Manzar Zahra - Academia.edu (original) (raw)

Papers by Manzar Zahra

Frontiers of Environmental Science & Engineering, 2019

Mesoporous silica nanoparticles (MSN), with higher water permeability than NaA zeolite, were used... more Mesoporous silica nanoparticles (MSN), with higher water permeability than NaA zeolite, were used to fabricate thin-film nanocomposite (TFN) reverse osmosis (RO) membranes. However, only aminoalkyl-modified MSN and low-pressure (less than 2.1 MPa) RO membrane were investigated. In this study, aminophenyl-modified MSN (AMSN) were synthesized and used to fabricate high-pressure (5.52 MPa) RO membranes. With the increasing of AMSN dosage, the crosslinking degree of the aromatic polyamide decreased, while the hydrophilicity of the membranes increased. The membrane morphology was maintained to show a ridge-and-valley structure, with only a slight increase in membrane surface roughness. At the optimum conditions (AMSN dosage of 0.25 g/L), when compared with the pure polyamide RO membrane, the water flux of the TFN RO membrane (55.67 L/ m 2 /h) was increased by about 21.6%, while NaCl rejection (98.97%) was slightly decreased by only 0.29%. However, the water flux of the membranes was much lower than expected. We considered that the enhancement of RO membrane permeability is attributed to the reduction of the effective thickness of the PA layer.

Catalysts

This study investigated the use of NiSe2/Ag3PO4 nanocomposite catalysts for the photocatalytic de... more This study investigated the use of NiSe2/Ag3PO4 nanocomposite catalysts for the photocatalytic degradation of RhB and BPA pollutants. Samples of pure NiSe2, Ag3PO4, and NiSe2/Ag3PO4 composites with varying NiSe2 (10%, 20%, and 30%) proportions were synthesized using hydrothermal techniques. The 20% NiSe2/Ag3PO4 composite showed the greatest photocatalytic efficiency for both RhB and BPA degradation. The study also examined the impact of various factors, such as the initial concentration of dye, catalyst amount, pH, and reaction time, on the photodegradation process. The 20% NiSe2/Ag3PO4 catalyst effectively degraded 10 ppm RhB in 20 min and 20 ppm BPA in 30 min. The physical properties of the samples were examined using SEM, PXRD, and energy-dispersive X-ray spectroscopy. The cycling runs of 20% NiSe2/Ag3PO4 also exhibited improved stability compared to Ag3PO4, with a degradation rate of 99% for RhB and BPA. The combination and synergistic effect of NiSe2 and Ag3PO4 played a vital r...

Nanomaterials and Nanotechnology

Bismuthoxide-based catalysts gained attention for photocatalytic remediation of environmental pol... more Bismuthoxide-based catalysts gained attention for photocatalytic remediation of environmental pollutants owing to their low cost, feasibility, stability, small, and tunable band gap. In the present work, bismuth molybdate was modified via transition metal doping to achieve maximum catalytic efficiency. This aim was accomplished by synthesizing novel Cu2+ and Ni2+ codoped bismuth molybdate (CuNi/Bi2MoO6, Cu/Bi2MoO6, and Ni/Bi2MoO6) which were utilized for heavy metal reduction and dyes degradation. Pure bismuth molybdate was also fabricated for comparative studies. All the prepared samples were characterized by XRD, Raman spectroscopy, SEM, and EDX. Optical studies for band gap calculations were carried out by UV-Visible spectrophotometry and decrease in band gap was observed in doped materials. Pseudo-first-order kinetic studies were performed to find the rate constants and regression values for Cr(VI) reduction and degradation of rhodamine B and malachite green using CuNi/Bi2MoO6. ...

Acta Chromatographica

A new precise, selective and reliable reversed phase high performance liquid chromatographic (RP-... more A new precise, selective and reliable reversed phase high performance liquid chromatographic (RP-HPLC) method has been developed and validated for the determination of Methyl paraben sodium (MPS) and Propyl paraben sodium (PPS) (preservatives) in Iron protein succinylate syrup. Optimized conditions were; Methanol: Water (65: 35) as mobile phase, UV/Vis detector at the wavelength of 254 nm and flow rate was set at 1.3 ml min−1. By applying the set of conditions, separation of components was carried out in less than 7 min for both the analytes. The method was validated according to International conference of Harmonization (ICH) guidelines and the analytical characteristic parameters of validation included specificity, limit of detection (LOD), limit of quantification, linearity, accuracy, precision and robustness were evaluated. The calibration curve was found to be linear in the range of 0.045 mg mL−1 to 0.075 mg mL−1 for Methyl paraben sodium and 0.015 mg mL−1 to 0.025 mg mL−1 for ...

Catalysts

This study used a supported liquid membrane system (SLM) using Celgard 2400 polypropylene as the ... more This study used a supported liquid membrane system (SLM) using Celgard 2400 polypropylene as the support, di(2-ethylhexyl) phosphoric acid (D2EHPA) as the carrier, and kerosene as the diluent. To obtain the best carrier concentration, D2EHPA concentrations between 0.04 and 0.6 M were used. The Cr (III) solutions used in the feed phase had various ionic strengths and were adjusted with NaCl at concentrations ranging from 0.25 to 1.75 M. To maintain a constant pH (4) in the feed phase, a 0.2 M acetic acid–sodium acetate buffer was utilized. Because the rate of Cr (III)-carrier complex formation at the interface of the feed solution and membrane increased up to 20 × 10−4 mol/L, it was discovered that transport of Cr (III) rose with an increase in chromium content in the feeding phase. For the optimization of the various stripping agents, HCl concentration was employed, from 0.25 M to 1.75 M. It was observed that Cr (III) transport increased with the increase in HCl concentration becaus...

Journal of Applied Chemical Science International

Sputtering is a technique used for thin film deposition on different substrates for centuries. In... more Sputtering is a technique used for thin film deposition on different substrates for centuries. In this technique, the source atoms or electrons are bombarded on the target material that sputters target metal atoms. The emitted target atoms are deposited on the substrate in the form of thin films. Several sputtering parameters control the rate at which films are deposited. These sputtering parameters include voltage applied, sputter yield, type of the gas used, type of the target material used, type of the substrate on which the thin films are to be deposited, the working pressure of the system, power, temperature of the system and substrate, angle of incidence of bombardment and distance between target and substrate. These parameters are essential to have thin films of desired thickness and properties. These properties include electrical properties, thermal properties, optical properties and chemical properties as well.

RSC Advances

In this investigation, anionic sodium dodecyl (SDS) and cationic cetyltrimethylammonium bromide (... more In this investigation, anionic sodium dodecyl (SDS) and cationic cetyltrimethylammonium bromide (CTAB) surfactants were separately applied to locally accessible wheat bran to remove chromium(vi).

The European Physical Journal Plus

TURKISH JOURNAL OF CHEMISTRY, 2021

Organic Solar Cells (OSCs) are becoming incredibly popular in photovoltaics because to their solu... more Organic Solar Cells (OSCs) are becoming incredibly popular in photovoltaics because to their solution tunability, flexibility, low temperature development, environmental friendliness and ease of integration. Despite these benefits, the energy conversion efficiency of OSCs is lowest than that of other cells based on solar energy. As a result, the emphasis will unavoidably be on boosting the efficiency of OSCs. With this concept, we created and incorporated a ZnO-PVA nanocomposite (NCs) film to see whether we could improve its efficiency. ZnO nanoparticles with several different concentrations in a PVA matrix were used to prepare the NCs films following the Solution Casting Approach. Each sample of all NCs films was analyzed using OSCs. The efficiency of OSCs differs significantly before and after application of prepared NCs coating. When applied on OSCs with structure [Carbon Fiber)/(CuO/Epoxy Resin)/( ZnO/Epoxy Resin)/Carbon Fiber], the film with an ideal Wt.% of ZnO; 14.50 percent ...

Anthropogenic Pollution Journal, Sep 1, 2021

Reactive and Functional Polymers, 2022

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

Materials Today Communications

Abstract Three distinct copper/nickel oxide doped zirconia (Cu-NiO-ZrO2) photocatalysts were synt... more Abstract Three distinct copper/nickel oxide doped zirconia (Cu-NiO-ZrO2) photocatalysts were synthesized using one pot hydrothermal method. In these synthesized photocatalysts Cu-NiO ratio were 1:1, 1:2, 2:1 while CuNiO to ZrO2 ratio was kept constant (1:4). It was observed that these prepared materials displayed strong photocatalytic properties for the reduction of 4-nitrophenol (NP) and degradation of methylene blue (MB) and methyl orange (MO) respectively. XRD pattern, BET surface area, SEM and EDX have determined the physical properties of these synthesized photocatalysts. The effect of initial dye concentration, photocatalyst dose, pH, and time on the efficiency of degradation were evaluated by selecting efficient catalyst for 4-nitrophenol (4-NP) reduction, methylene blue (MB) and methyl orange (MO) degradation respectively. It was found that the degradation efficiency of these pollutants decreased with increase in the solution’s pH and the initial concentration of dye while it enhanced by increasing the catalyst dose and irradiation reaction time during photocatalysis. Almost complete reduction of 4-NP was accomplished while using 20 mg/L of 4-NP and 0.02 g of catalyst within 5 min using 25 Mm NaBH4 solution. The reduction of 4-NP to 4-AP using Cu/NiO-ZrO2 photocatalyst follows pseudo-first order kinetics having a rate constant 0.882 min−1 with R2 value of 0.9957. In reactions of MB (50 mg/L) and MO (50 mg/L), approximately 99% degradation efficiency was achieved by using 0.03 g of catalyst dose with reaction time of 10 and 35 min, respectively.

Biological Trace Element Research

The present study deals with the assessment of essential trace and toxic elements in biological s... more The present study deals with the assessment of essential trace and toxic elements in biological samples (scalp hair) of healthy smoker and non-smoker residents of Lahore (the second most populous city), Pakistan. Human biomonitoring of various trace elements like zinc (Zn), iron (Fe), copper (Cu), chromium (Cr), cadmium (Cd), nickel (Ni), lead (Pb), and arsenic (As) was evaluated in human hair samples of smokers and non-smokers (males and females) as per IFCC criteria. For the purpose of comparison, scalp hair samples of age- and sex-equivalent healthy persons were also analyzed. The results of this study show that the concentrations (P95 values) of As (0.17, 0.81, and 0.91 μg/g), Cd (2.80, 3.81, and 3.16 μg/g), Cr (4.1, 4.2, and 5.3 μg/g), Cu (20.0, 21.0, and 21.9 μg/g), Ni (3.9, 4.6, and 4.3 μg/g), Pb (4.0, 4.8, and 5.0 μg/g), and Fe (49.0, 49.0, and 59.3 μg/g) were significantly higher in scalp hair samples of smokers than in referents, for various age groups (16–32 years, 33–50 years, and 51–62 years), respectively. The concentrations of Zn (165, 163, and 173 μg/g various age groups, respectively) in similar age group were found lower in the scalp hair samples of smokers than referents. Exposure of high toxic metal level through smoking and deficiency of Zn could be synergistic with the risk factors associated with the use of tobacco. Correlation studies for the elements in cigarette with the elements in scalp hair of male smokers show a highly positive correlation between Cr–Cd, Cr–Ni, Cu–Fe, and Ni–Zn.

Frontiers in Chemistry

Bentonite clay is an abundant and low-cost adsorbent and silk fibroin, a naturally occurring prot... more Bentonite clay is an abundant and low-cost adsorbent and silk fibroin, a naturally occurring protein, and both have a low capacity to remove lethal heavy metal ions from aqueous solution separately. To enhance their metal adsorbing capacity, a new silk fibroin-based bentonite composite was prepared for improving water quality by eliminating heavy metal ions i.e., lead, cadmium, mercury, and chromium. The as-synthesized composite shows better metal sorption capacity than either of them alone. To analyze their structural properties and characteristic functional groups, X-ray diffraction and Fourier-transform infrared spectroscopy were used. The specific surface area for silk/bentonite composite was about 4 m 2 /g that is smaller than the unmodified bentonite (23 m2/g) which indicates the impregnation of bentonite onto the silk fibroins. Scanning electron microscopy results shows the changes in morphology from plate aggregates to rosette like arrangements. The XRD results of clay/composite shows an increase in basal spacing (d 001 , from 1.55 to 3.34 nm) in comparison to pristine clay. FTIR results show the presence of organic moiety in SF clay composite. The mechanism of adsorption based on complex formation and ion exchange were proposed briefly. Various adsorption isotherms and kinetic models were applied for the removal of Pb(II), Cd(II), Hg(II), and Cr(VI). As the kinetic study was concerned, kinetic data fitted well to pseudo second order kinetics because experimental values of q e are much closer to the calculated values. The adsorption equilibrium was best studied by Langmuir isotherm whose regression coefficient values (0.985-0.995) are best when compared to Freundlich adsorption isotherm (0.954-0.990) and are indicative of homogeneity of adsorption sites on the SF/clay composite. The monolayer adsorption capacity for Cd(II), Pb(II), Hg(II), and Cr(VI) was found to be 11.35, 11.1, 10.5, and 10.2 mg/g, respectively.

Frontiers of Environmental Science & Engineering, 2019

Mesoporous silica nanoparticles (MSN), with higher water permeability than NaA zeolite, were used... more Mesoporous silica nanoparticles (MSN), with higher water permeability than NaA zeolite, were used to fabricate thin-film nanocomposite (TFN) reverse osmosis (RO) membranes. However, only aminoalkyl-modified MSN and low-pressure (less than 2.1 MPa) RO membrane were investigated. In this study, aminophenyl-modified MSN (AMSN) were synthesized and used to fabricate high-pressure (5.52 MPa) RO membranes. With the increasing of AMSN dosage, the crosslinking degree of the aromatic polyamide decreased, while the hydrophilicity of the membranes increased. The membrane morphology was maintained to show a ridge-and-valley structure, with only a slight increase in membrane surface roughness. At the optimum conditions (AMSN dosage of 0.25 g/L), when compared with the pure polyamide RO membrane, the water flux of the TFN RO membrane (55.67 L/ m 2 /h) was increased by about 21.6%, while NaCl rejection (98.97%) was slightly decreased by only 0.29%. However, the water flux of the membranes was much lower than expected. We considered that the enhancement of RO membrane permeability is attributed to the reduction of the effective thickness of the PA layer.

Catalysts

This study investigated the use of NiSe2/Ag3PO4 nanocomposite catalysts for the photocatalytic de... more This study investigated the use of NiSe2/Ag3PO4 nanocomposite catalysts for the photocatalytic degradation of RhB and BPA pollutants. Samples of pure NiSe2, Ag3PO4, and NiSe2/Ag3PO4 composites with varying NiSe2 (10%, 20%, and 30%) proportions were synthesized using hydrothermal techniques. The 20% NiSe2/Ag3PO4 composite showed the greatest photocatalytic efficiency for both RhB and BPA degradation. The study also examined the impact of various factors, such as the initial concentration of dye, catalyst amount, pH, and reaction time, on the photodegradation process. The 20% NiSe2/Ag3PO4 catalyst effectively degraded 10 ppm RhB in 20 min and 20 ppm BPA in 30 min. The physical properties of the samples were examined using SEM, PXRD, and energy-dispersive X-ray spectroscopy. The cycling runs of 20% NiSe2/Ag3PO4 also exhibited improved stability compared to Ag3PO4, with a degradation rate of 99% for RhB and BPA. The combination and synergistic effect of NiSe2 and Ag3PO4 played a vital r...

Nanomaterials and Nanotechnology

Bismuthoxide-based catalysts gained attention for photocatalytic remediation of environmental pol... more Bismuthoxide-based catalysts gained attention for photocatalytic remediation of environmental pollutants owing to their low cost, feasibility, stability, small, and tunable band gap. In the present work, bismuth molybdate was modified via transition metal doping to achieve maximum catalytic efficiency. This aim was accomplished by synthesizing novel Cu2+ and Ni2+ codoped bismuth molybdate (CuNi/Bi2MoO6, Cu/Bi2MoO6, and Ni/Bi2MoO6) which were utilized for heavy metal reduction and dyes degradation. Pure bismuth molybdate was also fabricated for comparative studies. All the prepared samples were characterized by XRD, Raman spectroscopy, SEM, and EDX. Optical studies for band gap calculations were carried out by UV-Visible spectrophotometry and decrease in band gap was observed in doped materials. Pseudo-first-order kinetic studies were performed to find the rate constants and regression values for Cr(VI) reduction and degradation of rhodamine B and malachite green using CuNi/Bi2MoO6. ...

Acta Chromatographica

A new precise, selective and reliable reversed phase high performance liquid chromatographic (RP-... more A new precise, selective and reliable reversed phase high performance liquid chromatographic (RP-HPLC) method has been developed and validated for the determination of Methyl paraben sodium (MPS) and Propyl paraben sodium (PPS) (preservatives) in Iron protein succinylate syrup. Optimized conditions were; Methanol: Water (65: 35) as mobile phase, UV/Vis detector at the wavelength of 254 nm and flow rate was set at 1.3 ml min−1. By applying the set of conditions, separation of components was carried out in less than 7 min for both the analytes. The method was validated according to International conference of Harmonization (ICH) guidelines and the analytical characteristic parameters of validation included specificity, limit of detection (LOD), limit of quantification, linearity, accuracy, precision and robustness were evaluated. The calibration curve was found to be linear in the range of 0.045 mg mL−1 to 0.075 mg mL−1 for Methyl paraben sodium and 0.015 mg mL−1 to 0.025 mg mL−1 for ...

Catalysts

This study used a supported liquid membrane system (SLM) using Celgard 2400 polypropylene as the ... more This study used a supported liquid membrane system (SLM) using Celgard 2400 polypropylene as the support, di(2-ethylhexyl) phosphoric acid (D2EHPA) as the carrier, and kerosene as the diluent. To obtain the best carrier concentration, D2EHPA concentrations between 0.04 and 0.6 M were used. The Cr (III) solutions used in the feed phase had various ionic strengths and were adjusted with NaCl at concentrations ranging from 0.25 to 1.75 M. To maintain a constant pH (4) in the feed phase, a 0.2 M acetic acid–sodium acetate buffer was utilized. Because the rate of Cr (III)-carrier complex formation at the interface of the feed solution and membrane increased up to 20 × 10−4 mol/L, it was discovered that transport of Cr (III) rose with an increase in chromium content in the feeding phase. For the optimization of the various stripping agents, HCl concentration was employed, from 0.25 M to 1.75 M. It was observed that Cr (III) transport increased with the increase in HCl concentration becaus...

Journal of Applied Chemical Science International

Sputtering is a technique used for thin film deposition on different substrates for centuries. In... more Sputtering is a technique used for thin film deposition on different substrates for centuries. In this technique, the source atoms or electrons are bombarded on the target material that sputters target metal atoms. The emitted target atoms are deposited on the substrate in the form of thin films. Several sputtering parameters control the rate at which films are deposited. These sputtering parameters include voltage applied, sputter yield, type of the gas used, type of the target material used, type of the substrate on which the thin films are to be deposited, the working pressure of the system, power, temperature of the system and substrate, angle of incidence of bombardment and distance between target and substrate. These parameters are essential to have thin films of desired thickness and properties. These properties include electrical properties, thermal properties, optical properties and chemical properties as well.

RSC Advances

In this investigation, anionic sodium dodecyl (SDS) and cationic cetyltrimethylammonium bromide (... more In this investigation, anionic sodium dodecyl (SDS) and cationic cetyltrimethylammonium bromide (CTAB) surfactants were separately applied to locally accessible wheat bran to remove chromium(vi).

The European Physical Journal Plus

TURKISH JOURNAL OF CHEMISTRY, 2021

Organic Solar Cells (OSCs) are becoming incredibly popular in photovoltaics because to their solu... more Organic Solar Cells (OSCs) are becoming incredibly popular in photovoltaics because to their solution tunability, flexibility, low temperature development, environmental friendliness and ease of integration. Despite these benefits, the energy conversion efficiency of OSCs is lowest than that of other cells based on solar energy. As a result, the emphasis will unavoidably be on boosting the efficiency of OSCs. With this concept, we created and incorporated a ZnO-PVA nanocomposite (NCs) film to see whether we could improve its efficiency. ZnO nanoparticles with several different concentrations in a PVA matrix were used to prepare the NCs films following the Solution Casting Approach. Each sample of all NCs films was analyzed using OSCs. The efficiency of OSCs differs significantly before and after application of prepared NCs coating. When applied on OSCs with structure [Carbon Fiber)/(CuO/Epoxy Resin)/( ZnO/Epoxy Resin)/Carbon Fiber], the film with an ideal Wt.% of ZnO; 14.50 percent ...

Anthropogenic Pollution Journal, Sep 1, 2021

Reactive and Functional Polymers, 2022

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

Materials Today Communications

Abstract Three distinct copper/nickel oxide doped zirconia (Cu-NiO-ZrO2) photocatalysts were synt... more Abstract Three distinct copper/nickel oxide doped zirconia (Cu-NiO-ZrO2) photocatalysts were synthesized using one pot hydrothermal method. In these synthesized photocatalysts Cu-NiO ratio were 1:1, 1:2, 2:1 while CuNiO to ZrO2 ratio was kept constant (1:4). It was observed that these prepared materials displayed strong photocatalytic properties for the reduction of 4-nitrophenol (NP) and degradation of methylene blue (MB) and methyl orange (MO) respectively. XRD pattern, BET surface area, SEM and EDX have determined the physical properties of these synthesized photocatalysts. The effect of initial dye concentration, photocatalyst dose, pH, and time on the efficiency of degradation were evaluated by selecting efficient catalyst for 4-nitrophenol (4-NP) reduction, methylene blue (MB) and methyl orange (MO) degradation respectively. It was found that the degradation efficiency of these pollutants decreased with increase in the solution’s pH and the initial concentration of dye while it enhanced by increasing the catalyst dose and irradiation reaction time during photocatalysis. Almost complete reduction of 4-NP was accomplished while using 20 mg/L of 4-NP and 0.02 g of catalyst within 5 min using 25 Mm NaBH4 solution. The reduction of 4-NP to 4-AP using Cu/NiO-ZrO2 photocatalyst follows pseudo-first order kinetics having a rate constant 0.882 min−1 with R2 value of 0.9957. In reactions of MB (50 mg/L) and MO (50 mg/L), approximately 99% degradation efficiency was achieved by using 0.03 g of catalyst dose with reaction time of 10 and 35 min, respectively.

Biological Trace Element Research

The present study deals with the assessment of essential trace and toxic elements in biological s... more The present study deals with the assessment of essential trace and toxic elements in biological samples (scalp hair) of healthy smoker and non-smoker residents of Lahore (the second most populous city), Pakistan. Human biomonitoring of various trace elements like zinc (Zn), iron (Fe), copper (Cu), chromium (Cr), cadmium (Cd), nickel (Ni), lead (Pb), and arsenic (As) was evaluated in human hair samples of smokers and non-smokers (males and females) as per IFCC criteria. For the purpose of comparison, scalp hair samples of age- and sex-equivalent healthy persons were also analyzed. The results of this study show that the concentrations (P95 values) of As (0.17, 0.81, and 0.91 μg/g), Cd (2.80, 3.81, and 3.16 μg/g), Cr (4.1, 4.2, and 5.3 μg/g), Cu (20.0, 21.0, and 21.9 μg/g), Ni (3.9, 4.6, and 4.3 μg/g), Pb (4.0, 4.8, and 5.0 μg/g), and Fe (49.0, 49.0, and 59.3 μg/g) were significantly higher in scalp hair samples of smokers than in referents, for various age groups (16–32 years, 33–50 years, and 51–62 years), respectively. The concentrations of Zn (165, 163, and 173 μg/g various age groups, respectively) in similar age group were found lower in the scalp hair samples of smokers than referents. Exposure of high toxic metal level through smoking and deficiency of Zn could be synergistic with the risk factors associated with the use of tobacco. Correlation studies for the elements in cigarette with the elements in scalp hair of male smokers show a highly positive correlation between Cr–Cd, Cr–Ni, Cu–Fe, and Ni–Zn.

Frontiers in Chemistry

Bentonite clay is an abundant and low-cost adsorbent and silk fibroin, a naturally occurring prot... more Bentonite clay is an abundant and low-cost adsorbent and silk fibroin, a naturally occurring protein, and both have a low capacity to remove lethal heavy metal ions from aqueous solution separately. To enhance their metal adsorbing capacity, a new silk fibroin-based bentonite composite was prepared for improving water quality by eliminating heavy metal ions i.e., lead, cadmium, mercury, and chromium. The as-synthesized composite shows better metal sorption capacity than either of them alone. To analyze their structural properties and characteristic functional groups, X-ray diffraction and Fourier-transform infrared spectroscopy were used. The specific surface area for silk/bentonite composite was about 4 m 2 /g that is smaller than the unmodified bentonite (23 m2/g) which indicates the impregnation of bentonite onto the silk fibroins. Scanning electron microscopy results shows the changes in morphology from plate aggregates to rosette like arrangements. The XRD results of clay/composite shows an increase in basal spacing (d 001 , from 1.55 to 3.34 nm) in comparison to pristine clay. FTIR results show the presence of organic moiety in SF clay composite. The mechanism of adsorption based on complex formation and ion exchange were proposed briefly. Various adsorption isotherms and kinetic models were applied for the removal of Pb(II), Cd(II), Hg(II), and Cr(VI). As the kinetic study was concerned, kinetic data fitted well to pseudo second order kinetics because experimental values of q e are much closer to the calculated values. The adsorption equilibrium was best studied by Langmuir isotherm whose regression coefficient values (0.985-0.995) are best when compared to Freundlich adsorption isotherm (0.954-0.990) and are indicative of homogeneity of adsorption sites on the SF/clay composite. The monolayer adsorption capacity for Cd(II), Pb(II), Hg(II), and Cr(VI) was found to be 11.35, 11.1, 10.5, and 10.2 mg/g, respectively.