Ammonia Removal from Aqueous Solutions by Iranian Natural Zeolite

Abstract

The capability of Iranian natural clinoptilolite for ammonia removal from aqueous solutions has been thoroughly studied. Both batch and continuous (column) experiments were carried out. The viability of this natural zeolite in reducing the leakage of ammonia to the environment through waste water streams was a main focus of this research. Through the batch experiments, the effect of process variables such as the size of zeolite particles, pH, and ammonia concentration of the feed solution on the kinetics of ammonia uptake were investigated. Ammonia removal occurred rapidly and within the first 15 minutes of contact time, a major part of ammonia was removed from the solution. An adsorption capacity about 17.8 mg NH₄ ⁺/g zeolite at feed ammonia concentration of 50 mg/L was obtained and the optimum range for pH was achieved about 5.5–7.6. The adsorption capacity of clinoptilolite in the continuous mode was about 15.16 and 15.36 mg NH₄ ⁺/g zeolite for the original and regenerated types of clinoptilolite, respectively, where feed ammonium concentration was 50 mg/L. Increasing the feed ammonium concentration to 100 mg/L did not reduce the capability of the column for its ammonium removal and up to a bed volume (BV) of 85, there was only less than 1 mg/L ammonium in the column outlet. Presence of cations such as Ca²⁺, Mg²⁺ and Na⁺ in the feed solution reduced the clinoptilolite adsorption capacity to about 11.68 mg NH₄ ⁺/g zeolite. Regeneration experiments were carried out using concentrated sodium chloride solutions, as well as tap water. Where tap water was used as the regenerant, gradual release of ammonium from exhausted clinoptilolite was observed.     

Adsorption of Ce(IV) Ions from Aqueous Solution by Silica Aerogels

The adsorption process of Ce(IV) ions from aqueous solution by the silica aerogels was studied. The silica aerogels with hydrophobicity were prepared by the sol-gel process, supercritical drying, and heat treatment. The SEM image and nitrogen adsorption-desorption isotherm show that the heat-treated silica aerogel was a co-continuous porous structure with high BET surface area and narrow pore size distribution. The adsorption of Ce(IV) ions onto the silica aerogels was found to be fitted well by pseudo-second-order kinetics and Langmuir isotherm model. The activation energy for Ce(IV) adsorption onto silica aerogels could be calculated to be about 17.88 kJ/mol, which implied that the attractive forces of adsorption were weak electrostatic forces accompanying most ion-exchange reactions. The thermodynamic parameters showed that the adsorption process was spontaneous and endothermic.     

ZSM-5沸石对水溶液中铅离子的吸附性能

研究了ZSM-5沸石对水溶液中铅离子（Pb^2＋）的吸附性能,考察了Pb^2＋初始浓度、吸附剂用量、pH值和吸附时间等因素对吸附的影响。结果表明：ESM-5沸石对水溶液中铅离子有较好的去除效果,当其用量为40g／L时,水溶液中铅离子的吸附去除率达到96．09％;吸附过程在180min时达到吸附平衡;溶液pH值和初始浓度对水溶液中铅离子的去除也有显著的影响,中性和碱性条件下的去除率大于酸性时的去除率;平衡吸附量与吸附平衡浓度之间的关系较好符合Freundlich和Langmuir等温吸附方程所描述的规律。     

天然泥炭对水中结晶紫的吸附行为

通过静态实验探讨了天然泥炭吸附水中结晶紫时的影响因素、动力学、等温式和热力学。结果表明,在研究条件下吸附90min后天然泥炭对结晶紫的吸附量为31.77～70.49mg.g-1,吸附量随着结晶紫初始浓度或温度的增加而增加,但随着天然泥炭用量的增加而减小。在pH为5～8时随着pH的增加而增加。此外,天然泥炭吸附结晶紫的速度较快,吸附90min后基本达到平衡。吸附动力学规律符合Lagergren准二级反应模型,不同温度下的吸附等温式都与Langmuir方程符合很好。热力学分析表明,吸附过程吸热,吸附焓变ΔH和熵变ΔS都为正值,吸附自由能变ΔG为负值。     

载银沸石吸附去除水中溴离子的特性研究

将天然沸石依次使用1 mol/LNaCl溶液、1moL/LHCl溶液、0.2 mol/LAgNO3溶液改性并于马弗炉中450℃焙烧2h制得载银沸石吸附剂.采用静态吸附方法,探讨了溴离子浓度、吸附时间、吸附剂用量、溶液pH值等因素对溴离子去除效果的影响.载银沸石投加量为0.9 g/L,溶液pH值为7,吸附时间为90 min时,溴离子去除效果达97％以上.拟二级动力学模型可以很好地描述载银沸石对溴离子的吸附动力学过程,其吸附平衡规律符合Langmuir等温线模型.     

Physicochemical Parameters of Cu(II) Ions Adsorption from Aqueous Solution by Magnetic-Poly(divinylbenzene-n-vinylimidazole) Microbeads

This study is aimed at the synthesis and characterization of the mesoporous magnetic-poly(divinylbenzene-1-vinylimidazole)[m-poly(DVB-VIM))microbeads(average diameter = 53–212 µm); their application as adsorbent in the removal of Cu(II) ions from aqueous solutions was investigated. The mesoporous m-poly(DVB-VIM) microbeads were prepared by copolymerizing of divinylbenzene (DVB) with 1-vinylimidazole (VIM). The mesoporous m-poly(DVB-VIM) microbeads were characterized by N₂ adsorption/desorption isotherms, ESR, elemental analysis, scanning electron microscope (SEM), and swelling studies. At fixed solid/solution ratio the various factors affecting adsorption of Cu(II) ions from aqueous solutions such as pH, initial concentration, amount of mesoporousm-poly(DVB-VIM)) microbeads, contact time, and temperature were analyzed. Langmuir, Freundlich, and Dubinin-Radushkvich isotherms were used the model adsorption equilibrium data. The Langmuir isotherm model was the most adequate. The pseudo first-order, pseudo-second-order, Ritch-second-order, and intraparticle diffusion models were used to describe the adsorption kinetics. The experimental data fitted to pseudo second-order kinetic. The study of temperature effect was quantified by calculating various thermodynamic parameters such as Gibbs free energy, enthalpy, and entropy changes. Morever, after the use in adsorption, the mesoporous m-poly(DVB-VIM) microbeads with paramagnetic property was separated via the applied magnetic force. These features make the mesoporous m-poly(DVB-VIM) microbeads a potential candidate for support of Cu(II) ions removal under magnetic field.     

甲苯法生产己内酰胺水溶液的吸附精制工艺试验研究

以活性炭、活性炭纤维及离子交换树脂作为吸附剂，在甲苯法己内酰胺水溶液中试验了不同吸附剂对己内酰胺水溶液中杂质的吸附能力。结果表明，当光密度均降低30％时，采用活性炭吸附，对己内酰胺中有机杂质的动态吸附容量为26．7mL／g；活性炭纤维杂乱填充时的动态吸附容量为67．48mL／g；强碱性离子交换树脂IAR900的动态吸附容量为46．66mL／mL。提出了活性炭纤维与离子交换树脂组合吸附工艺，当光密度均降低50％时，动态吸附容量为36．67mL／g，该组合工艺能有效去除己内酰胺水溶液中的杂质，提高了产品的质量。     

天然凹凸棒石对水中镉的吸附行为

通过静态实验探讨了天然凹凸捧石吸附水中镉（Cd^2＋）时的影响因素、动力学、等温式和热力学。结果表明,在实验条件下吸附90min后天然凹凸捧石对Cd^2＋的吸附量为6.07-13.15（mg·g^-1）,吸附量随着温度或Cd^2＋初始浓度的增加而增加,但天然凹凸棒石用量增加,吸附量却减少。在pH值为5-7时随着pH值的增加而增加。此外,天然凹凸捧石吸附Cd^2＋的速度较快,吸附60min后基本达到平衡。吸附动力学规律符合Lagergren准二级反应模型,不同温度下的吸附等温式都与Freundlich方程符合很好。热力学分析表明,吸附过程吸热,吸附焓变△H和熵变△s都为正值,吸附自由能变△G为负值。     

粉煤灰合成沸石对混合重金属离子的吸附研究

利用粉煤灰合成沸石吸附混合重金属离子Cu^2＋、Ni^2＋、Pb^2＋、Zn^2＋,考察初始浓度对沸石吸附4种混合重金属离子的吸附效果影响。结果表明：初始浓度对沸石吸附重金属离子的效果影响显著,当混合重金属离子初始浓度不同时,沸石对其去除率也不同。当初始浓度为50mg／L与100mg／L时,重金属离子去除顺序为Cu〉Pb〉Ni〉Zn。当初始浓度提高为200mg／L与300mg／L时,去除顺序变为Cu≈Pb〉Zn〉Ni。沸石对Pb^2＋与Cu^2＋两种重金属离子的吸附性能较强,而对Zn^2＋与Ni^2＋两种重金属离子的吸附能力较弱。     

高炉渣对碱性品蓝吸附性能的研究

本试验研究了高炉渣对碱性品蓝的吸附性能,借助电镜扫描(SEM)技术对吸附剂进行了表征,探讨了碱性品蓝的初始浓度、吸附时间、吸附剂投加量、吸附温度、离子强度和废水pH等因素对碱性品蓝去除率的影响,并从动力学和等温吸附模型探讨了吸附作用机理.实验结果表明:当吸附温度为室温(25℃)、吸附剂加入量为0.4g、吸附时间为120 min、废水pH为8、初始碱性品蓝浓度为100 mg/L、离子强度为0 mol/L时,碱性品蓝去除率达78.31％;高炉渣对碱性品蓝的吸附符合伪二级动力学方程和Freundlich等温吸附模型,并且吸附是容易发生的.     

饮用水沸石除氟的实验研究

本文通过静态搅拌实验和恒温震荡实验研究了接触时间、pH值、温度对沸石除氟效果的影响 ;测定了在 2 5℃时沸石除氟的吸附等温线 ,并对吸附等温线进行拟合 ,证明其符合Langmuir吸附等温式qe=0 .0 68Ce/(1 0 .0 868Ce) ;对吸附速度进行了数学处理 ,证明其符合斑厄姆吸附速度公式dq/dt=0 .0 0 1 8(qe-q) /t0 .2 2 。     

粉煤灰碱熔-水热合成沸石用于水溶液中汞的吸附

汞被认为是危害最为严重的重金属之一。目前虽已有大量水处理技术可用于水中汞的去除,但由于成本较高等原因均未实现大面积的工业化应用。以工业固废粉煤灰为原料通过碱熔-水热法合成了沸石,可将其应用于水溶液中汞的吸附。结果表明:碱熔活化可以使得粉煤灰中稳定的莫来石、石英及非晶相矿物转变为钠铝硅酸盐、硅酸钠和钠霞石等矿物;这些矿物可溶于氢氧化钠溶液中,形成富含钠、铝、硅的碱性溶液;在适宜的水热条件下,通过调配铝硅比,可合成纯度较高的NaA型沸石;该法合成的粉煤灰基沸石可有效吸附水溶液中的Hg(II),去除率可达95%左右,吸附过程符合拟二级吸附动力学模型,反应速率同时受到内外扩散影响。     

天然沸石对溶液中氨氮的吸附性能

实验测定了天然沸石对氨氮的动力学吸附曲线、热力学吸附等温线、吸附前后沸石颗粒界面电性质及红外谱图,得出以下结论:沸石吸附氨氮过程服从Langmuir方程式;15℃～35℃度时温度对吸附量的影响较小;吸附过程交换速率由液膜扩散和粒子扩散共同控制;证实沸石对水溶液中氨氮的吸附以离子交换为主。     

Removal of Phosphate from Aqueous Solution Using Zeolite Synthesized from Fly Ash by Alkaline Fusion Followed by Hydrothermal Treatment

The removal of phosphate from aqueous solution by the adsorption process using zeolite synthesized from fly ash was investigated in this study. The XRD patterns revealed that the major crystalline phase of the synthesized zeolite was gismondine. The phosphate immobilization capacity (PIC) increased significantly from 52.7 mg/g of fly ash to 102.9 mg/g of synthesized zeolite after conversion. The batch experiments were conducted to investigate the effect of pH, initial phosphate concentration, and adsorbent amount. The maximum adsorption capacity was obtained at the pH value of 7.0. The adsorption process followed Ho' pseudo-second-order model, and both liquid film and intra-particle diffusion were the rate-controlling step for the process. The adsorption equilibrium data had been analyzed by Langmuir, Freundlich, Radlich-Peterson, Koble-Corrigan, Tempkin, Dubinin-Radushkevich, and Generalized models. The results showed that the Langmuir model gave the best fit. The process was also found to be endothermic. The maximum phosphate adsorption capacity obtained was 132.02 mg/g (30°C), 156.36 mg/g (40°C) and 184.17 mg/g (50°C), respectively, suggesting that the synthesized zeolite is a promising material and can be used to remove phosphate from wastewater.     

油页岩灰渣合成Na-A沸石用于去除水溶液中Cu2+（英文）

Na-A zeolite was synthesized using oil shale ash （OSA）, which is a solid by-product of oil shale proc- essing. The samples were characterized by various techniques, such as scanning electron microscopy, X-ray diffrac- tion and Brunaner Emmet Teller method. The batch isothermal equilibrium adsorption experiments were performed to evaluate the ability of Na-A zeolite for removal of Cu （II） from aqueous solutions. The effects of operating pa- rameters, such as concentration of copper solutions, adsorbent dosages, pH value of solutions and temperature, on the adsorption efficiency were investigated. The equilibrium adsorption data were fitted with Langmuir and Freundlich models. The maximum adsorption capacity of Na-A zeolite obtained from the Langmuir adsorption iso- therm is 156.7 mg.g-t of Cu （lI）. The increase of pH level in the adsorption process suggests that the uptake of heavy metals on the zeolite follows an ion exchange mechanism. The batch kinetic data fit the pseudo-second order equation well. The thermodynamic parameters, such as changes in Gibbs free energy （AG）, enthalpy （AH） and en- tropy （AS）, are used to predict the nature of the adsorption process. The negative AG values at different tempera- tures confirm that the adsorption processes are spontaneous.     

壳聚糖交联微球对水中镍离子的吸附性能

以戊二醛为交联剂,采用反相悬浮法合成了壳聚糖交联微球,研究了该微球对Ni2+的吸附性能及其重复使用性。结果表明,壳聚糖交联微球对Ni2+的吸附条件是25℃时,p H 7.0,在50 m L质量浓度为300 mg/L Ni2+溶液中,投加0.05 g吸附剂,吸附2 h,吸附量为45.65 mg/g。该微球经0.1 mol/L盐酸解吸后可再生,重复使用7次,吸附量仍可达原来的81.9%。微球良好的再生性显著降低了处理成本,提高了处理效果,减少了二次污染。     

Removal of Fluoride from Water by Metal Ions (Al3+, La3+ and ZrO2+) Loaded Natural Zeolite

Abstract

In this study, the ion exchange of metal ions (Al³⁺, La³⁺ and ZrO²⁺) on modified zeolites was carried out using batch method. Fluoride removal from water using Al³⁺‐, La³⁺‐ and ZrO²⁺‐ exchanged zeolite was subsequently investigated to evaluate the fluoride sorption characteristics of the sorbents. Natural zeolite samples (<45 µm) were pre‐conditioned with HNO₃ solution (ZEO‐1), NaNO₃ solution (ZEO‐2), and deionized water (ZEO‐3) before loading Al³⁺, La³⁺, and ZrO²⁺ on zeolite. ZEO‐1 type zeolite had a higher capacity than ZEO‐2 and ZEO‐3 type zeolites. Metal exchange capacities are 0.233, 0.089, 0.090 mmol/g for ZrO²⁺‐, La³⁺‐, and Al³⁺‐ exchanged zeolite (ZEO‐1), respectively. Equilibrium isotherms fitted well to Langmuir and Freundlich models. Percent removal of fluoride from aqueous solution containing 2.5 mg F/L was 94% using metal loaded zeolite (ZEO‐1 type) at an adsorbent concentration of 6.00 g/L.     

碳纳米管吸附染料茜素红的性能研究

研究了碳纳米管对水中茜素红的吸附去除性能,结果表明:纯化的碳纳米管对水中茜素红的去除效果明显高于未纯化的碳纳米管,当其用量为0.1g时,纯化的碳纳米管对水中茜素红的吸附去除率达到87.3%;纯化的碳纳米管对水中茜素红的吸附在60分钟达到平衡;溶液pH值对水中茜素红的去除有一定的影响,在酸性和中性条件下的去除率大于碱性;温度升高,水中茜素红的去除率略有升高。平衡吸附量qe与平衡质量浓度pe之间的关系符合Freundlich和Langmuir等温吸附方程所描述的规律。     

Fe-Al柱撑膨润土吸附染料酸性大红的性能

制备了Fe-Al柱撑膨润土,研究了其对染料酸性大红的吸附去除性能,结果表明:Fe-Al柱撑膨润土对染料酸性大红有很好的去除效果,当其用量为0.1g时,染料酸性大红的吸附去除率达到92.6%;Fe-Al柱撑膨润土对染料酸性大红的吸附在60分钟达到平衡;pH值对染料酸性大红的去除有一定的影响,在酸性和碱性条件下的去除率大于中性。平衡吸附量qe与平衡质量浓度pe之间的关系符合Freundlich和Langmuir等温吸附方程所描述的规律。     

天然沸石制备4A沸石工艺探索

对六个天然沸石制备４Ａ沸石工艺方案进行了探索性试验,得出了两个较好的工艺方案,并对４Ａ沸石制备过程的主要影响因素进行了较详细的分析,为今后进一步研究指明了方向。