正癸醇在石墨/庚烷界面上的表面反胶团的形成

本文首次提出非极性固体自非水溶液中吸附两亲分子时界面上会形成表面反胶团的可能性。基于这一设想,结合二阶段吸附模型和质量作用定律,导出了通用的吸附公式。利用这一公式定量地解释了石墨自庚烷中吸附正癸醇的实验数据。结果表明正癸醇的表面反胶团的聚集数在3～6之间,随温度升高而下降。表面聚集的热力学计算指示表面反胶团形成的标准焓(△H°rhm)和熵(△S°rhm)皆是负的,说明过程不是熵驱动的,这与自水中吸附的情况不同。文中还报道了这个体系的临界表面反胶团浓度(rhmC)值。     

脂肪酰基谷氨酸钠与十六烷基三甲基溴化铵在水溶液中的相互作用

研究了Ｎ 脂肪酰基谷氨酸钠（ＦＡＧ Ｎａ）与十六烷基三甲基溴化铵（ＣＴＡＢ）混合水溶液的表面活性，测定了不同比例混合水溶液的表面张力—浓度曲线，得出临界胶束浓度及此时的表面张力。应用Ｇｉｂｂｓ吸附公式求出表面总吸附量，根据吸附层及胶束中两表面活性剂分子的相互作用参数公式求出吸附层及混合胶束组成。实验表明，此体系显示了较高的表面活性。     

阳离子表面活性剂在活性炭上的吸附研究

利用表面张力法测定了活性炭自水溶液中吸附阳离子表面活性剂3－烷氧基－2－羟丙基三甲基氯化铵（CnNCl)的吸附等温线，应用热力学公式计算出了吸附过程的ΔG^0、ΔH^0和ΔS^0，实验结果表明，CnNCl同系物的吸附量随温度的升高而降低，随表面活性剂中疏水基碳链的增长而升高。吸附过程为一熵增加过程。     

固液界面上表面活性剂吸附膜的组成与状态

根据表面活性剂在固液界面上的二阶段吸附模型,导出了各个别(包括单个吸附分子、表面胶团和表面空位的)等温线公式。计算结果表明单个分子的吸附量一般随浓度的增大先升后降,有最大值。表面胶团的量随浓度的增大呈S型地单调上升,最后趋极限值。表面空位数则随浓度的增大单调下降,但下降的方式与二阶段吸附的平衡常数有关。将由二阶段吸附模型导出的吸附等温线通用公式与Gibbs公式的积分式结合,可导出吸附膜的π-C关系,并可得出π-A曲线。结果表明表面活性剂在固液界面上的π-C曲线常显示有二阶段的性质,这在水面上可溶物的吸附膜中一般是没有的。另一方面,与水面上不溶物膜的结果相似,表面活性剂在固液界面上的π-A曲线显示有相变发生,这与表面胶团形成的观点是一致的。     

烷基醇与离子型表面活性剂在吸附层和不溶单分子膜中的相互作用

研究了正辛醇与十烷基硫酸钠、溴化十烷基三甲基铵、溴化十烷基铵二元混合物水溶液的表面吸附和胶团形成,以及十八醇与十八烷基硫酸钠、溴化十八烷基三甲基铵混合体系不溶膜的表面压-分子面积关系。结果表明:(1)少量正辛醇能大大提高离子表面活性剂(不论是正离子还是负离子性)的表面活性;溶液稀时,二组分的表面吸附是互相促进的,溶液较浓时(吸附近于饱和)则相互抑制(竞争吸跗);各体系表面分子相互作用参数βs皆有一较大负值;(2)十八醇与十八烷基硫酸钠、溴化十八烷基三甲基铵混合不溶膜比单一组分不溶膜有较强的凝聚性, 混合表面过剩自由能皆为负值。这些结果说明,烷基醇与离子(正或负)表面活性剂在吸附层及不溶单分子膜中皆有较强的相互作用;这种作用主要是碳氢链间的疏水效应和极性头之间的离子-偶极作用,而非氢键形成。     

血色素在固形载体上的吸附

由于吸附和解吸等温线一致，血色素在固形载体(胶铝矿、石墨化炭黑与吸附有卵磷脂的胶铝矿和石墨化炭黑)表面上的吸附是一个可逆和平衡过程。吸附等温线为Langmuir型。算出相应的Langmuir公式参数，这些参数可视为有效。因为被吸附物是含由活泼单体和不活泼伴生物(二聚物)所形成平衡混合物的溶液，所以吸附曲线是平衡形式血色素的全面吸附等温线。动力学分析表明，固形载体上血色素吸附层中伴生物的组成分布是通过该溶液完成的。     

二元表面活性剂混合水溶液的分子间相互作用——结构和温度对混合吸附的影响

通过表面张力的测定，用Gibbs吸附定理和Rosen以正规溶液理论为基础导出的吸附层组成公式，研究了十二烷基聚氧乙烯－3磺酸钠（C12E3）S与POE非离子表面活性剂（C10E5，C10E7）的二元体系在25℃和40℃下的纯水溶液中的表面吸附：并用分子间相互作用β参数和交换能ε讨论了吸附层中分子间的相互作用。结果表明：（1）非离子POE在混合吸附层中优先吸附，即使在溶液中的摩尔分数很低时（≈0．1），POE在表面层的摩尔分数也大于0．5。（2）两表面活性剂组分在吸附层中相互作用为吸引力。（3）POE的EO数增加，表面层中分子间作用力增强，POE的吸附趋势减弱，（4）温度升高，POE和C12E3S的吸附能力均降低，同时吸附层中分子间作用力减弱。     

基于静电作用选择性吸附染料的超分子凝胶剂

设计并合成了一系列季铵盐型凝胶剂，仅通过调控季铵盐烷基侧链的长度，可得到两种自组装模式不同的凝胶剂。通过FTIR、XRD研究了甲苯干凝胶的自组装模式。这两种干凝胶具有相反的表面Zeta电位，通过静电作用实现了对阴阳离子染料的选择性吸附。在二元阴阳离子混合染料水溶液中，表面带有负电荷的干凝胶可优先捕获阳离子染料，而表面带有正电荷的干凝胶可捕获阴离子染料。特别是表面带有负电荷的干凝胶对龙胆紫表现出优异的吸附性能，在60 min左右的平衡吸附量高达1313.16 mg/g。将凝胶剂负载于三聚氰胺海绵骨架表面，得到的改性海绵吸附染料种类与对其改性的干凝胶保持一致，且对染料的吸附量均明显高于干凝胶的吸附量，尤其是对龙胆紫的吸附量提升至2488.22 mg/g。     

活性炭表面热氧化对其吸附二苯并噻吩性能影响

本文主要研究活性炭表面氧化对其吸附二苯并噻吩性能的影响。将活性炭在不同低温下氧化制得表面氧化活性炭，用静态吸附法进行了二苯并噻吩在初始及氧化活性炭上的吸附等温线，应用Langmuir方程对吸附等温线进行拟合，用漫反射红外谱（DRIFTS）表征活性炭表面含氧基团，用Boehm滴定测定活性炭表面官能团含量，讨论了活性炭表面化学性质对其吸附二苯并噻吩的影响。结果表明：活性炭表面酸性含氧基团对二苯并噻吩的吸附有重要影响，酸性含氧基团越多，其吸附量越大。低温气相氧化活性炭提高了活性炭表面酸性含氧基团，提高了其对二苯并噻吩的吸附。氧化温度越高，其表面含氧基团含量越多，其对二苯并噻吩的吸附量也越大。Langmuir吸附等温线可适用于描述二苯并噻吩在活性炭表面上的吸附。     

花生壳生物炭负载钙钛矿材料对亚甲基蓝吸附性能研究

本文通过溶胶凝胶法在超声辅助下成功合成了复合材料BC@LF。通过SEM、XRD以及BET表征了材料的表面形貌、成分、晶型以及吸附参数。测试了BC@LF对亚甲基蓝(MB)的吸附能力,实验结果表明BC@LF可以快速吸附MB,并且其吸附能力与溶液pH以及温度呈正相关性。同时还测定了BC@LF的PZC结果表明pH低于6.9时BC@LF表面电位为正,p H高于6.9时BC@LF表面电位为负。根据实验结果分析了BC@LF在吸附MB过程中的吸附动力学和热力学,其中吸附动力学符合Elovich模型为化学吸附行为,吸附热力学符合Freundlich模型表明BC@LF为非均匀吸附。此外,选取了五种有机污染物对BC@LF进行吸附测试,得到了不错的吸附效果证明了BC@LF具有对有机污染物吸附的普适性。     

Electrokinetic potential of hydrated cement in relation to adsorption of chlorides

In this study, surface charge mechanism of cement hydrates and its relations to adsorption of chloride ions are investigated. Hydrated cement paste (HCP) shows net positive surface charge by dissociation and adsorption. In HCP, chlorides bind as Friedel's salt (chemical binding) as well as adsorb on the surface of hydrates (physical binding). A surface complexation model is used to predict the adsorption of chlorides on calcium silicate hydrates (C-S-H). A good agreement between experimental and predicted chloride adsorption isotherm clearly demonstrate that the chlorides adsorb on the surface of C-S-H and bringing additional negative surface charge (SiOHCl⁻). However, chloride ions neutralize the positively charged surfaces of portlandite and Friedel's salt by physical adsorption. From the results, it can be concluded that C-S-H is the dominant phase in terms of chloride adsorption in HCP.     

Impact of zeta potential of early cement hydration phases on superplasticizer adsorption

The zeta potential of early hydration products of cement was found to be a key factor for superplasticizer adsorption. A highly positive zeta potential results in a strong superplasticizer adsorption whereas a negative zeta potential does not allow adsorption. Synthetic ettringite precipitated from solution shows a highly positive zeta potential, hence it adsorbs great amounts of negatively charged superplasticizer. Monosulfate (AF_m) has a less positive zeta potential. Therefore, it adsorbs smaller amounts of superplasticizers. For syngenite, portlandite and gypsum, the zeta potential is around zero or negative. These phases do not adsorb superplasticizers. Consequently, a hydrating cement grain is best represented by a mosaic structure, with superplasticizer molecules mainly adsorbed on ettringite and some on monosulfate and C-S-H nucleated at surface.     

Adsorption of saccharides from aqueous solution onto activated carbon

The Freundlich's adsorption constants of 13 saccharides and 4 polyhydric alcohols from aqueous solutions onto an activated carbon have been determined and correlated with various physical constants. A good linear relationship is obtained between the adsorption constants and the physical constant such as molecular refraction or parachor. Further, the adsorption isotherms of saccharides can be predicted from the carbon atom number and the oxygen atom number in the molecular formula.     

Influence of covalent attachment of low molecular weight substances on the rejection and adsorption properties of crystalline proteinaceous ultrafiltration membranes

Many bacteria possess crystalline cell surface layers (S-layers) as their outermost cell envelope component. High-resolution electron microscopical and permeability studies on S-layers revealed pores with a size from 2–8 nm. Each type of S-layer lattice showed pores of identical size and morphology. By depositing S-layer fragments on appropriate microfiltration membranes and crosslinking the S-layer protein with glutaraldehyde, it was possible to produce ultrafiltration membranes with a crystalline and isoporous active filtration layer. Due to a surplus of free carboxyl groups on the surface of the S-layer lattice and in the pore areas, these composite S-layer ultrafiltration membranes (SUMs) showed a net negative charge. Upon converting the free carboxyl groups into neutral or positively charged groups by amidation, both the adsorption and rejection properties of SUMs could be altered. As expected, neutral SUMs showed the lowest unspecific protein adsorption. Membrane modification studies further demonstrated that in addition to the molecular size, the physicochemical properties of the immobilized compounds and the resulting interactions with the test proteins in solution determine the rejection characteristics of SUMs.     

The correlation between froth flotation response and collector adsorption from aqueous solution. Part I. Titanium dioxide and ferric oxide conditioned in oleate solutions

Samples of pure ferric oxide and titanium dioxide have been conditioned in aqueous oleate solutions over the pH range 2–12. The extent of oleate adsorption was determined from the heat of combustion of the adsorbed film, using DTA. Adsorption isotherms have been constructed at pH values above and below both the pK of oleic acid and the isoelectric points of the oxide surfaces.It appears that at low oleate concentrations, adsorption is due to negatively charged carboxylate ions interacting with positively charged surface sites. When sufficient surface has been covered with hydrophobic hydrocarbon chains, froth flotation becomes possible. With increasing oleate concentration, competition for positive sites forces the adsorbed ions into a vertical orientation, thereby exposing some previously covered surface. Once the positive sites have been “neutralised”, subsequent adsorption must occur at neutral or negative parts of the surface. This is likely to involve mutual attraction between the hydrocarbon groups of vertically adsorbed oleate ions, and those of oleate ions in solution. Newly adsorbed oleate ions would then be expected to be oriented with their negatively charged carboxylote groups away from the surface. Hence, increasing adsorption, as the collector concentration is increased, will lead to the surface becoming progressively less hydrophobic, and froth flotation may cease.     

氮气吸附法的致密砂岩孔隙结构分析

微观孔隙结构特征是研究储层中油气储存和运移的关键因素。选取鄂尔多斯盆地西峰地区长8段致密砂岩储层中的样品。通过氮气吸附实验,获得致密砂岩样品的孔隙结构参数。并讨论了各个结构参数与物性的相关性和影响因素。实验结果表明:根据IUPAC的分类,微观孔隙结构属于H3型。比表面积与孔隙度呈一般负相关,与渗透率具有较强的负相关性。微孔(<10nm)与中孔(10～50nm)对比表面积与孔隙体积贡献了80%。孔隙体积与孔隙度和渗透率的相关性均呈现一般正相关性。综合以上,较少的大孔发育可能是导致致密砂岩渗流能力较弱的原因。     

污水厂污泥制备吸附剂及其脱硫机理研究

以城市和石化污水厂生化活性污泥及剩余污泥为原料,采用不同方法制备烟气脱硫吸附剂,对影响产物吸附性能的因素进行了研究。结果表明城市污水厂剩余污泥利用热解炭化法制备的吸附剂脱硫性能较好,其吸附过程可用Freundlich模型来描述,SO2-O2-N2体系吸附机理主要为物理吸附,SO2-O2-H2O(g)-N2体系SO2发生了催化氧化,以化学吸附为主。     

CORONA DISCHARGE EFFECTS IN GAS-SOLID ADSORPTION: WATER VAPOR ON SILICA GEL AND FLY ASH

Equilibrium characteristics of water vapor adsorption on microporous silica gel and macroporous fly ash are investigated in the presence of corona discharges. The discharge is produced at a fine wire surface in a wire-cylinder electrode geometry, with the adsorbent sample placed in the inter-electrode space. A significant reduction in water vapor adsorption capacity is observed for both negative and positive coronas. Heat effects appear to be negligible. To provide a theoretical understanding of the altered equilibrium, three distinct mechanisms are proposed and evaluated. One mechanism, in particular, is seen to hold much promise.     

Ligand adsorption on different activated carbon materials for catalyst anchorage

Adsorption of naphtoic acid was investigated as a initial stage for the preparation of catalysts by heterogenisation of metal complexes. Four granular activated carbons and a carbon cloth showing different physical and chemical properties were used as sorbents. Adsorption of naphtoic acid was accomplished by all materials, being clear that an oxygen-rich surface chemistry has a negative effect on the physical adsorption of this molecule. The naphtoic acid molecule accommodates on the surface of narrow micropores. After adsorption, the samples were subjected to conditions similar to those used in hydrogenation reactions in order to quantify the amount of naphtoic acid that leaches from the surface of the adsorbent. According to the purpose of this research, all the carbons retain enough naphtoic acid.     

Electric field induced reversible switch in hydrogen storage based on single-layer and bilayer graphenes

In an ideal hydrogen storage system, binding strength should increase during adsorption whereas the opposite should be the case during desorption. These two seemingly contradictory requirements limit the types of systems that can be utilized. Density-functional theory (DFT) calculations are carried out to investigate hydrogen physisorption on Li-doped single-layer and bilayer graphenes. We propose that the superimposition of an electric field can be used to effectively control hydrogen adsorption. More specifically, we report that hydrogen binding can be enhanced under a positive electric field, whereas it can be weakened under a negative electric field. Our results show that the binding strength increases by 88% when a field with a magnitude of +0.020 au is imposed. Hirshfeld charge analysis results suggest that an increase in the binding strength will occur as long as the Li (or C) carries more positive (or negative) charges. Our calculations demonstrate that, in the case of Li-doped graphene, the application of a positive electric field yields an increase in binding strength during adsorption while a negative field decreases the binding strength during desorption.