改性凹凸棒土对水中抗生素的吸附作用

介绍改性凹凸棒土对水中阿莫西林和氨苄西林的吸附效果,考察了吸附时间、初始浓度、pH对改性凹凸棒土吸附抗生素的影响。结果表明,阿莫西林和氨苄西林在120min左右吸附达到平衡,在pH值为3的条件下吸附效果最佳。吸附过程符合伪二级动力学方程,Langmuir模型比Freundlich模型和Temkin模型更适合描述2种抗生素在改性凹凸棒土上的吸附行为。改性凹凸棒土对阿莫西林和氨苄西林的吸附过程是吸热过程,提高温度有利于促进吸附的进行。     

硫酸与氯化铝复合改性活性氧化铝吸附除氟研究

采用硫酸与氯化铝复合方法对活性氧化铝进行了改性,研究了改性活性氧化铝吸附动力学特征及主要影响因素,并测定了改性前后活性氧化铝的比表面积、孔容孔径和元素含量等,初步探讨了改性除氟的机理。结果表明,改性吸附剂对水中氟的吸附动力学符合拟2级吸附速率方程,其吸附行为更符合Langmuir等温线的拟合,即吸附为单分子层吸附,其最大吸附容量为6.46 mg/g,是未改性活性氧化铝的4.4倍;改性活性氧化铝的适宜pH为6~7,竞争离子由弱到强的的影响顺序为NO3-≈Cl-SO42-H2PO4-HCO3-HPO42-CO32-;BET和XRF分析表明,改性活性氧化铝除氟主要靠离子交换作用。     

颗粒化铁-铝-铈纳米吸附剂的除氟性能

采用在流化床中喷雾包覆方法将纳米吸附剂包覆在玻璃珠表面制备颗粒化吸附剂,考察了所制颗粒化纳米铁-铝-铈复合氧化物吸附剂在含氟水中的除氟性能. 结果表明,含氟初始浓度为10 mg/L时,颗粒化吸附剂的吸附速率符合拟一级反应动力学模型,吸附等温线符合Langmuir吸附模型,饱和吸附量达5.9 mg/g. 吸附容量随含氟水初始pH值升高而降低,吸附过程中溶液pH值逐渐趋近于中性;含氟水中其他阴离子对F-的吸附存在不同程度的竞争,竞争离子的影响顺序为NO3-"Cl-相似文献   

凹凸棒土的改性及其对己烷异构体的吸附性能

采用十六烷基三甲基溴化铵和β-环糊精对凹凸棒土进行改性,利用红外光谱和比表面积对改性的凹土进行表征,并通过静态和动态吸附实验,研究了凹土对己烷异构体的吸附行为,考察了吸附时间、吸附温度、流速等对吸附性能的影响。实验结果表明,凹土对己烷异构体的吸附量随吸附时间的延长和吸附温度的下降而增大,相同条件下正己烷在凹土上的吸附量大于异己烷;经过有机物改性后的凹土对己烷异构体的吸附性能优于原土,十六烷基三甲基溴化铵改性后的凹凸棒土对正己烷的吸附量可达到224 mg/g。己烷异构体在凹凸棒土上的吸附等温线符合二级动力学方程模型。     

凹凸棒土对水中结晶紫吸附行为的研究

文章主要以凹凸棒土为吸附剂,结晶紫为污染物进行吸附试验。分别研究了吸附等温线、吸附剂的投加量及吸附时间对吸附结果的影响。实验结果表明,凹凸棒土对水中结晶紫的吸附以Langmuir吸附模型为主,当凹凸棒土的投加量为20 mg时吸附时间为180 min时,吸附效果最好。     

改性凹凸棒土的制备及其对SO_2气体的吸附

利用盐酸对凹凸棒土进行改性,改性过程中用正交实验法研究了盐酸改性凹凸棒土的最佳条件,实验证明:盐酸浓度为1 mol/L,盐酸浸泡时间为1 h,热活化温度为250℃时凹凸棒土的改性效果最好。然后将改性好的凹凸棒土制作成复合分子筛,用以吸附SO_2气体,并比较其吸附效果的优劣。实验发现:改性后的凹凸棒土、活性炭、硅烷偶联剂、4A分子筛和氧化铝混合制得的复合分子筛吸附性能最佳。并对凹凸棒土、改性凹凸棒土和复合分子筛的BET、XRD、红外光谱和热重分析进行了测试。结果表明:凹凸棒土的复合分子筛对于吸附SO_2气体具有很好的效果。     

粉煤灰负载水合氧化铁处理含磷(V)废水

对粉煤灰负载水合氧化铁去除水中HPO42-的性能进行了实验研究,考察了吸附剂用量、HPO42-浓度、溶液pH值、溶液共存离子等因素对吸附的影响,分析了其在不同温度下的吸附等温线及对HPO42-的吸附动力学,结果表明,Langmuir和Freundlich方程能较好地描述吸附平衡,其吸附动力学符合Lagergren二级方程. 粉煤灰经过改性对HPO42-有很强的去除能力,在吸附剂用量8.0 g/L,pH=3的条件下,粉煤灰负载水合氧化铁对HPO42-的去除率可达97%. 共存离子浓度在5~30 mg/L时,SO42-, NO32-, CO32-和Cl-等对HPO42-的去除几乎没有影响,而SiO32-的存在则明显抑制HPO42-的去除.     

凹土处理造纸废水的技术研究

讨论了凹凸棒土的热处理改性方法,利用改性凹凸棒土对造纸黑液进行吸附脱色和降低COD性能研究,考察了改性温度,pH值、凹凸棒土投加量、吸附时间等因素的影响.结果表明：改性凹凸棒土对造纸黑液CODcr和色度有较好的去除能力,具有工业应用前景.     

Fe2O3/凹凸棒土吸附-光催化法处理间氯甲苯工业废水研究

采用酸化法对凹凸棒土进行改性,考察改性条件、投加量、吸附时间以及废水pH值等因素对吸附效果的影响。在盐酸浓度为4mol/L,煅烧温度为200℃时,在最佳吸附条件（改性凹凸棒土投加量0.500g/25mL,废水pH=4,吸附时间1h）下,吸附法处理染料中间体间氯甲苯废水,COD的去除率由改性前的2.2%提高到14.1%。采用浸渍法制备纳米Fe2O3/凹凸棒土复合催化剂并对其表征,XRD分析结果表明,该复合物中光催化剂主要由α-Fe2O3构成;用凹凸棒土吸附-光催化氧化联合法处理间氯甲苯工业废水,在催化剂加入量为1.0g/L,pH=2,紫外光或太阳光照6h条件下,废水COD去除率分别达到59.2%和52.3%。复合催化剂的光催化活性要远大于纯纳米α-Fe2O3的光催化活性。     

啶虫脒/希夫碱改性凹凸棒土缓释体系的制备与性能

采用后接枝方法制备希夫碱铜离子配合物改性凹凸棒土（Cu2 -Sal-ATP）,采用浸渍法制备啶虫脒/凹凸棒土（ATP）缓释体系。利用FTIR、XRD、N2吸附-脱附、SEM和DSC 对改性凹凸棒土的结构进行了表征,并探究了改性凹凸棒土对农药啶虫脒的吸附行为和缓释体系的释药行为。结果表明,啶虫脒是以非晶相存在于改性凹凸棒土中,药物装载未改变载体的结构。有机改性提高了凹凸棒土对药物的载药量,且经希夫碱铜离子配位改性体系的载药量最高,其吸附行为符合准二级动力学模型。希夫碱铜离子配位改性凹凸棒土载药体系的缓释效果优于相应的希夫碱改性凹凸棒土（Sal-ATP）体系,载药体系的释药行为可用Korsmeryer-Pappas动力学模型来描述。     

Cu2+、Cd2+、Zn2+在高炉水淬渣上的竞争吸附特性

利用等温吸附法考察了高炉水淬渣对Cu²⁺、Cd²⁺、Zn²⁺的单组分吸附和竞争吸附性能。结果表明,单一组分吸附时,金属离子吸附等温线属于“H”形等温线,吸附平衡符合Langmuir吸附等温模型,高炉水淬渣吸附的顺序为Cu²⁺ >Cd²⁺ >Zn²⁺,这与重金属离子电负性、水合离子半径及荷径比等有关。当加入竞争离子后,Cu²⁺的吸附等温线基本维持原来形状,且仍旧与Langmuir吸附等温模型比较相符,而Cd²⁺ 和Zn²⁺的吸附无法与现有等温吸附模型很好地拟合,等温线的形状由于竞争作用也与传统的等温线均不相同,同时各金属离子的吸附量都比单组分的吸附量降低了。吸附动力学过程先是一个快速阶段,然后进入慢速阶段。无论是单组分还是竞争条件下,伪二级动力学方程拟合结果较好,说明高炉水淬渣与Cu²⁺、Cd²⁺、Zn²⁺之间的吸附过程主要是以化学吸附为主。     

Comparison of adsorption equilibrium of glycyrrhizic acid and liquiritin on C18 column

The adsorption isotherms of glycyrrhizic acid (GA) and liquiritin (LQ) on a C₁₈ column were compared and the competitive adsorption of the two compounds was investigated. The experimental parameters in the equilibrium isotherms were estimated by linear and nonlinear regression analyses. The adsorption equilibrium data were correlated into the linear, Langmuir, competitive Langmuir, Freundlich, and Langmuir–Freundlich isotherm models. Over a moderate concentration range, the competitive Langmuir isotherm provided the best fit to the experimental data. The regression coefficients of the competitive Langmuir adsorption isotherms were 0.9754 and 0.9855 for the mixtures of GA and LQ, respectively. The coefficients obtained for the five isotherm models confirmed the superiority of the competitive Langmuir isotherm for analyzing the adsorption data of solutes.     

凹凸棒石吸附水溶性染料的热力学研究

通过静态吸附实验,研究凹凸棒石对水溶液中阳离子桃红FG、亚甲基蓝和直接耐酸大红4BS的吸附热力学特性,测定了298～328K范围内的吸附等温线。结果表明：在水溶液中3种染料在凹凸棒石上的吸附均符合Langmuir等温吸附方程。凹凸棒石对水溶液中的阳离子桃红FG和亚甲基蓝的吸附是一个吸热过程,而对直接耐酸大红4BS的吸附是放热过程。根据热力学函数关系计算出阳离子桃红FG、亚甲基蓝和直接耐酸大红4BS在凹凸棒石上的吸附焓变分别为0．49,0．26kJ／mol和-19．68kJ／mol。吸附Gibbs自由能变在-27．48～-31．21kJ／mol之间,表明凹凸棒石对3种水溶性染料的吸附是一自发的过程。凹凸棒石吸附3种水溶性染料均是熵增过程。     

Mechanism of the Adsorption of Ammonium Ions from Aqueous Solution by a Chinese Natural Zeolite

Abstract

The adsorption of ammonium ions onto a Chinese natural zeolite in an agitated batch adsorber was studied. A trial‐and‐error non‐linear method was developed to examine two widely used isotherms, the Langmuir and Freundlich. The data gained from the adsorption system fitted the Freundlich isotherm better. An ion exchange model, describing the relationship among the total metal ions in the solution, NH₄ ⁺ removed from the solution, and ions initially released from the zeolite, was developed for the adsorption system. In addition, a parameter of the ion exchange potential was defined to describe the adsorption mechanism. Ion exchange was the main mechanism that accounted for the adsorption of ammonium ions onto the Chinese natural zeolite.     

Hydrogel beads based on carboxymethyl cellulose for removal heavy metal ions

Environment‐friendly carboxymethyl cellulose (CMC) hydrogel beads were successfully prepared using epichlorohydrin (ECH) as a crosslinking agent in the suspension of fluid wax. There was an ether linkage formed between ECH and CMC, which was identified from bands in FTIR spectra of the prepared hydrogel. The prepared hydrogel beads with diameters about 4 mm were apparently spherical and fully transparent. The X‐ray diffraction (XRD) spectra indicated that the adsorption of metal ion onto the oxygen atom of carboxyl group led to change in crystallinity patterns of hydrogels. The scanning electron microscope (SEM) images clearly showed that the hydrogels had an internal porous structure. The adsorption capacity increased as initial concentrations of metal ions and the pH value of metal ion solution increased. Freundlich and Langmuir isotherm models were employed to analyze the data from batch adsorption experiments. There are vey good correlation coefficients of linearized equations for Langmuir model, which indicated that the sorption isotherm of the hydrogel beads for metal ions can be fitted to the Langmuir model. The maximum adsorption amount of hydrogel beads for metal ions is 6.49, 4.06, and 5.15 mmol/g for Cu(II), Ni(II), and Pb(II), respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Prediction of the band profiles of the mixtures of the 1-indanol enantiomers from data acquired with the single racemic mixture

The adsorption isotherm data of R- and S-1-indanol and of their racemic mixture on cellulose tribenzoate were measured by frontal analysis. These data were then fitted to the Langmuir, the Bilangmuir, the Toth, and the Langmuir-Freundlich isotherm models. The single component data fitted well to both the Bilangmuir and the Toth models. Combined with the lumped pore diffusion model (POR) of chromatography, these isotherms were used to calculate overloaded elution profiles of the pure enantiomers. The calculated and the experimental profiles agree excellently in all cases if the former are derived from the Bilangmuir model. The competitive experimental data also gave excellent agreement with the Bilangmuir model. The simultaneous fit of all the data, for the single components and the racemic mixture, gave again superior agreement with the bilangmuir model. The overloaded elution profiles of samples of the racemic mixture calculated with the Bilangmuir isotherm model combined with the POR model of chromatography gave results in very good agreement with the experimental band profiles of large samples of the racemic mixture. This confirms that in numerous cases the whole set of competitive isotherms of two enantiomers can be derived from the experimental data obtained only with the racemic mixture.     

Effect of competitive interference on the biosorption of lead(II) by Chlorella vulgaris

Batch experiments were carried out to asses the effect of Cu(II) and Zn(II) on the biosorption of lead(II) ions by non-living Chlorella vulgaris. The uptake of Pb(II) was examined for single, binary and ternary solutions at different initial concentrations and different pH values. The experimental results showed that the uptake increased with increasing pH from 3.0 to an optimum value of 5.0. The biosorption of Pb(II) was found to be adversely affected by the presence of Cu(II) ions, while Zn(II) ions seemed to have negligible effect on the process. The equilibrium data were fitted to four isotherm models: Langmuir, Freundlich, Sips and Dubinin–Radushkevich; the Sips isotherm gave the best fit for the data. Modeling of the controlling mechanisms indicated that both intrinsic kinetics and mass transfer played major roles in controlling the process. A new dimensionless parameter, Ψ, was defined to asses the relative contributions of the two mechanisms to the biosorption of lead(II). Mass transfer seemed to be the dominant mechanism at low initial lead(II) concentrations, while intrinsic kinetics dominates at high concentrations.     

Generalization of thermodynamic Langmuir isotherm for mixed-gas adsorption equilibria

This work presents a comprehensive thermodynamic model for both pure component isotherms and mixed-gas adsorption equilibria. A generalization of thermodynamic Langmuir isotherm, the proposed model assumes competitive adsorption of multiple adsorbates on adsorbent surface for mixed-gas adsorption equilibria, and it applies an area-based adsorption nonrandom two-liquid activity coefficient model in the activity coefficient calculations for the adsorbate phase. The resulting generalized Langmuir isotherm properly captures both surface loading dependence and adsorbate phase composition dependence for mixed-gas adsorption equilibria. The model is validated with accurate representations of gas adsorption equilibrium data for varieties of unary, binary, and ternary gas systems. The model results are further compared with those calculated from extended Langmuir isotherm and Ideal Adsorbed Solution Theory.     

Walnut shell supported nanoscale Fe0 for the removal of Cu(II) and Ni(II) ions from water

The walnut shell supported nanoscale zero‐valent iron (walnut‐nZVI) was prepared from sodium borohydride, iron(II) chloride tetrahydrate, and walnut shell by liquid phase chemical reduction and characterized by FTIR, TEM, and XRD. The composites were tested as adsorbent for the removal of Cu(II) or Ni(II) ions. The equilibrium data were analyzed by the Langmuir, Freundlich, Dubinin–Radushkevich, which revealed that Langmuir isotherm was more suitable for describing Cu(II) and Ni(II) ions adsorption than the other two isotherm models. The results indicated that the maximum adsorption capacity was higher than some other modified biomass waste adsorbents under the proposed conditions, were 458.7, 327.9 mg g^?1 for Cu(II) or Ni(II). The adsorption kinetics data indicated that the adsorption fitted well with the pseudo‐second‐order kinetic model. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43304.