阳离子表面活性剂对有机颜料艳红6B光催化降解的影响

 研究了阳离子表面活性剂四丁基溴化铵(TBAB)和十六烷基三甲基溴化铵(CTAB)对TiO2光催化降解艳红6B(R6B)的影响,讨论了表面活性剂与R6B的相互作用,给出了二者与TiO2之间的吸附模型. 结果表明,相同条件下,阳离子表面活性剂的加入可增加R6B的降解褪色速率,但表面活性剂自身并不降解. 在强酸(pH=3.00)和强碱(pH=12.60)条件下,R6B的降解褪色速率较快. pH值相同时,体系中TBAB的浓度变化对R6B降解褪色速率的影响不大,而CTAB浓度的变化对R6B降解褪色速率的影响较为明显,CTAB浓度为0.4 g/L时R6B的降解褪色速率最快.     

有机颜料与表面活性剂DBS混合物的光催化降解

以TiO₂为光催化剂,研究了表面活性剂十二烷基苯磺酸钠(DBS)和有机颜料耐晒大红BBN(BBN)为混合组分的光催化降解,结果表明,pH值、底物的用量对体系的降解有显著影响,在碱性条件下,DBS的降解速率相对较快,而在酸性环境时,颜料的降解较快,在TiO₂等电点时,降解最慢,酸性条件下, TiO₂对BBN和DBS的吸附性比在碱性和中性环境中大,BBN/DBS体系中, DBS增大了BBN的水溶性,但是没有明显提高BBN的降解褪色速度,DBS浓度为0.42 g/L时,颜料降解最快,0.042 g/L时次之,2.1 g/L时最低,在BBN降解过程中DBS自身也被降解,且略有促进作用。     

添加剂对有机颜料光催化降解的影响

 研究了(NH4)2S2O8,H2O2和表面活性剂十二烷基苯磺酸钠(DBS)对TiO2光催化降解颜料艳红6B的影响. 结果表明,(NH4)2S2O8的加入可提高颜料艳红6B的降解速率,以酸性及近中性条件较为适宜; H2O2的加入也可提高颜料艳红6B的降解速率,并可提高TiO2的重复使用次数; DBS的加入可降低颜料艳红6B的降解速率,但颜料艳红6B在酸性和碱性条件下降解较中性条件下快. DBS在中性条件下降解较快. 颜料艳红6B与DBS二者之间存在密切的共降解关系. 随着DBS浓度的增加,颜料艳红6B和DBS的降解速率均逐渐降低.     

非离子表面活性剂存在下光催化降解有机颜料

研究了加入非离子表面活性剂OP-10时有机颜料光催化降解过程,实验选用的颜料为艳红6B(C.I.Pigment Red482),以高压汞灯为光源,TiO2为催化剂.通过改变水溶液的pH值和OP-10的浓度,考察了颜料和OP-10各自的降解特性.实验结果表明,酸性条件下,OP-10的存在明显加快了颜料的降解,碱性条件下反而抑制了颜料的降解.中性条件下,OP-10的增溶对体系的降解有一定影响,浓度为0.126g/L(2.5cmc)时,颜料和OP-10降解效果最好.     

光催化降解污染物制氢反应与原位红外表征

研究了在Pt/TiO2悬浮体系中单组分和双组分污染物为电子给体光催化分解水制氢反应. 比较了污染物甲醛、甲酸和草酸为电子给体光催化放氢反应效率，发现其活性为：草酸 >甲酸 >甲醛.原位ATR（衰减全反射）红外研究结果表明，光催化放氢活性与污染物吸附特性有关.还研究了草酸与甲酸双组分污染物体系的光解水放氢和污染物降解动力学，发现总的放氢和污染物降解速率与污染物组分在TiO2表面的吸附强度和溶液浓度有关.污染物在TiO2表面的竞争吸附决定了反应动力学.原位ATR-IR方法研究双组分混合物体系的吸附，直观地证实了上述结果.     

表面活性剂对海藻酸钠稀水溶液剪切粘度的影响

通过粘度法考察了不同pH值时, 阴离子聚电解质海藻酸钠(NaAlg)与阴离子表面活性剂十二烷基硫酸钠(SDS)、阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)、非离子表面活性剂辛基酚聚氧乙烯醚(TritonX-100)以及它们的复配体系的相互作用. 研究表明, 在酸性条件下, SDS和TritonX-100与NaAlg之间主要是疏水作用, 随着表面活性剂浓度的增加, 体系粘度下降直到基本不变, CTAB与NaAlg主要发生静电作用和疏水作用, 体系粘度随CTAB浓度的增加呈现先上升后下降的趋势. 在实验条件下, TritonX-100浓度为0.05 mmol·L-1时, SDS的加入, 使得NaAlg/TritonX-100体系的零剪切粘度下降, 而CTAB的加入, 在pH=3.0和5.0时, NaAlg/TritonX-100体系的零剪切粘度出现上升, 在pH=6.4时, 该体系零剪切粘度下降.     

Pt/TiO2光催化重整降解2-氯乙醇水溶液制氢

在无氧条件下,进行了Pt担载的TiO2光催化有毒的2-氯乙醇(下文简称氯乙醇)重整制氢反应的研究.详细讨论了动力学因素如催化剂表面Pt化学状态、Pt担载量、溶液pH值、氯乙醇浓度等对产氢速率的影响,并用XRD、HNMR、XPS等技术进行了表征,探讨了氯乙醇降解和产氢反应机理.研究表明,在光催化降解氯乙醇的同时产生氢是完全可行的.催化剂表面的Pt以Pt0的化学状态存在,有利于析氧;溶液pH值对产生速率影响也很大,而氯乙醇的浓度变化只是在开始略有影响,浓度的增加对产氢并没有明显的影响.研究得出Pt担载的TiO2光催化重整氯乙醇制氢反应的最佳条件是Pt的最佳担载量约为1.0%;氯乙醇溶液浓度范围为0.04～0.10 M;最佳溶液pH值范围为4～10.     

有机颜料的光催化降解及添加表面活性剂的影响

研究了纳米TiO2浓度、颜料用量、pH值和紫外光强度对有机颜料纳米TiO2光催化降解速率的影响．添加表面活性剂十二烷基苯硝酸钠时，颜料溶解度增加，但降解速率减慢．     

不同催化系统降解甲基橙的效率比较及过程分析

以甲基橙模拟染料废水为降解目标,在自制的圆柱形不锈钢反应器中,比较三种不同的光催化系统:TiO2光催化、紫外光辐射及臭氧单独氧化的催化效率,检测脱色率、COD、pH值影响、臭氧及羟基自由基(·OH)的变化分析催化反应历程。研究表明:三种体系降解150 min后COD降解率分别为46.23%(UV),44.54%(O3)and 74.12%(TiO2),而120 min后脱色率达93.6%(UV),92.07%(O3)and 96.79%(TiO2)。三种体系在酸性条件下COD降解率和脱色率都最高。臭氧和羟基自由基检测显示,催化初期TiO2催化系统产生更多的臭氧,有利于后期·OH的产生。同时,利用·OH计算光催化反应速率也显示TiO2催化效率更好。     

TiO_2-SBA-15催化剂的制备、表征及光催化降解甲基橙

以钛酸四丁酯为钛源,以介孔分子筛SBA-15为载体,采用简单的方法制备TiO2-SBA-15催化剂,并采用FT-IR,XRD和N2吸附-脱附等方法对其进行表征.另外,将制备的TiO2-SBA-15催化剂应用于光催化降解甲基橙溶液,并讨论了钛含量、甲基橙浓度及溶液pH值对降解率的影响.结果表明:在钛酸四丁酯起始加入量为3.2mL,甲基橙浓度为10mg/L,溶液pH=3的条件下,TiO2-SBA-15光催化降解甲基橙的降解率可达到100%.     

两亲性阴离子HBPN与阳离子表面活性剂CTAB络合机理的研究

用动态光散射研究了两亲性阴离子HBPN(高度枝化的聚酯纳米微粒)和阳离子表面活性剂CTAB(十六烷基三甲基溴化铵)在缓冲液中的相互作用及HBPN/CTAB络合物的形成.结果表明:在静电作用下,于碱性溶剂中,HBPN与由CTAB分子所构成的胶束形成了核壳结构络合物HBPN/CTAB.络合物粒径的大小和稳定性可以通过溶液的pH值和CTAB浓度来控制.     

Adsolubilization of toluene and acetophenone as a function of surfactant adsorption

Adsolubilization, solubilization of organic compounds into adsorbed surfactant aggregates, has attracted much attention in the past few years. It is being explored for a variety of new commercial applications including the formation of engineered surfaces, pharmaceutical applications, and nanotechnology. Adsolubilization is strongly influenced by the amount of adsorbed surfactant, which in turn depends upon pH, ionic strength, and surfactant type and concentration. In this study, the adsorption of a cationic surfactant, cetyltrimethylammonium bromide (CTAB) on precipitated silica and the adsolubilization of organic solutes (toluene and acetophenone) into the adsorbed surfactant aggregates were examined as a function of surfactant adsorption at two pH values (5 and 8). Three levels of surfactant adsorption, corresponding to equilibrium concentration low in region II, high in region II, and low in region III of the adsorption isotherm, and the adsolubilization of toluene and acetophenone were investigated both in single- and mixed-solute systems. The results showed that the adsorption of CTAB depended strongly on pH and for each pH the adsolubilization increased with increasing surface adsorption. However, the adsolubilization behaviors of the adsorbed CTAB aggregates in different adsorption regions were quite distinct, suggesting that the structural arrangement of the surfactant aggregates may play an important part in addition to the amount of adsorbed surfactant. This phenomenon was more noticeable at low surfactant adsorption than at higher surface adsorption. In mixed-solute systems, the presence of acetophenone had little effect on the toluene adsolubilization. In contrast, a synergetic effect was observed in the adsolubilization of acetophenone in the presence of toluene.     

Encapsulation of curcumin in cationic micelles suppresses alkaline hydrolysis

The alkaline hydrolysis of curcumin was studied in three types of micelles composed of the cationic surfactants cetyl trimethylammonium bromide (CTAB) and dodecyl trimethylammonium bromide (DTAB) and the anionic surfactant sodium dodecyl sulfate (SDS). At pH 13, curcumin undergoes rapid degradation by alkaline hydrolysis in the SDS micellar solution. In contrast, alkaline hydrolysis of curcumin is greatly suppressed in the presence of either CTAB or DTAB micelles, with a yield of suppression close to 90%. The results from fluorescence spectroscopic studies reveal that while curcumin remains encapsulated in CTAB and DTAB micelles at pH 13, curcumin is dissociated from the SDS micelles to the aqueous phase at this pH. The absence of encapsulation and stabilization in the SDS micellar solution results in rapid hydrolysis of curcumin.     

Micellar-catalyzed alkaline hydrolysis of 2,4-dinitrochlorobenzene in a cationic gemini surfactant

Micellar-catalyzed alkaline hydrolysis of 2,4-dinitrochlorobenzene (DNCB) in the presence of a conventional cationic surfactant CTAB or a cationic gemini surfactant 1,2-ethane bis(dimethyldodecylammonium bromide) (12-2-12) were studied spectrophotometrically at 25 °C. It was found that both CTAB and 12-2-12 micelles accelerated the alkaline hydrolysis of DNCB, and the binding constant of the substrate to the micelle, K_S, for 12-2-12 (K_S = 310 M⁻¹) was larger than that for CTAB (85 M⁻¹), which suggested that DNCB molecules bound with gemini micelles more easily than with CTAB. However, the second-order rate constant in micellar pseudophase (k_M = 1.22 × 10⁻³ s⁻¹) for 12-2-12 was lower than k_M for CTAB (4.01 × 10⁻³ s⁻¹) because the substrate may enter the interior of the 12-2-12 micelles. It was found also that 12-2-12 had a similar catalysis mechanism to CTAB when the concentration of 12-2-12 was relatively low (ca. <5 mM). However, above this concentration, higher microviscosity and significant increases in aggregation number and micelle size with increased surfactant concentration may remarkably influence the hydrolysis reaction.     

SiO2掺杂TiO2催化超声降解甲基橙溶液

采用实验室合成的SiO2掺杂TiO2作为催化剂,以甲基橙超声降解反应为模型,研究了各种因素对SiO2掺杂TiO2催化超声降解甲基橙的影响.结果表明在SiO2掺杂TiO2催化剂作用下超声降解甲基橙的效果明显优于非掺杂的锐钛矿型TiO2的催化效果.SiO2掺杂TiO2催化剂用量在0.5～1.0g/L之间,超声波频率25kHz,输出功率1.0W/cm2,pH为1.0～3.0时,在甲基橙水溶液初始浓度20mg/L的条件下,80min,降解率达到了98%以上,COD的去除率也达到了99.0%.因此,SiO2掺杂TiO2催化超声降解有机污染物的方法具有很好的应用前景.     

Modified carbon paste sensor for cetyltrimethylammonium ion based on its ion-associate with tetrachloropalladate(II).

A comparative study was made between developed chemically modified carbon paste electrodes and PVC membrane electrodes for the cationic surfactant cetyltrimethylammonium bromide (CTAB). The carbon paste electrode modified with cetyltrimethylammonium-tetrachloropalladate(II) (CTA-TClP) provides a more sensitive and stable device than that shown by electrodes with an inner reference solution. The best performance was obtained by an electrode based on the paste containing 3.6 wt% CTA-TCIP, 1.8 wt% ethylhexadecyldimethylammonium bromide, 37.6 wt% graphite and 57 wt% tricresyl phosphate. The sensor exhibited a Nernstian response for CTAB over a wide concentration range of 3.5 x 10(-7) to 1.0 x 10(-3) M with a detection limit of 2.0 x 10(-7) M between pH 2.7 and 8.2 with a fast response time of 相似文献   

Effect of reactive and non-reactive counterion micelles upon the alkaline degradation of indomethacin

In the present paper, kinetics of alkaline degradation of well known drug, indomethacin (2-[1-(4-chlorobenzoyl)-5-methoxy-2-methylindol-3-yl]acetic acid), was studied in presence of excess [NaOH]. The rate of hydrolysis of substrate was independent of the [indomethacin] though it increased linearly with increasing the hydroxide ion concentration with a positive slope, suggesting the following rate law: k_obs = k₁[OH⁻]. Cationic surfactants having non-reactive ions (cetyltrimethylammonium bromide, CTAB and cetyltrimethylammonium sulfate (CTA)₂SO₄) first increased the rate constants at lower concentrations and then decreased it at higher concentrations while in case of the surfactant with reactive counterions (cetyltrimethylammonium hydroxide, CTAOH) the rate increases sharply at lower concentrations of surfactant until it reaches to a plateau in contrast to the appearance of maxima in case of CTAB and (CTA)₂SO₄. Anionic surfactant, sodium dodecyl sulfate (SDS), inhibited the reaction rate at all concentrations used in the study. Pseudophase ion-exchange model was used for analyzing the effect of cationic micelles while the inhibition by SDS micelles was fitted using the Menger–Portnoy model. The effect of salts (NaCl, NaBr and (CH₃)₄NBr) was also seen on the hydrolysis of indomethacin and it was found that all salts inhibited the rate of reaction. The inhibition followed the trend NaCl < NaBr < (CH₃)₄NBr.     

Capillary electrophoresis with capacitively coupled contactless conductivity detection for low molecular weight organic acids in different samples

CE with capacitively coupled contactless conductivity detection (CE-C(4)D) was explored and validated for the identification and quantification of organic acids in various types of samples. The analyses were performed under optimized conditions, using a buffer system composed of 20 mM MES-histidine (His), pH 6.0, 0.1 mM CTAB, 0.025% HP-beta-CD, and 10% methanol. The investigation included a study of the effects of buffer pH, concentration of CTAB, type and concentration of organic additives, on the migration behavior, resolution and selectivity of the organic acids. The intra- and interday RSDs (n = 6) obtained for migration time and peak area were typically in the range of 0.12-2% and 0.5-4%, respectively. Linearity, detection limits, and repeatability were evaluated. In order to evaluate the application potential of the developed method, real samples from different sources were analyzed. The results demonstrate that CE-C(4)D is a versatile tool for analyzing organic acids in beverages, Chinese herbal medicines (CHM) and plants as it allows for their detection, identification, and quantification.