Enhanced phosphate removal using zirconium hydroxide encapsulated in quaternized cellulose

Zirconium-based materials are efficient adsorbent for aqueous phosphate removal.However,current zirconium-based materials still show unsatisfied performance on adsorption capacity and selectivity.Here,we demonstrate a zirconium hydroxide encapsulated in quaternized cellulose(QC-Zr) for the selective phosphate removal.Zirconium hydroxide nanoparticles were simultaneously generated in situ with the QC framework and firmly anchored in the three-dimensional(3D) cross-linked cellulose chains.The maxi...     

矿物材料吸附去除污水中磷的试验研究

采用粉煤灰、高岭土、泥渣(取电厂澄清池排泥作脱水干燥处理)作为吸附剂深度处理污水中的磷,对比分析了3种吸附剂的吸附速度、吸附性能及除磷效果。结果表明:粉煤灰和高岭土用时20 min完成对磷的有效吸附,沉降泥渣用时5 min即可实现同等吸附效果;沉降泥渣对污水中磷的吸附能力较好,投加量为0.2 g/L的泥渣对磷的去除率可达98.1%,而投加量为0.2 g/L粉煤灰或高岭土对磷的去除率仅达到77.2%。     

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 show...     

Improved utilization of active sites for phosphorus adsorption in FeOOH/anion exchanger nanocomposites via a glycol-solvothermal synthesis strategy

Metal oxide/hydroxide-based nanocomposite adsorbents with porous supporting matrices have been recognized as efficient adsorbents for phosphorus recovery. Aiming at satisfying increasingly restrictive environmental requirements involving improving metal site utilization and lowering metal leakage risk, a glycol-solvothermal confined-space synthesis strategy was proposed for the fabrication of Fe OOH/anion exchanger nanocomposites（Fe/900s）with enhanced metal site utilization and reduced metal lea...     

纳米氢氧化钛及焙烧产物对磷酸根的吸附特性研究

以纳米氢氧化钛(NTH)作为吸附水溶液中磷酸根的吸附剂,考察了NTH不同焙烧温度下的分子式及其对PO43-吸附效果的影响.选择PO43-初始浓度为50 mg/L,通过正交试验确定在pH=2、吸附剂用量为0.1g、吸附时间为40min、温度25℃时,NTH吸附效果达到最佳,吸附量为55.5 mg/g,经200、300、400及500℃焙烧后的NTH对磷酸根的吸附量逐渐减小;吸附量分别为494、40.6、25.5及16.8 mg/g;NTH经800℃焙烧后,焙烧产物TiO2不具有吸附性.TG、XRD分析表明随着焙烧温度的升高,NTH的表面活性基团(-OH)数量逐渐减少.结果表明,吸附剂的吸附性与吸附剂表面羟基的数量有直接关系.     

固定化包埋颗粒对二级出水深度脱氮特性研究

采用包埋固定化颗粒对北京市某污水处理厂的二沉池出水进行深度脱氮处理,研究了驯化启动及稳定运行的条件和脱氮特性,对比了不同水力停留时间(HRT)、不同进水TN负荷的脱氮效能.结果表明,在水温为25℃、pH =7.2、水力停留时间为70 min、包埋颗粒填充率为30％时,投加碳源驯化一周后包埋固定化颗粒即能保持稳定高效的脱氮率,并具有良好的耐冲击负荷能力;进水TN负荷从0.5 kg·m-3· d-1逐渐提高至2.0 kg·m-3·d-1时,TN平均去除率达到86.6％.进水TN负荷为2.5 kg·m-3·d-1时,TN平均去除率仍能达到70％;在HRT为20 min时,出水硝氮＜1 mg·L-1,TN ＜5 mg·L-1;填充率由30％逐渐降低到20％时,TN去除率均能达到80％以上;填充率低于20％时,TN去除率随着填充率的减少而下降.试验确定包埋固定化菌的最佳填充率为20％.     

基于响应面优化条件下柚皮对Pb2+的吸附

采用Plackett-Burman(P-B)法和中心复合设计(Central Composite Design,简称CCD)对影响柚皮吸附Pb2+的6个条件进行筛选优化.P-B实验设计与统计学分析表明:pH值、Pb2+初始浓度、吸附剂用量是影响吸附率的3个关键因素.以吸附率为响应目标,对3因素进行中心复合设计,并经响应面法优化分析得到影响吸附率的二阶模型,确定了Pb2+吸附实验的最优操作条件:pH值5.4.Pb2+初始浓度为265.86mg·L-1,吸附剂用量为2.56 g·L-1,实测吸附率达到92.47%,吸附量为96.01 mg·g-1;整个吸附过程吸附剂柚皮没有经过任何化学预处理.效果优于一般的天然吸附剂.研究结果表明,柚皮是一种很具潜力的环保型廉价吸附剂.     

Efficient adsorption of Mn(Ⅱ) by layered double hydroxides intercalated with diethylenetriaminepentaacetic acid and the mechanistic study

In this study, greatly enhanced Mn(II) adsorption was achieved by as-synthesized diethylenetriaminepentaacetate acid intercalated Mg/Al layered double hydroxides(LDHsDTPA). The adsorption capacity of LDHs-DTPA was 83.5 mg/g, which is much higher than that of LDHs-EDTA(44.4 mg/g), LDHs-Oxalate(21.6 mg/g) and LDHs(28.8 mg/g). The adsorption data of aqueous Mn(II) using LDHs-DTPA could be well described by the pseudosecond order kinetics and Langmuir isotherm model. Thermodynamics study results also showed that the adsorption process of Mn(II) by LDHs-DTPA was exothermic as indicated by the negative ΔH value. Furthermore, based on the structural, morphological and thermostable features, as well as FT-IR and XPS characterizations of LDHs-DTPA and the pristine LDHs, the adsorption mechanism of Mn(II) was proposed. The carboxyl groups of DTPA were proposed to be the main binding sites for Mn(II), and the hydroxyl groups of LDHs also played a minor role in the adsorption process. Among the three common regeneration reagents, 0.1 mol/L Na_2CO_3 was the best for reusing LDHs-DTPA in Mn(II)adsorption. Besides, the Mn(II) adsorption performance could be hindered in the presence of typical inorganic ions, especially cations. Further specific modifications of LDHs-DTPA are suggested to get more selective adsorption of Mn(II) in practical applications.     

Effects of fluoride on the removal of cadmium and phosphate by aluminum coagulation

This study focuses on the effects of p H and fluoride at different molar ratios of fluoride to Al(R F:Al) on the removal of cadmium(Cd~(2+)) and phosphate by Al coagulation. Fluoride at R F:Al≥ 3:1 inhibits the removal of Cd over wide Al dose ranges from 5 to 10 mg/L as Al. The removal of phosphate decreases significantly at high R F:Al of 10:1 whereas at lowered R F:Al(i.e., ≤ 6:1), an adverse effect is observed only at insufficient Al doses below 2 mg/L. Fluoride shows inhibitive effects towards the removal of Cd at p H 7 and 8 and that of phosphate at p H 6. Fluoride decreases the ζ-potential in both systems, and the decreasing extent is positively correlated to the elevated R F:Al. The Al fluoride interactions include the formation of Al–F complexes and the adsorption of fluoride onto Al(OH)_3 precipitates, i.e., the formation of Al(OH)n F m. Al–F complex formation inhibits Al hydrolysis and increases residual Al levels, and a more significant increase was observed at lower p H. Al–F complexes at high R F:Al complicate the coagulation behavior of Al towards both negative and positive ionic species. Moreover, fluoride at low R F:Al shows little effect on Al coagulation behavior towards Cd~(2+)and phosphate, and the spent defluoridation adsorbent,i.e., aluminum(Al) hydro(oxide) with adsorbed fluoride at R F:Al of below 0.1:1, may be reclaimed as a coagulant after being dissolved.     

Effects of fluoride on the removal of cadmium and phosphate by aluminum coagulation

This study focuses on the effects of pH and fluoride at different molar ratios of fluoride to Al (R_F:Al) on the removal of cadmium (Cd²⁺) and phosphate by Al coagulation. Fluoride at R_F:Al ≥ 3:1 inhibits the removal of Cd over wide Al dose ranges from 5 to 10 mg/L as Al. The removal of phosphate decreases significantly at high R_F:Al of 10:1 whereas at lowered R_F:Al (i.e., ≤ 6:1), an adverse effect is observed only at insufficient Al doses below 2 mg/L. Fluoride shows inhibitive effects towards the removal of Cd at pH 7 and 8 and that of phosphate at pH 6. Fluoride decreases the ζ-potential in both systems, and the decreasing extent is positively correlated to the elevated R_F:Al. The Al fluoride interactions include the formation of Al–F complexes and the adsorption of fluoride onto Al(OH)₃ precipitates, i.e., the formation of Al(OH)_nF_m. Al–F complex formation inhibits Al hydrolysis and increases residual Al levels, and a more significant increase was observed at lower pH. Al–F complexes at high R_F:Al complicate the coagulation behavior of Al towards both negative and positive ionic species. Moreover, fluoride at low R_F:Al shows little effect on Al coagulation behavior towards Cd^2 + and phosphate, and the spent defluoridation adsorbent, i.e., aluminum (Al) hydro(oxide) with adsorbed fluoride at R_F:Al of below 0.1:1, may be reclaimed as a coagulant after being dissolved.     

应用铁铜双金属有机骨架活化过硫酸盐催化剂去除水中有机污染物的研究

基于MIL-101(Fe)的合成方法,首次采用合成前金属掺杂法制备了双金属有机骨架MIL-101(Fe,Cu)催化剂,并利用X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FTIR)、扫描电镜(SEM)和X射线能谱仪(EDS)对催化剂进行表征.同时,以罗丹明B(Rh B)为目标降解物,研究此催化剂催化过硫酸盐降解Rh B的性能,并初步尝试将催化剂应用于邻苯二甲酸二丁酯(DBP)的催化降解.XRD、FTIR、SEM和EDS等分析结果表明,铜离子的掺杂导致MIL-101(Fe)的结构与形貌发生了改变,提高了对污染物的吸附和催化降解作用.相比MIL-101(Fe),在90 min时MIL-101(Fe,Cu)对Rh B的去除率达到95%,在180 min时对DBP的去除率达到68%.此外,分析了催化剂催化性能提高的原因:配位竞争导致铁离子的不饱和趋向;形貌的变化加强了对污染物的吸附作用.     

天然黏土联合磷肥对农田土壤镉铅污染原位钝化修复效应研究

为研究天然黏土联合磷肥对农田土壤镉铅污染的原位钝化修复效应,在天津市某地开展了田间示范实验,以油麦菜、油菜和萝卜为模式作物,以海泡石、膨润土和磷肥等作为钝化修复材料,研究其对蔬菜可食部位生物量、镉铅含量和土壤中镉铅形态分布的影响,考察其对土壤镉铅污染的原位钝化修复效果.结果表明:磷肥、海泡石/磷肥复配、膨润土/磷肥复配...     

Synthesis of novel adsorbent by intercalation of biopolymer in LDH for the removal of arsenic from synthetic and natural water

This study focuses on the synthesis of nanocomposites named CCA and CZA that were prepared by the incorporation of cellulose(CL) in the Ca/Al and Zn/Al layered double hydroxide(LDH),respectively.These materials were then used for the uptake of As(Ⅲ)and As(V) from aqueous medium.Characterization of both nanocomposites(CCA and CZA) was done using FTIR and Raman analysis to identify the functional groups, N_2 adsorption-desorption isotherms to determine the specific surface area and pore geometry and XPS analysis to obtain the surface atomic composition.Some other characters were investigated using simultaneous TGA and DTA and elemental chemical analysis(CHNS/O).The crystallinity of the prepared nanocomposites was displayed by XRD patterns.Furthermore,the sheet-like structure of the LDHs and the irregularity of surface morphology with porous structure were observed by TEM and SEM microphotographs.Optimization of maximum adsorption capacity was adjusted using different parameters including pH,contact time and adsorbent dosage.The pseudo-second-order model was in good fitting with kinetics results.The adsorption isotherm results showed that CZA exhibits better adsorption capacity for As(Ⅲ) than CCA and the Langmuir isotherm model described the data well for both nanocomposites.Thermodynamic studies illustrated the endothermic nature of CCA and exothermic nature on CZA,as well as the fact that the adsorption process is spontaneous.A real water sample collected from well located in Gabes(Tunisia),has also been treated.The obtained experimental results were confirmed that these sorbents are efficient for the treatment of hazardous toxic species such as.     

Formation of CoAl layered double hydroxide on the boehmite surface and its role in tungstate sorption

Sorption of tungstate on boehmite(γ-Al OOH)is increased by co-sorption with Co~(2+)over the near-neutral p H range.Batch uptake experiments show up to a 3-fold increase in tungstate uptake over the range WO_4~(2-)=50–1000μmol/L compared to boehmite not treated with Co~(2+).Desorption experiments reveal a corresponding decrease in sorption reversibility for tungstate co-sorbed with Co~(2+).Reaction of boehmite with Co~(2+)results in the formation of Co Al layered double hydroxide(LDH),as confirmed by X-ray diffraction and X-ray absorption spectroscopy.Tungsten L_3-edge X-ray absorption near edge structure(XANES)reveals that W(VI)is octahedrally coordinated in all sorption samples,with polymeric tungstate species forming at higher tungstate concentrations.X-ray diffraction and X-ray absorption spectroscopy indicate that the mechanism for enhancement of tungstate uptake is the formation of surface complexes on boehmite at low tungstate concentrations,while exchange into the Co Al LDH becomes important at higher tungstate concentrations.The results provide a basis for developing strategies to enhance tungstate sorption and to limit its environmental mobility at near-neutral pH conditions.     

Effects of phosphate on the transport of graphene oxide nanoparticles in saturated clean and iron oxide-coated sand columns

In this study, transport behaviors of graphene oxide (GO) in saturated uncoated (i.e., clean sand) and goethite-coated sand porous media were examined as a function of the phosphate. We found that phosphate enhanced the transport of GO over a wide range of solution chemistry (i.e., pH 5.0–9.0 and the presence of 10 mmol/L Na⁺ or 0.5 mmol/L Ca²⁺). The results were mainly ascribed to the increase of electrostatic repulsion between nanoparticles and porous media. Meanwhile, deposition site competition induced by the retained phosphate was another important mechanism leading to promote GO transport. Interestingly, when the phosphate concentration increased from 0.1 to 1.0 mmol/L, the transport-enhancement effect of phosphate in goethite-coated sand was to a much larger extent than that in clean sand. The observations were primarily related to the difference in the total mass of retained phosphate between the iron oxide-coated sand and clean sand columns, which resulted in different degrees of the electrostatic repulsion and competitive effect of phosphate. When the background solution contained 0.5 mmol/L Ca²⁺, phosphate could be bind to sand/ goethite-coated sand surface by cation bridging; and consequently, promoted competition between phosphate and nanoparticles for deposition sites, which was an important mechanism for the enhanced effect of phosphate. Moreover, the DLVO theory was applicable to describe GO transport behaviors in porous media in the absence or presence of phosphate. Taken together, these findings highlight the important status and role of phosphate on the transport and fate of colloidal graphene oxide in the subsurface environment.     

Effect of Co(Ⅱ) dopant on the removal of Methylene Blue by a dense copper terephthalate

In this research, for the first time, a series of Co(Ⅱ) doped copper terephthalate(Co X-Cu BDC,where X is doping percentage) were successfully synthesized via solvothermal method and were tested for dye removal application. The physical properties of Co X-CuBDC were studied by several techniques including X-ray diffraction(XRD), field emission scanning electron microscopy(FESEM), energy-dispersive spectroscopy(EDS), thermogravimetric analysis(TGA)and Brunauer–Emmett–Teller(BET) surface area analysis. The incorporation of Co(Ⅱ) dopant leads to isomorphic substitution of Cu(II) in the CuBDC framework with the maximum doping percentage of 22. Doping and parent MOFs which are non-porous were used for removal of Methylene Blue(MB) from aqueous solution. Adsorption capacity of Co22-CuBDC and CuBDC are 52 and 58 mg/g, respectively, both of which are higher than the adsorption capacity recorded from several high porosity MOFs. Adsorption kinetic studies indicate that adsorption process follows pseudo-second order model while the adsorption mechanism is dominated by electrostatic attraction. Overall, even though these materials show non-porous characteristic,it can be used effectively in wastewater treatment application.     

Novel functional fiber loaded with carbon dots for the deep removal of Cr(VI) by adsorption and photocatalytic reduction

A novel functional fiber (PAN-CDs) loaded with carbon dots (CDs) with excellent photoreduction and adsorption properties for Cr(VI) was prepared via an amidization reaction between the CDs' carboxyl groups and amine groups on polyacrylonitrile (PAN)-based ion exchange fibers, which could completely preserve the fluorescence properties of the CDs. The photoluminescence (PL), photocatalysis and adsorption properties of PAN-CDs were characterized and analyzed. The PAN-CDs possess high adsorption capacity (297.6?mg/g) and excellent kinetic behavior (attaining adsorption equilibrium in 30?min) for Cr(VI) adsorption. Furthermore, the residual Cr(VI) (approximately 3?mg/L) after adsorption could be removed completely by subsequent photoreduction by the PAN-CDs. The Cr-saturated PAN-CDs could be easily separated by filtering and regenerated, with no observable decay of removal efficiency after five regeneration cycles. In addition, due to the PL quenching action of Cr(VI), the PAN-CDs can also be used as sensor for quantitative detection of trace Cr(VI) in aqueous solution.     

镧改性粉煤灰合成沸石的同步脱氨除磷研究

以火电厂固废粉煤灰为主要原料,采用改良水热法研制合成了低成本的P型沸石,对其进行了稀土镧改性处理,以强化其脱氮除磷能力.实验研究了改性镧离子浓度、投加量、pH值对同步去除氨氮和磷的影响;运用XRD和SEM分析技术对合成沸石进行了表征.结果表明,在改性镧离子浓度0.5%、pH值为4~8、投加量为10g/L时,改性后的合成沸石对氨氮和磷的去除率分别达到90%,95%以上.改性后的合成沸石对氨氮及磷的吸附动力学数据符合伪二级方程.Langmuir方程能更好地描述氨氮及磷在改性合成沸石上的等温吸附行为,氨氮和磷的Langmuir最大吸附量分别为3.94,1.65mg/g.     

沸石对水中磷吸附性能的初步研究

利用不同粒径的沸石对水中磷的吸附性能进行初步研究。结果表明：投加量7 g,反应时间60min,温度35℃,pH 3～9时沸石对水中磷的吸附效果最佳;沸石对磷的吸附动力学过程适合用拟二级速率方程进行拟合,拟合系数接近1;吸附等温线符合Freundlich方程所描述的规律,温度越高,沸石对磷的吸附性能越好;在相同的温度条件下,粒径越小的沸石对磷的吸附能力越强。