Adsorptive removal of phosphate by the bimetallic hydroxide nanocomposites embedded in pomegranate peel

This study aimed to fabricate new and effective material for the efficiency of phosphate adsorption. Two types of adsorbent materials, the zirconium hydroxides embedded in pomegranate peel (Zr/Peel) and zirconium-lanthanum hydroxides embedded in pomegranate peel (Zr–La/Peel) were developed. Scanning electronic microscopy (SEM), x-ray photoelectron spectroscopy (XPS) and x-ray diffraction (XRD) were evaluated to give insight into the physicochemical properties of these adsorbents. Zr–La/Peel exceeded the adsorption efficiency of Zr/Peel adsorbents in batch adsorption experiments at the same pH level. The peel as a host can strive to have a strong “shielding effect” to increase the steadiness of the entrenched Zr and La elements. La and Zr are hydroxide metals that emit many hydrogen ions during the hydrolysis reaction, which contribute to protonation and electrostatic attraction. The highest adsorption capacity of La–Zr/Peel for phosphate was calculated to be 40.21 mg/g, and pseudo second-order equation is very well fitted for kinetic adsorption. Phosphate adsorption efficiency was reduced by an increase of pH. With the background of coexisting Cl^?, little effect on adsorption efficiency was observed, while adsorption capacities were reduced by almost 20–30% with the coexistence of ${{\text{SO}}_4}^{2?}$, ${{\text{NO}}_3}^{?}$ and humic acid (HA).     

锆-十六烷基三甲基氯化铵改性活性炭对水中硝酸盐和磷酸盐的吸附特性

采用锆(Zr)和阳离子表面活性剂十六烷基三甲基氯化铵(CTAC)对活性炭进行联合改性,考察了所制备的Zr-CTAC改性活性炭对水中硝酸盐和磷酸盐的吸附去除作用,并探讨了相关的吸附去除机制.结果表明,Zr-CTAC改性活性炭对水中硝酸盐和磷酸盐均具备较好的吸附去除能力.Zr-CTAC改性活性炭对硝酸盐和磷酸盐吸附动力学过程满足准二级动力学模型.Langmuir、Freundlich和Dubinin-Radushkevich(D-R)等温吸附模型可以较好地描述Zr-CTAC改性活性炭对水中硝酸盐的等温吸附过程,Langmuir和D-R等温吸附模型可以较好地描述Zr-CTAC改性活性炭对水中磷酸盐等温吸附过程,通过Langmuir模型计算得到吸附剂对硝酸盐和磷酸盐的最大单位吸附量分别为7.58 mg·g-1和10.9 mg·g-1.高的p H会抑制Zr-CTAC改性活性炭对水中硝酸盐和磷酸盐的吸附.水中共存的Cl-、HCO-3和SO2-4等阴离子均会抑制Zr-CTAC改性活性炭对硝酸盐和磷酸盐的吸附,且对吸附硝酸盐的抑制作用较强而对吸附磷酸盐的抑制作用较弱.水中共存的磷酸盐对Zr-CTAC改性活性炭吸附硝酸盐的抑制作用较强,而水中共存的硝酸盐对Zr-CTAC改性活性炭吸附磷酸盐的抑制作用较弱.1 mol·L-1Na Cl溶液可以使90%左右被吸附到Zr-CTAC改性活性炭表面上的硝酸盐解吸下来.1 mol·L-1的Na OH溶液可以使78%左右被吸附到Zr-CTAC改性活性炭表面上的磷酸盐解吸下来.Zr-CTAC改性活性炭对硝酸盐的吸附机制主要包括阴离子交换作用和静电吸引作用,对磷酸盐的吸附机制主要包括配位体交换作用、阴离子交换作用和静电吸引作用.上述结果说明Zr-CTAC改性活性炭适合作为一种吸附剂去除废水中的硝酸盐和磷酸盐.     

锆改性沸石对水中磷酸盐和铵的吸附特性

采用锆对天然沸石进行改性,并研究了锆改性沸石对水中磷酸盐和铵的吸附特性.结果表明,锆改性沸石对水中磷酸盐和铵均具有很好的吸附能力.锆改性沸石对水中磷酸盐和铵的吸附动力学过程满足准二级动力学模型.Langmuir、Freundlich和Dubinin–Radushkevich(D–R)等温吸附模型可以很好地描述锆改性沸石对水中磷酸盐的等温吸附行为.Langmuir等温吸附模型可以很好地描述锆改性沸石对水中铵的等温吸附行为.由Langmuir等温吸附模型计算得到锆改性沸石对磷酸盐和铵的最大吸附容量分别达到26.2,7.82 mg/g.热力学参数表明锆改性沸石对水中磷酸盐的吸附是自发的吸热反应过程.锆改性沸石对水中磷酸盐的吸附能力随着pH值的增加而降低.当pH4~8时,锆改性沸石对水中铵的吸附能力较高;当pH低于4或高于8时,对铵的吸附能力下降.水中共存的Cl-、SO42-、HCO3-和NO3-等阴离子对锆改性沸石吸附磷酸盐的影响很小,而共存的SiO32-对磷酸盐的吸附则具有较强的负面影响.水中共存的Ca2+和Mg2+对锆改性沸石吸附铵的影响较小,而共存的K+和Na+对铵的吸附则具有较强的负面影响.锆改性沸石吸附水中磷酸盐的主要机制是阴离子配位体的交换,吸附水中铵的主要机制是与沸石中可交换阳离子的离子交换.     

High phosphate removal using La(OH)3 loaded chitosan based composites and mechanistic study

Our present study was to prepare a biomass-supported adsorbents with high adsorptive capacity and high selectivity to prevent the accelerated eutrophication in water body. To this end, different metal hydroxide (La, Zr and Fe) first was successfully loaded on chitosan microspheres. Then the quaternary ammonium group with different content was introduced into the adsorbent by polymerization. By comparison of adsorption properties, chitosan-La(OH)₃-quaternary ammonium-20% (CS-La-N-20%) has strong adsorption to phosphate (160 mg/g) by immobilizing nano-sized La(OH)₃ within a quaternary-aminated chitosan and it maintain high adsorption in the presence of salt ions. The pH results indicated that the CS-La-N-20% would effectively sequestrate phosphate over a wide pH range between 3 and 7 without significant La³⁺ leaching. What's more, adsorption capacity on the introduce of positively charged quanternary-aminated groups was significantly higher than that of the unmodified adsorbents at alkaline conditions. The column adsorption capacity reached 1300 bed volumes (BV) when phosphate concentration decreased until 0.5 mg/L at 6 BV/hr. The column adsorption/desorption reveals that no significant capacity loss is observed, indicating excellent stability and repeated use property. Characterizations revealed that phosphate adsorption on CS-La-N-20% through ligand exchange (impregnated nano-La(OH)₃) and electrostatic attraction (positively charged quanternary-aminated groups). All the results suggested that CS-La-N-20% can serve as a promising adsorbent for preferable phosphate removal in realistic application.     

Removal of trace arsenic（V） and phosphate from water by a highly selective ligand exchange adsorbent

The ligand exchange adsorbent could be used to remove the toxic arsenic(V) and phosphate efficiently from water even in the presence of foreign anions and possible to apply in chemical industry.     

Al改性柠条生物炭对P的吸附特性及其机制

为高效利用生物质能源,以常见农林废弃物柠条为原料,在650℃、3h条件下,采用限氧热裂解法制备生物炭,通过直接修饰法用Al改性柠条生物炭,进行批量吸附P实验.利用4种等温吸附模型（Langmuir、Freundlich模型、Temkim、D-R模型）和4种吸附动力学模型（准一级动力学、准二级动力学、Elovich模型、颗粒内扩散模型）以及pH值、添加量影响试验,探讨Al改性生物炭对P的吸附特性.同时,使用FTIR红外、元素分析、SEM和比表面积及孔径分析等技术表征了生物炭的理化性质,揭示了Al改性生物炭对P的吸附机理,并对比了多种改性生物炭对P的吸附效果.结果表明：柠条生物炭（NB）对P的吸附量很低,Al改性柠条生物炭（Al-NB）最佳改性比例为0.2：1,对P的吸附量是NB的8.35倍.Langmuir模型能够很好的描述Al-NB对P的等温吸附过程;Al-NB对P的吸附动力学符合准一级动力学模型,说明其吸附通过边界扩散完成的单层吸附.Al-NB对P的理论最大吸附量为19.97mg/g,平衡时间为24h.随着添加量的增大,Al-NB对P的吸附量不断减小,去除率逐渐增加,2.5g/L为最佳添加量;最适pH为4～10,当pH=7时,达到最大;吸附P后,溶液的pH值向中性范围倾靠,有一定缓冲作用.吸附机理包括：静电吸附作用,配体交换（羟基）,P与阴离子（NO₃^-）交换,颗粒内表面络合作用等.以期为水体富营养化治理提供科学依据.     

Friedel层状化合物对正磷酸根的去除效应及其作用机制

为了解Friedel化合物除磷的应用潜能,研究了Friedel化合物对正磷酸根的吸附动力学和吸附等温线,并结合反应后溶液中各离子浓度的变化和反应固相产物的XRD、红外光谱分析,探讨其除磷作用机理.结果表明:Friedel化合物对正磷酸根的吸附等温线符合Langmuir等温吸附方程,理论吸附容量为4.86mmol·g-1;Friedel化合物除磷作用机理主要为溶出钙离子的沉淀作用,同时存在氢氧化铝的固磷作用.     

海藻酸锆/聚N-异丙基丙烯酰胺半互穿网络凝胶球的除磷性能

利用离子交联和自由基聚合反应制备了一种海藻酸锆/聚(N-异丙基丙烯酰胺)半互穿网络凝胶球(ZA/PNIPAM),用于吸附水中的磷酸盐.考察了溶液初始pH、吸附剂投加量、初始磷酸盐浓度和共存阴离子等因素对凝胶球吸附性能的影响.结果表明:ZA/PNIPAM在pH=2时可获得较大的吸附能力;随着投加量的减少、初始磷酸盐浓度的升高,凝胶球的吸附性能逐渐增大;SO_4~(2-)对吸附性能影响较Cl~-和NO_3~-明显.准二级动力学模型和颗粒内部扩散模型可以较好地拟合动力学吸附数据,表明表面吸附和颗粒内部扩散是吸附速率的主要控制步骤.吸附等温线数据可以较好地被Freundlich模型描述,表明吸附过程为非均匀多分子层吸附.FTIR、XPS、零电荷点(pH_(pzc))的结果以及相关吸附数据揭示凝胶球吸附磷酸盐的机制为静电吸附(物理吸附)以及配位交换(化学吸附)的共同作用.经过4次循环再生后,ZA/PNIPAM吸附性能保持稳定,具有良好的重复使用性.     

氢氧化镧掺杂氧化铝去除水体磷酸盐性能研究

为有效去除水体中的磷酸盐,采用沉淀沉积方法合成了氢氧化镧〔La(OH)₃〕掺杂氧化铝(Al₂O₃)的吸附材料La(OH)₃(X)/Al₂O₃〔X表示吸附剂中的La(OH)₃质量含量〕,并对其吸附磷酸盐的性能进行研究. 结果表明:①Al₂O₃和La(OH)₃是吸附剂中磷酸盐的主要结合位点. ②磷酸盐初始浓度为50 mg/L时,La(OH)₃(19)/Al₂O₃吸附剂在初始阶段吸附较快,且在200 min左右达到吸附平衡. La(OH)₃(X)/Al₂O₃吸附剂对磷酸盐的吸附量随着La(OH)₃负载量的提高而升高,其吸附等温线符合Langmuir模型拟合. La(OH)₃(7)/Al₂O₃、La(OH)₃(13)/Al₂O₃、La(OH)₃(19)/Al₂O₃和La(OH)₃(27)/Al₂O₃对磷酸盐的最大吸附量可分别达到25.32、27.40、43.10和53.76 mg/g (以P计). 这表明La(OH)₃掺杂Al₂O₃后为磷酸盐提供更多的活性位点,有效提高了磷酸盐的吸附容量. ③La(OH)₃(19)/Al₂O₃对磷酸盐的吸附量随pH的升高而降低,共存阴离子影响试验表明,La(OH)₃(19)/Al₂O₃对磷酸盐具有较高的吸附选择性. ④经过5次吸附-脱附循环后,La(OH)₃(19)/Al₂O₃表现出稳定的吸附和再生性能,对实际水体磷酸盐的去除试验结果表明其可用于实际水体中磷酸盐的去除. 研究显示,La(OH)₃(19)/Al₂O₃的磷酸盐吸附速率快、吸附容量高、吸附选择性高,具有潜在的应用价值.      

膨胀蛭石同步脱铵除磷的影响因素研究

为探讨膨胀蛭石同步脱铵除磷能力,采用静态吸附实验考察了氨氮和磷酸盐共存时接触时间、粒径、pH值以及温度对膨胀蛭石去除氮磷效果的影响。结果表明,膨胀蛭石具有较好的同步脱铵除磷性能,在pH值为7,温度为25℃条件下,用1.00g粒径为80~100目膨胀蛭石对100mL氨氮和磷酸盐浓度分别为50mg/L和10mg/L的模拟污水处理4h后,氨氮和磷酸盐去除率分别达79.4%和93.0%,两者吸附过程均明显表现为"快速吸附,减速平衡"二阶段特征。中性条件下氨氮去除效果最好,酸性或碱性条件有利于磷酸盐去除,温度升高,氨氮去除率下降,磷酸盐去除率上升。等温吸附实验研究表明,膨胀蛭石对氨氮与磷酸盐的等温吸附线均较好的符合Langmuir方程。     

化学铁盐辅助除磷对生物除磷的影响研究

化学辅助除磷有助于污水厂实现磷达标,但其对生物系统存在潜在的影响。针对除磷药剂对生物除磷过程的影响展开研究,选用硫酸亚铁进行化学辅助除磷。药剂形成的化学污泥干扰生物除磷过程且成分复杂,故以磷酸铁、氢氧化铁模拟化学污泥,由钾离子、K/P摩尔比计算出同步除磷中的生物除磷,来探讨化学污泥对聚磷菌释磷/吸磷过程的影响。结果表明,连续投加硫酸亚铁使聚磷菌的释磷量、吸磷量降低;系统中磷酸铁含量0.075 mmol/L时聚磷菌的释磷和吸磷能力提高了约25%,磷酸铁含量0.15 mmol/L时对聚磷菌吸磷有抑制作用;氢氧化铁对聚磷菌释磷、好氧初期吸磷均有抑制作用。生物污泥与化学污泥存在交互作用。     

浙江省四种类型土壤酸缓冲性能初析

用酸定量回漓和土壤BS-pH缓冲曲线定性比较浙江省四种类型土壤酸缓冲性能的强弱.结果表明,酸性淋溶土缓冲能力虽较弱,但缓冲区出现范围较宽(BS20—80％)且缓冲性能较持久.近中性水成土则大体相反.四种土壤对SO_4~(2-)的吸附容量甚大,吸附过程符合Freundlich方程表述的规律.水和1.0 mol/L KNO_3对土壤吸附态SO_4~(2-)解吸率甚低(<40％).     

Adsorption and recovery of phosphate from water by amine fiber, effects of co-existing ions and column filtration

A weak-base adsorption fiber, acrylic amine fiber (AAF), was prepared for removal and recovery of phosphate from water. The adsorption properties of the AAF for phosphate and effects of co-existing ions were investigated using batch and column filtration experiments, scanning electron microscope, and Fourier transform infrared techniques. Experimental results showed that AAF had a high phosphate adsorption capacity of 119?mg/g at pH?7.0. The effects of calcium, sulfate, carbonate, nitrate, and fluoride showed that sulfate and calcium inhibited phosphate adsorption. However, AAF showed higher binding affinity toward phosphate than sulfate. Column filtration results showed that AAF could filter 1420 bed volumes of tap water containing 1.0?mg-P/L of phosphate. The saturated AAF could be regenerated using 0.5?mol/L hydrochloric acid solution and reused. After desorption, phosphate was recovered through precipitation of hydroxyapatite (Ca₅(PO₄)₃OH). The easy of regeneration, good adsorption performance, and the fiber morphology of AAF make it an attractive alternative for phosphate recovery from multiple water sources.     

Preparation and utilization of wheat straw anionic sorbent for the removal of nitrate from aqueous solution

In order to reduce the impact of eutrophication caused by agricultural residues(i.e.,excess nitrate)in aqueous solution,economic and effective anionic sorbents are required.In this article,we prepared anionic sorbent using wheat straw.Its structural characteristics and adsorption properties for nitrate removal from aqueous solution were investigated.The results indicate that the yield of the prepared anionic sorbent,the total exchange capacity,and the maximum adsorption capacity were 350%,2.57 mEq/g,and 2.08 mmol/g, respectively.The Freundlich isotherm mode is more suitable than the Langmuir mode and the adsorption process accords with the first order reaction kinetic rate equation.When multiple anions(SO_4~(2-),H_2PO_4~-,NO_3~-,and NO_2~-)were present,the isotherm mode of prepared anionic sorbent for nitrate was consistent with Freundlich mode;however,the capacity of nitrate adsorption was reduced by 50%.In alkaline solutions,about 90% of adsorbed nitrate ions could be desorbed from prepared anionic sorbent.The results of this study confirmed that the wheat straw anionic sorbent can be used as an excellent nitrate sorbent that removes nitrate from aqueous solutions.     

水合氧化铁对含磷废水的吸附特性研究

以Fe(NO3)3为前驱物,制备了水合氧化铁吸附剂样品,以NaOH为解吸剂,研究了样品对模拟废水中磷酸根的吸附和解吸性能。结果表明,水合氧化铁对磷酸根有较好的吸附效果;随着pH的降低,水合氧化铁对磷酸根的吸附能力增强,在pH为2时吸附达92.5%;吸附前15 min吸附速率较快,约150 min达到平衡,吸附动力学曲线符合二级动力学模型;用水合氧化铁对初始浓度为50~100 mg/L模拟含磷废水吸附,随着初始浓度的增大,磷的去除率下降;水合氧化铁对磷酸根的吸附等温线较符合Langmuir吸附模型;用NaOH对水合氧化铁行解吸,浓度为40 g/L有最好的解吸率,60 min时达到解吸平衡。     

镁铁层状双金属氢氧化物对磷酸盐的吸附作用及对内源磷释放的控制效果及机制

为确定镁铁层状双金属氢氧化物(Mg/Fe-LDH)添加对水体内源磷释放的控制效果及机制,本文首先研究了Mg/FeLDH对水中磷酸盐的吸附特征和机制,再研究了其添加对底泥磷吸附能力的影响以及对上覆水和间隙水中磷的影响进而评估了吸附磷酸盐后Mg/Fe-LDH中磷的稳定性.结果发现,与准一级和准二级动力学模型相比,Mg/Fe-LDH对水中磷酸盐的吸附动力学过程更好地满足Elovich模型;与Langmuir模型相比,Freundlich和Dubinin-Radushkevich模型更加适合用于描述Mg/Fe-LDH对水中磷酸盐的等温吸附行为;当溶液pH值为4～10时,吸附容量相对较高,而当pH值由10增加到11时,吸附容量则显著下降;共存Ca~(2+)和Mg~(2+)对吸附起促进作用,Na~+和Cl~-的影响可以忽略不计,而SO_4~(2-)和HCO_3~-则对吸附起负面影响.阴离子交换、静电吸引、配位体交换和内层配合物形成是Mg/Fe-LDH吸附水中磷酸盐的主要机制.Mg/Fe-LDH添加不仅会降低上覆水中溶解性活性磷(SRP)浓度而且会降低间隙水中SRP浓度.Mg/Fe-LDH添加也会显著增强底泥对水中磷酸盐的吸附能力,且投加量越大,促进效果越明显.被Mg/Fe-LDH所吸附的磷酸盐主要以NH_4 Cl提取态磷(NH_4Cl-P)、氧化还原敏感态磷(BD-P)和金属氧化物结合态磷(NaOH-rP)形态存在,分别占总磷的13.7%、34.0%和52.3%.被Mg/Fe-LDH所吸附的磷酸盐中大约有一半的磷会以较为稳定的形式存在不容易被重新释放.考虑到被Mg/Fe-LDH所吸附磷酸盐中大约有一半的磷会以不稳定的形式存在,存在重新释放的风险,因此将吸附饱和后的Mg/Fe-LDH进行回收是非常必要的.     

氢氧化铌对水溶液中磷酸根的吸附特性研究

以氢氟酸法制备的氢氧化铌作为磷酸根的吸附剂,考察了氢氧化铌用量及焙烧温度对吸附效果的影响。在25℃,磷酸根初始浓度为50mg/L、体积200mL的条件下,确定吸附剂的最佳用量为0.1g,此时氢氧化铌原样对磷酸根的最大吸附量为48.2mg/g。上述条件下,经200、300、400、500℃焙烧后的氢氧化铌对磷酸根的最大吸附量依次为25.9、15.6、11.6、7.5mg/g。分析表明,随着焙烧温度的升高,表面羟基逐渐减少,氢氧化铌对磷酸根的吸附能力逐渐降低。在吸附过程中,焙烧前后的氢氧化铌对磷酸根吸附速率均较快(20min达到吸附平衡)。     

不同锆负载量锆改性膨润土对水中磷酸盐吸附作用的对比

通过实验对比考察了不同锆负载量的锆改性膨润土对水中磷酸盐的吸附作用.结果表明,锆改性膨润土对水中磷酸盐的吸附动力学过程符合准二级动力学模型,整个过程可以分为快速吸附阶段、缓慢吸附阶段和平衡吸附阶段,其中缓慢吸附阶段的吸附速率受膜扩散和颗粒内扩散所控制.锆改性膨润土对水中磷酸盐的吸附等温实验数据可以采用Langmuir、Freundlich、Sips和Dubinin-Radushkevich等温吸附模型进行拟合.实验条件下,磷酸盐吸附性能随pH增加而降低.溶液共存的Na~+、K~+和Ca~(2+)促进了锆改性膨润土对磷酸盐的吸附,并且Ca~(2+)的促进作用远远大于Na~+和K+,而溶液共存的HCO-3和SO2-4一定程度上抑制了锆改性膨润土对磷酸盐的吸附.锆改性膨润土吸附水中磷酸盐的主要机制为配位体交换并形成内层磷酸盐配合物.锆改性膨润土对水中磷酸盐的吸附能力随着锆负载量的增加而增加,而锆改性膨润土中单位质量ZrO_2对水中磷酸盐的吸附量则随着锆负载量的增加而降低.当ZrO_2负载量由3.61%增加到13.15%时锆改性膨润土的最大单层单位吸附量(以P计)显著地由3.83 mg·g~(-1)增加到9.03 mg·g~(-1),而继续增加ZrO_2负载量至19.63%时锆改性膨润土的最大单层单位吸附量则缓慢地提高到9.66 mg·g~(-1)(以P计).当ZrO_2负载量由3.61%逐渐增加到19.63%时,锆改性膨润土中单位质量ZrO_2的磷酸盐最大吸附量[m(P)/m(ZrO_2)]由106 mg·g~(-1)逐渐下降到49.2 mg·g~(-1).综合考虑吸附剂的经济成本和吸附容量,ZrO_2负载量为13.15%锆改性膨润土更为适合作为吸附剂去除水中磷酸盐.     

V2O5/AC在含SO2气氛中对气态Hg0的吸附脱除研究

利用固定床反应器研究了模拟烟气(N_2、SO_2、O_2)气氛下,气态Hg~0在V_2O_5/AC催化剂上的吸附脱除行为.考察了V_2O_5担载量、SO_2浓度和吸附温度等对V_2O_5/AC吸附脱除Hg~0的影响,并对V_2O_5/AC上吸附汞的形态进行了XPS分析表征.研究发现,V_2O_5/AC对Hg~0的吸附能力远大于载体AC.汞的吸附量与V_2O_5/AC中V_2O_5的质量分数有关,随着V_2O_5质量分数从0.5%增加到1.0%,汞的吸附量从75.9 μg·g~(-1)增加到89.6 μg·g~(-1) (无氧) 和115.9 μg·g~(-1)增加到185.5 μg·g~(-1) (有氧),远高于相同吸附条件下的AC上的汞吸附量 (9.6 μg·g~(-1)和23.3 μg·g~(-1)).SO_2对Hg~0的吸附有促进作用,主要是由于SO_2和Hg~0在V_2O_5/AC上发生了化学反应.但是当SO_2体积分数从500×10~(-6)增加到2 000×10~(-6)时,V_2O_5/AC对汞的吸附量只增加了5%.不同温度下的实验结果表明,V_2O_5/AC催化剂在150℃左右的吸附脱除Hg~0的能力最高,汞的吸附量达到98.5 μg·g~(-1) (无氧) 和187.7 μg·g~(-1) (有氧).XPS 分析结果表明,在V_2O_5/AC催化剂表面有HgO和HgSO_4生成,证实了V_2O_5和SO_2的作用.     

Removal of phosphate by Fe-coordinated amino-functionalized 3D mesoporous silicates hybrid materials

Phosphate removal from aqueous waste streams is an important approach to control the eutrophication downstream bodies of water. A Fe(III) coordinated amino-functionalized silicate adsorbent for phosphate adsorption was synthesized by a post-grafting and metal cation incorporation process. The surface structure of the adsorbent was characterized by X-ray di raction, N2 adsoropion/desoprotion technique, and Fourier transform infrared spectroscopy. The experimental results showed that the adsorption equilibrium data were well fitted to the Langmuir equation. The maximum adsorption capacity of the modified silicate material was 51.8 mg/g. The kinetic data from the adsorption of phosphate were fitted to pseudo second-order model. The phosphate adsorption was highly pH dependent and the relatively high removal of phosphate fell within the pH range 3.0–6.0. The coexistence of other anions in solutions has an adverse e ect on phosphate adsorption; a decrease in adsorption capacity followed the order of exogenous anions: F?? > SO2?? 4 > NO??3 > Cl??. In addition, the adsorbed phosphate could be desorbed by NaOH solutions. This silicate adsorbent with a large adsorption capacity and relatively high selectivity could be utilized for the removal of phosphate from aqueous waste streams or in aquatic environment.