Adsorption of 2,2′-bipyridyl onto sepiolite,attapulgite and smectite group clay minerals from anatolia: The FT-IR and FT-Raman spectra of surface and intercalated species

The adsorption of 2,2-bipyridyl by natural sepiolite, attapulgite, hectorite, saponite and natural and ion exchanged (Mn, Fe, Co, Ni, Cu, Zn or Sn) bentonites has been investigated by FT-IR and FT-Raman spectroscopy. Spectroscopic results indicate that most of the adsorbed molecules are coordinated to either exchangeable cations (in the case of smectite group clays) or Lewis acidic centres (in the case of sepiolite and attapulgite) as bidentate ligands. The formation of monoanionic surface species has also been detected, to a relatively small extent. No physisorbed surface species has been observed. XRD patterns and UV-visible spectra of the samples are also recorded for additional information.Author for correspondence.     

凹凸棒黏土对燃煤PM2.5排放及团聚捕集特性影响

在固定床反应系统上考察凹凸棒黏土对燃煤可吸入颗粒物PM_2.5的排放及团聚捕集特性影响,分析凹凸棒黏土添加量以及添加凹凸棒黏土情况下燃烧气氛、燃烧温度和钙硫物质的量比等参数对燃煤PM_2.5的数量浓度、质量浓度以及团聚捕集率的影响规律。结果表明,煤燃烧过程中添加凹凸棒黏土可以显著降低PM_2.5排放浓度,凹凸棒黏土的添加量不宜超过3%(质量分数);空气气氛下燃烧产生的PM_2.5多于O₂/CO₂气氛;随着钙硫物质的量比的增大,PM₁的质量浓度减小,但PM_1~2.5的质量浓度增大,颗粒物的粒径有向更大粒径转移的趋势;燃烧温度的升高会促进PM_2.5各粒径范围颗粒物的生成,降低了凹凸棒黏土对PM_2.5团聚捕集率。     

Preparation of polyvinylidene fluoride/modified attapulgite composite ultrafiltration membrane

Some modified attapulgites (ATPs), such as surface modified by amino (‐NH₂) or polymethylmethacrylate (PMMA) were used to prepare polyvinylidene fluoride (PVDF)/ATP composite ultrafiltration membranes by nonsolvent induced phase separation method. The excellent compatibility between PMMA or amino and PVDF may promote the dispersion of ATP in PVDF. The thermal, mechanical, hydrophilic, and micro‐morphology of the composite ultrafiltration membranes were characterized. The results showed that with the addition of the modified ATP, the properties of the membranes, such as mechanical and hydrophilic, were improved. When the content of ATP‐g‐PMMA was 2%, the overall performance of the PVDF composite membranes was the best.     

Enhanced Adsorption of Sulfonamides by Attapulgite-Doped Biochar Prepared with Calcination

The extensive use of sulfonamides seriously threatens the safety and stability of the ecological environment. Developing green inexpensive and effective adsorbents is critically needed for the elimination of sulfonamides from wastewater. The non-modified biochar exhibited limited adsorption capacity for sulfonamides. In this study, the attapulgite-doped biochar adsorbent (ATP/BC) was produced from attapulgite and rice straw by calcination. Compared with non-modified biochar, the specific surface area of ATP/BC increased by 73.53–131.26%, and the average pore width of ATP/BC decreased 1.77–3.60 nm. The removal rates of sulfadiazine and sulfamethazine by ATP/BC were 98.63% and 98.24%, respectively, at the mass ratio of ATP to rice straw = 1:10, time = 4 h, dosage = 2 g∙L⁻¹, pH = 5, initial concentration = 1 mg∙L⁻¹, and temperature = 20 °C. A pseudo-second-order kinetic model (R² = 0.99) and the Freundlich isothermal model (R² = 0.99) well described the process of sulfonamide adsorption on ATP/BC. Thermodynamic calculations showed that the adsorption behavior of sulfonamides on the ATP/BC was an endothermic (ΔH > 0), random (ΔS > 0), spontaneous reaction (ΔG < 0) that was dominated by chemisorption (−20 kJ∙mol⁻¹ > ΔG). The potential adsorption mechanisms include electrostatic interaction, hydrogen bonding, π–π interaction, and Lewis acid–base interactions. This study provides an optional material to treat sulfonamides in wastewater and groundwater.     

Morphological analysis of bead–string shaped and core–shell attapulgite@polystyrene (ATP@PS) particles via emulsion polymerization

A convenient method for the preparation of bead–string shaped and core–shell attapulgite@polystyrene (ATP@PS) composite particles through emulsion polymerization from needle‐shaped attapulgite is reported. The pretreatment of attapulgite with cetyltrimethylammonium bromide (CTAB) in ultrasonic is essential for successful encapsulation and for creating strong interfacial interaction between attapulgite and polystyrene (PS). The different morphologies of the ATP@PS particles, bead–string shaped and core–shell shaped, obtained with different amounts of styrene charges, were characterized by transmission electron microscopy (TEM). Encapsulation mechanisms of the two morphologies were also developed. Copyright © 2007 John Wiley & Sons, Ltd.     

非皂基凹凸棒石润滑脂磨损修复机理研究

以表面有机改性的亚微米凹凸棒石粉体为稠化剂,稠化合成型基础油聚α-烯烃,制成3号非皂基润滑脂.采用SRV-Ⅳ型摩擦磨损试验机进行摩擦磨损试验,并利用SEM、EDS和XPS分析磨痕表面和截面的形貌,元素组成、分布与价态,以及物相组成.结果表明:非皂基凹凸棒石润滑脂在摩擦过程中能够在磨损表面形成由Mg、O、Fe、C和Si等元素组成的,含有多个物相的,厚度不均的复合修复层.最后,结合修复层形成过程,提出了修复层形成机理.     

Synthesis of Poly(butylene terephthalate)/Attapulgite Nanocomposites by In-Situ Polymerization and Its Crystallization Behavior

Poly(butylene terephthalate) (PBT)/attapulgite (AT) nanocomposites were prepared via in-situ polymerization without pre-modification of AT. By this method, PBT chains were successfully grafted onto the surface of AT, which was confirmed by Fourier transform infrared spectroscopy and thermogravimetric analysis. Scanning electron microscope examination indicated the uniform dispersion of AT nanoparticles in PBT matrix. The crystallization behavior of PBT/AT nanocomposites was investigated by X-ray diffraction patterns, differential scanning calorimetry, and step-scan differential scanning calorimetry. The non-isothermal crystallization processes were analyzed with the Avrami, Ozawa, and Mo methods. Crystallization activation energies of the samples were also determined by the Kissinger method. The results indicated that AT could act as a heterogeneous nucleating agent in PBT crystallization and lead to an acceleration of crystallization, while AT also acted as a physical hindrance to retard the transport of polymer chains to the growing crystals.     

A Kinetic Study on the Thermal Degradation of Polypropylene/Attapulgite Nanocomposites

In this work, a polypropylene (PP)/attapulgite nanocomposite was prepared via melt blending using a novel organically modified attapulgite (OATP). The thermal stability of PP/clay nanocomposites compared to pure PP was examined in nitrogen using a kinetic analysis. The kinetic parameters, including reaction order and activation energy (A and E _a) of the degradation process were determined by applying the Flynn‐Wall‐Ozawa method using derivative thermogravimetric (DTG) curves. At the same time, the effect of organic attapulgite on thermal decomposition of polypropylene matrix was analyzed. As a result, PP/OATP nanocomposites have slightly higher degradation temperature than that of the pure PP. The values of the reaction order of PP and PP/OATP nanocomposites are close to 1 in the nonisothermal degradation process. The activation energies of PP/OATP nanocomposites also increase slightly compared to the pure PP, thus it is suggested that the org‐attapulgite has little effect on the thermal stability of the pure PP.     

氨基硅烷偶联剂改性凹凸棒土的制备及其吸附性能

采用双氨基硅烷偶联剂KH-792对盐酸改性凹凸棒土(HATT)进行改性,使用FTIR、TGA、DSC、XRD和BET等对目标产物(KHATT)进行了表征。 研究了KHATT对模拟水样中Cr(Ⅵ)的吸附性能,系统考察了模拟水样中Cr(Ⅵ)的初始浓度、pH值、吸附时间及KHATT用量等因素对Cr(Ⅳ)去除率的影响。 结果表明,在KHATT用量为3 g/L、吸附时间为40 min、pH值为5.5的条件下,KHATT对Cr(Ⅵ)的去除率最高,达85.15%;且KHATT经再生后第4次的吸附量仍可达到第1次吸附量的90%以上。 对吸附的过程和机理进行了初步探讨。     

The sorption mechanisms of Th(Ⅳ) on attapulgite

The surface properties of intrinsic and activated attapulgite were studied using potentiometric titration.The sorption mechanisms of Th(IV) on intrinsic and activated attapulgite were investigated by employing surface complexation model and FITEQL 3.2 code.The results indicated that the sorption sites of intrinsic attapulgite involved in the sorption process were main ion exchange site(≡ XNa/K),strong site(≡ SsOH) and weak site(≡ SwOH),while only strong site(≡ SsOH) and weak site(≡ SwOH) were predominant fo...