河流沉积物对典型PPCPs的吸附特性及其影响因素

采用批平衡实验方法,研究了黄浦江沉积物对环丙沙星(CIP)、四环素(TC)、磺胺甲唑(SMX)和三氯生(TCS)的吸附特性,探讨了吸附时间、初始浓度、溶液p H值和温度等因素对吸附过程的影响.结果表明,CIP、TC、SMX和TCS在沉积物中的吸附过程均呈现先快速后缓慢的变化趋势,等温吸附平衡时间约为4 h.溶液p H值对CIP、TC和TCS的吸附过程具有显著影响,但对SMX的吸附影响较小.目标PPCPs吸附过程符合准二级反应动力学方程,吸附常数为4.89×10-3~1.96×10-2kg·(min·mg)-1.吸附等温线能较好地符合Freundlich方程和线性方程,高温不利于CIP和TCS吸附,而利于TC和SMX吸附.沉积物对CIP、TC和TCS的吸附能力较强,但对SMX吸附效果较差,当初始浓度为10 mg·L-1时,沉积物对CIP、TC、SMX和TCS的平衡吸附量分别可达702.8、733.1、54.7和695.0 mg·kg-1.     

Enhanced activation of peroxydisulfate by strontium modified BiFeO3perovskite for ciprofloxacin degradation

A series of Sr-doped BiFeO₃ perovskites (Bi_1-xSr_xFeO₃, BSFO) fabricated via sol-gel method was applied as peroxydisulfate (PDS) activator for ciprofloxacin (CIP) degradation. Various technologies were used to characterize the morphology and physicochemical features of prepared BSFO samples and the results indicated that Sr was successfully inserted into the perovskites lattice. The catalytic performance of BiFeO₃ was significantly boosted by strontium doping. Specifically, Bi_0.9Sr_0.1FeO₃ (0.1BSFO) exhibited the highest catalytic performance for PDS activation to remove CIP, where 95% of CIP (10 mg/L) could be degraded with the addition of 1 g/L 0.1BSFO and 1 mmol/L PDS within 60 min. Moreover, 0.1BSFO displayed high reusability and stability with lower metal leaching. Weak acidic condition was preferred to neutral and alkaline conditions in 0.1BSFO/PDS system. The boosted catalytic performance can be interpreted as the lower oxidation state of Fe and the existence of affluent oxygen vacancies generated by Sr doping, that induced the formation of singlet oxygen (¹O₂) which was confirmed as the dominant reactive species by radical scavenging studies and electron spin resonance (ESR) tests. The catalytic oxidation mechanism related to major ¹O₂ and minor free radicals was proposed. Current study opens a new avenue to develop effective A-site modified perovskite and expands their application for PDS activation in wastewater remediation.     

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.     

两种纳米颗粒对沸石吸附环丙沙星的影响

为了探明纳米颗粒（NPs）共存对抗生素在黏土矿物上的吸附的影响,以沸石为供试黏土矿物,环丙沙星（CIP）为目标污染物,研究了不同温度、 pH值和离子强度条件下,纳米氧化锌（ZnO NPs）和纳米二氧化钛（TiO₂ NPs）这2种NPs对沸石吸附CIP的影响,并结合沸石的表面特征探讨不同类型NPs对CIP吸附的影响机制.结果表明,除5 mg·L^-1ZnO NPs共存时,轻微促进了CIP的吸附,其他NPs浓度均对CIP产生不同程度的抑制,抑制程度表现出TiO₂ NPs>ZnO NPs的顺序;随温度升高,NPs的存在增强了沸石对CIP吸附的增温正效应;当离子强度由0.001mol·L^-1增加到0.01mol·L^-1时,CIP的吸附量下降,但2种NPs的存在均减弱了离子强度的负效应;溶液pH会影响CIP的存在形态和NPs的性质,进而影响CIP的吸附.沸石对单一CIP的吸附存在静电引力、氢键和孔径填充作用,ZnO NPs主要通过静电引力竞争吸附位点对CIP吸附产生影响,而TiO     

Effective adsorption of quadrivalent cerium by synthesized laurylsulfonate green rust in a central composite design

The layered laurylsulfonate intercalated green rust (lauryl-S GR) was synthesized to evaluate the influence of synthesis parameters and aqueous conditions on the adsorption of Ce^IV. The maximum adsorption capacity of 305.58 mg/g by lauryl-S GR was predictably obtained. The pseudo-first-order kinetic model was appropriate in fitting the whole uptake process in a weak acid environment. Three isotherm models including Langmuir, Freundlich, and Tempkin were all reliable in depicting the isotherm adsorption process. The maximum monolayer adsorption capacity of lauryl-S GR towards Ce^IV was 315.46 mg/g. Ce species including CeO and Ce₂O₃ besides CeO₂ were matched in the XPS distribution, directly indicating the reduction reaction brought by Fe^II in the GR occurred to hydrated Ce^IV ions during the adsorption. Nano-sized Ce particles attached to the lauryl-S GRs after the adsorption experiments were observed in the morphological characterization. Flocculated materials were formed on the surface of the lauryl-S GR at a pH of 7, which further reduced the active sites and disrupted the continuous uptake of Ce^IV to the lauryl-S GR. This study expands the application of GRs and supplies an ideal iron-based material for the construction of the affiliated recovery pathway to the traditional separation of Ce.     

Preparation and characterization of boron-doped corn straw biochar: Fe (Ⅱ) removal equilibrium and kinetics

Nowadays, iron ions as a ubiquitous heavy metal pollutant are gradually concerned and the convenient and quick removal of excessive iron ions in groundwater has become a major challenge for the safety of drinking water. In this study, boron-doped biochar (B-BC) was successfully prepared at various preparation conditions with the addition of boric acid. The as-prepared material has a more developed pore structure and a larger specific surface area (up to 897.97 m²/g). A series of characterization results shows that boric acid effectively activates biochar, and boron atoms are successfully doped on biochar. Compared with the ratio of raw materials, the pyrolysis temperature has a greater influence on the amount of boron doping. Based on Langmuir model, the maximum adsorption capacity of 800B-BC_1:2 at 25 °C, 40 °C, 55 °C are 50.02 mg/g, 95.09 mg/g, 132.78 mg/g, respectively. Pseudo-second-order kinetic model can better describe the adsorption process, the adsorption process is mainly chemical adsorption. Chemical complexation, ions exchange, and co-precipitation may be the main mechanisms for Fe²⁺ removal.     

Hepatitis A Virus Disinfection in Water by Solar Photo–Fenton Systems

This study evaluates and compares the effectiveness of solar photo–Fenton systems for the inactivation of hepatitis A virus (HAV) in water. The effect of solar irradiance, dark- Fenton reaction and three different reactant concentrations (2.5/5, 5/10 and 10/20 mg/L of Fe²⁺/H₂O₂) on the photo–Fenton process were tested in glass bottle reactors (200 mL) during 6 h under natural sunlight. Disinfection kinetics were determined both by RT-qPCR and infectivity assays. Mean water temperatures ranged from 25 to 27.3 °C, with a maximum local noon UV irradiances of 22.36 W/m². Photo–Fenton systems yielded increased viral reduction rates in comparison with the isolated effect under the Fenton reaction in darkness (negligible viral reduction) or the solar radiation (0.25 Log of RNA reduction). With the highest concentration employed (10–20 mg/L Fe²⁺–H₂O₂), an average RNA reduction rate of ~ 1.8 Log (initial concentration of 10⁵ pfu/mL) and a reduction of 80% in the infectivity capacity were reached. Results showed a strong synergistic effect between Fe²⁺/H₂O₂ and sunlight, demonstrating that significant disinfection rates of HAV under photo–Fenton systems may occur with relatively higher efficiency at middle environmental temperatures and without the need for an energy-intensive light source.     

How do inundation provoke the release of phosphorus in soil-originated sediment due to nitrogen reduction after reclaiming lake from polder

Different N and P fractions in microcosm incubation experiment was measured using high-resolution in-situ Peeper and DGT techniques combining with sequential extraction procedure. The results showed the synchronous desorption and release of PO₄^3-, S^2- and Fe²⁺ from the solid soil-originated sediment. This trend indicated that the significant reduction of Fe-P and SO₄^2- occurred in the pore water during the inundation. The concentrations of PO₄^3- in the overlying water and pore water increased to more than 0.1 and 0.2 mg/L at the beginning of the incubation experiment. Decreased NO₃^-concentrations from more than 1.5 mg/L to less than 0.5 mg/L combining with increasing NH₄⁺ concentrations from less than 1 mg/L to more than 5 mg/L suggested the remarkable NO₃^- reduction via dissimilatory nitrate reduction to ammonia (DNRA) pathway over time. High NH₄⁺ concentrations in the pore water aggravated the release of Fe²⁺ through reduction of Fe(III)-P as electric acceptors under anaerobic conditions. This process further stimulated the remarkable releasing of labile PO₄^3- from the solid phase to the solution and potential diffusion into overlying water. Additionally, high S^2- concentration at deeper layer indicated the reduction and releasing of S^2- from oxidation states, which can stimulated the NO₃^- reduction and the accumulation of NH₄⁺ in the pore water. This process can also provoke the reduction of Fe-P as electric acceptors following the release of labile PO₄^3- into pore water. Generally, inundation potentially facilitate the desorption of labile P and attention should be paid during the reclaiming lake from polder.     

粒径对水合氧化镧除氟效果的影响

针对La2O3·nH2O的高效除氟作用,确定了La2O3·nH2O除氟的最佳pH,在此基础上研究了La2O3·nH2O的粒径对其除氟容量以及除氟动力学的影响,并与活性氧化铝除氟效果进行了对比.结果表明:La2O3·nH2O除氟的最佳pH为5.5～6.5;La2O3·nH2O对氟的吸附基本符合Langmuir单分子层吸附原理;随着粒径的减小,其最大吸附容量及吸附速率均有明显的提高.试验中粒径为0.038～0.050mm的La2O3·nH2O粒径为 > 0.500～0.710mm的La2O3·nH2O相比,前者的最大吸附容量是后者的3.32倍;当平衡ρ(氟)为1 mg,L时,前者计算所得的吸附容量是后者的10.13倍.与活性氧化铝相比,当平衡ρ(氟)为1mg/L时,相同粒径的La2O3·nH2O的吸附容量是活性氧化铝的2.55～13.88倍.     

Antimony(V) removal from water by iron-zirconium bimetal oxide: Performance and mechanism

A Fe-Zr binary oxide adsorbent has been successfully synthesized using a co-precipitation method. It showed a better performance for antimonate (Sb(V)) removal than zirconium oxide or amorphous ferric oxide. The experimental results showed that the Fe-Zr adsorbent has a capacity of 51 mg/g at an initial Sb(V) concentration of 10 mg/L at pH 7.0. Sb(V) adsorption on the Fe-Zr bimetal oxide is normally an endothermic reaction. Most of the Sb(V) adsorption took place within 3 hr and followed a pseudo second-order rate law. Co-existing anions such as SO₄^2-, NO₃^- and Cl^- had no considerable effects on the Sb(V) removal; PO₃^4- had an inhibitory effect to some extent at high concentration; while CO_₃^2- and SiO₄^4- showed significant inhibitory effects when they existed in high concentrations. The mechanism of Sb(V) adsorption on the adsorbent was investigated using a combination of zeta potential measurements, XPS, Raman, FT-IR observations and SO₄^2- release determination. The ionic strength dependence and zeta potential measurements indicated that inner-sphere surface complexes were formed after Sb(V) adsorption. Raman and XPS observations demonstrated that both Fe-OH and Zr-OH sites at the surface of the Fe-Zr adsorbent play important roles in the Sb(V) adsorption. FT-IR characterization and SO₄^2- release determination further demonstrated that the exchange of SO₄^2- with Sb(V) also could promote the adsorption process. In conclusion, this adsorbent showed high potential for future application in Sb(V) removal from contaminated water.     

Effects of surfactants on the combined toxicity of TiO2 nanoparticles and cadmium to Escherichia coli

The combined ecological toxicity of TiO₂ nanoparticles (nano-TiO₂) and heavy metals has been paid more attention. As the common pollutants in water environment, surfactants could affect the properties of nanoparticles and heavy metals, and thus further influence the combined toxicity of nano-TiO₂ and heavy metals. In this study, the effects of sodium dodecyl benzene sulfonate (SDBS) and Tween 80 on the single and combined toxicities of Cd^2 + and nano-TiO₂ to Escherichia coli (E. coli) were examined, and the underlying influence mechanism was further discussed. The results showed both SDBS and Tween 80 enhanced the toxicity of Cd^2 + to E. coli in varying degrees. The reaction of SDBS and Cd^2 + could increase the outer membrane permeability and the bioavailability of Cd, while Tween 80 itself could enhance the outer membrane permeability. The combined toxicity of nano-TiO₂ and Cd^2 + to E. coli in absence of surfactant was antagonistic because of the adsorption of Cd^2 + to nano-TiO₂ particles. However, in the presence of SDBS, both SDBS and nano-TiO₂ influenced the toxicity of Cd^2 +, and also SDBS could adsorb to nano-TiO₂ by binding to Cd^2 +. The combined toxicity was reduced at Cd^2 + lower than 4 mg/L and enhanced at Cd^2 + higher than 4 mg/L under multiple interactions. Tween 80 enhanced the combined toxicity of nano-TiO₂ and Cd^2 + by increasing the outer membrane permeability. Our study firstly elucidated the effects of surfactants on the combined toxicity of nano-TiO₂ and Cd^2 + to bacteria, and the underlying influencing mechanism was proposed.     

Minimizing Bias in Virally Seeded Water Treatment Studies: Evaluation of Optimal Bacteriophage and Mammalian Virus Preparation Methodologies

One key assumption impacting data quality in viral inactivation studies is that reduction estimates are not altered by the virus seeding process. However, seeding viruses often involves the inadvertent addition of co-constituents such as cell culture components or additives used during preparation steps which can impact viral reduction estimates by inducing non-representative oxidant demand in disinfection studies and fouling in membrane assessments. The objective of this study was therefore to characterize a mammalian norovirus surrogate, murine norovirus (MNV), and bacteriophage MS2 at sequential stages of viral purification and to quantify their potential contribution to artificial oxidant demand and non-representative membrane fouling. Our results demonstrate that seeding solvent extracted and 0.1 micron filtered MNV to ~10⁵ PFU/mL in an experimental water matrix will result in additional total organic carbon (TOC) and 30 min chlorine demand of 39.2 mg/L and 53.5 mg/L as Cl₂, respectively. Performing sucrose cushion purification on the MNV stock prior to seeding reduces the impacts of TOC and chlorine demand to 1.6 and 0.15 mg/L as Cl₂, respectively. The findings for MNV are likely relevant for other mammalian viruses propagated in serum-based media. Thus, advanced purification of mammalian virus stocks by sucrose cushion purification (or equivalent density-based separation approach) is warranted prior to seeding in water treatment assessments. Studies employing bacteriophage MS2 as a surrogate virus may not need virus purification, since seeding MS2 at a concentration of ~10⁶ PFU/mL will introduce only ~1 mg/L of TOC and ~1 mg/L as Cl₂ of chlorine demand to experimental water matrices.     

Carbon dioxide adsorption behaviors of aluminum-pillared montmorillonite-supported alkaline earth metals

The Al-pillared montmorillonite-supported alkaline earth metal 5M/Al-PILC (PILC = pillared clay, M = Mg, Ca, Sr, and Ba) and xMg/Al-PILC (x = 1, 3, 5, and 7 wt.%) samples were prepared using an impregnation method. Physical properties of the materials were determined by means of X-ray diffraction (XRD) and N₂ adsorption-desorption, and their CO₂ adsorption behaviors were investigated using the thermogravimetric analyzer (TG), CO₂ temperature-programmed desorption (CO₂-TPD), and in situ diffuse reflectance infrared transform spectroscopy (in situ-DRIFTS) techniques. It is shown that 5Mg/Al-PILC possessed the highest CO₂ adsorption capacity (2.559 mmol/g). The characterization results indicate that Al-pillaring increased the specific surface area of montmorillonite, which was beneficial for the adsorption of CO₂. The CO₂ adsorption process on the sample was mainly chemical adsorption, and alkalinity was the main factor influencing its adsorption capacity. The alkalinity of the sample was enhanced by loading an appropriate amount of alkaline earth metal, and the adsorbed CO₂ was present in the form of bicarbonate and carbonate. In addition, the 5Mg/Al-PILC sample exhibited an excellent regeneration efficiency. We believe that the outcome of this research would provide a good option for developing highly effective CO₂ adsorption materials.     

Environmental factors affecting degradation of perfluorooctanoic acid (PFOA) by In2O3 nanoparticles

Nanophotocatalysts have shown great potential for degrading poly- and perfluorinated substances (PFAS). In light of the fact that most of these catalysts were studied in pure water, this study was designed to elucidate effects from common environmental factors on decomposing and defluorinating perfluorooctanoic acid (PFOA) by In₂O₃ nanoparticles. Results from this work demonstrated that among the seven parameters, pH, sulfate, chloride, H₂O₂, In₂O₃ dose, NOM and O₂, the first four had statistically significant negative effects on PFOA degradation. Since PFOA is a strong acid, the best condition leading to the highest PFOA removal was identified for two pH ranges. When pH was between 4 and 8, the optimal condition was: pH = 4.2; sulfate = 5.00 mg/L; chloride = 20.43 mg/L; H₂O₂ = 0 mmol/L. Under this condition, PFOA decomposition and defluorination were 55.22 and 23.56%, respectively. When pH was between 2 and 6, the optimal condition was: pH = 2; sulfate = 5.00 mg/L; chloride = 27.31 mg/L; H₂O₂ = 0 mmol/L. With this condition, the modeled PFOA decomposition was 97.59% with a defluorination of approximately 100%. These predicted results were all confirmed by experimental data. Thus, In₂O₃ nanoparticles can be used for degrading PFOA in aqueous solutions. This approach works best when the target contaminated water contains low concentrations of NOM, sulfate and chloride and at a low pH.     

Selenium uptake and simultaneous catalysis of sulfite oxidation in ammonia-based desulfurization

Accelerating the (NH₄)₂SO₃ oxidation gives rise to the reclaiming of byproduct, while there are secondary environmental risks from reduction of the coexisted selenium species by sulfite. In this study, a bi-functional Co-SBA-15-SH, were synthesized through Co impregnation and sulfhydryl (-SH) decoration, which can simultaneously uptake Se and accelerate sulfite oxidation efficiently. Meanwhile, the adsorption kinetics and migration mechanism of Se species were revealed through characterization and density functional calculations, with maximum adsorption capacity of 223 mg/g. The inhibition of Se⁰ re-emission and poisonous effect of Se on sulfite oxidation was also investigated. Using the findings of this study, the ammonia desulfurization can be improved by enabling purification of the byproduct and lowering the toxicity of effluent by removing toxic pollutants.     

Highly efficient and selective removal of low-concentration antibiotics from aqueous solution by regenerable Mg(OH)2

The prevalent presence of fluoroquinolone antibiotics in aquatic environments has attracted considerable attention because of their harmful effects on humans and the ecological environment. Magnesium hydroxide nanocrystals were found to act as a simple and effective adsorbent to remove low-concentration ciprofloxacin (CIP) in aqueous solution. The as-prepared Mg(OH)₂ nanocrystals exhibited excellent CIP adsorption performance and high selectivity toward CIP molecules compared with other antibiotics or aromatics, e.g., norfloxacin (NOR) and eosin B (EB). The adsorbent showed pH-dependent adsorption, indicating that the adsorption process is probably dominated by an electrostatic interaction mechanism. In addition, structural analysis of the adsorbent indicated that coordination and hydrogen bonding between CIP and Mg(OH)₂ nanocrystal might also be involved in the adsorption process. Moreover, the adsorbent could be easily recovered by pyrolysis and hydration without significant reduction of adsorption capacity. The superior adsorption behavior of Mg(OH)₂ nanocrystal indicates that it may serve as a potential adsorbent material candidate for the selective removal of CIP from aquatic environments.     

Amino-functionalized core-shell magnetic mesoporous composite microspheres for Pb(II) and Cd(II) removal

Amino-functionalized Fe3O4@mesoporous SiO/ core-shell composite microspheres NH2-MS in created in multiple synthesis steps have been investigated for Pb（Ⅱ） and Cd（Ⅱ） adsorption. The microspheres were characterized by transmission electron microscope （TEM）, scanning electron microscope （SEM）, N2 adsorption-desorption, zeta potential measurements and vibrating sample magnetometer. Batch adsorption tests indicated that NH2-MS exhibited higher adsorption affinity toward Pb（Ⅱ） and Cd（Ⅱ） than MS did. The Langmuir model could fit the adsorption isotherm very well with maximum adsorption capacity of 128.21 and 51.81 mg/g for Pb（Ⅱ） and Cd（Ⅱ）, respectively, implying that adsorption processes involved monolayer adsorption. Pb（Ⅱ） and Cd（Ⅱ） adsorption could be well described by the pseudo second-order kinetics model, and was found to be strongly dependent on pH and humic acid. The Pb（Ⅱ）- and Cd（Ⅱ）-loaded microspheres were effectively desorbed using 0.01 mol/L HC1 or EDTA solution. NH2-MS have promise for use as adsorbents in the removal of Pb（Ⅱ） and Cd（Ⅱ） in wastewater treatment processes.     

On-going nitrification in chloraminated drinking water distribution system (DWDS) is conditioned by hydraulics and disinfection strategies

Within the drinking water distribution system (DWDS) using chloramine as disinfectant, nitrification caused by nitrifying bacteria is increasingly becoming a concern as it poses a great challenge for maintaining water quality. To investigate efficient control strategies, operational conditions including hydraulic regimes and disinfectant scenarios were controlled within a flow cell experimental facility. Two test phases were conducted to investigate the effects on the extent of nitrification of three flow rates (Q = 2, 6, and 10 L/min) and four disinfection scenarios (total Cl₂=1 mg/L, Cl₂/NH₃-N=3:1; total Cl₂=1 mg/L, Cl₂/NH₃-N=5:1; total Cl₂=5 mg/L, Cl₂/NH₃-N=3:1; and total Cl₂=5 mg/L, Cl₂/NH₃-N=5:1). Physico-chemical parameters and nitrification indicators were monitored during the tests. The characteristics of biofilm extracellular polymetric substance (EPS) were evaluated after the experiment. The main results from the study indicate that nitrification is affected by hydraulic conditions and the process tends to be severe when the fluid flow transforms from laminar to turbulent (2300<Re<4000). Increasing disinfectant concentration and optimizing Cl₂/NH₃-N mass ratio were found to inhibit nitrification to some extend when the system was running at turbulent condition (Q = 10 L/min, Re = 5535). EPS extracted from biofilm that was established at the flow rate of 6 L/min had greater carbohydrate/protein ratio. Furthermore, several nitrification indicators were evaluated for their prediction efficiency and the results suggest that the change of nitrite, together with total organic carbon (TOC) and turbidity can indicate nitrification potential efficiently.     

Lead removal from water using organic acrylic amine fiber (AAF) and inorganic-organic P-AAF, fixed bed filtration and surface-induced precipitation

Granular porous sorbents were normally used for heavy metals removal from water. To search for the new commercial sorbent and treatment strategy, an organic acrylic amine fiber (AAF) and phosphorus loading inorganic-organic AAF (P-AAF) were prepared and used for lead (Pb) removal from water. A new strategy of inorganic-organic coupling technology was proposed for Pb removal, based on the hypothesis of surface-induced precipitation mechanism. The AAF showed a Pb adsorption capacity of 417 mg/g from the Langmuir fitting, while the column filtration technology was further applied to measure the adsorption edge and applications. Effects of different initial Pb concentrations, hydraulic retention time, and co-existing P were considered in the filtration experiments. The presence of 0.8 mg/L P in water significantly improved the Pb breakthrough point from 15,000 to 41,000 bed volumes of water spiked with 85 µg/L Pb, while the P-AAF fixed bed showed better removal of Pb than AAF SEM/EDX and XRD spectra were employed for determining the surface functional groups and the formation of surface-induced precipitation of pyromorphite (Pb₅(PO₄)₃OH) on AAF. This study verified the application of AAF sorbent for Pb removal and the enhanced effect of coating P on AAF, thus improved our fundamental understanding and application of the surface chemistry process of Pb with P.     

Simultaneous removal of arsenic and antimony from mining wastewater using granular TiO2: Batch and field column studies

Coexisting arsenic (As) and antimony (Sb) in mining wastewater is a common and great concern. On-site simultaneous removal of As and Sb from mining wastewater was achieved by using a reusable granular TiO₂ column in this study. To evaluate the accuracy of the scale-up procedure, As and Sb adsorption from wastewater was studied in both large (600 g TiO₂) and small columns (12 g TiO₂) based on the proportional diffusivity rapid small-scale column tests (PD-RSSCTs) design. The comparable As and Sb breakthrough curves obtained from small and large columns confirmed the accuracy of the PD-RSSCT theory in the design of large-scale columns. Meanwhile, the consistent As and Sb adsorption results from batch and column experiments suggested that TiO₂ adsorption for As and Sb can be predicted from bench-scale tests. Charge distribution multi-site complexation (CD-MUSIC) and one-dimensional transport modeling integrated in the PHREEQC program were performed to study the adsorption behaviors of As and Sb on the TiO₂ surface. Coexisting ions, such as Ca^2 +, Mg^2 +, and Si^4 +, play an important role in As and Sb adsorption, and the breakthrough curves were well simulated after considering the compound ion effects. The results from this study highlight the surface reactions of As and Sb on TiO₂ and provide a practical way for on-site remediation of industrial wastewater.