The ability of bentonite to adsorb phenol from cyclohexane decreased as the water to cyclohexane ratio was increased. Furthermore, hysteresis was observed in phenol desorption from bentonite in aqueous solutions. The equilibrium data in aqueous solutions was well represented by the Langmuir and Freundlich isotherm models. The removal of phenol from aqueous solutions was observed without surface modification.     

负载壳聚糖膨润土的制备及其吸附性能的影响

以天然膨润土和壳聚糖为原料，制得一种新型水处理剂——负载壳聚糖膨润土，研究了制备条件对酸性大红印染废水处理效果的影响。实验表明，当壳聚糖的浓度为30 g/L、膨润土质量与壳聚糖溶液体积之比为0.7、浸泡时间80 min、微烘时间15 min时，壳聚糖改性膨润土对酸性大红印染废水的脱色率可达97%。对改性土进行比表面积测定、电镜扫描及X-射线衍射等结构特性分析，证明壳聚糖的引入改变了膨润土在水中的分散状态，增强了其对污染物的吸附和离子交换能力。     

Sorption kinetics and isotherm modelling of imidacloprid on bentonite and organobentonites

Bentonite was modified by quaternary ammonium cations viz. cetytrimethylammonium (CTA), cetylpyridinium (CP), rioctylmethylammonium (TOM) and pcholine (PTC) at 100% cation exchange capacity of bentonite and was characterized by X-ray diffraction, CHNS elemental analyser and Fourier transform infrared spectroscopy. The sorption of imidacloprid on organobentonites/bentonite was studied by batch method. Normal bentonite could adsorb imidacloprid only upto 19.31–22.18% while all organobentonites except PTC bentonite (PTCB), enhanced its adsorption by three to four times. Highest adsorption was observed in case of TOM bentonite (TOMB) (76.94–83.16%). Adsorption kinetic data were fitted to pseudo-first-order, pseudo-second-order and intraparticle diffusion models. For normal bentonite data were best fitted to pseudo-first-order kinetic, while for organobentonites fitted to pseudo-second-order kinetics. Sorption data were analysed using Freundlich, Langmuir, Temkin and Dubinin–Radushkevich isotherm models. Data were well fitted to Freundlich adsorption isotherm. Product of Freundlich adsorption constant and heterogeneity parameter (K_f.1/n) was in following order: TOMB (301.87) > CTA bentonite (CTAB) (152.12) > CP bentonite (CPB) (92.58) > bentonite (27.25). Desorption study confirmed hysteresis and concentration dependence. The present study showed that the organobentonite could be a good sorbent for removal of imidacloprid from natural water sample also. Percentage adsorption and Distribution coefficient (mL g^?1) value of different adsorbent was in following order: TOMB (74.85% and 297.54) > CTAB (55.78% and 126.15) > CPB (45.81% and 84.55) > bentonite (10.65% and 11.92).     

羟基金属柱撑膨润土吸附氟的性能研究

将膨润土进行改性制得4种羟基金属柱撑膨润土,用XRD考察了层间结构,并将它们应用于含氟废水的吸附处理中,研究了各种吸附剂的吸附速率、介质的pH、吸附剂用量、饱和吸附曲线和吸附剂的重复使用性.结果表明,改性得到的羟基金属柱撑膨润土的层间距都明显变大,在实验条件下对氟离子的吸附性能为羟基铁铝复合柱撑膨润土>羟基铁柱撑膨润土>羟基铝柱撑膨润土.该类吸附剂对氟离子还具有较好的重复使用性.     

皂土对CuCl2的吸附性能

研究了CuCl2在荷结构负电荷皂土上的吸附性能,考察了pH、无机以及有机添加剂等因素的影响,并结合IR和XRD实验结果探讨了吸附机理。研究表明,皂土对CuCl2有很强的吸附能力,其吸附动力学和吸附等温线分别符合准二级速率方程和Langmuir方程。初始pH增大,吸附量增加。无机以及有机添加剂均能能明显抑制吸附。Cu2+在皂土上的吸附层在微观上可分为因化学键合作用而形成的内络合层和因静电作用而形成的外络合层。     

皂土对CuCl_2的吸附性能

研究了CuCl2在荷结构负电荷皂土上的吸附性能,考察了pH、无机以及有机添加剂等因素的影响,并结合IR和XRD实验结果探讨了吸附机理。研究表明,皂土对CuCl2有很强的吸附能力,其吸附动力学和吸附等温线分别符合准二级速率方程和Langmuir方程。初始pH增大,吸附量增加。无机以及有机添加剂均能能明显抑制吸附。Cu2＋在皂土上的吸附层在微观上可分为因化学键合作用而形成的内络合层和因静电作用而形成的外络合层。     

纳米有机膨润土对苯酚的吸附性能研究

通过对天然膨润土改性,制备纳米有机膨润土并用于吸附苯酚,探讨了吸附时间、溶液pH、纳米有机膨润土投加量等因素对苯酚吸附的影响。结果表明,吸附在5 min内快速达到平衡,溶液pH可以影响苯酚在溶液中的状态,是影响苯酚吸附性能的重要因素。纳米有机膨润土吸附苯酚的过程可用伪二级反应动力学方程来描述,伪二级吸附速率常数为1.3 g/(mg.min)。吸附等温线符合Langmuir等温方程,在25℃时,Langmuir理论最大吸附容量可达到536.32 mg/g,吸附热力学参数表明吸附过程是自发的、放热的物理吸附过程。     

铁基膨润土对水中磷酸根的吸附热力学及动力学研究

采用铁盐改性制得铁基膨润土,研究了其对水中磷酸根的吸附性能及影响因素,结果表明,通过对膨润土的改性提高了磷的去除率,含磷废水初始pH值的大小对磷的去除率影响不大,初始浓度越低越有利于磷的去除。磷的去除率随改性膨润土的投加量增大而提高,随温度升高而增大。进一步研究表明,改性膨润土对磷的吸附是吸热反应,其吸附等温线可采用Langmuir等温吸附方程拟合;改性膨润土对磷的吸附是快速吸附,在20 min内,磷去除率达70%以上,符合准二级吸附动力学模型。     

Removal of phenols from water accompanied with synthesis of organobentonite in one-step process

A novel technology of wastewater treatment was proposed based on simultaneously synthesis of organobentonite and removal of organic pollutants such as phenols from water in one-step, which resulted that both surfactants and organic pollutants were removed from water by bentonite. The effects of contact time, pH and inorganic salt on the removal of phenols were investigated. Kinetic results showed that phenols and cetyltrimethylammonium bromide (CTMAB) could be removed by bentonite in 25 min. The removal efficiencies were achieved at 69%, 92% and 99%, respectively, for phenol, p-nitrophenol and beta-naphthol at the initial amount of CTMAB at about 120% cation exchange capacity of bentonite. Better dispersion property and more rapid bentonite sedimentation were observed in the process. The results indicated that the one-step process is an efficient, simple and low cost technology for removal of organic pollutants and cationic surfactants from water. The proposed technology made it possible that bentonite was applied as sorbent for wastewater treatment in industrial scale.     

A coupled THC model of the FEBEX in situ test with bentonite swelling and chemical and thermal osmosis

The performance assessment of a geological repository for radioactive waste requires quantifying the geochemical evolution of the bentonite engineered barrier. This barrier will be exposed to coupled thermal (T), hydrodynamic (H), mechanical (M) and chemical (C) processes. This paper presents a coupled THC model of the FEBEX (Full-scale Engineered Barrier EXperiment) in situ test which accounts for bentonite swelling and chemical and thermal osmosis. Model results attest the relevance of thermal osmosis and bentonite swelling for the geochemical evolution of the bentonite barrier while chemical osmosis is found to be almost irrelevant. The model has been tested with data collected after the dismantling of heater 1 of the in situ test. The model reproduces reasonably well the measured temperature, relative humidity, water content and inferred geochemical data. However, it fails to mimic the solute concentrations at the heater-bentonite and bentonite-granite interfaces because the model does not account for the volume change of bentonite, the CO(2)(g) degassing and the transport of vapor from the bentonite into the granite. The inferred HCO(3)(-) and pH data cannot be explained solely by solute transport, calcite dissolution and protonation/deprotonation by surface complexation, suggesting that such data may be affected also by other reactions.