蔗渣纤维素-海藻酸钙-膨润土多孔微球的制备及其对罗丹明B吸附性能的研究

以蔗渣纤维素、海藻酸钠为三维网络框架,膨润土为吸附功能单元,采用金属离子交联法联合物理包载法制备蔗渣纤维素-海藻酸钙-膨润土多孔微球,研究其对罗丹明B吸附性能,探究其吸附机理。采用扫描电镜(SEM)、X射线衍射(XRD)和热重(TG)等表征手段分别对多孔微球形貌、晶相和热稳定性进行表征。结果表明：在固液比2g/L,染料溶液pH=3,体积为25mL,初始浓度为400mg/L,吸附温度为318K,吸附360min后,吸附量高达87.14mg/g。多孔微球吸附罗丹明B过程符合准二级动力学模型,罗丹明B在多孔微球吸附遵循Langmuir等温线吸附模型。吸附罗丹明B前后,多孔微球为类球形,具有一定孔隙结构;多孔微球中膨润土晶型结构无明显改变,且具有一定热稳定性。     

载当归羧甲基纤维素-海藻酸钠复合微球的制备和表征

采用W/O乳液法,在不同条件下,用Ca2+交联和戊二醛交联制备了羧甲基纤维素(CMC)-海藻酸钠(SA)复合微球。SEM结果显示,当m(CMC)∶m(SA)=1∶5、温度为60℃时,球形较好。采用FT-IR分析了复合微球的化学结构。对复合微球的溶胀率、药物包封率进行表征,结果显示复合微球在磷酸缓冲液中的溶胀率达到700%,且溶胀速度快。该复合微球对当归(ASD)具有较好的缓释作用。     

PPy/TiO2复合微球的制备及其吸附-紫外光催化性能研究

以盐酸为无机酸,采用原位聚合法制备出不同摩尔比的聚吡咯/二氧化钛(PPy/TiO_2)复合微球,以亚甲基蓝(MB)染料为目标污染物,考察了PPy/TiO_2复合微球的吸附-紫外光催化性能以及影响因素。结果表明:制备PPy/TiO_2复合微球的最佳条件为摩尔比10∶1,投加量为1.5g/L;提高反应温度有利于光催化效率的提升,但对吸附量影响小;在酸性条件下废水中MB的去除效果优于中性和碱性条件下的去除效果;影响因素优化后,经30min吸附和3h紫外光催化处理,MB的去除率可达99.1%;PPy/TiO_2复合微球对MB和孔雀石绿这2种离子染料均有较高的去除率;紫外光催化降解MB的反应符合Langmuir-Hinshelwood动力学模型;复合微球循环使用20次对MB的去除率依然可达到92.7%以上,说明PPy/TiO_2复合微球有极强的循环稳定性和应用潜力。     

海藻酸钠/多壁碳纳米管复合水凝胶球的制备及对次甲基蓝的吸附研究

以海藻酸钠(SA)、多壁碳纳米管(MWNTs)为主要原料,通过溶胶-凝胶法制备复合水凝胶球,研究了微球对次甲基蓝(MB)溶液的吸附脱色效果。结果表明:当海藻酸钠溶液的加入量为2%、多壁碳纳米管的含量为0.15%时,120h后微球对次甲基蓝的吸附率可达83.46%。     

埃洛石纳米管热敏复合微球的制备及吸附性能

通过种子乳液聚合法在埃洛石纳米管(HNTs)表面包覆聚N-异丙基丙烯酰胺(PNIPAM),制备了HNTs/PNIPAM热敏复合微球。利用红外光谱仪(FT-IR)、粒度仪、比表面积测试仪(BET)对复合微球的结构和形貌进行了分析,通过分光光度法研究了复合微球对亚甲基蓝的吸附性能。结果表明,复合微球粒径约为1.8μm,比表面积约为18.2m2/g;其体积相转变温度约为33.6℃,具有热敏性。实验条件下,复合微球对溶液中亚甲基蓝(MB)的吸附率为99.4%,吸附MB后的复合微球在室温下再生60min后,MB解吸附趋于平衡,进一步在40℃进行解吸附时,微球中MB可以进一步释放。     

海藻酸钠/纤维素水凝胶球的制备与应用

利用基于p H值反转的落球法制备出不同质量分数的纤维素和海藻酸钠复合水凝胶球,并采用扫描电子显微镜(SEM)和傅里叶变换红外光谱(FTIR)对凝胶样品的形貌和化学态进行表征。结果表明海藻酸钠含量≤50%时凝胶球可以保持稳定的球形结构,内部为纤维链交叉聚集的三维网络多孔结构。复合凝胶球对亚甲基蓝、金胺O和臧红T等阳离子染料有着良好的吸附效果,含有50%海藻酸钠凝胶球对亚甲基蓝的吸附量为163.36 mg/g,吸附过程满足准二阶动力学方程,经过5次吸附脱附实验后仍然保持初始81%的吸附量。因此,该复合凝胶球可以作为一种低成本的生物吸附剂用于染料处理领域。     

具有核壳结构的氧化石墨烯/聚醚砜微球的制备及其毒素吸附性能

氧化石墨烯(GO)是一种很具应用潜力的石墨烯纳米材料,由于具备超大的比表面积和表面带电的特性,在对水污染物吸附方面具有优异的性能。然而,氧化石墨烯良好的水中分散性以及纳米尺寸特性,使其在应用过程中难以控制和回收。文中针对此问题,采用聚醚砜对氧化石墨烯进行包覆,通过液-液相分离方法制备出具有核壳结构的氧化石墨烯-聚醚砜复合微球。选用阳离子染料亚甲基蓝(MB)作为被吸附物来考察微球的吸附量、吸附动力学以及吸附热力学。研究发现,该复合微球对MB的最大吸附量高达363.21mg/g,并且可通过提高壳层的亲水性来增大微球的吸附速率。     

KCl改性海藻酸钠微球的吸附性能

目的 为了提高海藻酸钠微球的吸附容量和脱色率。方法 以海藻酸钠为原料，共混聚乙烯醇、沸石制备得到一种海藻酸钠微球，在此基础上进行KCl改性，制备得到海藻酸钠微球吸附剂KSPZ(KCl?SA?PVA?zeolite Microsphere)。通过单因素试验得到最佳吸附条件，对吸附前、后样品进行表征，并探究其吸附机理。结果 得到KSPZ的最佳吸附条件，即pH值为9，吸附剂添加量为1 g/L，吸附时间为6 h，亚甲基蓝(Methylene blue，MB)的初始质量浓度为500 mg/L，此时吸附容量为426.63 mg/g，脱色率为85.33%。通过扫描电子显微镜观察到MB被成功吸附在KSPZ表面，其傅里叶红外光谱说明KSPZ与MB之间存在氢键和静电相互作用，且吸附过程符合准二级动力学、Langmuir型等温吸附模型，表明其吸附过程为物理扩散，并伴随着化学吸附。结论 KSPZ是一种稳定性好、脱色率高的吸附剂，为海藻酸钠复合材料在染料废水处理中的应用提供了理论指导。     

原位聚合法制备纳米核-壳型PS-CHO@RGO复合微球及其催化活化过硫酸氢钾降解亚甲基蓝

还原氧化石墨烯(RGO)具有比表面积大、电子传输效率高、吸附速率快等优点,在处理油污、重金属离子、有机染料等领域均有应用,但由于自团聚而造成的分散性差等问题限制了其进一步应用。采用原位聚合法制备纳米核-壳型聚苯乙烯醛基微球(PS-CHO)@RGO复合微球。利用TEM、Raman、XRD、XPS及绝缘电阻测试仪对PS-CHO@RGO复合微球的形貌及理化性能进行表征。以亚甲基蓝(MB)为目标污染物,探究了PS-CHO@RGO复合微球在少量过硫酸氢钾(PMPS)存在下的氧化活性,并提出了降解机制。结果表明,RGO片层均匀包覆于PS-CHO微球表面,有效改善了分散性。制备所得PS-CHO@RGO复合微球的渗透阈值低,导电网络完善。降解实验中,PS-CHO@RGO复合微球可以激发PMPS生成硫酸根自由基(SO_4~-·),MB的氧化降解率显著提高,60 min内可达98%以上。PS-CHO@RGO复合微球同时表现出良好的稳定性,通过高速离心的方式实现循环利用。     

聚丙烯/海泡石复合材料的制备、表征及力学性能

采用十六烷基三甲基溴化铵(CTAB)对海泡石(SEP)进行有机化改性,制备有机改性海泡石(OSEP)和聚丙烯(PP)/SEP复合材料。经SEM、XRD、FT-IR、TG和CA分析,表明海泡石表面吸附有一定量的季铵盐分子,并且部分季铵盐分子顺利进入海泡石孔道。经TG分析,800℃时OSEP的残留质量比SEP提高17.63%。复合材料的拉伸、冲击和WAXD测试表明,OSEP的加入减少了β晶型的含量,增加了α晶粒的含量,有效提高了复合材料的力学性能。当OSEP含量为1.5%时,能获得力学性能较优的复合材料。     

纳米Fe3O4@茶渣/海藻酸钙磁性复合材料制备及其对亚甲基蓝的吸附性能与吸附机制

采用离子共沉淀技术在茶渣(Tea waste, TW)表面沉积纳米Fe₃O₄粒子(TW@nano-Fe₃O₄),用溶胶凝胶法制备茶渣@纳米Fe₃O₄/海藻酸钙(TW@nano-Fe₃O₄/CA)磁性复合微球,通过SEM、XPS、XRD、振动样品磁强计(VSM)及万能试验机对材料结构和性能进行了表征与测试,并研究了其对水溶液中亚甲基蓝(Methylene blue, MB)的吸附性能与机制。结果表明,TW@nano-Fe₃O₄/CA复合微球磁性响应明显,粒径为1.2~1.7 mm。微球表面粗糙、褶皱,内部为疏松多孔道结构。随TW@nano-Fe₃O₄含量增加,微球粒径增加,磁响应增强,但对MB的吸附量缓慢下降;TW@nano-Fe₃O₄/CA微球对MB的吸附动力学数据与准二级动力学方程拟合较好,等温吸附过程符合Langmuir模型,对MB的吸附过程是自发性和熵减小的放热过程。在303 K下,质量配比为TW@nano-Fe₃O₄∶CA=4∶1的复合微球对MB的Langmuir最大吸附量为272.5 mg·g^-1,比TW提高86.7%,并具有良好的再生与循环使用性能。     

Absorbents based on maleic anhydride-modified cellulose fibers/diatomite for dye removal

In this work, an absorbent consisting of the maleic anhydride-modified cellulose beads combined with alkali-treated diatomite (MCDBs) was prepared in an attempt to remove basic dyes. An appropriate amount of calcium carbonate was added during the formation of MCDBs to increase the pore structure under an acidic condition. The synthesized MCDBs were characterized with FT-IR, TGA, and BET. The degree of carboxylation of MCDBs was quantified using a polyelectrolyte titration method. The removal of basic dyes such as methylene blue (MB) and methyl violet (MV) from aqueous solution was systematically investigated. The influence of pH, shaking time, and temperature on the removal process was identified. The results indicated that the MCDBs had a strong adsorption capacity toward basic dyes. The adsorption capacity increased from 51.6 to 116.6 mg/g for MB, depending on the initial concentration of the dye. A similar trend was also found for MV, i.e., adsorption increased from 30.5 to 61.1 mg/g. The experimental data fitted two kinetic models; the results demonstrated that the adsorption of MB and MV onto the MCDBs fits the pseudo-second-order model very well. The removal efficiencies of the basic dyes under the optimal conditions were up to 97.5 %. The adsorption data were also fitted using Langmuir, Freundlich, and Temkin isotherms, separately. It was found that the adsorption process for the basic dyes was better described by the Langmuir isotherm model.     

Characterization of new sorbent constructed from Fe3O4/chitin magnetic beads for the dynamic adsorption of Cd2+ ions

Novel magnetic chitin (CM) beads were successfully prepared by in situ synthesis of Fe₃O₄ nanoparticles in regenerated chitin beads (Ch beads) for the packing fixed-bed columns. The interpenetrated porous structure in the regenerated Ch beads at the swollen state served as templates for the inorganic nanoparticle preparation. The morphology and structure of the hybrid nanomaterials were characterized with scanning transmission electron microscopy, transmission electron microscopy, thermal gravimetry analysis, X-ray diffraction, and Fourier transform infrared spectroscopy, and the Cd²⁺ ion adsorption capacity of the CM beads was determined by UV–Vis spectrophotometry. The results revealed that the CM beads exhibited efficient adsorption of Cd²⁺ ions in the aqueous solution, as a result of the microporous structure, large surface area, and affinity for metal ions. The equilibrium process of this fixed-bed column was well described by Thomas and Bohart–Adams model, indicating that the external mass transfer was the rate-limiting process at the beginning of adsorption. The adsorption equilibrium was better described by the bed depth–service time model, indicating that the Cd²⁺ uptake could be controlled by external mass transfer at the beginning and intraparticle diffusion at a later stage of the adsorption. The CM beads loaded with the Cd²⁺ could be regenerated and reused easily. The CM beads should have potential applications in the chromatography packing and adsorbent both at the laboratory and industrial scales.     

Preparation of a novel Fe3O4/graphite oxide nanosheet/citric acid-crosslinked β-cyclodextrin polymer composite to remove methylene blue from water

A novel composite basing on the Fe₃O₄ nanoparticle, the graphite oxide nanosheet (GON), and the citric acid-crosslinked β-cyclodextrin polymer (CA-CDP) was prepared for the purpose of removing the methylene blue (MB) dye from water. The structure of the resultant Fe₃O₄/GON/CA-CDP composite was investigated by the scanning electron microscope, the two dimensional EDS mapping, the thermal gravimetric analyzer, the Fourier transform infrared spectroscope, the wide angle X-ray diffraction, the X-ray photoelectron spectroscope, and the zeta potential measurement. The Fe₃O₄/GON/CA-CDP composite not only had a good MB adsorption capacity of 173 mg/g but also a high saturation magnetization of 36.4 emu/g. It was found that the MB adsorption capacity of the Fe₃O₄/GON/CA-CDP composite increased with the increasing initial MB solution pH value especially in the low-pH-value range. Moreover, the MB adsorption mechanism, the MB adsorption isotherm, and the MB adsorption kinetic of the Fe₃O₄/GON/CA-CDP composite were investigated. It was found that 1) the good adsorption ability of the Fe₃O₄/GON/CA-CDP composite for the MB dye originated from the electrostatic attraction, the Lewis acid-Lewis base interaction, the host-guest supramolecular interaction and the π-π interaction, and 2) the MB adsorption isotherm and the MB adsorption kinetic of the Fe₃O₄/GON/CA-CDP composite could be well explained by the Sips model and the intraparticle diffusion model, correspondingly.     

Kinetics of mercury ions removal from synthetic aqueous solutions using by novel magnetic p(GMA-MMA-EGDMA) beads

Poly(glycidylmethacrylate-methylmethacrylate), p(GMA-MMA-EGDMA), magnetic beads were prepared via suspension polymerization in the presence of ferric ions. The epoxy groups of the beads were converted into amino groups via ring opening reaction of the ammonia and, the aminated magnetic beads were used for the removal of Hg(II) ions from aqueous solution in a batch experiment and in a magnetically stabilized fluidized bed reactor (MFB). The magnetic p(GMA-MMA-EGDMA) beads were characterized with scanning electron microscope (SEM), FT-IR and ESR spectrophotometers. The optimum removal of Hg(II) ions was observed at pH 5.5. The maximum adsorption capacity of Hg(II) ions by using the magnetic beads was 124.8+/-2.1 mgg(-1) beads. In the continuous MFB reactor, Hg(II) ions adsorption capacity of the magnetic beads decreased with an increase in the flow-rate. The maximum adsorption capacity of the magnetic beads in the MFB reactor was 139.4+/-1.4 mgg(-1). The results indicate that the magnetic beads are promising for use in MFB for removal of Hg(II) ions from aqueous solution and/or waste water treatment.     

Grass waste: A novel sorbent for the removal of basic dye from aqueous solution

The aim of the present work was to investigate the feasibility of grass waste (GW) for methylene blue (MB) adsorption. The adsorption of MB on GW material was studied as a function of GW dose (0.05–1.20 g), solution pH 3–10, contact time and initial concentration (70–380 mg/L). The influence of these parameters on the adsorption capacity was studied using the batch process. The experimental data were analyzed by the Langmuir and Freundlich isotherms. The adsorption isotherm was found to follow the Langmuir model. The monolayer adsorption capacity was found to be 457.640 mg/g. The kinetic data were fitted to the pseudo-first-order and pseudo-second-order models, and were found to follow closely the pseudo-second-order kinetic model. The results revealed that GW adsorbent is potentially low-cost adsorbent for adsorption of MB.     

Adsorption of a cationic dye (methylene blue) onto spent activated clay

The adsorption characteristics of methylene blue (MB) onto spent activated clay (SAC), a waste produced from an edible oil manufacturer was investigated. Results showed that the adsorption increased with increasing MB concentration, temperature, and pH. The adsorption equilibrium data was well fitted by multilayer adsorption isotherm. The maximum adsorption capacities for MB ranged from 0.94x10(-4) to 3.41x10(-4)mol/g between 5 and 45 degrees C. Thermodynamic parameters suggest that the adsorption is spontaneous and endothermic. We proposed a modified double exponential equation accounting both with chemical and mathematical point of view to describe the adsorption kinetic data. The increases of mass transfer and adsorption capacity were mainly attributed to the interlayer of the SAC expanding at higher temperature. An activation energy of 13.5 kcal/Kmol was determined suggesting that the adsorption involved a chemical reaction mechanism.     

Adsorptive features of poly(glycidyl methacrylate-<Emphasis Type="Italic">co</Emphasis>-hydroxyethyl methacrylate): effect of porogen formulation on heavy metal ion adsorption

Preparation of crosslinked copolymer beads based on glycidyl methacrylate (GMA), 2-hydroxyethyl methacrylate (HEMA), and divinyl benzene for the use of heavy metal adsorption has been investigated. In our study, a series of porous copolymer beads were synthesized by suspension polymerization in the presence of porogens, 1-dodecanol, toluene, and heptane at different dilutions. The effect of the porogens on the surface appearance and the porous structure of copolymer beads was studied by scanning electron microscopy and BET method. Diethylene triamine chelating copolymers were obtained through a reaction between amine groups of diethylene triamine and epoxide pendant groups of GMA. Adsorption isotherm and quantitative analysis for adsorption capacity involving copper, chromium, manganese, cadmium, iron, and zinc ions were investigated using atomic absorption spectrophotometer. The adsorption was a function of types of metal ions, adsorption time, and solution properties including pH and metal concentration. Adsorption equilibrium was achieved in approximately 50 min with a maximum adsorption capacity at pH 5.0. The Langmuir isotherm was found to be well fitted on the adsorption behavior. The maximum metal adsorption capacities in single ion solution in mole basis were in the order Cu(II) > Cr(VI) > Mn(II) > Zn(II) > Cd (II) > Fe(II). It was found that introducing porogen in the polymerization mixture produced the copolymer beads with better adsorption capacity. The maximum Cu(II) adsorption capacity of chelating poly(GMA-co-HEMA) beads were 1.35 mmol/g (85.79 mg/g) measured from the beads prepared in the presence of 1-heptane with 50% dilution. Consecutive adsorption–desorption experiments showed that crosslinked poly(GMA-co-HEMA) micro-beads can be reused almost without any change in the adsorption capacity.     

Preparation and characterization of distillers’ grain based activated carbon as low cost methylene blue adsorbent: Mass transfer and equilibrium modeling

In this study, an orthogonal array design method was employed to optimize carbon preparation from distillers’ grain (DGAC). The physical and chemical properties of the produced DGAC were characterized using scanning electron microscopy (SEM), N₂ adsorption–desorption technique (Brunauer-Emmett-Teller, BET), and fourier transform infrared spectroscopy (FTIR). The BET surface area of DGAC was found to be 1430?m²/g, with average pore diameter of 2.19?nm. Batch experiments were carried out to study the adsorption of methylene blue (MB) onto DGAC. External mass transfer model, internal diffusion model, Boyd model and pseudo-second-order model were used to fit the adsorption kinetic process of MB adsorption onto DGAC. The results shows the external mass transfer model could only describe the adsorption for the initial 5?min, and later the internal diffusion in the pores of the carbon particles became a main resistance, chemisorption was also involved in the adsorption process. The adsorption equilibrium was described best by Langmuir isotherm with maximum adsorption capacity of 934.6?mg/g of MB at 55°C, thermodynamic studies confirmed that the adsorption of MB onto DGAC was spontaneous and thermodynamically favourable. These findings support the potential of using distillers’ grain as raw material to prepare well-developed porous texture adsorbent with huge MB removal capacity.