Electrochemical behavior and the determination of furan in beverage samples using glassy carbon electrode

Furan is a possible human carcinogen in many types of foods. A new and sensitive electro analytical method for determination of furan has been developed and validated. The best condition for electrochemical response was obtained with 0.1 M britton-rabinson buffer solution [pH=5] a glassy carbon electrode [GCE] was used as the working electrode, a Ag/AgCl/ KCl[sat.] electrode served as the reference electrode, and a platinum wire as the auxiliary electrode under the Differential Pulse Voltammetry [DPV] mode. The peak current obtained from DPV was linearly dependent on the Furan concentration in the range 12-360 Micro M [0.81-24.5 ppm] with correlation coefficients of 0.999 and a limit of detection [LOD] of 3 Micro M [0.2 ppm] and limit of quantification [LOQ] of 10 Micro M [0.68 ppm] were calculated, respectively. The values of the electron-transfer coefficient [Alpha] involved in the rate determining step calculated from the linear plots of Ep against ln [v] in the pH range investigated were 0.8 confirming the irreversible nature of the oxidation peak. The reproducibility of the method was tested by analyzing 10 samples containing 30 Micro M of Furan. The RSD% of the method thus obtained was 3.0% which showed excellent reproducibility for this developed methods

Sensitivity analysis of METRIC-based evapotranspiration algorithm

METRIC [Mapping Evapotranspiration at High Resolution with Internalized Calibration] is known as an appropriate surface energy balance model for the estimation of the spatial distribution of evapotranspiration [ET] in semi-arid regions. Based on lysimeter measurements, METRIC has shown ET estimates of 10% on a sub-field scale on a daily basis. There is a need to identify how the model is sensitive to the input parameters. Therefore, the most influential parameters in the algorithm can be identified and the model can be further improved. Sensitivity analysis at three levels of vegetation cover shows that METRIC is highly sensitive to dT, surface temperature, net radiation, sensible heat flux, surface albedo, soil heat flux, and air temperature. It is also moderately sensitive to friction velocity, aerodynamic resistance to heat transfer, surface emissivity and less sensitive to leaf area index, soil adjusted vegetation index, wind speed [except wind speed at low level of vegetation cover][4], and roughness length for momentum [except Z[om]<0.1]. A two-factor analysis of the algorithm's primary inputs showed that the pair albedo-surface temperature is the most and the normalized vegetation index-soil adjusted vegetation index or normalized vegetation index-leaf area index is the least effective pair in this model. In order to improve the accuracy of METRIC, this study suggests upgrading the equations for the above-mentioned effective variables

Pre-concentration and determination of platinum [IV] in water samples using chelating resin by inductively coupled plasma atomic emission spectroscopy [ICP-AES]

A chelating resin is prepared by condensation polymerization of aniline with formaldehyde and characterized by FT-IR, elemental analysis and studied for the preconcentration and determination of trace Platinum ion from environmental water sample using inductively coupled plasma-atomic emission spectroscopy [ICP-AES]. The optimum pH value for sorption of the metal ions was 5. The maximum adsorption capacities of resin [aniline- formaldehyde] were determined as 21.25, 14.72 and 11.9 mg/g at different temperatures 20, 30 and 40°C, respectively. The best desorption of the metal ions from resin was obtained by 0.5 mol/L nitric acid as eluting agent. The profile of Platinum uptake on this sorbent reflects good accessibility of the chelating sites in the aniline-formaldehyde. The equilibrium adsorption data of Platinum ion modified resin were analyzed by four isotherm models such as Langmuir, Freundlich ,Temkin and Redlich-Peterson. Langmuir isotherm parameters obtained from the four Langmuir linear equations by using linear method, Langmuir-1 is the most popular linear form, and it had the highest coefficient of determination compared with the other Langmuir linear equations. The thermodynamic parameters [DELTAG, DELTAH, and DELTAS] were also determined using the equilibrium constant values obtained at different temperatures. The results showed that the adsorption for Pt [IV] ion was spontaneous nature and exothermic. The method was applied for Platinum ions determination from tap water sample

New chelating resin for preconcentration and determination of molybdenum by inductive couple plasma atomic emission spectroscopy

A chelating resin is prepared by condensation polymerization of aniline with formaldehyde and characterized by Fourier transform infrared spectrometer, elemental analysis and thermogravimetric analysis and studied for the preconcentration and determination of trace Molybdate ion from environmental water sample using inductive couple plasma atomic emission spectroscopy. The optimum pH value for sorption of the metal ion was 5. The sorption capacity of functionalized resin is 3.1 mg/g. The chelating sorbent can be reused for 20 cycles of sorption-desorption without any significant change in sorption capacity. The best desorption of the metal ions from resin was obtained by 0.5 mol/L nitric acid as eluting agent. The profile of molybdenum uptake on this sorbent reflects good accessibility of the chelating sites in the aniline- formaldehyde. Scatchard analysis revealed that the homogeneous binding sites were formed in the polymers. The equilibrium adsorption data of Molybdate ion modified resin were analyzed by five isotherm models such as Langmuir, Freundlich and Temkin. Langmuir isotherm parameters obtained from the four Langmuir linear equations by using linear method. Based on the Langmuir isotherm analysis, the monolayer adsorption capacity was determined to be 4.03 mg/g at 20 °C. The method was applied for molybdenum ions determination from river water sample

new potentionmetric sensor for determination of cesium ion in environmental samples

A new cesium ion selective PVC membrane based on parent calix [4] arene was developed for potentiometric determination of cesium in environmental samples. The electrode based on p-5, 11,17,23 tetra [tert-butyl] 25,26,27,28-tetrahydoxy calix [4] arene [TCH] as ionophor, dibutyl phthalate [DBP] as plasticizer, sodium tetra phenyl borate [NaTPB] and oleic acid as lipophilic salt and additive showed the best performance. The electrode exhibits a good Nernstian response in a concentration range of 1x10 [-1]-3.16x 10[-5] M of cesium, with a slope of 58.5 +/- 0.6 mv per decade and a detection limit of 1.58 x 10 [-5] M. It exhibits a good selectivity for cesium in comparison with alkali, alkaline earth, and dome transition metal ions. The electrode response and selectivity remained almost unchanged for more than a month. The effect of membrane composition, pH and concentration of internal solution on the potential response of the electrode were also studied. The applicability of the electrode to real samples was also assessed

Use of horizontal flow roughing filtration in drinking water treatment

In order to evaluate the feasibility of implementation of horizontal-flow roughing filtration for drinking water treatment a pilot was designed and run at the bank of Zayandehroud river near the village of Chamkhalifeh. Pilot running was performed in summer 2003 [July, August and September], when the quality of river water was in relatively worst condition. The filter is comprised from three different parts which are separated with perforated baffles. Each compartment is filled with some local sand and gravel considering a special decreasing size regime. The overall function of the filter in removing turbidity and total suspended solids is acceptable. Additionally, iron, manganese and color and coliform removal are also been covered to some extent. Achieved results in this study shows that horizontal-flow roughing filtration may be considered as a packed, low-cost and efficient pretreatment process incase surface water is used as water supply for treatment. Furthermore, when small scale societies are considered and when no major pollutants exist in the water supply as the case in this study this system may be posed as a total treatment system, in which treated water exited from the filter may be sent to distribution network after a simple post chlorination

Biological nitrate removal form water resources

During the recent decades, the increasing trends in nitrate ion concentration in ground water sources have meant more research to find effective procedures for the prevention of even more water contamination by nitrogen sources. In this study a pilot was designed to examine the application of biological method for eliminating nitrate from the water of well No.903 of Mehrabad Airport, Tehran, Iran. Design, installation and running processes were done from April to November 2003. A fixed biological bed containing five-centimeter trunk pipes 16 mm in diameter were installed in the reactor and the system was operated with upflow current. Instead of Methanol, Acetic acid was used as the carbon source because of its easier acceptance by the public, lower price and availability as well as easier storage. The pilot was run in different hydraulic retention times from 48 h up to one hour. Considering economical, operational and maintenance factors, retention time of 2 h was determined to be optimum, in which 77% nitrate removal was achieved. Considering a ratio of 2 for COD/N, inlet COD of about 140 mg/L and the optimum retention time, COD removal of about 80% is also accomplished in this process. The amount of nitrite concentration, pH values, COD and turbidity is also evaluated versus different hydraulic retention times

Solid waste management in Tabriz petrochemical complex

Tabriz petrochemical complex is located in the northwest of Iran. Major products of this industry include raw plastics like, polyethylene, polystyrene, acrylonitrile, butadiene, styrene, etc. Sources of waste generation include service units, health and cure units, water, power, steam and industrial processes units. In this study, different types of solid waste including hazardous and non hazardous solid wastes were investigated separately. The aim of the study was to focus on the management of the industrial wastes in order to minimize the adverse environmental impacts. In the first stage, locating map and dispersion limits were prepared. Then, the types and amounts of industrial waste generated in were evaluated by an inventory and inspection. Wastes were classified according to Environmental Protection Agency and Basel Standards and subsequently hazards of different types were investigated. The waste management of TPC is quite complex because of the different types of waste and their pollution. In some cases recycling/reuse of waste is the best option, but treatment and disposal are also necessary tools. In this study, using different sources and references, generally petrochemical sources, various solid waste management practices were investigated and the best options were selected. Some wastes should be treated before land filling and some of them should be reused or recycled. In the case of solid waste optimization, source reduction ways were recommended as well as prior incineration system was modified

Evaluation of the quality and self purification potential of Tajan River using Qual2E model

Tajan River is among significant rivers of Caspian Sea water basin. Pollution sources that threaten the quality of water in Tajan River may be classified in to two categories namely point and non-point sources. Major pollutants of latter category are Mazandaran wood and pulp, Paksar dairy products and Sari Antibiotic production factories, as well as 600-dastgah residential area. On the other hand, non-point sources whose waste is considered as a distributed load consist of Sari municipal wastewater and agriculture-related pollutants that are drained towards the river. In order to model the quality of river flow, Qual2E model is taken in to consideration. Considering TDS, the river quality is completely acceptable in cold seasons. However, in spring and summer the value of this parameter is increased and this causes some restrictions in the use of this water for irrigation of specific sensitive crops. Agricultural activities and consequent irrigated waters are the major causes of higher reported TDS values in warm seasons. Current status of DO is completely acceptable and this is highly related to the relative high value of width on depth ratio along the river. BOD and COD locate in a fairly poor condition. Quality deterioration is more noticeable in cold seasons. Higher rate of precipitation and consequent greater runoff generation towards the river basin justify the relative increase of mentioned parameters in fall and winter. Generally, non-point pollution sources are more contributed in deterioration of Tajan River water quality