氢氧化镧-天然沸石复合材料对水中低浓度磷酸盐的吸附作用

采用液相沉淀法将氢氧化镧和天然沸石进行复合,制备得到镧-沸石复合材料,并通过批量吸附实验考察了该复合材料对水中磷酸盐的吸附作用,特别是考察了该复合材料去除水中低浓度磷酸盐的影响因素.结果表明,当制备复合材料时沉淀pH值为5~7或13时,复合材料对水中磷酸盐的吸附能力较差;当沉淀pH值控制为9~12,复合材料对水中磷酸盐的吸附能力较好,且当沉淀pH值由9增加到11时,复合材料的吸磷能力明显增加,继续增加pH值由11~12时,复合材料的吸磷能力基本不变.沉淀pH值为11时制备的镧-沸石复合材料对水中磷酸盐的吸附平衡数据可以较好地采用Langmuir模型加以描述,根据Langmuir模型预测的最大磷酸盐吸附量为44 mg·g~(-1)(磷酸盐溶液pH 7和反应温度30℃);该复合材料对水中低浓度磷酸盐的吸附动力学可以较好地采用准二级动力学模型加以描述.当磷酸盐溶液pH值由3增加到8时,沉淀pH值为11条件下制备得到的镧-沸石复合材料对低浓度磷酸盐的吸附能力增加,继续增加磷酸盐溶液pH值时,该复合材料对磷酸盐的吸附能力下降;与磷酸盐溶液共存的氯离子和硫酸根离子不会抑制该复合材料对低浓度磷酸盐的吸附,而碳酸氢根离子则会略微抑制该复合材料对磷酸盐的吸附;与磷酸盐溶液共存的腐殖酸会抑制该复合材料对水中低浓度磷酸盐的吸附.当磷酸盐溶液pH值为7时,沉淀pH值为11时镧-沸石复合材料吸附磷酸盐的机制主要为配位体交换作用.因此,沉淀pH值为11时制备得到的镧-沸石复合材料适合作为吸附剂去除水和废水中低浓度磷酸盐.     

羟基磷灰石对水中刚果红的吸附作用研究

通过吸附实验考察了羟基磷灰石对水中刚果红的吸附作用,结果表明羟基磷灰石对水中的刚果红具备良好的吸附效果.准二级动力学模型适合描述羟基磷灰石对水中刚果红的吸附动力学过程.Langmuir、Freundlich和Dubinin-Radushkevich(D-R)等温吸附模型可以用于描述羟基磷灰石对水中刚果红的吸附平衡数据.羟基磷灰石对水中刚果红的吸附是自发和放热的过程.当pH超过8时,羟基磷灰石对水中刚果红的吸附能力随pH的增加而明显降低.吸附了刚果红的羟基磷灰石经过热再生后可以循环使用,并且热再生后的羟基磷灰石对水中刚果红的吸附性能良好.当pH低于羟基磷灰石的零电荷点时,磷灰石吸附水中刚果红的机制是静电吸引、氢键和路易斯酸碱反应;当pH高于羟基磷灰石的零电荷点时,羟基磷灰石吸附水中刚果红的机制是氢键和路易斯酸碱反应.上述结果表明,羟基磷灰石适合作为一种吸附剂去除废水中的刚果红.     

鸟粪石-沸石复合材料对水中镉的吸附性能研究

研究以氧化镁负载沸石回收污水中氮磷得到的鸟粪石-沸石复合材料(STR-NZ)为吸附剂,用于对水体中重金属镉的吸附去除.实验采用SEM-EDS、XRD和FTIR等手段对STR-NZ材料进行表征,并考察了投加量、初始pH和反应时间等对STR-NZ材料去除水中Cd~(2+)的影响.结果表明:氧化镁负载沸石材料主要以鸟粪石沉淀的方式实现对水中磷酸盐和氨氮的回收;STR-NZ对水溶液中Cd~(2+)的吸附量随pH的增大呈先增加后趋于平衡的趋势,当Cd~(2+)的初始浓度为50 mg·L~(-1)时,STR-NZ的最佳投加量为0.2 g·L~(-1),Cd~(2+)最大吸附量为249.35 mg·g~(-1), STR-NZ对Cd~(2+)的吸附动力学符合准二级动力学模型,对Cd~(2+)的等温吸附符合Langmuir等温吸附模型,STR-NZ主要通过Cd_5(PO_4)_3(OH)沉淀的方式实现对水中Cd~(2+)的去除.     

改性氧化石墨烯/壳聚糖功能材料对刚果红的吸附研究

以氧化石墨烯(GO)和壳聚糖(CS)为前体物,以乙二胺四乙酸二钠(EDTA-2Na)为表面改性剂,制备了一种新型改性氧化石墨烯/壳聚糖功能材料(GEC),并将此材料作为吸附剂用于水中刚果红的吸附去除,探讨了时间、pH值、吸附剂投加量、温度及初始浓度对GEC吸附去除刚果红的影响.结果表明,GEC对水中刚果红具备良好的吸附能力,且在pH=2~12的范围内都具有较佳的吸附效果.GEC对刚果红的吸附动力学可以较好地用伪二级动力学模型进行描述,其吸附数据可应用Langmuir吸附等温模型进行拟合,其吸附过程是自发的吸热反应过程.根据Langmuir模型计算得到GEC室温条件下最大吸附量为175.43 mg·g~(-1).用2 mol·L~(-1)NaOH溶液在60℃水浴条件下对GEC进行脱附再生实验,在重复循环利用6次后,GEC对刚果红的吸附量仅下降了5.89%,刚果红的去除率仍保持在88%以上.以上结果表明,GEC适合作为一种有效的吸附剂去除水中刚果红.     

溴化十六烷基吡啶改性沸石对水中菲的吸附作用

采用不同浓度的溴化十六烷基吡啶(CPB)溶液对天然沸石进行改性,制备得到了单层和双层CPB改性沸石,并通过批量吸附实验考察了这两种CPB改性沸石对水中菲的去除作用.结果表明,单层和双层CPB改性沸石对水中菲均具备良好的吸附能力.CPB改性沸石对水中菲的去除率随吸附剂投加量的增加而增加,而CPB改性沸石对水中菲的单位吸附量随吸附剂投加量的增加而降低.CPB改性沸石对水中菲的吸附动力学过程满足准二级动力学模型.CPB改性沸石对水中菲的吸附平衡数据可以采用线性模型和Freundlich模型加以描述.CPB改性沸石对水中菲的吸附过程是一个自发和放热的过程.单层CPB改性沸石吸附水中菲的机制主要是疏水作用,双层CPB改性沸石吸附水中菲的机制主要是有机相分配作用.当双层CPB改性沸石的CPB负载量为单层CPB改性沸石的CPB负载量的2倍时,前者对水中菲的吸附能力略微强于后者.以上结果表明,双层和单层CPB改性沸石均可以用于水中菲的去除;为节约成本,单层CPB改性沸石与双层CPB改性沸石相比更适合用于水中菲的去除.     

金属离子改性腐植酸钠吸附剂的制备及其除氟性能

为提高水中F-的吸附去除效率,以腐植酸钠(NaA)为原料,用铝盐和钙盐通过凝胶聚合法对其改性,制备了金属离子改性腐植酸钠吸附剂(标记为MMNaA). 用SEM及XRD表征吸附剂的结构和形貌,通过静态吸附实验探讨了MMNaA对水中F-的吸附性能并与传统的γ-Al2O3吸附剂进行比较.结果表明,MMNaA对水中F-的等温吸附结果与Langmuir方程能较好地拟合, 用Langmuir方程计算出的饱和吸附容量为208.77mg/g;吸附过程遵循准2级动力学方程,其速率控制步骤包括边界层扩散和内部扩散2个过程;在pH 5~9时MMNaA对水中F-具有较高的吸附去除率.当吸附剂用于深度处理实际含氟废水时,与γ-Al2O3相比,MMNaA适用的pH值范围更广,满足达标排放时所需的投加量更小、吸附时间更短.     

吸附剂用量对二级出水中氨氮去除效果的研究

以二级出水中氨氮的吸附处理为研究对象,对活性炭吸附法和沸石吸附法去除二级出水中氨氮进行试验研究。在一定范围内,吸附剂用量对氨氮的去除效果有较大的影响,相同条件下,吸附剂投加量越大,氨氮去除率越高,但增加到一定程度后,对氨氮的吸附作用减弱,在实际应用中控制吸附剂的投加量是必要的。当吸附剂用量为15 mg时,活性炭吸附效果要明显高于沸石的;当吸附剂用量大于30 mg时,沸石的吸附效果要远远好于活性炭的。     

粉煤灰合成沸石对Cr~(3+)的去除能力及影响因素研究

研究了粉煤灰合成沸石对废水中Cr~(3+)的去除能力,分析了接触时间、pH、沸石投加量、Cr~(3+)初始浓度、温度等因素对Cr~(3+)过程吸附的影响.试验结果表明,合成沸石的主要成分为一种无名沸石.合成沸石对Cr~(3+)具有较快的吸附速度,吸附过程符合二级反应动力学.在pH 2.0~12.0范围内,合成沸石对Cr~(3+)都具有较高的去除效率.Cr~(3+)去除率随着沸石投加量的增加而增加,随着Cr~(3+)初始浓度的升高而降低.Langmuir等温线模型对吸附数据具有更好的非线性拟合效果,所得最大吸附量为111.7 mg·g-1.热力学研究表明吸附过程为吸热反应.与原沸石相比,利用Na Cl再生后的沸石的Cr~(3+)去除率下降11.42%~14.10%,但仍可循环利用.上述实验结果表明本文合成的沸石具有较好的除Cr~(3+)的应用潜力.     

改性木屑对水中刚果红的吸附性能研究

对十六烷基三甲基溴化铵(CTAB)改性木屑用于水中刚果红(CR)的去除进行了研究.用扫描电子显微镜(SEM)和傅里叶红外光谱分析仪(FTIR)对木屑和改性木屑的性能进行表征.探讨了反应时间、pH、温度、剂量以及离子强度对改性木屑去除CR的影响.实验结果表明,CTAB改性后的木屑对刚果红的吸附量明显增大,改性前后木屑的最大吸附量分别为30.30和111.36 mg·g-1.反应过程在前20 min内反应速率很快,并约在120 min内达到吸附平衡.吸附动力学符合伪二级动力学模型.最佳反应温度为328 K,吸附剂最适投加量为0.09 g,吸附量的大小与溶液的初始pH值有关,且增加盐浓度,改性木屑的吸附能力增加.吸附等温线符合Langmuir方程,且吸附过程为吸热反应.     

沸石分子筛对水中2,4-二甲基苯酚的吸附特性研究

以沸石分子筛为吸附剂,采用批次试验,研究静态吸附对水中2,4-二甲基苯酚(2,4-DMP)的吸附去除效果,比较了3种不同类型的沸石分子筛对2,4-DMP的吸附性能,选择其中吸附性能最好的沸石分子筛FAU-Y为吸附剂,分别考察了溶液初始p H、吸附剂投加量对吸附效果的影响,并对吸附动力学和吸附等温线进行了分析。结果表明,FAU-Y对2,4-DMP具有较大的吸附量,在2,4-DMP初始浓度为250 mgL,溶液初始p H为5.2,吸附剂投加量为5.0 gL时,室温条件下反应24h可以达到吸附平衡状态,饱和吸附容量为48.22 mgg;初始p H为2.0~9.3时,对FAU-Y吸附2,4-DMP没有明显影响;吸附动力学和吸附等温线分析结果表明,二级动力学能更好地描述FAU-Y对2,4-DMP的吸附,Langmuir-Freundlich吸附等温线对吸附平衡数据的拟合优于Langmuir吸附等温线和Freundlich吸附等温线。     

Removal of Cs from water and soil by ammonium-pillared montmorillonite/Fe3O4 composite

To remove cesium ions from water and soil, a novel adsorbent was synthesized by following a one-step co-precipitation method and using non-toxic raw materials. By combining ammonium-pillared montmorillonite (MMT) and magnetic nanoparticles (Fe₃O₄), an MMT/Fe₃O₄ composite was prepared and characterized. The adsorbent exhibited high selectivity of Cs⁺ and could be rapidly separated from the mixed solution under an external magnetic field. Above all, the adsorbent had high removal efficiency in cesium-contaminated samples (water and soil) and also showed good recycling performance, indicating that the MMT/Fe₃O₄ composite could be widely applied to the remediation of cesium-contaminated environments. It was observed that the pH, solid/liquid ratio and initial concentration affected adsorption capacity. In the presence of coexisting ions, the adsorption capacity decreased in the order of Ca^2 + > Mg^2 + > K⁺ > Na⁺, which is consistent with our theoretical prediction. The adsorption behavior of this new adsorbent could be expressed by the pseudo-second-order model and Freundlich isotherm. In addition, the adsorption mechanism of Cs⁺ was NH₄⁺ ion exchange and surface hydroxyl group coordination, with the former being more predominant.     

支化聚乙烯亚胺功能化磁性纳米吸附剂的制备及对Cu2+的吸附研究

为解决水体中重金属Cu²⁺污染,本研究首先采用水热法制备得到超顺磁四氧化三铁纳米粒子,然后使用对Cu²⁺具有强络合作用的含有丰富氨基官能团的支化聚乙烯亚胺接枝到纳米粒子表面,得到Fe₃O₄@BPEI磁性纳米吸附剂。采用红外光谱（FTIR）、X射线粉末衍射（XRD）、透射电子显微镜（TEM）等对其结构、尺寸及形貌进行表征。研究了不同吸附因素对吸附剂吸附Cu²⁺的影响,确定了最佳吸附条件,并通过吸附动力学模型和吸附等温线模型进一步探讨吸附机理。结果表明：支化聚乙烯亚胺成功接枝到四氧化三铁纳米粒子表面。最佳吸附条件为pH=6.0、吸附平衡时间为40 min、吸附剂用量为10 mg。通过实验数据拟合,Fe₃O₄@PEI吸附Cu²⁺的过程符合Langmuir等温吸附方程和拟二级动力学模型,表明吸附过程为化学吸附控制的单分子层覆盖,在303 K时,模型理论饱和吸附量为141.24 mg/g。表明支化聚乙烯亚胺修饰的磁性纳米吸附剂对Cu²⁺具有较强的吸附能力,对水体中Cu²⁺的去除具有一定的应用前景。     

石墨烯基磁性复合材料吸附水中亚甲基蓝的研究

建立了一种超声辅助共沉淀法制备磁性Fe3O4/氧化石墨烯(Fe3O4/GO)纳米粒子.透射电镜和磁滞回线研究表明,该复合物具有小的颗粒尺寸和超顺磁性.该磁性纳米材料可以吸附废水中的染料亚甲基蓝,实验研究了溶液pH值、吸附剂的用量、时间和温度对亚甲基蓝去除率的影响.结果表明,pH值在6~9范围内,Fe3O4/GO都能高效地吸附亚甲基蓝.反应过程在前25 min反应速率很快,到180 min内达到吸附平衡.该磁性纳米材料对亚甲基蓝的吸附符合Langmuir吸附等温模型和准二级动力学方程,吸附过程是一个自发和吸热过程.该吸附材料对亚甲基蓝吸附容量高,在313 K时Fe3O4/GO的饱和吸附量为196.5 mg·g-1.另外,可以方便地通过外部磁场分离回收吸附剂,利用过氧化氢可以再生重复使用,是一种优良的吸附染料废水的材料.     

Modification of a magnetic carbon composite for ciprofloxacin adsorption

A magnetic carbon composite, Fe₃O₄/C composite, was fabricated by one-step hydrothermal synthesis, modified by heat treatment under an inert atmosphere (N₂), and then used as an adsorbent for ciprofloxacin (CIP) removal. Conditions for the modification were optimized according to the rate of CIP removal. The adsorbent was characterized by Fourier transform infrared spectroscopy, X-ray diffraction measurements, vibrating-sample magnetometry, scanning electron microscopy, transmission electron microscopy, and N₂ adsorption/desorption isotherm measurements. The results indicate that the modified adsorbent has substantial magnetism and has a large specific area, which favor CIP adsorption. The effects of solution pH, adsorbent dose, contact time, initial CIP concentration, ion strength, humic acid and solution temperature on CIP removal were also studied. Our results show that all of the above factors influence CIP removal. The Langmuir adsorption isotherm fits the adsorption process well, with the pseudo second-order model describing the adsorption kinetics accurately. The thermodynamic parameters indicate that adsorption is mainly physical adsorption. Recycling experiments revealed that the behavior of adsorbent is maintained after recycling for five times. Overall, the modified magnetic carbon composite is an efficient adsorbent for wastewater treatment.     

碘化阶层孔氧化硅纳米球对水中典型有机氯污染物的吸附性能研究

采用共缩聚法,成功地原位合成了碘改性的阶层多孔氧化硅纳米球（SiO₂-I）,研究了其基于卤键作用对典型有机氯污染物六六六的吸附性能,并考察了改性剂I-硅烷含量和pH值对吸附效果的影响.实验结果表明,该纳米材料对六六六表现出优异的吸附富集性能,吸附速率快,60 min内对六六六的去除率为71.6%,240 min内达到吸附平衡,去除率可达98.3%,最大吸附量为178.6 mg·g^-1;吸附动力学符合拟二级动力学模型;碘物种的加入提高了阶层多孔氧化硅的吸附速率和吸附效率.另外,为了便于纳米吸附材料的分离,本研究对SiO₂-I纳米球进行了磁性化.研究发现,磁性化修饰后,SiO₂-I纳米材料仍然保留对六六六优异的吸附富集性能,240 min时的吸附去除率达90.3%.     

Fe3O4@SiO2-Chitosan的制备及其对水中Cu2+的吸附效能研究

以SiO_2包覆Fe_3O_4,戊二醛为交联剂,交联壳聚糖(Chitosan, CTS),制得Fe_3O_4@SiO_2-Chitosan复合磁性纳米粒子.以Fe_3O_4和Fe_3O_4@SiO_2为对照,采用X射线衍射、透射电镜和傅立叶红外光谱对其进行表征分析,并测定了投加量、pH值、吸附时间和温度等因素对Cu~(2+)吸附效果的影响,从动力学、热力学以及再生回用性能评价等方面对其吸附性能进行了探究.结果表明Fe_3O_4@SiO_2-Chitosan对Cu~(2+)的吸附过程符合准二级吸附动力学模型和Langmuir模型,为自发、放热、优惠型的单分子层化学吸附.在pH为6.0, 298 K下达到最大吸附量154.8 mg·g~(-1),吸附解吸4次后吸附容量变化不大,说明Fe_3O_4@SiO_2-Chitosan具有较高的吸附容量,可作为处理含铜废水和回收铜的高效吸附剂.     

Removal of tetracycline from aqueous solution by a Fe3O4 incorporated PAN electrospun nanofiber mat

Pollution of antibiotics, a type of emerging contaminant, has become an issue of concern, due to their overuse in human and veterinary application, persistence in environment and great potential risk to human and animal health even at trace level. In this work, a novel adsorbent, Fe₃O₄ incorporated polyacrylonitrile nanofiber mat (Fe-NFM), was successfully fabricated via electrospinning and solvothermal method, targeting to remove tetracycline (TC), a typical class of antibiotics, from aqueous solution. Field emission scanning electron microscopy and X-ray diffraction spectroscopy were used to characterize the surface morphology and crystal structure of the Fe-NFM, and demonstrated that Fe-NFM was composed of continuous, randomly distributed uniform nanofibers with surface coating of Fe₃O₄ nanoparticles. A series of adsorption experiments were carried out to evaluate the removal efficiency of TC by the Fe-NFM. The pseudo-second-order kinetics model fitted better with the experimental data. The highest adsorption capacity was observed at initial solution pH 4 while relative high adsorption performance was obtained from initial solution pH 4 to 10. The adsorption of TC on Fe-NFM was a combination effect of both electrostatic interaction and complexation between TC and Fe-NFM. Freundlich isotherm model could better describe the adsorption isotherm. The maximum adsorption capacity calculated from Langmuir isotherm model was 315.31 mg/g. Compared to conventional nanoparticle adsorbents which have difficulties in downstream separation, the novel nanofiber mat can be simply installed as a modular compartment and easily separated from the aqueous medium, promising its huge potential in drinking and wastewater treatment for micro-pollutant removal.     

新型材料磁性氧化锆的除氟效能

采用一步共沉淀法制备了磁铁矿纳米颗粒为核和水合氧化锆为壳的磁性氧化锆材料,研究了其除氟性能.结果表明,磁性氧化锆对氟的Langmuir最大吸附量为35. 46 mg·g~(-1),远高于磁铁矿、活性氧化铝和活性炭.磁性氧化锆对氟的吸附过程较快且吸附动力学数据符合准二级动力学模型,吸附过程为吸热反应.磁性氧化锆对氟的吸附量随pH升高而降低. Cl~-、NO_3~-和SO_4~(2-)的共存对磁性氧化锆除氟没有明显影响,而HCO_3~-和CO_3~(2-)明显抑制氟的吸附.磁性氧化锆吸附的氟可通过1mol·L~(-1)NaOH成功脱附,脱附率99. 5%～99. 6%.脱附后的磁性氧化锆经过再生处理可继续使用.磁性氧化锆对实际井水中的氟的去除效果低于纯水,但适当增加投加量仍可以达到饮用水标准对氟浓度的要求.磁性氧化锆制备简单、使用后可从水中磁分离从而可反复使用,因此是一种有较好应用前景的除氟材料.     

Removal of tetracycline from aqueous solution by a Fe3O4 incorporated PAN electrospun nanofiber mat

Pollution of antibiotics, a type of emerging contaminant, has become an issue of concern, due to their overuse in human and veterinary application, persistence in environment and great potential risk to human and animal health even at trace level. In this work, a novel adsorbent, Fe₃O₄ incorporated polyacrylonitrile nanofiber mat (Fe-NFM), was successfully fabricated via electrospinning and solvothermal method, targeting to remove tetracycline (TC), a typical class of antibiotics, from aqueous solution. Field emission scanning electron microscopy and X-ray diffraction spectroscopy were used to characterize the surface morphology and crystal structure of the Fe-NFM, and demonstrated that Fe-NFM was composed of continuous, randomly distributed uniform nanofibers with surface coating of Fe₃O₄ nanoparticles. A series of adsorption experiments were carried out to evaluate the removal efficiency of TC by the Fe-NFM. The pseudo-second-order kinetics model fitted better with the experimental data. The highest adsorption capacity was observed at initial solution pH 4 while relative high adsorption performance was obtained from initial solution pH 4 to 10. The adsorption of TC on Fe-NFM was a combination effect of both electrostatic interaction and complexation between TC and Fe-NFM. Freundlich isotherm model could better describe the adsorption isotherm. The maximum adsorption capacity calculated from Langmuir isotherm model was 315.31 mg/g. Compared to conventional nanoparticle adsorbents which have difficulties in downstream separation, the novel nanofiber mat can be simply installed as a modular compartment and easily separated from the aqueous medium, promising its huge potential in drinking and wastewater treatment for micro-pollutant removal.