Umer Shafique

Removal of Pb(II) and Cd(II) from water by adsorption on peels of banana.

The adsorption of lead(II) and cadmium(II) on peels of banana has been studied in batch mode using flame atomic absorption spectroscopy for metal estimation. Concerned parameters like adsorbent dose, pH, contact time and agitation speed were investigated. Langmuir, Freundlich and Temkin isotherms were employed to describe adsorption equilibrium. The maximum amounts of cadmium(II) and lead(II) adsorbed (qm), as evaluated by Langmuir isotherm, were 5.71 mg and 2.18 mg per gram of powder of banana peels, respectively. Study concluded that banana peels, a waste material, have good potential as an adsorbent to remove toxic metals like lead and cadmium from water.

Removal of chromium (III) by using coal as adsorbent.

The adsorption of Cr(III) by two different coal varieties from Lakhra and Thar coalfields (Pakistan) have been studied in batch mode. The effect of adsorbent dose, pH, contact time and agitation speed on the adsorption of Cr(III) by both the coals were investigated. Adsorption equilibrium was achieved in 40-50 min. The Langmuir, Freundlich and Temkin adsorption isotherms were used to elucidate the observed sorption phenomena. The maximum Cr(III) removal was 2.61 mg of Cr(III) per gram of LC (Lakhra coal) and 2.55 mg of Cr(III) per gram of TC (Thar coal) as evaluated from Langmuir isotherm. The heat of sorption was in the range 3.75-3.87 kJ/mol as evaluated from Temkin isotherm. Best results were obtained at pH>5. It is proposed that low rank coals of Pakistan can be used for removal of toxic metals like Cr(III) from industrial effluents/waste waters.

Micro-determination of arsenic in aqueous samples by image scanning and computational quantification

Arsenic is highly toxic in all of its forms found in natural groundwater. An improved method for the estimation of inorganic arsenic at low levels (μg L−1) in water has been proposed. The method involves the generation of arsine in a specially designed cell by borohydride reduction of arsenite (AsO21−). The resulting arsine is passed through a filter paper pre-dipped in mercuric bromide solution giving a yellowish brown complex. The color intensity of the spots is calculated by scanning the spotted paper and analyzing the image using specially designed software. The method was found to be effective at trace levels having a linear response at the concentration range 2–20μg L−1 (8–80ng). The detection limit of the proposed method is 1 μg L−1 (4 ng) which can be reduced further by making some modifications to the apparatus. The method was successfully applied to the analysis of synthetic samples and field samples of water.

Removal of Chromium on Polyalthia longifolia Leaves Biomass

Adsorption is an environmental friendly process for removal and/or recovery of heavy metals from wastewater. In recent years, it has been substantiated as a popular technique to treat industrial waste effluents, with significant advantages. In this work, batchwise removal of chromium (III) ions from water by Polyalthia longifolia leaves was studied as a function of adsorbent dose, pH, contact time, and agitation speed. Surface characteristics of the leaves were evaluated by recording IR spectra. The Langmuir, Freundlich, and Temkin adsorption isotherms were employed to explain the sorption process. It was found that one gram of leaves can remove 1.87 mg of trivalent chromium when working at pH 3.0. It has been concluded that Polyalthia longifolia leaves can be used as cost-effective and benign adsorbents for removal of Cr(III) ions from wastewater.

Determination of trace metals by voltamperometry in zebra mussel (Dreissena polymorpha) employed as environmental bio-indicator

Abstract In the present work, metals (cadmium, lead, copper, nickel, tin, selenium, and mercury) have been estimated in the Ebro River (Spain) using the zebra mussel (Dreissena polymorpha) as an environmental bio-indicator. In two sequential studies, in 2006 and 2008, concentrations of metals were calculated in water as well as in the shells and fleshes of the zebra mussels. Samples were collected from assorted locations of the river. Metals were determined successfully at trace levels through voltamperometry, a sensitive technique. It has been noted that analysis of bioaccumulators like zebra mussels can be helpful in evaluating metal pollution in water.

A Rapid, Economical, and Eco-Friendly Method to Recycle Terephthalic Acid from Waste Poly (Ethylene Terphthalate) Bottles

A method has been proposed to rapidly degrade waste PET (polyethylene terphthalate) bottles and recover terephthalic acid (TPA) in good yield. The method involves fusion of PET bottle chips with caustic soda in a china-clay crucible placed on the silicon carbide (SiC) slab by exposure to microwaves in a domestic oven. The PET waste was converted to water-soluble sodium salt of TPA in just 4 minutes. Afterwards, the solution was acidified with HCl to recover TPA in high yield. The method can be used to design environmentally benign and fast industrial prototypes to recycle terephthalic acid from waste PET bottles.

Removal of chromium from water using pea waste – a green approach

Abstract Agro-waste materials have carboxylic and phenolic groups that play the main role in metal adsorption. The advantages of these materials include easy availability, low cost, and reasonable metal removal capacity. One of the materials (usually considered as waste) is pea waste (pods). Present work comprises adsorption of chromium from aqueous solution using powder of pods of garden peas (Pisum sativum) in batch. Important parameters like adsorbent dose, pH, contact time, and agitation speed were studied. Adsorption equilibrium was explained by Langmuir, Freundlich, and Temkin isotherms. Maximum chromium uptake (q m) was 3.56 mg/g of adsorbent. Heat of adsorption, as evaluated by Temkin isotherm was 1.96 kJ/mol. It is proposed that pea pods can be an effective and environmentally benign (green) adsorbents for removal of chromium from industrial effluents and waste waters.

Analysis of Roman-Hispanic Archaeological Ceramics using Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a useful tool for characterization of archaeological samples because it involves little or no sample preparation, and it allows on-site rapid and nondestructive analysis. In this study, ceramics from the archaeological site of Labitolosa (Huesca) were analyzed qualitatively and quantitatively. Furthermore, a protocol is described for the determination of iron in archaeological materials by interpolating calibration graphs and standard addition. Moreover, the potential of LIBS for direct quantitative analysis of iron in real archaeological materials was evaluated, and optimum analytical conditions were determined. The reproducibility of LIBS spectra from different archaeological samples was investigated as a function of the number of laser shots. The results were compared with those of a reference material.

Novel methods to determine sulfide in aqueous samples by quantification of lead sulfide spots

Two new, simple, accurate, and economical methods to find out sulfide (S2−) at low levels (10−9 g) in aqueous samples have been proposed. The first method involved the generation of hydrogen sulfide (H2S) in a specially designed small cell by interacting sulfide solution with hydrochloric acid. The resulting H2S is passed through a filter paper pre-dipped in lead acetate solution that made dark brown lead sulfide spots on the paper. In the second method, micro-liter drops of sulfide solution are applied on silica gel TLC pre-moistened with the lead acetate solution that developed lead sulfide spots. The color densities of the spots were calculated by scanning the spotted paper and TLC and analyzing the image using a specially developed software. The TLC method was more effective at trace levels having a linear response in the range 5–100 ng in comparison to 100–900 ng of the H2S method. Statistical examination of the calibration line validated the pertinence of these methods for the analysis of reduced form of sulfur in aqueous samples, particularly when dealing with small sample volumes.

Removal of sulfide ions from water using rice husk

Sulfide is an unwanted anion present in tannery effluents. In this study, a raw material namely rice husk has been used to check its performance to remove sulfide ions from water in batch adsorption experiments. The effects of various physical parameters such as contact time, pH, shaking speed and temperature have been investigated to optimize the conditions for maximum adsorption efficiency. Rice husk was further pretreated with calcium chloride, zinc chloride and organic solvents to check any change in uptake capacity of the adsorbent. Langmuir, Freundlich and Temkin isotherms were used to explain the nature and mechanism of adsorption. The results argue that rice husk could be a useful material to treat sulfide-containing wastewaters. GRAPHICAL ABSTRACT