Removal of Cu（ll） ions from aqueous solution by activated carbon impregnated with humic acid

Humic acid （HA） was impregnated onto powdered activated carbon to improve its Cu（II） adsorption capability. The optimum pH value for Cu（II） removal was 6. The maximum adsorption capacity of HAimpregnated activated carbon was up to 5.98mg.g-1, which is five times the capacity of virgin activated carbon. The adsorption processes were rapid and accompanied by changes in pH. In using a linear method, it was determined that the equilibrium experimental data were better represented by the Langmuir isotherm than by the Freundlich isotherm. Surface charges and surface functional groups were studied through zeta potential and FTIR measurements to explain the mechanism behind the humicacid modification that enhanced the Cu（II） adsorption capacity of activated carbon.     

微波消解-石墨炉原子吸收光谱法测定鸡排泄物中总砷的方法研究（Study on the Determination Method of Total Arsenic in Fowl Dung by Microwave Digestion-Atomic and Graphite Furnace Atomic Absorption Spectrometry）

建立检测鸡排泄物中总砷含量的微波消解-石墨炉原子吸收光谱法.使用硝酸镁和硝酸钯混合溶液作为基体改进剂,在灰化温度1200℃、原子化温度2400℃条件下,采用石墨炉原子吸收光谱法测定鸡排泄物中的总砷含量.结果表明,总砷浓度在0～100ng·mL-1范围内符合郎伯-比尔定律,线性回归方程为Y=0.0013X+0.0098,决定系数0.9976,方法的回收率为98.8%～101.9%,精密度为2.81%,检出限为0.100mg·kg-1.     

Simultaneous removal of Co,Cu, and Cr from water by electrocoagulation

This study provides an electrocoagulation process for the removal of metals such as cobalt, copper, and chromium from water using magnesium as anode and galvanized iron as cathode. The various parameters like pH, current density, temperature, and inter electrode distance on the removal efficiency of metals were studied. The results showed that maximum removal efficiency was achieved for cobalt, copper, and chromium with magnesium as anode and galvanized iron as cathode at a current density of 0.025?A?dm^?2 at pH 7.0. First- and second-order rate equations were applied to study adsorption kinetics. The adsorption process follows second-order kinetics model with good correlation. The Langmuir and Freundlich adsorption isotherm models were studied using the experimental data. The Langmuir adsorption isotherm favors monolayer coverage of adsorbed molecules for the adsorption of cobalt, copper, and chromium. Temperature studies showed that adsorption was endothermic and spontaneous in nature.     

Optimization of methyl orange removal from aqueous solution by response surface methodology using spent tea leaves as adsorbent

The effective disposal of redundant tea waste is crucial to environmental protection and comprehensive utilization of trash resources. In this work, the removal of methyl orange （MO） from aqueous solution using spent tea leaves as the sorbent was investigated in a batch experiment. First, the effects of various parameters such as temperature, adsorption time, dose of spent tea leaves, and initial concentration of MO were investigated. Then, the response surface methodology （RSM）, based on Box- Behnken design, was employed to obtain the optimum adsorption conditions. The optimal conditions could be obtained at an initial concentration of MO of 9.75 mg·L-1, temperature of 35.3℃, contact time of 63.8 min, and an adsorbent dosage 3.90 g· L-1. Under the optimized condi- tions, the maximal removal of MO was 58.2%. The results indicate that spent tea leaves could be used as an effective and economical adsorbent in the removal of MO from aqueous solution.     

Biosorption of Cr（VI） by carbonized Eupatorium adenophorum and Buckwheat straw： thermodynamics and mechanism

High quality and low cost carbon can be prepared from Eupatorium adenophorum （E. adenophorum） and Buckwheat straw. The biosorbent was used for Cr（VI） removal. The effect of experimental parameters, such as pH, sorbent dosage and temperature were examined and the optimal experimental condition was determned. Solution pH is found influencing the adsorp- tion. Cr（VI） removal efficiency is found to be maximum （98%） at pH= 1. Langmuir and Freundlich adsorption isotherms were applicable to the adsorption process and their constants were evaluated. The adsorption data obtained agreed well with the Langmuir sorption isotherm model. The maximum adsorption capacities for Cr（VI） ranged from 46.23 to 55.19mg.g^-1 for temperature between 298 K and 308 K under the condition of pH = 1.0. Thermodynamic parameters such as free energy change （AG）, enthalpy （AH） and entropy （AS） indicate a spontaneous, endothermic and increased randomness nature of Cr（VI） adsorption. Studies found that the raw E. adenophorum and buckwheat straw mixed materials with simple treatment had a high efficiency for the removal of Cr（VI） and would be a promising adsorbent.     

Adsorptive removal of As(III) and As(V) from water and wastewaters using an anion exchanger derived from polymer-grafted banana stem

In this study, the adsorption characteristics of As(III) and As(V) from water and wastewater using polyacrylamide-grafted banana stem with quaternary ammonium functionality (PGBS-AE) were investigated. Infrared spectroscopic, and thermogravimetric analyses were performed to affirm the polymer grafting, functionality, morphology, and thermal stability. Batch experiments were carried out to understand the effect of contact time, concentration, pH, adsorbent dose, and temperature of the solution for the adsorption of As(III) and As(V) onto PGBS-AE. Equilibrium was achieved within 1 h and the optimum pH was found to be 9.0 and 3.0 for As(III) and As(V), respectively. Isotherm studies showed that the Langmuir equation fits best. Maximum adsorption capacities of 50 and 5.5?g?kg^?1 were obtained for As(III) and As(V) at 30°C. The endothermic nature of adsorption was evident as the adsorption efficiency increased with temperature. The thermodynamic parameters were evaluated to explain the feasibility of adsorption and to predict the nature of adsorption. The competence of the adsorbent for practical purposes was also analyzed by treating with a fertilizer industry effluent sample. Studies pertaining to adsorbent regeneration and readsorption of As(III) and As(V) were carried out for four consecutive cycles.     

Simultaneous quantification of several classes of antibiotics in water,sediments, and fish muscles by liquid chromatography-tandem mass spectrometry

Precise and sensitive methods for the simultaneous determination of different classes of antibiotics, including sulphonamides, fluoroquinolones, macrolides, tetracyclines, and trimethoprim in surface water, sediments, and fish muscles were developed. In water samples, drugs were extracted with solid-phase extraction （SPE） by passing 1000 mL of water through hydrophilic lipophilic balanced （HLB） SPE cartridges. Sediment samples were solvent-extracted, followed by tandem SPE （strong anion exchange （SAX） ＋ HLB） clean-ups. Fish muscles were extracted by a mixture of acetonitrile and citric buffer （80：20, v/v） solution, and cleaned by SPE. Liquid chromatography-tandem mass spectrometry （LC-MS/ MS） with multiple reaction monitoring （MRM） detection was employed to quantify all compounds. The recoveries for the antibiotics in the spiked water, sediment, and fish samples were 60.2%-95.8%, 48.1%-105.3%, and 59.8%- 103.4%, respectively. The methods were applied to samples taken from Dianchi Lake, China. It showed that concentrations of the detected antibiotics ranged from limits of quantification （LOQ） to 713.6 ng- L1 （ofloxacin） in surface water and from less than LOQ to 344.8 μg·kg-1 （sulphamethoxazole） in sediments. The number of detected antibiotics and the overall antibiotic concentrations were higher in the urban area than the rural area, indicating the probable role of livestock and human activities as important sources of antibiotic contamination. In fish muscles, the concentration of norfioxacin was the highest （up to 38.5 μg·kg-1）, but tetracyclines and macrolides were relatively low. Results showed that the methods were rapid and sensitive, and capable of determining several classes of antibiotics from each of the water, sediment, and fish matrices in a single run.     

Laboratory study on high-temperature adsorption of HCI by dry-injection of Ca（OH）2 in a dual-layer granular bed filter

Combustion-generated hydrogen chloride （HCl） is considered to be a very hazardous acid gaseous pollutant. This paper presents a laboratory study on the dry adsorption of HCl. The experiments were conducted in a dual-layer granular bed filter, at gas temperatures of 500℃-700℃ and n（Ca）/n（Cl）molar ratios of 1.0-5.0 using the silver nitrate titration method by dry adsorbent powders Ca（OH）2. Mainly, the adsorption efficiency of HCI and utilization efficiency of Calcium were studied, by varying relevant factors including n（Ca）/n（Cl）, tempera- ture, feeding method, water vapor and CO2. With a relatively higher HCl concentration of 1000ppm, the experimental results revealed that 600℃ may be the optimum temperature for HCl adsorption when optimum n （Ca）/n（Cl） was 2.5 in our tests. The results also demonstrated that the feeding at a constant pressure was more effective, and the HCl adsorption efficiency could rapidly reach over 90% with n（Ca）/n（Cl） = 2.5 at 600℃. Furthermore, the HCl adsorption efficiency was found to be slightly promoted by water vapor, while could be impeded by CO2, and the utilization efficiency of calcium could be up to 74.4% without CO2, while was only 36.8% with CO2 when n（Ca）/n（Cl） was 2.5 at 600℃.     

高效液相色谱-串联质谱法同时检测水体中26种药物及个人护理品

通过优化固相萃取条件和高效液相色谱-串联质谱参数,建立了可以同时检测地表水和地下水中26种典型药物及个人护理品(pharmaceuticals and personal care products,PPCPs),包括磺胺类、大环内酯类、喹诺酮类、酰胺醇类、精神类、消炎止痛类以及个人护理品的检测方法.通过将水样pH值调节...     

Adsorptive removal of rhodamine B from textile wastewater using water chestnut (Trapa natans L.) peel: adsorption dynamics and kinetic studies

Water chestnut peel, an agricultural bio-waste, was used as a biosorbent for removal of rhodamine B (RhB), basic textile dye, from an aqueous solution. The effects of various experimental parameters were studied. The equilibrium data correlated well with a Freundlich isotherm (R² = 0.98–0.99) followed by a Halsey isotherm model (R² = 0.98–0.99) which indicated heterogeneity of the adsorbent surface and multilayer adsorption of RhB dye onto the water chestnut peel waste (WCPW). High correlation coefficients (R² = 0.99) together with close agreement between experimental q_e (0.4–1.7 mg g^?1) and calculated q_e (0.4–2.5 mg g^?1) suggested that the adsorption process followed pseudo-second-order kinetics, with k₂ values in the range of 52–3.4 × 10^?1 g mg^?1 min^?1 at different concentrations. The overall mechanism of adsorption was controlled by both liquid-film and intra-particle diffusions. The negative values of change in Gibb's free energy (?ΔG⁰ = 19.2–29.2 kJ mol^?1) and positive values of change in enthalpy (ΔH⁰ = 30.9–117.6 kJ mol^?1) revealed the process to be spontaneous and endothermic. WCPW was found to be an effective adsorbent for removal of RhB, a cationic dye, from an aqueous solution.     

Effective removal of Cobalt(II) ions from aqueous solutions and nuclear industry wastewater using sulfhydryl and carboxyl functionalised magnetite nanocellulose composite: batch adsorption studies

A new adsorbent sulfhydryl and carboxyl functionalized magnetite nanocellulose composite [(MB-IA)-g-MNCC] was synthesized by graft co-polymerization of itaconic acid onto magnetite nanocellulose (MNCC) using EGDMA as cross linking agent and K₂S₂O₈ as free radical initiator. The adsorption occurs maximum in the pH 6.5. The best fitted kinetic model was found to be pseudo-second-order kinetics. Therefore the mechanism of Co(II) adsorption onto (MB-IA)-g-MNCC follows ion exchange followed by complexation. The Langmuir model was the best fitted isotherm model for the adsorption of Co(II) onto the (MB-IA)-g-MNCC. Simulated nuclear power plant coolant water samples were also treated with (MB-IA)-g-MNCC to demonstrate its efficiency for the removal of Co(II) from aqueous solutions in the presence of other metal ions. To recover the adsorbed Co(II) ions and also to regenerate the adsorbent to its original state 0.1?M HCl was used as suitable desorbing agent. Six cycles of adsorption-desorption experiments were conducted and was found that adsorption capacity of (MB-IA)-g-MNCC has been decreased from 97.5% in the first cycle to 84.7% in the sixth cycle. Recovery of Co(II) using 0.1?M HCl decreased from 93.2% in the first cycle to 79.3% in the sixth cycle.

Abbreviations: T: absolute temperature; q_e: amount adsorbed at equilibrium; q_t: amount adsorbed at time t; CELL: cellulose; Co: cobalt; C_e: concentration at equilibrium; C_HCl: concentration of HCl; C_NaOH: concentration of NaOH; C_A: concentrations of acid; C_B: concentrations of base; W_g: dry weight of composite; W_i: dry weight of MNCC; DS: energy dispersive spectra; EGDMA: ethylene glycol dimethacrylate; Ce: equilibrium concentration; K_L: equilibrium constant; F: Faradays constant; FTIR: Fourier transform infrared spectra; ΔG^o: free energy change; K_F: Freundlich adsorption capacity; 1/n: Freundlich constant; R: gas constant; D: grafting density; EC_o: initial concentration; IA: itaconic acid; IA-g-MNCC: itaconic acid-grafted-magnetite nanocellulose composite; b: Langmuir constant; MNCC: magnetite nanocellulose composite; Q⁰: Maximum adsorption capacity; (MB-IA)-g-MNCC: 2-mercaptobenzamide modified itaconic acid-grafted-magnetite nanocellulose composite; NC: nanocellulose; pH_pzc: Point of zero charge; K₂S₂O₈: potassium peroxy sulphate; k₁: pseudo-first-order rate constant; k₂: pseudo-second-order rate constant; SEM: scanning Electron Microscope; b_s: Sips adsorption capacity; Q_s: Sips maximum adsorption capacity; ΔH°: standard enthalpy change; ΔS°: standard entropy change; A: surface area; σ₀: surface charge density; 1/n_s: surface heterogeneity factor; VSM: vibrating sample magnetometer; V: volume of solution; W: weight of (MB-IA)-g-MNCC; M_composite: weight of the composite; XRD: X-ray diffraction     

Impact of drought on the ecological and chemical status of surface water and on the content of arsenic and fluoride pollutants of groundwater in the province of Salamanca (Western Spain)

The impact of drought on the ecological and chemical status of surface and groundwaters of the River Tormes (River Duero basin, northwestern Iberian Peninsula) was studied to evaluate the evolution of the quality of the river during its passage through the city of Salamanca (Spain). The Water Quality Index (WQI) of the river revealed that the drought period of 2005 did not significantly affect water chemical quality. However, during the study period differences were found in surface water ecological quality, using phytoplankton quality as AN indicator. These differences may be accentuated as a result of regulation of the River Tormes by the Santa Teresa reservoir. Arsenic and fluoride concentrations were measured in water wells, finding higher arsenic concentrations after the drought period and no correlation between the arsenic and fluoride contents. The results are useful for an overall understanding of potential impact of climate change on the ecological and chemical status of water in regional systems.