Degradation of common pharmaceuticals and personal care products in mixed solutions by advanced oxidation techniques

Widespread detection of pharmaceutical compounds in water environment has been a serious concern recently, while conventional sewage treatments are ineffective for their elimination. But, advanced oxidation techniques are very promising to remove varieties of organic contaminants in water. This research aims to elucidate oxidation potentials of sixteen commonly used pharmaceutical compounds in mixed solutions by seven advanced oxidation techniques in laboratory batch experiments. The removal profiles exhibited four distinct patterns: a) easily degradable by all seven techniques, b) not easily degradable by all seven techniques, c) easily degradable by ozone-based techniques, but not by ultraviolet radiation-based techniques and d) easily degradable by ultraviolet radiation-based techniques, but not by ozone-based techniques. Ozone-based techniques rather than ultraviolet radiation-based techniques were very powerful for simultaneous removal of the compounds efficiently. Moreover, ozonation combined with ultraviolet radiation was the most appropriate technique for simultaneous removal of the tested compounds efficiently. Increased ozone dissolution and decomposition with ozone-based techniques did not always enhance the compounds’ removal. Physicochemical properties of the compounds and solution pH also presumably played an important role on the removal which merits further attention.     

Adsorptive removal of azo dyes from aqueous solutions by natural bentonite under static and dynamic flow conditions

This work reports new findings on the physisorption of Foron Blue 291 on natural bentonite under both static and dynamic flow conditions of the aqueous solution that may prove important when using the adsorption technique for wastewater treatment. The quantity of dye retained by the solid matrix under both ideal exchange conditions between dyes and adsorbents given in a batch reactor and a pulse injection of dissolved azo dye in a soil column composed of a mixture of mean grain-sized sand and bentonite at different flow rates and at various mass fractions of bentonite was studied. Column experiments involving the use of a non-reactive tracer (Fluorescein) were performed to examine hydrodynamic behaviours of the clay/sand mixture studied. It is shown that advective–dispersive transport across a clay/sand mixture may be characterized by a double porosity medium. The results obtained on the reactive transport of Foron Blue 291 underscore that Foron Blue 291 adsorption depends heavily on the mass fraction of clay in a clay/sand mixture. With a clay mass fraction of 30 %, 77 % of the dissolved Foron Blue 291 mass was irreversibly removed by the adsorbent. At low flow rates, removal ratios obtained from the dynamic reactive system were similar to those obtained through previous static reactor experiments.     

Removal of fluoride from aqueous solution by modified fly ash

Removal of fluoride from aqueous solution by modified fly ash was studied in batch model. The influences of the contact time, the initial F^- concentration, the dosage of fly ash, and the temperature on removal of F have been studied, respectively. It was found that fly ash modified with dilute HCl has the maximum adsorption of fluoride from aqueous solutions, and that the retention of fluoride ions by material was 85% or higher with initial 10 mg F^-/L. First-order kinetics was observed for the adsorption process, which follows the Langrnuir and Freundlich isotherms. The thermodynamic parameters such as ΔG0, ΔH0, ΔS0 were calculated from Langmuir constants. The positive value of ΔH0 （1.273 J/mol） confirms the endothermic nature of adsorption.     

粉煤灰处理含氟废水的正交试验研究

对粉煤灰处理含氟废水进行了正交试验研究。结果表明各因素对F-去除率的影响顺序为:pH>V/M>T>CF-,极差R分别为49.6、9.1、4.9和3.6;在pH=5、V/M=10、T=3h时,粉煤灰对于CF-<500 mg/L的废水具有较好的去除效果;粉煤灰吸附F-的行为符合Langmuir等温方程,方程为Ce/qe=0.251 8Ce+6.087 3。     

Study of anaerobic biodegradation of pharmaceuticals and personal care products: application of batch tests

This study evaluated three types of pharmaceuticals and personal care products (methylparaben, ibuprofen and triclosan) at concentration levels of 300, 500, 1000 and 2000 µg/L by implementing batch tests using anaerobic processes and granular biomass. The study aimed to identify the mechanisms of biodegradation and sorption in the degradation of these compounds. The inoculum was granular sludge from a laboratory-scale anaerobic reactor. The characterization results of the inoculum showed an anaerobic biomass with high activity, good sedimentation and a high percentage of organic matter. The results of the removal of the pollutants showed high degradation percentages for methylparaben (close to 99%), with negligible sorption in the sludge. The results also showed insignificant ibuprofen sorption but removal close to 0%. Triclosan showed high biomass sorption and low biodegradation. In addition, at the concentrations tested, none of the compounds had a negative or inhibitory effect on the microbial populations of the system.     

药物和个人护理用品对地下水污染的风险评价

为进一步明确污泥土地利用过程中新型有机污染物—药物和个人护理用品（PPCPs）对地下水污染的风险,采用数学模型初步预测和评价了29种PPCPs在砂土和壤土2种介质条件下对地下水污染的风险。结果表明：砂土条件下,环丙沙星、氧氟沙星、土霉素、诺氟沙星和咖啡因等5种PPCPs的风险指数大于1,具有高地下水污染风险,其中,除咖啡因外,其余4种PPCPs均为抗生素类药物,应加强其在地下水中的监测和防控。壤土条件下,29种PPCPs对地下水均表现为低污染风险。吸附强度是影响PPCPs对地下水污染风险的最主要因素。PPCPs在包气带中的半衰期、有机碳-水分配系数、土壤密度、有机碳含量、含有机质的上层土壤层厚度是模型主要的敏感参数。不确定性分析显示,PPCPs的有机碳-水分配系数和其在包气带中的半衰期的改变对地下水污染风险评价结果影响较大。验证表明,地下水污染风险指数越大的PPCPs在地下水中的检出率也越高,说明评价结果具有一定的合理性。今后应加强对PPCPs降解产物、地下水中安全浓度值、共存PPCPs相互作用及介质非均质性影响等方面的研究,以便更加精确地评价PPCPs对地下水污染的风险。     

Phosphate removal using compounds prepared from paper sludge and fly ash

Using waste as a resource to control phosphate pollution is a rising trend. This study describes the use of paper sludge (PS) and fly ash (FA), industrial solid wastes, to prepare materials with high phosphate uptake efficiency. The process consisted of pretreatment (mechanical milling), calcination, acidification (HCl), and post-treatment (aging, drying and grinding). The maximal phosphate uptake (>92 %) was achieved using PS together with FA either at PS/FA = 0.5 g/g or at PS/FA = 2.0 g/g, both calcined at 900 °C for 2 h and stirred with HCl (HCl/FA = 3 mL/g) for 1 h. With increasing calcination temperature and decreasing acid, the crystallinity of samples declined, and phosphate uptake (PU) increased. The PU process could be well described by the pseudo-second order kinetic model, while equilibrium state could be reasonably modeled by Langmuir isotherm. Neutral and weak alkaline pH promoted the PU efficiency, and 0.3 g sample/100 mL was the cost-effective dosage under the experimental conditions. The enhanced phosphate uptake of PS and FA provides alternative materials for phosphate removal from wastewater by the use of solid wastes in paper-making industries.     

Advantage of almond green hull over its resultant ash for chromium(VI) removal from aqueous solutions

The discharge of industrial effluents containing hexavalent chromium can be very harmful for the environment. Therefore, Cr(VI) should be removed from contaminated water, and especially from wastewater, to prevent its discharge into the environment. This study is aimed at analyzing the factors that affect the removal of Cr(VI) with the use of almond green hull and ash adsorbent. The effects of pH (2–10), adsorbent dose (2–24 g/L), Cr(VI) concentration (10–100 mg/L), exposure time (1–60 min), and temperature (5–50 °C) were examined. The surface morphology, pore size of adsorbent surfaces were characterized with SEM, EDX, FTIR. Maximum removal occurred at pH = 2. Results showed that the removal yield increased with the rise of exposure time and temperature. The data indicate that due to limited site on adsorbent surface, the removal efficiency decreased as initial Cr(VI) concentration increased. When the adsorbent dose was increased, the removal yield increased in the case of the bioadsorbent as well; however, in the ash adsorbent, there was an increase followed by a decreasing trend. The study highlights that almond green hull can be more efficient than its ash in the removal of Cr(VI) from aqueous solution. As a general result of study, it can be argued that almond green hull bioadsorbent and the obtained carbon are able to remove Cr(VI) from aqueous solutions; thus, they can be used as efficient and economical substitutes for existing adsorbents like activated carbon, for the removal of chromium from polluted aqueous solutions.     

Adsorptive removal of eight heavy metals from aqueous solution by unmodified and modified agricultural waste: tangerine peel

Analysis was carried out using tangerine peel aiming its use as a potential adsorbent of eight heavy metal ions (Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn) from aqueous solution. This agricultural waste was tested both in its untreated and also chemically modified form. Based on Fourier transformation infrared spectra, a comparison of biosorbent structure before and after chemical treatment was made. Batch adsorption tests were conducted at different pH and mass of sorbent to examine the influence on the effectiveness of simultaneous removal of tested ions. Kinetic studies were conducted at optimum pH 5.0 and sorbent dosage 300 mg. The pseudo-second-order kinetic model best fit the experimental data with high correlation coefficients (r² > 0.9997). By optimizing listed parameters, high removal efficiencies (> 89%) were achieved. According to the results obtained in this study, the remediation of water polluted with heavy metals could be done using modified tangerine peel as an agricultural waste material.     

Hydrothermal synthesis of hydroxy sodalite from fly ash for the removal of lead ions from water

Zeolites are known to possess valuable physiochemical properties such as adsorption, cation exchange, molecular sieving, and catalysis. In addition, zeolites are highly selective scavengers of a variety of heavy metals from liquid effluents through the process of ion exchange. The present study was performed to hydrothermally synthesize Na₈[AlSiO₄]₆(OH)₂·2H₂O (also known as hydroxy sodalite hydrate). Due to its small aperture size, this material can be an ideal candidate for the separation of small molecules and ions from aquatic and gas mixtures. Synthetic zeolites offer many advantages over natural zeolites, such as higher ion affinity and adsorption capacity. Batch adsorption isotherm studies were conducted to evaluate the obtained adsorbent for the lead ion removal from aqueous media. Modeling lead ion adsorption using Langmuir and Freundlich isotherm expressions determined the capacity of the adsorbent. A removal efficiency of 98.1 % in a 3.0 g/l adsorbent/solution mixture with a maximum adsorption capacity of 153.8 mg/g was obtained. One potential application of the synthesized zeolite is for the lead removal in point-of-use treatment devices.     

The kinetic studies of the cobalt ion removal from aqueous solutions by dolomite-based sorbent

The kinetics of Co(II) ions adsorption on thermally activated dolomite was studied with respect to the calcination temperature of natural dolomite. The sorption of Co(II) onto all samples is reasonably fast: The first 30–35 min accounts for approximately 70–80 % of Co(II) removal from feed solutions. In order to select the main rate-determining step in the overall uptake mechanism, a series of experiments were performed and data obtained were interpreted in terms of film diffusion control, intraparticle diffusion, pseudo-first-order and pseudo-second-order models. From the modeling of kinetic data, it can be concluded that adsorption of Co(II) ions from aqueous solution by heat-treated dolomite is a complex phenomenon and occurs in a mixed diffusion mode—the kinetic data are well described by the pseudo-second-order equation. The possible multistage sorption mechanism involving film diffusion and intraparticle diffusion control steps as well as chemical interaction between Co(II) ions and calcined dolomite is proposed.     

水热活化法提取粉煤灰中的氧化铝

采用高压水热活化法对预先烧制的粉煤灰进行碱溶实验,探讨钙硅摩尔比、碱液浓度、液固比、苛性比、反应温度、反应时间等影响因素对于氧化铝溶出率的影响。考虑到氧化铝溶出率及反应成本等各方面因素,得出氧化铝溶出的适宜条件。结果表明:碱溶条件下,钙硅摩尔比为1.0,溶液碱浓度为350 g/L,液固比为10∶1,苛性比为14,反应温度280℃,活化时间为2 h。通过氧化铝溶出工艺条件的优化,可使氧化铝提取率达到95%以上。     

Magnetic stability of power-plant fly ash in different soil solutions

Temporal stability of magnetic parameters of anthropogenic ferrimagnetics in model soil conditions was studied. Fly ash from a power plant was used as original contaminant material, while soil reactive medium was modeled by different soil solutions. Changes in mass-specific magnetic susceptibility (χ), percentage frequency dependent magnetic susceptibility (χ_FD%), hysteresis parameters and thermomagnetic curves were measured for samples which underwent different leaching time periods. Virtually constant magnetic susceptibility values were obtained, independently on the soil medium (acid, neutral). On the other hand, the original highly non-stoichiometric maghemite phase rapidly transformed to stable magnetite. In some cases (model of free-draining soils) further decrease of Curie temperature (T_c) to 550–560°C is observed.     

黏土质白云岩去除水中铅离子作用及机理

黏土质白云岩是新生代形成的弱固结沉积白云岩,具有丰富且开放的孔隙率及高化学反应活性,其作为环境工程材料的应用值得探讨。本文研究了黏土质白云岩去除溶液中铅的效果和作用机理,考察了黏土质白云岩除铅动力学以及初始浓度、固液比对除铅效果的影响。结果表明,黏土质白云岩与不同浓度的铅溶液反应达到平衡所需的时间不同,初始铅浓度越高反应平衡时间越长,与铅浓度100 mg/L溶液反应70 h才基本达到平衡;黏土质白云岩除铅效果主要受反应平衡后溶液的p H值控制,固液比也可影响溶液p H值;固液比越高,平衡p H值越高,铅去除越完全;黏土质白云岩去除溶液中铅离子的作用机制是其中的白云石诱导的铅沉淀,白云石溶解同时形成了碱式碳酸铅。     

Improvement of cadmium ion electrochemical removal from dilute aqueous solutions by application of multi-stage electrolysis

Improvement of cadmium ion electrochemical removal from dilute aqueous solutions in a spouted bed reactor was investigated. Enlargement of cathode surface area from 1,000 to 1,500 cm² resulted in a decrease of nearly 30 % in both of the process time and the specific energy consumption. Application of a three-stage electrolysis process for a solution containing initial concentration of 270 ppm cadmium ion, resulted in the removal of 99.9 % cadmium ion in 135 min with the specific energy consumption of 2.29 kWh/kg, 23 % less than the value of a single-stage process. For a solution with cadmium ion initial concentration of 180 ppm, 99.9 % of cadmium ion was removed in 135.5 min by application of a two-stage electrolysis process, while the specific energy consumption was 2.82 kWh/kg, 30 % less than that of a single-stage process. For a solution with cadmium ion initial concentration of 90 ppm, 99.5 % of cadmium ion was removed in 100.2 min with the specific energy consumption of 3.78 kWh/kg in a single-stage electrolysis process.     

Hexavalent chromium removal from aqueous solutions by using low-cost biological wastes: equilibrium and kinetic studies

The batch removal of hexavalent chromium from aqueous solutions using almond shell, activated sawdust, and activated carbon, which are low-cost biological wastes under different experimental conditions, was investigated in this study. The influences of initial concentration, adsorbent dose, adsorbent particle size, agitation speed, temperature, contact time, and pH of solution were investigated. The adsorption was solution pH dependent and the maximum adsorption was observed at a solution pH of 2.0. The capacity of chromium adsorption under equilibrium conditions increased with the decrease in particle sizes. The equilibrium was achieved for chromium ion after 30?min. Experimental results showed that low-cost biosorbents are effective for the removal of pollutants from aqueous solution. The pseudo-second-order kinetic model gave a better fit of the experimental data as compared to the pseudo-first-order kinetic model. Experimental data showed a good fit with the Freundlich isotherm model. Changes in the thermodynamic parameters, including Gibbs free energy (??G_o), enthalpy (??H_o), and entropy (??S_o), indicated that the biosorption of hexavalent chromium onto almond shell, activated sawdust, and activated carbon was feasible, spontaneous, and endothermic in the temperature range 28?C50?°C.     

Pharmaceuticals and personal care products transference-transformation in aquifer system

Pharmaceuticals and personal care products (PPCPs) are a new kind of contaminant widely existing in the surface water and groundwater environment. In recent years, PPCPs have been received widely attention from many researchers. The migration and transformation of PPCPs are mainly photolysis, biodegradation, adsorption and hydrolysis in aquifer environment. The influencing factors of PPCPs migration include PPCPs' own physical and chemical properties, types and contents of organic matter, pH, lithology, geotechnical structure and the thickness of vadose zone, etc. At present, the research of PPCPs in China is still in the primary stage, especially on the contaminant in aquifer system. Therefore, the research in this field needs to be further strengthened.     

Formation and kinetics of porous cordierite from fly ash

Porous cordierite ceramics were prepared from a mixture of coal fly ash and basic magnesium carbonate at 1100-1350℃. Porosity, flexural strength and thermal expansion coefficient of the samples sintered at 1300℃ were estimated to be 26%, 65 MPa and 4.21×10^-6/℃, respectively. The kinetics of the formation progress was investigated by stepwise isothermal dilatometry （SID） accompanied with XRD, SEM and porosity measurement. It was found that the isothermal shrinkage data from SID could be well analyzed to get kinetic parameters according to the erapirical rate equation developed by Makipirtti-Meng, dY/dt=nk（T）Y（1-Y）（Y/1-Y）^（1/n）,where Y is the fractional shrinkage during the sintering process and n is a dimensionless component. The apparent activation energy △E values for 900-1000℃ and 1050-1 150℃ were 1294 and 1778 kJ/mol, respectively.     

Biosorption of Cu(II) and Pb(II) from aqueous solutions by chemically modified spent coffee grains

In this research, spent coffee grains were modified with citric acid solutions (0.1 and 0.6 M) to increase the quantity of carboxylic groups improving its metal adsorption capacity. Added functional groups on modified and non-modified spent coffee grains were identified and quantified by attenuated total reflection Fourier transform infrared analyses and potentiometric titrations, respectively. These adsorbents were used for the removal of lead (II) and copper (II) from aqueous solutions at 30 °C and different pH in batch systems. In addition, adsorption–desorption experiments were conducted to evaluate the possibility of re-using the modified adsorbent. Potentiometric titrations data reveal that the quantity of carboxylic groups was increased from 0.47 to 2.2 mmol/g when spent coffee grains were modified with 0.1 and 0.6 M citric acid. Spent coffee grains treated with 0.6 M citric acid, achieved a maximum adsorption capacity of 0.77 and 1.53 mmol/g for lead (II) and copper (II), respectively, whereas non-modified spent coffee grains only reached 0.24 and 0.19 mmol/g for lead (II) and copper (II), respectively. Desorption of lead (II) and copper (II) achieved around 70 % using 0.1 N HCl for non-modified and modified spent coffee grains with 0.6 M citric acid. It is suggested that lead (II) and copper (II) species were adsorbed mainly on the carboxylic groups of modified spent coffee grains and these metals may be exchanged for hydrogen and calcium (II) ions during adsorption on non-modified spent coffee grains. Finally, the adsorption equilibrium was reached after 400 min for modified spent coffee grains with 0.6 M citric acid. Modified spent coffee grains are a promising option for removing metal cations from aqueous solutions due to its low cost and high adsorption capacity (about 10 times higher than the activated carbons).