膨润土深加工制备P型沸石

以廉价的膨润土为原料,分别进行了氢氧化钠水溶液高温活化和氢氧化钠碱熔活化制备P型沸石的实验,合成了两种结构不同的P型沸石,并对合成产品作了表征和物化性能测试.结果表明:碱法工艺具有资源利用率高,无废液排放等优点.合成的P型沸石性能比4A沸石优越,是理想的洗涤助剂替代品.     

Adsorption of humic acid onto pillared bentonite

Pillared bentonite, a clean and cost-effective adsorbent with high specific areas of 111.3 m²/g and high basalspacing of 1.98 nm, was prepared for the removal of humic acid from water. It is effective for the removal of humic acid with a high adsorption capacity of 537 mg/g, and adsorption is favored under acid conditions. Adsorption is dependent on ionic strength and dissolved NaCl enhanced adsorption. Over 97% removal was observed under natural pH conditions from humic acid solutions containing 10 mg/L Ca²⁺ or Mg²⁺, which suggests that pillared bentonite can be an effective adsorbent for the removal of humic acid for drinking water purification. Pillared bentonite can be regenerated with NaOH, and the regeneration efficiency reaches 83% and 85% when the concentration of NaOH reaches 0.025 and 0.05 mol/L. The mechanism for adsorption of humic acid to pillared bentonite is discussed.     

Adsorption behaviour of Cu and Cd onto natural bentonite

The adsorption behaviour of Cu²⁺ and Cd²⁺ onto bentonite was studied as a function of temperature under optimized conditions of amount of adsorbent, particle size, pH, concentration of metals, and shaking time. The adsorption patterns of metal ions onto followed the Langmuir, Freundlich and Dubinin-Radushkevich isotherms. This included adsorption isotherms of single-metal solutions at 298-333 K by batch experiments. The thermodynamic parameters such as variation of enthalpy ΔH, variation of entropy ΔS and variation of Gibbs free energy ΔG were calculated from the slope and intercept of lnK_o vs. 1 / T plots. The adsorptions were endothermic reactions. The results suggested that natural bentonite was suitable as sorbent material for the recovery and adsorption of metal ions from aqueous solutions.     

Adsorption of phosphates using transition metals-modified bentonite clay

ABSTRACT

Phosphorus is a micronutrient but when it exists in abundance, it can have detrimental environmental impact. Bentonite (Bent) modified with Fe, Co and Ni salts were synthesized and evaluated for adsorption of phosphate ions from water. Results indicated that metal-modified bentonite have lower crystallinity compared to the native bentonite. Batch adsorption experiments showed maximum adsorption capacities of 20.88, 46.95, 29.07 and 6.57 mg/g for Fe-Bent, Co-Bent, Ni-Bent and Bent, respectively. The pseudo-second-order kinetic model provided a better fit for all adsorbents. The competition effect of coexisting anions were not significant for Fe and Ni modified bentonite.     

Aqueous Phase Adsorption of Cephalexin onto Bentonite and Activated Carbon

The adsorption of cephalexin in aqueous solution has been investigated using bentonite and activated carbon as the adsorbents. Batch kinetics and isotherm studies were carried out to evaluate the effect of contact time, adsorbent dosage, pH, particle size, and temperature. Adsorption equilibrium data were well represented by the Langmuir and Freundlich isotherm models. The adsorption intensity was found to be increased as the aqueous phase pH increased, and had a maximum at pH = 6.1. The pseudo-first order, pseudo-second order, and intraparticle diffusion kinetic models were used to describe the kinetic data. The experimental data fitted very well with the pseudo-second-order kinetic model and also followed the simple external and intraparticle model.     

Adsorption of cadmium and zinc from aqueous solution on natural and activated bentonite

The adsorption of cadmium and zinc ions on natural bentonite heat-treated at 110°C or at 200°C and on bentonite acid-treated with H₂SO₄ (concentrations: 0·5 mol dm^?3 and 2·5 mol dm^?3), from aqueous solution at 30°C has been studied. The adsorption isotherms corresponding to cadmium and zinc may be classified respectively as H and L types of the Giles classification which suggests the samples have respectively a high and a medium affinity for cadmium and zinc ions. The experimental data points have been fitted to the Langmuir equation in order to calcualte the adsorption capacities (X_m) and the apparent equilibrium constants (K_a) of the samples; X_m and K_a values range respectively for 4·11 mg g^?1 and 1·90 dm³ g^?1 for the sample acid-treated with 2·5 mol dm^?3 H₂SO₄ [(B)-A(2·5)] up to 16·50 mg g^?1 and 30·67 dm³ g^?1 for the natural sample heat-treated at 200°C [B-N-200], for the adsorption process of cadmium, and from 2·39 mg g^?1 and 0·07 dm³ g^?1, also for B-A(2·5), up to 4·54 mg g^?1 and 0·45 dm³ g^?1 [B-N-200], for the adsorption process of zinc. X_m and K_a values for the heat-treated natural samples were higher than those corresponding to the acid-treated ones. The removal efficiency (R) has also been calculated for every sample; R values ranging respectively from 65·9% and 8·2% [B-A(2·5)] up to 100% and 19·9% [B-N-200], for adsorption of cadmium and zinc.     

膨润土吸附水中Cr(Ⅵ)的实验研究

研究了钠化膨润土对Cr6 的吸附行为,考察了溶液中Cr6 的初始质量浓度、吸附剂用量、pH、搅拌时间、温度、粒度等因素对膨润土吸附的影响.结果表明,钠化膨润土对于Cr6 的吸附在1h基本达到吸附平衡,吸附量随溶液pH的增大、温度的升高、膨润土粒度的增加以及溶液中Cr6 的初始质量浓度的增高而降低.在混合体系中,共存离子的存在影响金属离子的吸附效率,共存离子的质量浓度与Cr6 相近时,对Cr6 的吸附效果影响很大,其中,Zn2 的影响大于Pb2 ;共存离子的质量浓度远大于Cr6 时,Zn2 基本没有影响,Pb2 却能提高对Cr6 的吸附效率.     

膨润土对核素的吸附行为研究

介绍了内蒙古高庙子膨润土的EDXRF分析,得到了内蒙古高庙子膨润土的元素构成,并论述了近几年膨润土对核素的吸附行为研究,主要影响因素包括:pH值、吸附时间、温度、离子强度、无机离子、腐殖酸等。并对每种影响因素对不同核素的影响效果进行了总结。     

膨润土合成有机膨润土的研究

本文以辽宁抚顺膨润土为原料,对有机膨润土的合成进行了研究,并对所得产品进行了XRD、SEM、IR和DAT／TG等表征。     

Adsorption of Rhodamine B onto O-Carboxymethylchitosan-N-Lauryl

The adsorption of a cationic dye (rhodamine B; RB) on O-carboximethyl-N-acetylated (L-CMCh) in aqueous solution was investigated. The effect of the process parameters such as the contact time, pH, and temperature are reported. Both temperature and pH influence dye adsorption. To determine the adsorption capacity, the equilibrium adsorption data were analyzed by the Langmuir, Langmuir-Freundlich, and Redlich-Peterson isotherm models. The results showed better agreement with the Langmuir-Freundlich model than the other models. The maximum adsorption capacity of RB for L-CMCh was determined as 38.5 mg g^?1 at pH 8.5 and 25°C. The kinetic results follow a pseudo-second-order rate equation. The activation energy value for adsorption of RB on L-CMCh was found to be 52.0 kJ mol^?1. The negative values of Gibbs free energy and enthalpy show the adsorption to be spontaneous and exothermic. The negative value of the enthalpy for adsorption of RB onto L-CMCh shows the adsorption to be exothermic.     

膨润土负载壳聚糖吸附剂对苯酚的吸附性能研究

将壳聚糖与膨润土复合制得一种固体吸附剂(CCB),并用于水溶液中苯酚的吸附。详细研究了吸附体系中溶液pH值、苯酚起始浓度对吸附的影响,将吸附平衡数据用Langmuir和Freundlich方程进行对比分析。结果表明:温度为25℃的条件下,溶液pH值为4.0时,吸附容量最大,达到63.69 mg/g;吸附量随苯酚起始浓度的增大而增大,吸附过程符合Langmuir和Freundlich模型,其中Langmuir模型更为适合。     

多孔有机膨润土的制备及对水中硫化物的吸附研究

将膨润土与优质煤粉按一定的比例混合挤压成型,高温焙烧,用氯化十六烷基吡啶进行有机改性,制得了表面为阳离子的多孔有机膨润土.将改性土用于水中硫化物吸附试验,结果表明:最佳吸附条件为pH=8、温度30℃、改性土用量50 g/L、振荡4 h,吸附率达93.6%.     

锰改性膨润土深度处理含铅废水的试验研究

采用氯化锰对膨润土进行改性,并用于深度处理含铅废水,考察了吸附时间、溶液初始pH值及吸附剂投加量对Pb2+吸附率的影响。结果表明在原水中Pb2+的质量浓度为1 mg/L,pH值为6,吸附时间为40 min,吸附剂投加量为20 mg/L,混凝剂投加量为60 mg/L的条件下,Pb2+的吸附率达到95%以上,出水中Pb2+的质量浓度小于0.05 mg/L,满足GB 3838—2002《地表水环境质量标准》Ⅲ类标准的要求。     

膨润土有机改性及吸附性能研究

结合天然膨润土的层状结构以及阳离子型表面活性剂的正电性和疏水性,以十六烷基三甲基溴化铵(CTMAB)为改性剂,制得有机阳离子改性膨润土。研究了有机改性膨润土投加量、p H值、吸附时间及吸附温度对甲基橙模拟废水脱色率的影响。试验结果表明:有机改性膨润土的投加量为4 g/L,吸附时间为40 min,废水p H值为6.0,吸附温度为35℃时,有机改性膨润土对甲基橙模拟废水的脱色率可以达到98.1%。     

Effects of experimental variables on phosphate adsorption on bentonite

The adsorption process of phosphate ions on a bentonite from Almería (East-Andalucía, Spain) was studied at 30°C over a range of experimental conditions such as saline (0.1 M KCl) or non-saline medium, natural or calcium homoionic bentonite and different pH values. In order to calculate the adsorption capacities (X_m) of the samples, the experimental data points were fitted to the Langmuir equation. X_m values ranged from 0.42 μg P g^?1 for the natural sample in non-saline medium to 0.74 μg P g^?1 for the same sample in saline medium, the X_m value corresponding to the calcium homoionic bentonite sample being intermediate. At different pH conditions, X_m increased from 0.28 μg P g^?1 at a pH of 1.3 to 1.53 μg P g^?1 at a pH of 4.4, and then decreased to 0.42 μg P g^?1 at a pH of 8.7.     

Adsorption of Cu(II) and Cr(VI) onto Treated Shorea dasyphylla Bark: Isotherm,Kinetics, and Thermodynamic Studies

The efficacy of treated Shorea dasyphylla bark for Cu(II) and Cr(VI) adsorption was assessed in a batch adsorption system as a function of pH, agitation period, and initial metal concentration. The equilibrium nature of Cu(II) and Cr(VI) adsorption was described by the Freundlich, Langmuir, and Dubinin-Radushkevich isotherms. The maximum monolayer capacities of treated Shorea dasyphylla bark, estimated from the Langmuir equation were 184.66 and 42.72 mg/g for Cu(II) and Cr(VI), respectively. The experimental results were fitted using pseudo-first order, pseudo-second order and intraparticle diffusion kinetic models; the pseudo-second order showed the best conformity to the kinetic data. Thermodynamic parameters such as enthalpy change (ΔH°), free energy change (ΔG°) and entropy change (ΔS°) were determined by applying the Van't Hoff equation. The adsorption of Cu(II) and Cr(VI) onto treated Shorea dasyphylla bark was found to be spontaneous and exothermic. The adsorption mechanism was confirmed by means of Fourier transform infrared (FTIR) and Energy dispersive X-ray (EDX) spectroscopy. The dimensionless constant separation factor (R _L), indicated that treated Shorea dasyphylla bark was favorable for Cu(II) and Cr(VI) adsorption.     

改性膨润土吸附重金属离子的研究与应用进展

膨润土具有很强的吸附能力,通过对膨润土进行改性,可提高其对重金属离子的去除能力.国内外学者对改性膨润土用于含重金属离子污水的处理进行了广泛的研究.概述了膨润土改性制备方法和表征手段,讨论了影响改性膨润土吸附重金属离子的主要因素.对近年来国内外改性膨润土吸附水体中铬、镉、汞、铅、镍等重金属离子的应用研究进行了综述,并指出了改性膨润土用于重金属废水处理存在的问题和今后的研究方向.     

Removal of Nitrate from Water by Adsorption onto Zinc Chloride Treated Activated Carbon

Abstract

Adsorption study with untreated and zinc chloride (ZnCl₂) treated coconut granular activated carbon (GAC) for nitrate removal from water has been carried out. Untreated coconut GAC was treated with ZnCl₂ and carbonized. The optimal conditions were selected by studying the influence of process variables such as chemical ratio and activation temperature. Experimental results reveal that chemical weight ratio of 200% and temperature of 500°C was found to be optimum for the maximum removal of nitrate from water. Both untreated and ZnCl₂ treated coconut GACs were characterized by scanning electron microscopy (SEM), Brunauer Emmett Teller (BET) N₂‐gas adsorption, surface area and Energy Dispersive X‐Ray (EDX) analysis. The comparison between untreated and ZnCl₂ treated GAC indicates that treatment with ZnCl₂ has significantly improved the adsorption efficacy of untreated GAC. The adsorption capacity of untreated and ZnCl₂ treated coconut GACs were found 1.7 and 10.2 mg/g, respectively. The adsorption of nitrate on ZnCl₂ treated coconut GAC was studied as a function of contact time, initial concentration of nitrate anion, temperature, and pH by batch mode adsorption experiments. The kinetic study reveals that equilibrium was achieved within one hour. The adsorption data conform best fit to the Langmuir isotherm. Kinetic study results reveal that present adsorption system followed a pseudo‐second‐order kinetics with pore‐diffusion‐controlled. Results of the present study recommend that the adsorption process using ZnCl₂ treated coconut GAC might be a promising innovative technology in future for nitrates removal from drinking water.     

羟基铁铝柱撑膨润土在含铬废水处理中的应用

以FeCl3、AlCl3和Na2CO3配制柱化剂,以钠基膨润土为原料,制备了羟基铁铝柱撑膨润土,并研究了其作为絮凝剂对含Cr(Ⅵ)废水的处理效果.结果表明:羟基铁铝柱撑膨润土对Cr(Ⅵ)有很好的去除效果,羟基铁铝柱撑膨润土投加量、pH及搅拌时间对Cr(Ⅵ)的吸附有较明显的影响,其中羟基铁铝柱撑膨润土投加量的影响最为显著...     

膨润土在水处理方面的应用研究进展

介绍了膨润土的结构与基本性质,探讨了近年来改性膨润土在含重金属离子废水、有机废水及含磷废水中的应用研究进展,并指出目前膨润土在环境应用中存在的问题及应用前景。