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Determination of Nitrite and Nitrate in Natural Waters Using Flow Injection with Spectrophotometric Detection
MOHAMMAD YAQOOB, ABDUL NABI AND PAUL JOHN WORSFOLD
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A simple and sensitive flow injection spectrophotometric method is reported for the room temperature determination of nitrite and nitrate based on the Griess reaction and a copperised cadmium column for reduction of nitrate. Calibration graphs were linear over the range 2 – 1000 µg N L1 (R2 = 0.9997 and 0.9999, n = 9) with a limit of detection (3 s.d.) of 1.0 µg N L1 and relative standard deviations (n = 10) of 0.9 and 1.2% for 50 µg N L1 nitrite and nitrate respectively. The sample throughput was 50 h1. The effect of reagent concentrations, physical parameters (flow rate, sample volume, reaction coil and copperised cadmium column length) and the potential interferences are reported. The effect of salinity on the blank and on the determination of nitrite and nitrate are also presented. The method was applied to natural waters (rainwater, freshwater and estuarine water) and the results for nitrite + nitrate (140 – 7310 µg N L1) were not significantly different (95% confidence interval) from results obtained using a segmented flow analyser reference method with spectrophotometric detection.
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FTIR, DC Current Conduction, Ionic Conductivity, and Resistivity Studies of PEO Based Polymer Composite System
MOHAMMAD SALEEM KHAN, SABIHA SULTANA, NOOR-UL-AMIN AND MOHAMMAD SUBHAN
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Polymeric composites of Iron chloride (FeCl3) doped Poly (ethylene oxide) fabricated in various weight fractions were subjected to FTIR, AC impedance test, DC conductivity and resistivity respectively. FTIR data confirms the complexation of FeCl3. DC test and AC impedance results reveal that direct current (DC) carrying capacity and ionic conductivity of the fabricated composites increases with increasing FeCl3 content, while reverse trend was observed for resistivity. The current findings are strongly supported by the decreasing trend in the energy band gap values for the FeCl3 doped PEO composites.
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Spin Trapping Radicals from Lipid Oxidation in Liposomes in the Presence of Flavonoids
NASIMA ARSHAD, NAVEED KAUSAR. JANJUA, LEIF HORSFELT SKIBSTED AND MOGENS LARSEN ANDERSEN
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Interactions of four structurally related flavonoids – quercetin, rutin, morin and catechin with peroxyl radicals using liposome/N-tert-butyl-α-phenylnitrone (PBN) and liposome/α-(4-pyridyl-N-oxide)-N-tert-butylnitrone (POBN)-spin trap systems have been studied through spin trapping ESR. Results obtained were different from that of conjugated diene analysis experiments, where lag phases indicated radical scavenging activity of all the flavonoids. No clear lag phase was observed in ESR experiments under same conditions. In the presence of flavonoids decreasing ESR signals of spin adducts in PBN, while no or negligibly smaller spin adducts with POBN system were observed which may be attributed to the possibility that spin traps interacted with free radicals. Experiments with buffer/spin trap systems without liposome revealed that spin adducts were only stable with catechin and destroyed by quercetin, rutin and morin in buffer/spin trap systems. These results further assured that quercetin, rutin and morin not only interacted with peroxyl radicals but also with spin adducts.
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Cyclic Voltammetric Study of Complexes of Fe (III) with Saponins Isolated from Cicer aritinum and Glycyrrhizin
SAMINA SHAH KHAN, SYED ARIF KAZMI AND HUMERA ANWER
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Cyclic voltammetric study was used to analyze three new saponins (isolated from the seeds of Cicer aritinum) along with a known saponin soyasaponin I and β sitosterol glycoside isolated saponins as well as glycyrrhizin. These studies were carried out in aqueous medium at Glassy carbon (GCE) electrode vs. Ag|AgCl reference electrode. Results revealed that the voltammograms of Fe(III) with isolated saponins are irreversible while that of Fe(III)-glycyrrhizin complex is reversible. Even though precise Eo values of their Fe(III) complex could not be determined,it is clearly indicated that Fe(III) forms complexes with these saponins. The ability to form strong complexes with Fe(III) therefore reduces the availability of Fe(III) by saponins.
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Impact of Treated Industrial Effluents on Adam Sohaba Distributory Water at Sadiqabad (Pakistan) – A Case Study
MUHAMMAD ISMAIL CHUGHTAI, SHAHID ABBAS, TAYYBAH SHAHEEN AND ABDUL RASUL AWAN
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A study was carried out to investigate the impact of treated effluents of Fertilizer Plant on seasonal variations in physico-chemical parameters of Adam Sohaba Distributory water at Ahmaddali, Sadiqabad. Water samples were collected and analyzed on monthly basis for the period of ten months. Results indicated that air and water temperatures, light penetration and photoperiod showed higher values in summer than winter season. The values of turbidity, boiling point, pH, dissolved O2, acidity, alkalinity, residual sodium carbonates were decreased in mixed water as compared to distributory water in almost all months while the values of viscosity, surface tension, conductivity, free CO2, carbonates, bicarbonates, total hardness, total solids, total volatile solids, total dissolved solids, total volatile dissolved solids, sodium, calcium, magnesium, chlorides and sodium adsorption ratio were slightly increased in mixed water indicating the effect of treated industrial effluents. The monitored parameters were compared with water quality standards and most of them were found to be in the permissible limits indicating the proper functioning of wastewater treatment plant. The comparative study of Adam Sohaba Distributory water before and after mixing the treated effluents revealed that there was slight difference in water quality parameters. On the other hand, overall water quality parameters varied significantly which may be due to addition of urban wastes.
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Effect of HRT on SBR Performance for Treatability of Combined Domestic and Textile Wastewaters
MUHAMMAD SAQIB NAWAZ AND SHER JAMAL KHAN
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Textile wastewater contains organics and color dyes which need to be treated before discharging into receiving water bodies. Sequencing batch reactor (SBR) is proved promising against textile wastewater due to its high organic and nutrient removal efficiencies. In this study the influence of variable hydraulic retention time (HRT) on the performance of SBR in treating combined textile and domestic wastewater was evaluated. Six SBRs were operated in parallel at 12 and 8 hrs HRTs respectively, three for synthetic and three for real textile plus domestic wastewater. SBRs were operated at constant temperature 25 ± 1 0C and pH 7 ± 1 to avoid seasonal effects. The biological oxygen demand (BOD) removal efficiency was consistent at 73% while, total suspended solids (TSS) removal efficiency increased from 52 to 63% in SBRs with decrease in HRT from 12 to 8 hrs. The organic loading rate (OLR) increased from 0.45 to 0.68 Kg/m3/d, SVI decreased from 94 to 84 mL/g and chemical oxygen demand (COD) removal efficiency increased in real waste water (RWW) SBRs from 59 to 63% with decrease in HRT from 12 to 8 hrs. Low COD removal at 12 hr HRT can be attributed to poor settling characteristics of sludge due to possible filamentous growth at low F/M (0.03) and greater SRT (28 days) as compared to 8 hr HRT condition, where F/M was 0.05 and SRT of 20 days.
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Chemical Modification of Oryza sativa Linnaeus Husk with Urea for Removal of Brilliant Vital Red and Murexide Dyes from Water by Adsorption in Environmentally Benign Way
RABIA REHMAN, TARIQ MAHMUD, FARAH KANWAL, MUHAMMAD NAEEM ASLAM, RABIA LATIF AND HINA NISAR
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Oryza sativa Linnaeus is an important food item all around the world. Due to its huge consumption, a large amount of rice husk is generated as agrowaste which can be used for water treatment by adsorption. Its adsorption capacity further can be enhanced by chemical medication. In the present study, urea modified rice husk has been used for removing Brilliant Vital Red and Murexide form water in an efficient way. After optimizing operating conditions, isothermal and thermodynamical studies were carried out, which showed that maximum adsorption capacity of urea modified rice husk for removing Brilliant Vital Red and Murexide dyes were 28.93 and 30.74 mg.g-1. Adsorbent characterization was carried out by recording its FT-IR spectra.
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Orthogonal Test Design Based Analysis of Factors Controlling Simultaneous Anaerobic Sulfide and Nitrate Removal Process
JING CAI, PING ZHENG, MAHMOOD QAISAR, ZUOFU XIE AND JUNYUAN JI
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The present study deals with comprehensive analysis of the main factors like the effects of pH, influent substrate concentration and hydraulic retention time (HRT) driving simultaneous anaerobic sulfide and nitrate removal process. The analysis involved a multi-factorial orthogonal experiment. The results of range and variance analyses showed that decreasing influent substrate concentration might improve the effluent quality. Consequent to controlling the reaction pH at 7.0±0.1, the effluent quality was the best keeping influent sulfide concentration of 220 mg•L-1 and HRT of 10 h. Influent substrate concentration and HRT had significant bearing on the substrate removal rate, while pH had no significant effect. Decreasing HRT was a better option to increase substrate removal rate. Controlling the reaction pH around 7.0±0.1, feeding influent sulfide concentration of 520 mg•L-1 at HRT of 4h resulted in the optimum substrate removal rate.
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Thermal Behavior, Non-Isothermal Decomposition Reaction Kinetics and Thermal-Safety Evaluation on 3-Amino-4-chloroximidofurazan
BIAO YAN, HONGYA LI, HAIXIA MA, JIRONG SONG AND FENGQI ZHAO
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3-Amino-4-chloroximidofurazan (ACOF) is an important precursor of synthesizing new furazanon (furoxano) energetic compounds. Its thermal behavior was studied by the differential scanning calorimetry (DSC) method. The results of this study show that there are three exothermic decomposition processes. Its kinetic parameters of the intense exothermic decomposition process were obtained from the analysis of the DSC curves. The apparent activation energy, pre-exponential factor and the mechanism function are 153.54 kJmol−1, 1014.34 s−1 and f(α) = 2(1-α)[–ln(1-α)]1/2, respectively. The specific heat capacity of ACOF was determined with a continuous Cp mode of micro–calorimeter. Using the relationship between Cp and T with the thermal decomposition parameters, the time of the thermal decomposition from initialization to thermal explosion (adiabatic time-to-explosion, tTIAD), the self-accelerating decomposition temperature (TSADT), thermal ignition temperature (TTIT), critical temperatures of thermal explosion (Tb) and period of validity (t0.9) were obtained to evaluate its thermal safety.
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Comparison of Three Analytical Methods for Separation of Mineral and Chelated Fraction from an Adulterated Zn-EDTA Fertilizer
MUHAMMAD SALIK ALI KHAN, MUHAMMAD AKRAM QAZI, SHAHID MAHMOOD MIAN, NIAZ AHMED, NAVEED IQBAL KHAN, MUHAMMAD AKRAM AND MUHAMMAD ASIF ALI
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Different analytical procedures are being employed in the world to quantify the chelated portion in a Zn-EDTA fertilizer. Agriculture Department, Government of the Punjab is following Shahid′s analytical method in this regard. This method is based on Ion-chromatography (IC) that separates the mineral zinc (Zn) from an adulterated Zn-EDTA fertilizer sample i.e. mixture of mineral and chelated Zn fractions. To find out its effectiveness and suitability, this comparative study was carried out by analyzing adulterated, non-adulterated Zn-EDTA standard and Zn-EDTA samples taken from market in thrice following three methods namely Shahid′s (IC) analytical method, Atomic Absorption Spectrophotometric (AAS) method based on the principle of precipitating the mineral Zn fraction at high pH value by using alkali solution of suitable concentration and analysis of filtrate containing only chelated fraction and Association of Official Analytical Chemists (AOAC) method FM-841 respectively. Adulterated Zn-EDTA samples were prepared by mixing of known quantity of mineral Zn with chelated Zn-EDTA standard. The results showed that Shahid′s analytical method and AAS method, both successfully estimated the chelated fraction. The AOAC FM-841 method was insensitive to put a ceiling on the mineral fraction hence did not furnish the reliable results. The Shahid′s analytical method was selected being equally effective to produce reliable results both for solid and liquid Zn-EDTA samples. The AAS method was comparable in only liquid samples.
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