Application of magnetic particles modified with amino groups to adsorb copper ions in aqueous solution

A magnetic adsorbent can be easily recovered from treated water by magnetic force,without requiring further downstream treatment.In this research,amine-functionalized silica magnetite has been synthesized using N-[3-(trimethoxysilyl)propyl]-ethylenediamine(TPED) as a surface modification agent.The synthesized magnetic amine adsorbents were used to adsorb copper ions in an aqueous solution in a batch system,and the maximum adsorption was found to occur at pH 5.5 ± 0.1.The adsorption equilibrium data fitted t...     

Removal of fluoride from water using titanium-based adsorbents

Three adsorbents including TiO₂, Ti-Ce, and Ti-La hybrid oxides were prepared to remove fluoride from aqueous solution. The Ti-Ce and Ti-La hybrid adsorbents obtained by the hydrolysis-precipitation method had much higher sorption capacity for fluoride than the TiO₂ adsorbent prepared through hydrolysis. Rare earth (Ce and La) oxides and TiO₂ exhibited a synergistic effect in the hybrid adsorbents for fluoride sorption. The sorption equilibrium of fluoride on the three adsorbents was achieved within 4 h, and the pseudo-second-order model described the sorption kinetics well. The sorption isotherms fitted the Langmuir model well, and the adsorption capacities of fluoride on the Ti-Ce and Ti-La adsorbents were about 9.6 and 15.1 mg·g⁻¹, respectively, at the equilibrium fluoride concentration of 1.0 mg·L⁻¹, much higher than the 1.7 mg·g⁻¹ on the TiO₂. The sorption capacities of fluoride on the three adsorbents decreased significantly when the solution pH increased from 3 to 9.5. The electrostatic interaction played an important role in fluoride removal by the three adsorbents, and Fourier transform infrared (FTIR) analysis indicated that the hydroxyl groups on the adsorbent surface were involved in fluoride adsorption.     

磷酸改性生物炭负载硫化锰去除废水中重金属镉

采用磷酸作为活化剂对黍糠生物炭进行改性,得到富含活性官能团的功能性生物炭（fCBC）,并将其作为硫化锰（MnS）的载体,最终成功制备出硫化锰负载的磷酸改性生物炭（MnS-fCBC）,可用于水体中镉（Cd）的高效去除.系统评价了初始浓度、初始pH值以及MnS-fCBC投加量对于吸附反应的影响. MnS-fCBC表现出优越的吸附Cd的能力,在初始Cd浓度为200mg/L、pH=6和投加量1g/L的条件下,MnS-fCBC对于Cd的吸附容量最大,达145.15mg/g.吸附反应受pH值影响显著,在偏酸性条件下能取得较好的去除效果.通过X射线衍射仪（XRD）和拉曼光谱仪（Raman）对MnS-fCBC进行结构表征分析,结合批次试验探讨了Cd的去除机理.结果表明,表面络合和化学沉淀是Cd去除的主要机理.材料的回用性能试验显示,在5次循环使用后,材料依然有较高的Cd去除能力,表明其具有较高的可重用性.因此,MnS-fCBC可作为一种高效的Cd吸附剂,应用于含Cd废水处理.     

磁性铝基MOF的表征和对水体中氟化物吸附性能研究

我国多地的地表水受到成土母质或背景值的影响,氟离子浓度均超过1.0 mg/L,即高于GB 3838-2002《地表水环境质量标准》Ⅲ类标准限值.为了实现地表水的快速降氟和吸附材料的便捷回收,通过水热法制备了磁性Al-MOF@Fe₃O₄吸附材料,使用扫描电极（SEM）、X射线衍射仪（XRD）、X射线光电子能谱仪（XPS）和孔隙度分析仪（BET）对材料的形貌和化学组成进行了表征.结果表明:①Al-MOF@Fe₃O₄具有不规则的晶体形状和直径更小的介孔结构,能够提供更高的比表面积吸附氟离子.②吸附试验结果表明,Al-MOF/Fe₃O₄的吸附量达到了75.2 mg/g,吸附过程更加符合拟二阶动力学模型,证明了化学吸附是该除氟过程的主要机理.③增加吸附剂投加和降低氟离子初始浓度,有助于提高除氟效率,但却难以得到较高的吸附量,同时碱性条件不利于氟离子的吸附,阴离子对除氟性能的影响程度表现为CO₃2- > HCO₃- > SO₄2- > PO₄3- > Cl-.④对吸附机理的研究表明,氟离子是通过取代Al-OH实现稳定和快速地脱离水体,使用NaOH溶液淋洗可以实现吸附剂的高效再生.⑤5次循环吸附试验后,复合材料依然保留了71.4 mg/g的吸附能力和良好的磁性.在实际地表水中进行除氟试验,该吸附剂可以将氟化物浓度从1.17 mg/L降至0.2 mg/L以下.研究显示,Al-MOF@Fe₃O₄纳米材料可以作为地表水除氟材料,实现对低浓度氟离子的高效去除.      

Pb(Ⅱ) biosorption using chitosan and chitosan derivatives beads: Equilibrium, ion exchange and mechamsm studies

The study examined the adsorption of Pb(Ⅱ) ions from aqueous solution onto chitosan, chitosan-GLA and chitosan-alginate beads.Several important parameters influencing the adsorption of Pb(Ⅱ) ions such as initial pH, adsorbent dosage and different initial concentration of Pb(Ⅱ) ions were evaluated. The mechanism involved during the adsorption process was explored based on ion exchange study and using spectroscopic techniques. The adsorption capacities obtained based on non-linear Langmuir isotherm for chitosan, chitosan-GLA and chitosan-alginate beads in single metal system were 34.98, 14.24 and 60.27 mg/g, respectively. However,the adsorption capacity of Pb(Ⅱ) ions were reduced in the binary metal system due to the competitive adsorption between Pb(Ⅱ) and Cu(Ⅱ) ions. Based on the ion exchange study, the release of Ca~(2+), Mg~(2+), K~+ and Na~+ ions played an important role in the adsorption of Pb(Ⅱ) ions by all three adsorbents but only at lower concentrations of Pb(Ⅱ) ions. Infrared spectra showed that the binding between Pb(Ⅱ) ions and the adsorbents involved mostly the nitrogen and oxygen atoms. All three adsorbents showed satisfactory adsorption capacities and can be considered as an efficient adsorbent for the removal of Pb(Ⅱ) ions from aqueous solutions.     

Pb(Ⅱ) biosorption using chitosan and chitosan derivatives beads: Equilibrium,ion exchange and mechanism studies

The study examined the adsorption of Pb(II) ions from aqueous solution onto chitosan, chitosan-GLA and chitosan-alginate beads. Several important parameters influencing the adsorption of Pb(II) ions such as initial pH, adsorbent dosage and different initial concentration of Pb(II) ions were evaluated. The mechanism involved during the adsorption process was explored based on ion exchange study and using spectroscopic techniques. The adsorption capacities obtained based on non-linear Langmuir isotherm for ch...     

Evaluation of zeolites synthesized from fly ash as potential adsorbents for wastewater containing heavy metals

Both pure-form zeolites (zeolites A and X) were synthesized by applying a two-stage method during hydrothermal treatment of fly ash prepared initial gel. The difference of adsorption capacity of both fly ash-synthesized zeolits was assessed under the same adsorption conditions. Copper and zinc were chosen as target heavy metal ions. It was found that adsorption capacity of zeolite A showed much higher value than that of zeolite X. Thus, attention was focused on investigating the removal performance of heavy metal ions in aqueous solution on the synthetic pure-form zeolite A from fly ash, zeolite HS (hydroxyl-solidate) prepared from the residual fly ash (after synthesis of pure-form zeolite A from fly ash) and a commercial grade zeolite A. Batch method was employed to study the influential parameters such as initial pH value, adsorbents dosage and adsorption temperature on the adsorption process. The equilibrium data were well fitted by the Langmuir model and showed the affinity: Cu2+ > Zn2+ (adsorbent FA-ZA). The removal mechanism of metal ions followed adsorption and ion exchange processes. Attempts were also made to recover heavy metal ions and regenerate adsorbents (adsorbent FA-ZA).     

Adsorption of humic acid from aqueous solution on bilayer hexadecyltrimethyl ammonium bromide-modified zeolite

Surfactant-modified natural zeolites (SMNZ) with different coverage types were prepared by loading hexadecyltrimethyl ammonium bromide (HTAB) onto the surface of a natural zeolite. The adsorption behavior of humic acid (HA) on SMNZ was investigated. Results indicate that the adsorbent SMNZ exhibited a higher affinity toward HA than the natural zeolite. HA removal efficiency by SMNZ increased with HTAB loading. Coexisting Ca²⁺ in solution favored HA adsorption onto SMNZ. Adsorption capacity decreased with an increasing solution pH. For typical SMNZ with bilayer HTAB coverage, HA adsorption process is well described by a pseudo-second-order kinetic model. The experimental isotherm data fitted well with the Langmuir model. Calculated maximum HA adsorption capacities for SMNZ with bilayer HTAB coverage at pH 5.5 and 7.5 were 63 and 41 mg·g⁻¹, respectively. E2/E3 (absorbance at 250 nm to that at 365 nm) and E4/E6 (absorbance at 465 nm to that at 665 nm) ratios of the residual HA in solution were lower than that of the original HA solution. This indicates that the HA fractions with high polar functional groups, low molecular weight (MW), and aromaticity had a stronger tendency for adsorption onto SMNZ with bilayer HTAB coverage. Results show that HTAB-modified natural zeolite is a promising adsorbent for removal of HA from aqueous solution.     

Synthesis, characterization and application of Lagerstroemia speciosa embedded magnetic nanoparticle for Cr(VI) adsorption from aqueous solution

Lagerstroemia speciosa bark (LB) embedded magnetic nanoparticles were prepared by co-precipitation of Fe²⁺ and Fe³⁺ salt solution with ammonia and LB for Cr(VI) removal from aqueous solution. The native LB, magnetic nanoparticle (MNP), L. speciosa embedded magnetic nanoparticle (MNPLB) and Cr(VI) adsorbed MNPLB particles were characterized by SEM–EDX, TEM, BET-surface area, FT-IR, XRD and TGA methods. TEM analysis confirmed nearly spherical shape of MNP with an average diameter of 8.76 nm and the surface modification did not result in the phase change of MNP as established by XRD analysis, while led to the formation of secondary particles of MNPLB with diameter of 18.54 nm. Characterization results revealed covalent binding between the hydroxyl group of MNP and carboxyl group of LB particles and further confirmed its physico-chemical nature favorable for Cr(VI) adsorption. The Cr(VI) adsorption on to MNPLB particle as an adsorbent was tested under different contact time, initial Cr(VI) concentration, adsorbent dose, initial pH, temperature and agitation speed. The results of the equilibrium and kinetics of adsorption were well described by Langmuir isotherm and pseudo-second-order model, respectively. The thermodynamic parameters suggest spontaneous and endothermic nature of Cr(VI) adsorption onto MNPLB. The maximum adsorption capacity for MNPLB was calculated to be 434.78 mg/g and these particles even after Cr(VI) adsorption were collected effortlessly from the aqueous solution by a magnet. The desorption of Cr(VI)-adsorbed MNPLB was found to be more than 93.72% with spent MNPLB depicting eleven successive adsorption–desorption cycles.     

用铁酸盐型磁性吸附剂去除偶氮染料酸性红B

通过对几种磁性铁酸盐型吸附剂Mfe₂O₄(M=Fe,Mn,Cu)的表面特性及去除染料酸性红B(ARB)的吸附性能与催化氧化再生性能的研究,证明该类吸附剂能够有效地吸附去除水中的酸性红B,经磁分离,用H₂O₂/Fe²⁺体系可以同时氧化有机物与再生吸附剂,吸附剂可以循环使用.pH值对吸附能力有很大影响,对于MnFe₂O₄和Fe₃O₄,发生最大吸附的pH值范围在3.5～3.8,而对于CuFe₂O₄ pH值则在4.5～4.8时有最大吸附能力.CuFe₂O₄的吸附容量最大,MnFe₂O₄次之,FeO₄最小;3种吸附剂的吸附等温线均符合Langmuir吸附模型.在发生吸附的pH值范围内,吸附剂吸附染料后其Zeta电位比吸附前均有明显降低.再生实验表明,3种吸附剂再生后,其比表面积明显增大,表面元素组成发生很大变化,其吸附能力也明显提高.     

PAAm/HACC半互穿网络水凝胶的制备及其对水中腐殖酸的吸附性能

采用原位聚合热合成法成功制备了聚丙烯酰胺-壳聚糖季铵盐半互穿网络水凝胶(PAAm/HACC semi-IPN)新型吸附剂(s-IPN 1.5)和(s-IPN 3),并用于吸附水体中的腐殖酸.利用扫描电镜(SEM)、红外光谱(FT-IR)、X射线衍射光谱(XRD)等方法对吸附剂的结构进行表征.考察了溶液pH、离子强度、接触时间、腐殖酸初始浓度及温度等对吸附剂吸附腐殖酸的影响.结果表明s-IPN 3的吸附效果要优于s-IPN 1.5.吸附剂对腐殖酸的吸附量随着pH的增大而减小,随温度的升高而增大,且一定的离子强度有助于吸附剂对腐殖酸的吸附.吸附过程能较好地用准二级动力学模型及Sips等温模型进行拟合.吸附剂在pH 7.0,离子强度0.01 mol·L-1,温度为298 K条件下的最大吸附量可高达238.08 mg·g-1,吸附效果显著,能有效去除水体中的腐殖酸.     

氯化十六烷基吡啶改性活性炭对水中硝酸盐的吸附作用

采用阳离子表面活性剂氯化十六烷基吡啶(CPC)对活性炭进行了改性,并通过实验考察了CPC改性活性炭对水中硝酸盐的吸附作用.结果表明,CPC改性活性炭对水中的硝酸盐具备较好的吸附能力.CPC改性活性炭对水中硝酸盐的吸附能力明显高于未改性的活性炭.CPC改性活性炭对水中硝酸盐的吸附能力随着CPC负载量的增加而增加.CPC改性活性炭对水中硝酸盐的吸附动力学满足准二级动力学模型.CPC改性活性炭对水中硝酸盐的吸附平衡数据可以较好地采用Langmuir等温吸附模型加以描述.根据Langmuir等温吸附方程,CPC负载量(以活性炭计)为444 mmol·kg-1的改性活性炭对水中硝酸盐的最大单位吸附量为16.1 mg·g-1.CPC改性活性炭对水中硝酸盐的吸附能力随着pH的增加而降低.水中共存的氯离子、硫酸根离子和碳酸氢根离子会抑制CPC改性活性炭对水中硝酸盐的吸附.升高反应温度略微降低了CPC改性活性炭对水中硝酸盐的吸附能力.采用1 mol·L-1的NaCl溶液可以使95%左右吸附到CPC改性活性炭上的硝酸盐解吸下来.CPC改性活性炭吸附水中硝酸盐的主要机制是阴离子交换和静电吸引作用.上述实验结果说明,CPC改性活性炭适合作为一种吸附剂用于去除水中的硝酸盐.     

Pb（II） biosorption using chitosan and chitosan derivatives beads： Equilibrium, ion exchange and mechanism studies

The study examined the adsorption of Pb(II) ions from aqueous solution onto chitosan, chitosan-GLA and chitosan-alginate beads. Several important parameters influencing the adsorption of Pb(II) ions such as initial pH, adsorbent dosage and di erent initial concentration of Pb(II) ions were evaluated. The mechanism involved during the adsorption process was explored based on ion exchange study and using spectroscopic techniques. The adsorption capacities obtained based on non–linear Langmuir isotherm for chitosan, chitosan-GLA and chitosan-alginate beads in single metal system were 34.98, 14.24 and 60.27 mg/g, respectively. However, the adsorption capacity of Pb(II) ions were reduced in the binary metal system due to the competitive adsorption between Pb(II) and Cu(II) ions. Based on the ion exchange study, the release of Ca2+, Mg2+, K+ and Na+ ions played an important role in the adsorption of Pb(II) ions by all three adsorbents but only at lower concentrations of Pb(II) ions. Infrared spectra showed that the binding between Pb(II) ions and the adsorbents involved mostly the nitrogen and oxygen atoms. All three adsorbents showed satisfactory adsorption capacities and can be considered as an e cient adsorbent for the removal of Pb(II) ions from aqueous solutions.     

硫脲改性猪粪生物质炭对模拟农田径流中镉和草甘膦吸附特征

为同时去除农田地表径流中的重金属和农药,利用猪粪制备未改性猪粪生物质炭（简称"未改性生物质炭"）和硫脲改性猪粪生物质炭（简称"改性生物质炭"）,分析比较硫脲改性对生物质炭的pH、元素组成、表面含氧官能团和巯基含量等理化性质的影响,并系统地研究了单一和复合污染体系中初始浓度对两种生物质炭吸附水溶液中镉（Cd）和草甘膦效率的影响.结果表明:①与未改性生物质炭相比,改性生物质炭的pH、O/C（原子比）和H/C（原子比）降低,比表面积增大,含氧官能团和巯基含量增加.②与未改性生物质炭相比,改性生物质炭对Cd和草甘膦的吸附能力增强,最大表观吸附量（Q_max）增加了近3倍;随着Cd和草甘膦初始浓度的增加,未改性和改性生物质炭对Cd和草甘膦的吸附量逐渐增加,增加量最高分别达18.52%和7.60%.③单一污染体系中两种生物质炭对Cd或草甘膦的吸附更符合Langmuir等温吸附模型,说明其对Cd或草甘膦的吸附机理是单分子层的吸附起主导作用.④复合污染体系中,未改性和改性生物质炭对Cd的吸附能力分别增加了25.28%和21.26%,未改性生物质炭对Cd的最大表观吸附量增加了29.34%,但改性生物质炭对Cd的最大表观吸附量降低了47.28%;未改性和改性生物质炭对草甘膦的吸附能力减弱,但最大表观吸附量分别增加了2.63和3.45倍.研究显示,硫脲改性猪粪生物质炭作为一项有前景的新技术,为解决实际环境中的复合污染问题提供了经济环保的技术手段.      

Factors influencing antibiotics adsorption onto engineered adsorbents

The study evaluated the adsorption of two antibiotics by four engineered adsorbents (hypercrosslinked resin MN-202, macroporous resin XAD-4, activated carbon F-400, and multi-walled carbon nanotubes (MWCNT)) from aqueous solutions. The dynamic results demonstrated the dominant influence of pore size in adsorption. The adsorption amounts of antibiotics on XAD-4 were attributed to the hydrophobic effect, whereas steric hindrance or micropore-filling played a main role in the adsorption of antibiotics by F-400 because of its high microporosity. Aside from F-400, similar patterns of pH-dependent adsorption were observed, implying the importance of antibiotic molecular forms to the adsorption process for adsorbents. Increasing the ionic concentration with CaCl2 produced particular adsorption characteristics on MWCNT at pH 2.0 and F-400 at pH 8.0, which were attributed to the highly available contact surfaces and molecular sieving, respectively. Its hybrid characteristics incorporating a considerable portion of mesopores and micropores made hypercross linked MN-202 a superior antibiotic adsorbent with high adsorption capacity. Furthermore, the adsorption capacity of MWCNT on the basis of surface area was more advantageous than that of the other adsorbents because MWCNT has a much more compact molecular arrangement.     

板栗内皮对水溶液中镉的吸附研究

采用生物吸附法去除水体重金属污染具有重要的现实意义.本文以板栗内皮为吸附剂,研究了溶液pH值、反应时间、吸附剂投加量对水溶液中镉的吸附量与去除率的影响;通过模型拟合、离子交换实验、电镜扫描（SEM）和红外光谱（FTIR）分析,对吸附机理进行了探讨.结果表明：板栗内皮是一种理想的镉吸附剂,适应pH值范围宽（3～6）,达到...     

水合氧化镧吸附除磷的试验研究

以开发新型高效除磷吸附剂材料为目的,以金属水合氧化物MeH(metal hydrate)为试验对象,对所选材料进行了吸附除磷性能评价.通过对多种水合金属氧化物吸附除磷性能的比较研究,发现水合氧化镧LaH(lan-thanum hydrate)具有优异的除磷吸附容量,其吸附容量大约为参照物粉末活性氧化铝的十几倍.该吸附剂的吸附容量随pH值变化显著,在pH=3附近达最大值;吸附等温线较符合Langmuir方程;进行了抗无机阴离子干扰能力测试,给出了干扰离子的影响顺序;该吸附剂对正磷酸根的去除性能优越,但对聚磷酸根的去除效果不理想.试验结果表明,水合氧化镧在平衡吸附容量、pH适应范围等方面与参照物活性氧化铝相比较,具有优异的性能.     

基于铁锰泥的除砷吸附剂性能比较及吸附机理

为解决反冲洗铁锰泥粉末吸附剂（BSPA）使用后难以泥水分离问题,将除铁锰水厂生物滤池产生的反冲洗泥制成颗粒吸附剂（GA）和磁性粉末吸附剂（MPA）,并对BSPA、GA和MPA的除砷性能进行了比较,通过SEM、TED、XRD、BET、FTIR等技术对3种材料进行了表征,寻找3种吸附剂之间除砷性能差异的根源.结果表明,BSPA、GA和MPA对As （V）的最大吸附容量分别为40.980,5.048,8.694mg/g,改性后的吸附材料GA和MPA对砷的吸附能力下降.BSPA是一种以纤铁矿为主的无定形结构混合物,并混有针铁矿和结晶度差的水铁矿,GA的XRD图谱中出现石英晶体和少量赤铁矿晶体的衍射峰,而MPA的主要成分为结晶程度较高的磁赤铁矿.3种材料中均存在有利于吸附的含羟基官能团.BSPA、MPA和GA的比表面积分别为253.150,238.660,43.803m²/g.物相改变且结晶程度增加、表面羟基减少和比表面积降低是导致GA和MPA的砷吸附容量比BSPA低的主要因素.     

Adsorption thermodynamics and kinetic investigation of aromatic amphoteric compounds onto different polymeric adsorbents

The adsorption behavior of p-aminobenzoic acid and o-aminobenzoic acid onto the different polymeric adsorbents was systematically investigated as a function of the solution concentration and temperature.Experimental results indicated that the equilibrium adsorption data of the four polymeric adsorbents fitted well in the Freundlich isotherm.The adsorption capacity of multi-functional polymeric adsorbent NJ-99 was the highest,which might be attributed to the strong hydrogen-bonding interaction between the amino groups on the resin and the carboxyl group of aminobenzoic acid.The adsorption capacity of o-aminobenzoic acid onto any adsorbent was higher than p-aminobenzoic acid.Thermodynamic studies suggested the exothermic,spontaneous physical adsorption process.Adsorption kinetics results showed that the adsorption followed the pseudo-second-order kinetics model and the intraparticle mass transfer process was the rate-controlling step.     

污泥含炭吸附剂对Cu^2＋的吸附实验研究

研究了采用ZnCl2化学活化法制备的污泥含炭吸附刺去除水溶液中Cu^2＋的效果,考察了溶液pH值、吸附时间、吸附剂用量和Cu^2＋浓度等对去除率的影响。实验结果表明,污泥含炭吸附剂对Cu^2＋具有较强的吸附性能,吸附平衡时间约为1h;pH值是影响吸附的主要因素,实际应用中一般控制在pH=5．0;Cu^2＋的浓度不宜过高,为了达到较好的去除效果,实际应用中吸附剂用量一般不能低于2g／100mL溶液。