Makshoof Athar

Biosorption of heavy metal ions using wheat based biosorbents – A review of the recent literature

Conventional technologies for the removal/remediation of toxic metal ions from wastewaters are proving expensive due to non-regenerable materials used and high costs. Biosorption is emerging as a technique offering the use of economical alternate biological materials for the purpose. Functional groups like carboxyl, hydroxyl, sulphydryl and amido present in these biomaterials, make it possible for them to attach metal ions from waters. Every year, large amounts of straw and bran from Triticum aestivum (wheat), a major food crop of the world, are produced as by-products/waste materials. The purpose of this article is to review rather scattered information on the utilization of straw and bran for the removal/minimization of metal ions from waters. High efficiency, high biosorption capacity, cost-effectiveness and renewability are the important parameters making these materials as economical alternatives for metal removal and waste remediation. Applications of available adsorption and kinetic models as well as influences of change in temperature and pH of medium on metal biosorption by wheat straw and wheat bran are reviewed. The biosorption mechanism has been found to be quite complex. It comprises a number of phenomena including adsorption, surface precipitation, ion-exchange and complexation.

Antifungal compounds from Melia azedarach leaves for management of Ascochyta rabiei, the cause of chickpea blight

The antifungal activity of Melia azedarach L. leaves was investigated against Ascochyta rabiei (Pass.) Lab., the cause of destructive blight disease of chickpea (Cicer arietinum L.). Bioassay guided fractionation revealed that the chloroform fraction of the methanolic extract of M. azedarach leaves was highly effective against A. rabiei. Six compounds, namely β-sitosterol (1), β-amyrin (2), ursolic acid (3), benzoic acid (4), 3,5 dimethoxybenzoic acid (5) and maesol (6) were isolated from the chloroform fraction through column chromatography. The in vitro antifungal activity of compounds 2–5 was evaluated against A. rabiei. A commercial fungicide, mancozeb, was used as a positive control. Different concentrations of mancozeb and the isolated compounds, ranging from 0.0039 to 4 mg mL−1, were used in the antifungal bioassay, and data regarding minimum inhibitory concentration (MIC) was recorded 24, 48 and 72 h after incubation. All concentrations of mancozeb inhibited the fungal spore germination at all three incubation periods. The tested compounds exhibited variable antifungal activity against the target fungal pathogens. All compounds showed their highest antifungal activity after 24 h of incubation. Compound 2 was found to be the most effective, with an MIC of 0.0156 mg mL−1, followed by compounds 3, 4 and 5, with MIC values of 0.0312, 0.25 and 0.125 mg mL−1, respectively.

Biosorption of heavy metals from aqueous solutions using indigenous and modified lignocellulosic materials

Abstract This critical review emphasizes on the potential applications of low-cost lignocellulosic material in the field of heavy metal pollution remediation. It contains the information related to binding mechanism, relative uptake capacities, effect of modification on increment in uptake capacities, equilibrium, kinetic and thermodynamic modeling involved. This effort offers a good understanding about the role of functional groups in biosorption process. However, there exists a large barrier which inhibits the industry to switch on the biosorption process in place of conventional technologies. Future investigations on (1) assessment of low-cost lignocellulosic materials on multi-metal samples and real world samples, (2) low-cost methods of modification, (3) development of multifunctional lignocellulosic materials can help to decrease this barrier.

Simultaneous removal of Pb(II), Cd(II) and Cu(II) from aqueous solutions by adsorption on Triticum aestivum - a green approach

The presence of heavy metals in industrial effluents as a single component is generally very rare. The present study provides information about adsorption behaviour of lead, cadmium and copper in single and multi-component system using triticum aestivum (wheat straw) as adsorbent. It has been shown that adsorption of a certain metal ion is greatly affected by the presence of other metal ions. Effects of process parameters (adsorbent dose, contact time, pH, agitation speed etc.) have been studied. pH 4-6 have been found suitable for metal removal. Adsorption mechanism has been evaluated using five adsorption isotherm models (Langmuir, Freundlich, Temkin, Harkin- Jura and Halsey Isotherms). Removal of cadmium in multi-component system is greater as compared in single component system indicating the metal competition for adsorption sites. Kinetic and thermodynamic parameters have also been calculated and obtained results were found closely related to the reported literature. Positive values of ?H° for lead, cadmium and copper shows feasibility of the process and the spontaneous nature of adsorption.

Thermodynamics of Biosorption for Removal of Co(II) Ions by an Efficient and Ecofriendly Biosorbent (Saccharum bengalense): Kinetics and Isotherm Modeling

In this research work, a low-cost biomass derived from the pulp of Saccharum bengalense (SB) was used as an adsorbent material/biosorbent for the removal of Co(II) ions from aqueous solution. Langmuir, Freundlich Timken, and Dubinin-Radushkevich (D-R) adsorption isotherms have been applied to further define the mechanism of sorption. From the comparison of different adsorption isotherm models, it was found that biosorption of Co(II) by SB followed Langmuir and Freundlich models. The sorption capacity for cobalt of Saccharum bengalense was ( mg/g) at 323K. A comparison of kinetic models applied to the adsorption of Co(II) onto Saccharum bengalense was evaluated for the pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion and Banghams kinetics models. It was found that the pseudo-second-order mechanism is predominant. Activation parameters evaluated from thermodynamics and kinetic parameters such as free energy change ,  kJ/mol), enthalpy change ,  kJ/mol), and entropy change ,  kJ/mol) revealed the spontaneous, endothermic, and feasible nature of adsorption process. The results of the present investigation suggested that Saccharum bengalense (SB) can be used as an environmentally and economically feasible biosorbent for the removal of Co(II) from aqueous solutions.

Insight to rapid removal of Pb(II), Cd(II), and Cu(II) from aqueous solution using an agro-based adsorbent Sorghum bicolor L. biomass

ABSTRACT The present study proposed the adsorption characteristics of Pb(II), Cd(II), and Cu(II) on to Sorghum bicolor L. (commonly, Charee in Pakistan) biomass from aqueous solutions. The influence of different process parameters, such as the adsorbent dose, solution pH, contact time, agitation speed, and initial metal ion concentration, were studied thoroughly to evaluate optimum conditions for adsorption. Maximum adsorption for all metal ions has taken place at pH 5.0–6.0. Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherm models in a nonlinear fashion were used to explain the phenomenon. Maximum adsorption capacity of Sorghum bicolor L. biomass was 6.289 mg/g, 7.87 mg/g, and 4.34 mg/g for Pb(II), Cd(II), and Cu(II), respectively. Adsorption mechanism was explored by pseudo-first-order and pseudo-second-order kinetic models and it was found that the process followed pseudo-second-order kinetics. Thermodynamic study indicated the process favorability. The study concluded that the Sorghum Bi...

Impact of transport and industrial emissions on the ambient air quality of Lahore City, Pakistan

Lahore’s population is growing at a rate of 4% a year. It is widely perceived that because of this rapid growth, the level of services provided to the city’s 7 million inhabitants has substantially deteriorated. This study presents the finding of ambient air quality monitoring carried out in Lahore City, Pakistan. The ambient air quality was monitored for criteria pollutants carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3), particulate matter (TSP and PM10), lead (Pb), and noise level at ten different locations of the city. The sampling locations were selected in a way to draw a representative profile of air quality, covering both newly developed as well as highly congested urban centers. The sulfur dioxide, lead, and suspended particulate concentration was found very high as compared to the ambient air quality standards of US Environmental Protection Agency and WHO guidelines. The 24-h average noise was exceeding the WHO limits at majority of the locations. The study presents the severity of air pollution in Lahore City, and findings would help city management to develop monitoring and mitigation measures to improve the air quality of the city.

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.

Source, concentration, and distribution of elemental mercury in the atmosphere in Toronto, Canada.

Atmospheric gaseous elemental mercury [GEM] at 1.8, 4, and 59 m above ground, in parking lots, and in indoor and outdoor air was measured in Toronto City, Canada from May 2008-July 2009. The average GEM value at 1.8 m was 1.89 ± 0.62 ng m(-3). The GEM values increased with elevation. The average GEM in underground parking lots ranged from 1.37 to 7.86 ng m(-3) and was higher than those observed from the surface parking lots. The GEM in the indoor air ranged from 1.21 to 28.50 ng m(-3), was higher in the laboratories than in the offices, and was much higher than that in the outdoor air. All these indicate that buildings serve as sources of mercury to the urban atmosphere. More studies are needed to estimate the contribution of urban areas to the atmospheric mercury budget and the impact of indoor air on outdoor air quality and human health.

Insight into the binding of copper(II) by non-toxic biodegradable material (Oryza sativa): effect of modification and interfering ions

The present studies are focused on the use of non-toxic biodegradable straw from Oryza sativa in its simple and modified forms for the binding of copper(II) ions. A relatively new “green” method was adopted for modification with urea under microwaves. The studies have been performed by using the aqueous solution of Cu(II) ions with and without the presence of Cd(II) and Pb(II) as interfering ions. FTIR analysis showed the presence of oxygen- and nitrogen-containing functional groups in simple and modified materials. The emergence of new bands and shifts in the peaks confirmed the modification. The kinetics of the process was studied using the commonly employed mathematical models. Although Elovich model seemed to fit yet coefficient of determination did not reinforce it. Pseudo-second-order model was found to explain the kinetics of the binding of metal ions by simple and modified straw. The equilibrium was studied using the non-linear approach. Based on root mean square error values, it was found that Langmuir model was the most suitable model, followed by Temkin model. Surface areas were compared for single and multi-metal systems. The effect of pH was also studied. Under the studied set of conditions, the modification of straw caused a decrease in the equilibrium time of contact and increase in the biosorption capacities. The presence of other ions decreased the capacities drastically due the competition to bind with the materials.