Rabia Rehman

ISOTHERMAL AND THERMODYNAMICAL MODELING OF CHROMIUM (III) ADSORPTION BY COMPOSITES OF POLYANILINE WITH RICE HUSK AND SAW DUST

The adsorption of Cr (III) from water by polyaniline composites with rice husk and saw dust of Eucalyptus camaldulensis has been investigated in this study. The surface of adsorbents was characterized by FT-IR. Effect of various operational conditions like agitation time, initial pH, adsorbent dose, particle size of composites and temperature were studied in batch mode. The suitability of the data was confirmed by Langmuir and Freundlich isotherms. Thermodynamic studies showed that adsorption of Cr (III) on these composites occur spontaneously. Rice husk and saw dust modified the morphology of polyaniline by preventing its aggregation and improving its adsorption capacity.

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.

Sorptive removal of lead (II) from water using chemically modified mulch of Madhuca longifolia and Polyalthia longifolia as novel biosorbents

Abstract In this study, dried leaves (mulch) of Madhuca longifolia and Polyalthia longifolia have been used for removing Pb(II) from aqueous media. Their biosorption capacities were enhanced by chemical treatment using dipping methodology. It is found that formalin modified M. longifolia leaves and acetone modified P. longifolia leaves have greater biosorption capacity as compared to non-modified leaves. After optimizing operational parameters, Langmuir, Freundlich, and Temkin isotherms were applied to equilibrium data for determining maximum biosorption capacities, heat of biosorption, and biosorption intensities. The maximum biosorption capacity “q m” values were 17.18, 25.77, 14.11, 4.50, 8.99, and 6.99 mg/g using simple M. longifolia leaves, base modified M. longifolia leaves, formalin modified M. longifolia leaves, simple P. longifolia leaves, base modified P. longifolia leaves, and acetone modified P. longifolia leaves correspondingly. Thermodynamic revealed that biosorption using these biosorbents ...

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.

Brilliant Green Dye Elimination from Water Using Psidium guajava Leaves and Solanum tuberosum Peels as Adsorbents in Environmentally Benign Way

The aim of this study is to check the feasibility of Psidium guajava (Guava) leaves and peels of Solanum tuberosum (Potato) as biosorbents in removal of Brilliant Green (BG) in batch mode. Surface analysis of biosorbents was done by FT-IR and quantitatively analyzed by Boehm titration. The removal of dye was confirmed by UV-VIS spectroscopy. Isothermal modeling was studied by using Langmuir, Freundlich, and Temkin isotherms. Various isothermal parameters for adsorption of Brilliant Green such as  mg/g, 1.173 mg/g , and −2.397 KJ/mol were noted for Solanum tuberosum peels (PP) and Psidium guajava leaves (GL), respectively. Similarly pH, moisture content, and various metals were quantitatively analyzed. Results showed that leaves of Psidium guajava were more effective for removal of Brilliant Green.

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.

Adsorptive removal of a textile cationic dye from water using tartaric acid modified Bassia longifolia dried leaf mulch

Adsorption of pollutants on chemically modified agro-waste materials is a suitable alternative of costly methodologies of wastewater treatment. In this work, the dried leaves of Bassia longifolia had been used for removing methylene blue (M.B) dye from textile effluent after chemically modifying them with tartaric acid. All the operational parameters of adsorption were optimised and employed for isothermal modeling of equilibrium data for determining the mechanism of dye removal from water. Correlation coefficient values of Langmuir and Freundlich isothermal linear relationships indicated that both chemisorption and physiosorption are involved in removing this cationic dye from water. Maximum adsorption capacity of tartaric acid modified Bassia longifolia leaves is 30.74 mg/g of the adsorbent. Spontaneity of this process is clear from negative values of ∆ G o and separation factor values, which are less than unity. These results suggested that tartaric acid modified Bassia longifolia leaves can be employed for wastewater treatment efficiently in an economical and benign way.

N-[4-(Phenyl­imino­meth­yl)phen­yl]acetamide 0.67-hydrate

The title compound, C15H14N2O·0.67H2O, was prepared by the reaction of 4-acetoaminebenzaldehyde and aniline. The asymmetric unit contains six organic molecules and four water molecules. The dihedral angles between the aromatic ring planes in each organic molecule vary from 42.4 (2) to 53.8 (2)°. In the crystal, an extensive network of intermolecular N—H⋯O, O—H⋯N and O—H⋯O hydrogen bonds link the molecules into [010] chains.