一种喹啉阳离子聚合物粘土水化抑制剂研究

以丙烯酰胺(AM),烯丙醇聚氧乙烯醚(APEG)和溴化烯丙基喹啉(QAB)为单体,制备了一种阳离子聚合物AM/APEG/QAB。考察了单体配比、pH、引发剂浓度以及温度等合成条件对防膨率的影响。对聚合物进行了FTIR、1H NMR及TG表征。研究了不同浓度下聚合物溶液的防膨率,并利用XRD研究了聚合物溶液对钠蒙脱土(Na-MMT)层间距的影响。结果表明:该聚合物在浓度为2 wt%时的防膨率能达到78%。与低浓度的KCl互配不仅能够有效降低Na-MMT层间距到15.80,同时能够将岩心在水中浸泡后压入硬度保留率从42.6%提高至75.0%。

地层粘土水化的总体机理和影响因素

地层粘土水化的总体机理可分为两步：第一步是水化学势之差引起的宏观水迁移，渗透压和毛细管力可在该步中起显著作用；第二步是粘土颗粒与水结合，导致粘土膨胀、软化、脱落或分散运移。对这两步都有影响的因素为：粘土的矿物成分、交换性阳离子、分散度和颗粒间结合力等；主要影响第一步的因素有井眼水的压力、粘度和活度。目前很难改变前一类因素，通常主要是控制后一类因素以尽量阻缓水向地层中迁移。

聚胺与氯化钾抑制性的对比实验研究

近年来开发出的聚胺水基钻井液,被认为是最接近逆乳化钻井液性能的高性能水基钻井液。新型聚胺强页岩抑制剂也因其分子结构独特、抑制性能突出越来越受到人们重视。通过抑制膨润土造浆实验、屈曲硬度实验、页岩滚动分散实验、耐崩散实验、页岩膨胀实验以及X射线衍射粘土层间距分析等实验手段,对比评价了聚胺强页岩抑制剂与传统常用抑制剂氯化钾的抑制性。结果表明,与氯化钾相比,聚胺抑制性能优异,能有效抑制粘土水化分散,在加量较少时即能发挥长期抑制作用,且具有较好的抗温性能。配伍性实验表明,聚胺与膨润土及常用处理剂具有较好的配伍性。以SDA为主要水化抑制剂构建了聚胺水基钻井液,实验评价表明,该体系具有优良的抗盐、抗钙和抗劣土污染性能。此外,对聚胺的抑制机理进行了探讨分析。

Acid-activated and WO_x-loaded montmorillonite catalysts and their catalytic behaviors in glycerol dehydration

The use of H2SO4‐,HCl‐,H3PO4‐,and CH3COOH‐activated montmorillonite(Mt)and WOx/H3PO4‐activated Mt as catalysts for the gas‐phase dehydration of glycerol was investigated.The WOx/H3PO4‐activated Mt catalysts were prepared by an impregnation method using H3PO4‐activated Mt(Mt‐P)as the support.The catalysts were characterized using powder X‐ray diffraction,Fourier‐transform infrared spectroscopy,N2adsorption‐desorption,diffuse reflectance ultraviolet‐visible spectroscopy,temperature‐programmed desorption of NH3,and thermogravimetric analysis.The acid activation of Mt and WOx loaded on Mt‐P affected the strength and number of acid sites arising from H+exchange,the leaching of octahedral Al3+cations from Mt octahedral sheets,and the types of WOx(2.7≤x≤3)species(i.e.,isolated WO4/WO6‐containing clusters,two‐dimensional[WO6]polytungstates,or three‐dimensional WO3crystals).The strong acid sites were weakened,and the weak and medium acid sites were strengthened when the W loading on Mt‐P was12wt%(12%W/Mt‐P).The12%W/Mt‐P catalyst showed the highest catalytic activity.It gave a glycerol conversion of89.6%and an acrolein selectivity of81.8%at320°C.Coke deposition on the surface of the catalyst led to deactivation.

PREPARATION AND PROPERTIES OF CLAY/POLY（N-ISOPROPYLACRYLAMIDE-co-A CRYL AMIDE） NANOCOMPOSITE HYDROGELS

A series of clay/poly（N-isopropylacrylamide-co-acrylamide） nanocomposite hydrogels （S-N-M gels） have been successfully prepared by in situ polymerization. The mechanical properties, swelling behavior of S-N-M gels and the transparency changes during polymerization of S-N-M gels have been systematically investigated. Compared to traditional hydrogels, S-N-M gels show excellent tensile properties and their swelling ratio increases with increasing acrylamide （AAm） content. The results of stress relaxation indicate that the stress loss decreases with increasing AAm content. It was surprisingly found that the transparency during all S-N-M gel synthesis changes abruptly, and the changes become more abrupt with increasing N-isopropylacrylamide content. It was concluded that the fact may be related to the hydrophilicity of copolymers. The weaker the hydrophilicity of copolymer, the more apparent the transparency change during S-N-M gels polymerization. We believe the relationship between hydrophilicity of copolymer and transparency changes will help to design novel nanocomposite hydrogels.

Research on the Critical Conditions for Clay Particle Release During Saline Aquifer Freshening Process

Water sensitivity phenomenon occurs during saline aquifer freshening process in seawater intrusion area, and clay particles released in the phenomenon can damage the infiltration capacity of the aquifer. In order to find out the factors and mechanisms for clay particle release, laboratory column infiltration experiments simulating saline aquifer freshening process were designed to measure the critical conditions(critical flow velocity, critical salt concentration and critical ionic strength) and force analysis for clay particle according to DLVO electric double layer theory was employed to illustrate the mechanisms for particle release. The research results showed that critical flow velocity for clay particle release is influenced by salt concentration of injecting solution. When salt concentration of injecting solution is very high, clay particles are not released, indicating that there does not exist a critical flow velocity in this situation. As salt concentration of injecting solution decreases, particles start to be released. The critical salt concentration for clay particle release is 0.052 mol L-1 in our work, which was determined by a constant-flux experiment for stepwise displacement of high concentration Na Cl solution. The critical ionic strength for clay particle release decreases as Ca2+ molar content percentage of the mixed solution of Na Cl and Ca Cl2 increases following the first-order exponential decay equation y = 0.0391e-0.266 x + 0.0015.

Treatment of Rural Effluents Using Fortified Sand-Clay： Interaction Bacteria-Clay for the Formation of Biofilm

The ability of some Tunisian sand-clays in rural wastewater treatment was investigated in this study. The sand-clays were characterized by studying the mineralogical and geochemical characteristics using X-ray diffractometer and atomic absorption spectrophotometer （AAS）, respectively. Performance efficiency studies were conducted to determine the best combination ratio of sand-clay/pebbles. Sand-clay fortified with pebbles in the ratio 3：1 gave the optimum water purification while combination ratio 1：3 gave the least. The fortified sand-clays were used in the treatment of wastewater from rural locality. On the other hand, bacteria play an important role in determining the properties and behavior of clay minerals in natural environments and such interactions have great potential for creating stable biofilms and carbon storage sites in soils, but our knowledge of these interactions are far from complete. The purpose of this study was to understand better the effects of bacteria-generated biofilms on clay interlayer expansion. Mixtures of a colloidal, 2-water smectite clay and Pseudomonas aereginosae in a minimal media suspension evolve into a polysaccharide-rich biofilm aggregate in time-series experiments lasting up to 1 week. X-ray diffraction analysis reveals that upon aggregation, the clay undergoes an initial interlayer contraction.

Sandwich layered double hydroxides with graphene oxide for enhanced water desalination

Layered double hydroxides(LDHs)are a class of two-dimensional(2D)clay compounds that consist of positively charged host layers and exchangeable interlayer anions.The stability of their assemblies in aqueous environment is a challenge due to the extremely high hydrophilicity,which limits their use in membrane-based technologies.Here,we propose a graphene oxide(GO)armour protection strategy to substantially improve the stability of LDH membranes in aqueous solution.The sandwich structured GO/LDH/GO membranes(GLGMs)possess a negative-positive-negative charge heterojunction in the vertical direction that effectively blocks the transport of both cations and anions,i.e.,NaCl,but allows the permeation of water molecules.Following this mechanism,the GLGMs are used for desalination in a forward osmosis mode.A high rejection rate of over 95.2% for NaCl and water flux of over 2.1 Lm^(-2)h^(-1) are achieved with simulated seawater.

Development of limestone calcined clay cement concrete in South China and its bond behavior with steel reinforcement

Limestone calcined clay cement(LC^3),consisting of ordinary Portland cement(OPC)clinker,calcined clay,limestone powder,and gypsum,has been considered a promising solution to current challenges in the cement and concrete industry,such as high carbon emissions,high energy consumption,and resource shortages.This study carries out a series of experimental investigations of LC^3-based paste,mortar,and concrete,including microstructural analyses(e.g.hydration product characterization and pore structure analysis)and macro-scale testing(e.g.workability and mechanical properties),using raw materials from south China.The results show that,in LC^3 paste,the replacement of clinker by calcined clay and limestone leads to an increased volume of small pores but decreased total volume of pores.The workability of LC^3 mortar and concrete can be readily tailored using conventional superplasticizers.When designed for comparable 28-d compressive strength,the LC^3 mortar and concrete tend to have lower early-age compressive strength,but comparable compressive strength and higher flexural strength than those of the OPC counterparts at late ages.This study also examines the bond-slip behavior between LC^3 concrete and steel bars and finds that the bond strength is comparable to that of OPC concrete with the same 28-d compressive strength,but that the LC^3 concrete-rebar interface exhibits higher bond-slip stiffness.These findings on LC^3 concrete provide fundamental information and guidance for furthering the application of LC^3 binder in structural concrete in the near future.