Co(Ⅱ)在磁性埃洛石上的吸附行为研究

采用化学共沉淀法成功制备了磁性埃洛石,运用扫描电子显微镜(SEM)、红外光谱仪(FT-IR)、X射线衍射仪(XRD)和振动样品磁强计(VSM)等手段详细表征了改性前后埃洛石的结构和形态,并采用静态批量平衡法对Co(Ⅱ)在磁性埃洛石上的吸附行为和机理进行探究,考察了料液比、平衡时间、p H值和温度等因素对吸附的影响.实验结果表明:温度为50℃时,Co(Ⅱ)在磁性埃洛石上的最大吸附容量为17.5mg·g-1.p H7.5时,随着p H增加,吸附量增大;当p H=7.5时,吸附量达到最大;以后即使p H增大,吸附量也不会明显变化.动力学过程符合准二级动力学方程;热力学过程符合Langmuir吸附等温线;升高温度利于Co(Ⅱ)在磁性埃洛石上吸附.     

不同水分条件下铁基氧化物对土壤砷的稳定化效应研究

应用等温吸附试验及室内模拟培养的方法,研究了Fe2O3、Nano-Fe2O3和铁锰双金属氧化物(FMBO)等铁基氧化物对砷的吸附特性和对不同含水量土壤中砷的稳定化效应.从等温吸附试验结果来看,3种铁基氧化物对As(V)和As(Ⅲ)的吸附过程符合准二级动力学方程,12 h后基本达到吸附平衡,吸附等温线符合Langmuir方程,FMBO对As(V)和As(Ⅲ)的吸附容量显著大于Fe2O3和Nano-Fe2O3,且对As(Ⅲ)的饱和吸附容量大于As(V),能够起到氧化和吸附的双重作用.从对不同含水量土壤中砷的稳定化效果来看,Nano-Fe2O3和FMBO在风干和田间持水量土壤中均能达到90%以上的稳定化效率,显著高于Fe2O3;在土壤水分饱和条件下,FMBO的稳定化效率仍保持在93.5%以上,且能够将土壤中As(Ⅲ)氧化成As(V),而Fe2O3和Nano-Fe2O3分别仅为29.4%、81.4%.3种铁基氧化物的添加会使土壤中砷的结合态发生变化,Fe2O3、NanoFe2O3主要使砷由F1非专性吸附态和F2专性吸附态向F4结晶铁锰或铁铝水化氧化物结合态转变,添加FMBO主要向F3无定形或弱结晶铁锰或铁铝水化氧化物结合态转变.总体看来,在非饱和状态的土壤,Nano-Fe2O3和FMBO均为良好的稳定化材料,而对于长期淹水的稻田或地下水位较高的地区,或者由于降雨造成土壤滞水等情况,FMBO可以作为一种优良的稳定化材料用于土壤砷污染修复.     

废旧Zn-C电池-活性污泥炭的制备及对SO_2的吸附

以污水厂二次污泥为主要原料,掺杂不同量的废旧Zn-C电池电极材料,采用Zn Cl2活化法制备出废旧Zn-C电池-活性污泥炭,表征分析污泥炭样品的碘吸附值、BET、FT-IR、SEM-EDS和XRD,并进行了低浓度SO2气体动态吸附试验.试验结果表明,污泥与电池粉末质量比为3∶1时,污泥炭的碘吸附值和比表面积分别达到750.6 mg·g-1和708.5 m2·g-1,优于纯污泥炭;回归分析表明,污泥炭吸附低浓度SO2的速率可用班厄姆公式描述,吸附平衡表达式可用Freundlih方程、Langmuir等温方程式表达,而Freundlih方程拟和效果更好.     

磁性石墨烯吸附水中Cr(Ⅵ)研究

以氧化石墨和铁盐为原料,采用化学沉淀法制备出磁性石墨烯复合材料,运用静态吸附实验研究了吸附动力学、热力学、等温吸附模型以及不同因素如p H、温度、时间对Cr(Ⅵ)吸附的影响.结果表明,吸附动力学符合假二级动力学模型;与Freundlich模型相比,Langmuir模型更适合描述吸附过程.热力学参数为:ΔHθ=33.89 k J·mol-1,ΔSθ=120.15 J·(mol·K)-1,ΔGθ=-2.51 k J·mol-1(303 K),这表明吸附过程是吸热并且自发的.实验最佳p H值为2,升高温度和延长时间均有利于吸附的进行.初始Cr(Ⅵ)浓度为5 mg·L-1时,重复利用3次后吸附量由3.9 mg·g-1下降到2.1 mg·g-1.在磁铁存在的条件下吸附剂可轻易从溶液中分离出来,利用Na OH可使其再生,因此可作为去除Cr(Ⅵ)的良好吸附剂.     

热水环境中Na+活化斜发沸石吸附钙离子除硬过程研究

本实验以Na+活化天然斜发沸石为吸附剂模拟研究其在工业热水环境中对钙离子(Ca2+)吸附除硬,考察了吸附剂的活化/再生条件、溶液p H等影响因素,并对Ca2+吸附动力学和热力学行为进行了分析探讨.结果表明:1该吸附过程具有准二级动力学特征且更符合Langmuir吸附等温模型;2温度升高可有效提升Ca2+吸附效率,而对其最大吸附量影响较小;3过程属化学吸附且为自发、吸热的熵增反应;4建议溶液p H控制在6~10之间,且当初始Ca2+浓度小于20 mg·L-1时活化斜发沸石可再生高效使用9次以上.研究证明活化斜发沸石是一种工业热能动力系统高温在线除硬的理想吸附剂.     

铜在壳核结构磁性颗粒上的吸附:效能与表面性质的关系

为了揭示吸附剂的吸附效能与其组成、结构及表面性质之间的关系,本研究对两种壳核结构磁性颗粒Fe_3O_4/Mn O2与Fe-Mn/Mn O2的形貌特征、表面性质进行了系统表征,并对铜在磁性颗粒表面的吸附行为与机制进行了详细研究.表征结果表明磁核Fe_3O_4与Fe-Mn具有相似的尖晶石类晶体结构,包覆Mn O2后,晶体结构均未发生明显变化.但Mn的引入,增强了磁核与外壳间的结合作用,Fe-Mn比Fe_3O_4包覆MnO_2的量更多、更均匀,进而使Fe-Mn/Mn O2具有更高的比表面积与更低的等电点.吸附实验结果表明,Fe-Mn的最大铜吸附容量33.7 mg·g-1(pH 5.5)高于Fe_3O_4的17.5 mg·g-1(pH 5.5);包覆MnO_2以后,铜吸附性能显著增强,Fe-Mn/MnO_2最大铜吸附容量升高至58.2 mg·g-1(p H 5.5),为Fe_3O_4/MnO_2的2.6倍,且优于多数文献报道的磁性吸附剂.机制研究表明铜在Fe_3O_4/Mn O2与Fe-Mn/MnO_2的表面发生了特性吸附,形成了内层表面络合物.综上所述,磁性颗粒的吸附效能与其组成成分、形貌结构及表面性质之间具有显著的相关性.     

单宁酸铁吸附去除水中无机氮的性能与机制研究

通过批量吸附实验,研究了一种新型吸附材料——单宁酸铁吸附去除水中无机氮(NH+4-N、NO-2-N和NO-3-N)的效果及其吸附机制.结果表明,单宁酸铁对NH+4-N和NO-2-N具有优先选择性,当单宁酸铁与NH+4-N和NO-2-N的质量比为200时,NH+4-N和NO-2-N去除率均大于95%.运用吸附动力学模型、Weber-Morris方程、Langmuir和Freundlich方程进行实验数据拟合的结果表明,NH+4-N和NO-2-N在单宁酸铁表面分别进行单分子层和多分子层的吸附,其吸附过程符合二级动力学模型,并且颗粒外部扩散和表面吸附起主要的作用.NH+4-N与分布于单宁酸铁外表面的氧负离子通过静电作用结合,NO-2-N则与单宁酸铁中的铁离子通过静电作用和配位作用结合.本研究为单宁酸铁作为吸附剂的发展与应用提供了科学依据.     

Development and physicochemical characterization of a new magnetic nanocomposite as an economic antibiotic remover

Maghemite (ϒ-Fe₂O₃) nanoparticles were impregnated to nanoporous carbon obtained from tomato waste (TWNC). The prepared magnetic composite (MTWNC) was characterized and used to remove tetracycline (TC) from water and then easily be separated from the medium by a magnetic technique. The morphologies and surface chemistries of both magnetic and non-magnetic nanoporous carbons were studied by FTIR, XRD, SEM, SEM-EDX, VSM, BET surface area, proximate and elemental analysis determinations. Batch adsorption studies were carried out and the effects of pH, initial TC concentration, adsorbent dose, ionic strength and temperature were investigated. The adsorption kinetics of TC on MTWNC could be expressed well by the pseudo-second order model, and sorption isotherms were described by Langmuir equation with maximum adsorption capacity of 60.60 mg/g at pH 4 and 50 °C. Thermodynamic parameters showed that the adsorption of TC onto MTWNC was feasible, spontaneous and endothermic. Furthermore, the recyclability of the adsorbent was tested with 0.01 M NaOH solution, and the results show that the synthesized composite adsorbent could be employed repeatedly in wastewater treatment.     

Adsorptive removal of basic dyes from aqueous solutions by surfactant modified bentonite clay (organoclay): Kinetic and competitive adsorption isotherm

Cationic surfactant (Hexadecyltrimenthylammonium chloride) modified bentonite clay was prepared and systematically studied for its adsorption behavior as an efficient adsorbent for the removal of basic dyes such as methylene blue (MB), crystal violet (CV) and Rhodamine B (RB) from aqueous phase. Organo modified clay shows better capacity for the removal of three dyes. The adsorption process was found to be dependent on pH and initial dye concentration. The maximum dye sorption was found to be at a pH of 9.0 (99.99% for MB, 95.0% for CV and 83.0% for RB). The adsorption capacity for the dyes was found to be 399.74, 365.11 and 324.36 μmol/g for MB, CV and RB, respectively at 30 °C. The equilibrium uptake was attained within 240 min. The kinetic studies were revealed that sorption follows a pseudo-second-order kinetic model which indicates chemisorption between adsorbent and adsorbate molecules. Adsorption isotherm indicates non-energetically adsorption sites which fit with Freundlich isotherm model. The fitness of kinetics and isotherm models was evaluated by using HYBRID error analysis function. Competitive adsorptions of dyes were studied by using binary component systems.     

利用Cu-Fe复合金属氧化物净化水中的磷

研究了利用Cu-Fe复合金属氧化物净化水中磷的过程。实验结果表明,在吸附剂的制备过程中,加入Cu可以显著提高吸附剂对水中磷的净化效率,Cu的适宜加入量为Cu/Fe摩尔比1∶2。在磷净化过程中,p H值对Cu-Fe复合金属氧化物的净化效率有显著影响,较低的p H值有利于磷的净化;水中磷的净化率随吸附剂用量的增加而增加,适宜的投加量为0.2 g/100 m L;吸附剂对水中磷的净化速度较快,磷的吸附率在5 min内达到87.08%,吸附2 h达到平衡,磷的净化率为98.85%;Cu-Fe复合金属氧化物净化水中磷的吸附等温线符合Langmuir方程,磷的最大吸附量为11.36 mg/g。