M. Iqbal Bhanger

Lead sorption by waste biomass of hazelnut and almond shell

The potential to remove Pb(2+) ion from aqueous solutions using the shells of hazelnut (HNS) (Corylus avellana) and almond (AS) (Prunus dulcis) through biosorption was investigated in batch experiments. The main parameters influencing Pb(2+) ion sorption on HNS and AS were: initial metal ion concentration, amount of adsorbent, contact time and pH value of solution. The influences of initial Pb(2+) ion concentration (0.1-1.0mM), pH (2-9), contact time (10-240 min) and adsorbent amount (0.1-1.0 g) have been investigated. Equilibrium isotherms have been measured and modelled. Adsorption of Pb(2+) ions was in all cases pH-dependent showing a maximum at equilibrium pH values between 6.0 and 7.0, depending on the biomaterial, that corresponded to equilibrium pH values of 6.0 for HNS and 7.0 for AS. The equilibrium sorption capacities of HNS and AS were 28.18 and 8.08 mg/g for lead, respectively after equilibrium time of 2h. The adsorption data fit well with the Langmuir isotherm model and the experimental result inferred that adsorption, chelation and ion exchange are major adsorption mechanisms for binding Pb(2+) ion to the sorbents.

Ultra-trace level determination of hydroquinone in waste photographic solutions by UV-vis spectrophotometry.

A simpler UV-vis spectrophotometric method was investigated for hydroquinone (HQ) determination using KMnO(4) as oxidizing agent for conversion of HQ to p-benzoquinone (BQ) as well as signal enhancer. Various parameters such as analytical wavelength, stability time, temperature, pH, solvent effect and interference of chemicals were checked and parameters optimized by using 1mugml(-1) standard solution of HQ. Beers Law was applicable in the range of 0.07-2mugml(-1) and 0.005-0.05mugml(-1) at 245.5nm and at 262nm for aqueous standard solutions of HQ with linear regression coefficient value of 0.9978 and 0.9843 and detection limit of 0.021mugml(-1) and 0.0016mugml(-1) HQ, respectively. Standard deviation of 1.7% and 2.4% was true for 1mugml(-1) and 0.03mugml(-1) HQ solution (n=11) run at respective wavelengths. The method was successfully applied to dilute waste photographic developer samples for free HQ determination.

Simultaneous determination of oxalic and citric acids in urine by high-performance liquid chromatography

A simple method for the simultaneous determination of oxalic and citric acids had been developed using reversed-phase HPLC. An aqueous solution containing potassium dihydrogen phosphate (0.25%) and tetrabutylammonium hydrogen sulphate (2.5 mmol) at pH 2.0 was used as mobile phase. Under these conditions both the components were well resolved and detected at 210 nm. The recovery for oxalic and citric acids was 97% and 102%, respectively. The method presented here was applied to urine specimens of a large number of urolithic patients and control subjects. Because of the simplicity of the method its application provides better means of monitoring the concentration of oxalic and citric acids in the formation of renal calculi.

The efficacy of nitrosonaphthol functionalized XAD-16 resin for the preconcentration/sorption of Ni(II) and Cu(II) ions

Amberlite XAD-16 resin has been functionalized using nitrosonaphthol as a ligand and characterized employing elemental, thermogravimetric analysis and FT-IR spectroscopy. The sorption of Ni(II) and Cu(II) ions onto this functionalized resin is investigated and optimized with respect to the sorptive medium (pH), shaking speed and equilibration time between liquid and solid phases. The monitoring of the influence of diverse ions on the sorption of metal ions has revealed that phosphate, bicarbonate and citrate reduce the sorption up to 10-14%. The sorption data followed Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherms. The Freundlich parameters computed are 1/n=0.56+/-0.03 and 0.49+/-0.05, A=9.54+/-1.5 and 6.0+/-0.5 mmol g(-1) for Ni(II) and Cu(II) ions, respectively. D-R isotherm yields the values of X(m)=0.87+/-0.07 and 0.35+/-0.05 mmol g(-1) and of E=9.5+/-0.23 and 12.3+/-0.6 kJ mol(-1) for Ni(II) and Cu(II) ions, respectively. Langmuir characteristic constants estimated are Q=0.082+/-0.005 and 0.063+/-0.003 mmol g(-1), b=(4.7+/-0.2)x10(4) and (7.31+/-0.11)x10(4)l mol(-1) for Ni(II) and Cu(II) ions, respectively. The variation of sorption with temperature gives thermodynamic quantities of DeltaH=-58.9+/-0.12 and -40.38+/-0.11 kJ mol(-1), DeltaS=-183+/-10 and -130+/-8 J mol(-1)K(-1) and DeltaG=-4.4+/-0.09 and -2.06+/-0.08 kJ mol(-1) at 298 K for Ni(II) and Cu(II) ions, respectively. Using kinetic equations, values of intraparticle transport and of first order rate constant have been computed for both the metal ions. The sorption procedure is utilized to preconcentrate these ions prior to their determination in tea, vegetable oil, hydrogenated oil (ghee) and palm oil by atomic absorption spectrometry using direct and standard addition methods.

A simple spectrophotometric method for the determination of trace level lead in biological samples in the presence of aqueous micellar solutions

A very simple, ultra-sensitive and fairly selective new spectrophotometric method has been developed for the rapid determination of lead(II) at ultra-trace level using 1,5-diphenylthiocarbazone (dithizone) in presence of aqueous micellar solutions. The proposed method enabled the determination of lead down to µg l−1 in human blood and urine in aqueous media without resource of any “clean-up” step. The most remarkable point of this method is that the presence of micellar system avoids the previous steps of solvent extraction and reduces the cost, toxicity while enhancing the sensitivity, selectivity and the molar absorptivity. The complex formation of lead in blood with dithizone was completed within a minute at room temperature and the absorbance remains stable for 24 h. The average molar absorption coefficient and Sandells sensitivity were found to be 3.99×105 l mol−1 cm−1 and 30 ng cm−2 of Pb, respectively. Linear calibration graphs were obtained for 0.06–60 mg l−1 of PbII; the stoichiometric composition of the chelate is 1:2 (Pb:dithizone). The interference from over 60 cations, anions and complexing agents has been studied at 1 mg l−1 of PbII. The method was successfully used in the determination of lead in several biological samples (human blood and urine and bovine liver), solution containing both lead(II) and lead(IV) and complex synthetic mixtures. The results of biological analyses by the spectrophotometric method were in excellent agreement with those obtained by AAS. The results of lead concentration in biological samples were varied with age, sex and place which have been discussed.

Horseradish Peroxidase Immobilized into Organogel-Silica Composite for Transformation of Chlorophenols to Biodegradable Organic Acids

Fenol ve türevleri tehlikeli çevresel atıklardır ve bu nedenle çevreden uzaklaştırılmaları gerekir. Klorofenollerin enzimatik oksidasyonu uygun bir seçenek olarak düşünülür ama fenolik bileşiklerin polimerizasyonu nedeniyle çökmesine yol açar ve kontamine suların güvenli bir şekilde atılması yönünde flokülasyonun ek bir adımını gerektirir. Bu çalışmada, setiltrimetilamonyum bromür ters mikroemülsiyon ile mikroemülsiyon organojel ve jelatin hazırlandı ve yaban turpu peroksidazı (HRP, E.C.1.11.1.7) için immobilizasyon matriksi olarak kullanıldı. Bu malzeme sulu çözeltilerin kararlılığını artırmak için silika ile daha fazla sertleştirilmiştir. Bu kompozit malzeme enzimatik kinetiği ve klorofenollerin oksidasyonu için çalışılmış ve sulu ortamlarda 2-klorofenol (2-CP), 2,4-diklorofenol (2,4-DCP) ve 2,4,6-triklorofenolü (2,4,6-TCP) hidrojen peroksit varlığında okside etmek için katalizör olarak kullanılmıştır. Dikkat edilmesi gereken konu fenoller, tipik polimerize ürünler yerine organik asitlere dönüştürülmüştür. Kompozit malzemelerin koruyucu etkisi fenollerin polimerizasyon tepkimelerini açıklamak için incelenmiştir. Michaelis-Menten sabiti ve serbest ve immobilize sistemdeki enzimin aktivitesi sırasıyla üç modifiye Michaelis-Menten denklemleri ve ilerleme eğrisi deneyleri ile değerlendirilmiştir. İmmobilize HRP, düşük tepkime hız sabiti (Vmax) ve Michaelis sabiti (Km) değerlerini serbest HRP ile karşılaştırmak için izlenmiştir. Ayrıca, temas süresi, pH, hidrojen peroksit derişimi, enzim dozu ve analit derişimi parametreleri ile optimize edilmiştir. Farklı optimizasyon koşulları altında, fenollerin ve türevlerinin fosfat tamponunda oksidatif uzaklaştırılması % 95-99 arasında gerçekleştirilmiştir.