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In this study, a biodegradable natural polymer chitosan was modified with salicylaldehyde to prepare salicylaldehyde functionalized chitosan nanoparticles (N-Ch-Sal). The N-Ch-Sal was characterized by atomic force microscopy (AFM), scanning electron microscopy-energy-dispersive X-ray (SEM-EDX), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). The salicylaldehyde functionalized chitosan nanoparticles (N-Ch-Sal) (~80 nm) were then used for the adsorption of three heavy metals viz., Cu(II), Cd(II) and Pb(II) ions. The above-mentioned techniques were also employed for evaluation of changes in N-Ch-Sal after metal adsorption. The parameters affecting the adsorption of metal ions including pH, contact time, amount of adsorbent, initial metal ion concentration and the effect of interfering ions, were studied thoroughly and optimized. The concentration of metal ions remaining in the aqueous system after adsorption experiments was analyzed by ICP-MS. At optimal conditions, sorption capacity of Pb(II) ion was found to be highest i.e., 123.67 followed by Cu(II) (84.60) and Cd(II) (63.71 mg/g). The adsorption process followed the pseudo-second-order kinetic model and fitted well with the Langmuir adsorption isotherm. The adsorption method was applied to a real tap water sample for the quantification and removal of Pb(II) ions. The concentration of Pb(II) ions in the tested sample was 4.88 ppb.

In this study, we prepare synthetic arsenic-imprinted polymer (As-IP) by simple precipitation polymerization method by using 4-vinyl pyridine and 2-hydroxyethyl methacrylate as ligand and functional monomer use for the selective elimination of arsenic (As3+) from the aqueous environment. To achieve maximum sorption capacity several factors, i.e., pH, agitation time, shaking speed and sorbent dose were optimized. This prepared polymer was characterized by using SEM, EDX and FT-IR. Adsorption isotherm and kinetic data of As3+ follow the Langmuir isotherm and pseudo-second-order kinetic model. The maximum sorption capacity of As-IP is 106.3 mg/g. The limit of detection and limit of quantification were found to be 0.87 and 2.9 µg/L, respectivley. The relative selectivity factors of As-IP as compared to NIP for As3+/Cr3+, As3+/Al3+, As3+/Ni2+, As3+/Cu2+, As3+/NO3−, As3+/PO43− and As3+/SO42− were 1.445, 1.779, 1.469, 1.168, 1.481, 1.802 and 2.367, respectively. The adsorption efficiency of As3+ ions by using As-IP from real water samples was approximately 99% which shows that As-IP has good sorption capability and highly selective for the extraction of arsenic ions. Graphical representation of As-IP

In the present study, enactments and separation characteristics of five extensively utilized adsorbents for enhancement and purification of Grewia asiatica Anthocyanins (ACNs) extracts were analysed. Among five tested resins (AB-8, Sepabeads Sp-700, C18SPE Cartridge, Sepabeads Sp-207 and AB-80), AB-8 resin exhibited the best adsorbent ability for Grewia asiatica ACNs (84.24mg/mL resin). Results of static adsorption tests revealed that AB-8 resin selected for kinetics and isotherm experiments followed a pseudo 2nd order model along with Langmuir isotherm. In order to improve operational procedure, dynamic adsorption and desorption tests were done on a packed column of AB-8 resin. Optimum factors for subsequent adsorption-desorption experiments; processing volume 20ml, flow rate 2 mL/min with elution solvent of acidified methanol (1%v/v) were used. HPLC and LC-MS/MS profiles of the purified extract confirmed seven ACNs in Grewia asiatica samples, out of which cyanidin-3-O-(6"acetylglucoside) comprises 44-63% (695 μg/g) of total ACNs composition. Moreover, pigment purification using AB-8 resin did not alter ACNs mixture composition after purification but enhance the peak intensity and gives effective purification. Hence present work reveals that the separation procedure established through column chromatography providing an effective methodology to enhance the purification of ACNs from Grewia asiatica.

In the present study, As3+ imprinted polymer as an active detoxification material has been synthesized through microwave assisted preparation method. By inducing the microwave radiation during the polymerization process decreases the reaction time to about 10 folds than conventional method. The imprinted polymer is one of the best possible techniques for the removal of arsenic, and various other contaminants from drinking water. The SEM and FTIR analyses have been conducted to clarify microstructure, surface morphology and size distribution of the synthesized imprinted polymer. The main parameters affecting the pzc, pH, agitation time, shaking speed, concentration, the temperature of adsorbent and percent of sorption, have been examined and optimized by Taguchi design. Taguchi L9 orthogonal array was employed to optimize the important factors versus % sorption values with nine experimental runs at 3 levels. Moreover, to understand the reaction phenomenon Langmuir and Freundlich isotherms, kinetic models and thermodynamics of adsorption process were calculated. The relative selectivity coefficient of imprinted polymer for As3+/Cd2, As3+/Zn2+, As3+/Ni2+were respectively 45.93, 131.01, 262.63 times greater than for non-imprinted polymer. The limit of detections (LOD) and limit of quantification (LOQ) of the proposed procedure for As3+ ion was found to be 1.0 µg/L and 3.3 µg/L for the As3+ ion respectively, with the relative standard deviation (RSD) of 4%. The excellent adsorption performance along with their low cost and convenient synthesis makes this range of adsorbent highly promising for commercial applications in drinking water purification and water treatment.

The present study describes a simple and facile precipitation polymerization technique. For the synthesis of Cd2+ion-imprinted polymer for the selective detoxification of toxic Cd2+ ions from the aqueous samples. The resultant Cd2+-imprinted polymer was characterized by the EDX, SEM, and FTIR. Different parameters were optimized during the adsorption study to achieve the maximum adsorption capability i.e. pH, equilibrium time, temperature shaking speed, and adsorbent dose. The maximum adsorption capacity of Cd2+ion-imprinted polymer was 62.9 mg. g−1 at pH 6. The kinetic study was best defined by pseudo-second-order, while the Langmuir isotherm model well fitted to present data. Good linearity was achieved in (10–100 μg. L−1) concentration range with LOD 0.88 μg. L−1 and LOQ 2.95 μg. L−1. The relative selective factor (K’) of Cd2+-ion and interfering ions was greater than 1 due to the imprinting effect. The developed method was validated by the spiking addition method and obtained good results in accordance with spiking values in real samples. The synthesized ion-imprinted polymer shown higher adsorption capacity than previously reported methods for the selective removal of Cd2+-ions from aqueous samples.

Human body is greatly exposed to aluminum due to its high abundance in the environment. This nonessential metal is a threat to the patients of chronic renal disorders, as it is easily retained in their plasma and quickly accumulates in different tissues. Thus, there is great need to remove it from the aqueous environment. In this study, Al3+ imprinted semiinterpenetrating polymer network (semi-IPN)-based cryogel composite was prepared and applied for the purification of environmental and drinking water samples from aluminum. Poly (2-hydroxyethyl methacrylate) (pHEMA) discs were produced via cryogenic treatment and imprinted semi-IPN was introduced to the 3-(trimethoxysilyl) propyl acrylate-modified macroporous cryogel discs. The adsorption properties and selectivity of the aluminum (III) imprinted semi-IPN cryogel composite were studied in detail. The imprinted semi-IPN cryogel composite showed good selectivity towards aluminum (III) ions with the imprinting factor (IF) of 76.4 in the presence of competing copper (II), nickle (II), and iron (III) ions. The maximum adsorption capacity of 271 mu mol g(-1) was obtained for aluminum (III) at pH 7.0 within 10 min using imprinted semi-IPN cryogel composite. The good selectivity and reusability of aluminum (III)-imprinted semi-IPN cryogel composite makes this material an eligible candidate for the purification of drinking water from aluminum (III) leaving important minerals remained in the water.

Egusi seed shells (ESS) were used as precursor for the preparation of two activated carbons (ACs) following H3PO4 and ZnCl2 activation. The effect of factors controlling the preparation of ACs such as chemical activating agent concentration (2 - 10 M), activation temperature (400°C - 700°C) and residence time (30 - 120 min) were optimized using the Box-Behnken Design (BBD). The optimized activated carbons based H3PO4 (ACP) and ZnCl2 (ACZ) were characterized by N2 adsorption, elemental analysis, atomic force microscopy (AFM), Boehm titration and Fourier transformed infrared (FTIR) techniques. The specific surface area was found to be 1053.91 and 1009.89 m2·g-1 for ACP and ACZ respectively. The adsorbents had similar surface functionalities and were both microporous. The effect of various parameters such as initial pH, concentration, and contact time on the adsorption of nitrate ions on ACP and ACZ in aqueous solution was studied. ACZ demonstrated better adsorption capacity (8.26 mg·g-1) compared to ACP (5.65 mg·g-1) at the same equilibrium time of 20 min. The adsorption process was governed by a “physical interactions” phenomenon for both adsorbents.

In present work chitosan functionalized magnetic nanoparticles (CMNPs) were successfully prepared and investigated for the removal of Reactive Orange 107 dye (RO 107) from water. The chitosan was extracted from shrimp shells (Penaeus merguiensis) and was characterized by solubility test and fourier transform infrared spectroscopy (FTIR). Degree of deacetylation of chitosan was examined by 1H-NMR and potentiometric titration method. Thereafter, the chitosan was used for synthesis of CMNPs. The synthesized CMNPs were characterized by FTIR, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), thermal gravimetric analysis (TGA) and atomic force microscopy (AFM). Effects of various variables such as contact time, pH, stirring speed, adsorbent dosage, temperature, and concentration of electrolyte on extraction efficiency were evaluated. Freundlich isotherm model fits better that shows the removal of RO 107 with CMNPs by multilayer adsorption behaviour. Furthermore, kinetic study showed that adsorption process followed pseudo-second order kinetic model regulated by chemisorption. Thermodynamic analysis explained that adsorption of RO 107 onto CMNPs was endothermic as well as spontaneous. The developed CNMPs were applied to environmental remediation of spiked RO 107 treated waste water samples with 96.20% removal potential, hence, offered an effective sorbent for removal of RO 107 contaminated water samples.

This study concerns the investigation of dissipation, adsorption, and degradation of triazophos in different soils from Pakistan. These processes help in the disappearance of pesticide from the environment. Gas chromatography was used for dissipation and adsorption analysis while for degradation study mass spectrometer was used in addition of gas chromatography (GC-MS). The dissipation rate of triazophos in three different soils was 90% over 30 days with average half-life of 9.059 days. From dissipation study it was inferred that rate is variable in each soil due to climatic changes, soil nature and soil-pesticide interactions. Adsorption experiment has revealed that the adsorption of this pesticide to soil follows the pseudo first order kinetic model with rate constant value of 0.479/h and Freundlich isotherm with adsorption capacity of 1.832 mol/g. Degradation study has displayed two major metabolites, one is phosphorothioic acid, S-[2-[(1-cyano-1-methylethyl) amino]-2-oxoethyl] O,O-diethyl ester at ret...

The aim of study is to investigate the removal ability of some natural adsorbents for fluoride ion from aqueous solution. The batch dynamic adsorption method was carried out at neutral pH as the functions of contact time, adsorbent dose, adsorbate concentration, temperature and effect of co-anions, which are commonly present in water. The sorption kinetics and equilibrium adsorption isotherms of fluoride on natural adsorbing materials had been investigated at afore-mentioned optimized. Equilibrium adsorption isotherms, viz., Freundlich and Langmuir isotherms were investigated. Lagergren and Morris-Weber kinetic equations were employed to find the rate constants. The negative enthalpy ΔH = -46.54 KJ·mol-1 and Gibbs free energy calculated was ΔG288-333—(2.07785, 3.08966, 4.1064, 4.90716 and 5.38036 KJ·mol-1) respectively, envisage exothermic and spontaneous nature of sorption.

This work reports the application of banana peel as a novel bioadsorbent for in vitro removal of five mycotoxins (aflatoxins (AFB1, AFB2, AFG1, AFG2) and ochratoxin A). The effect of operational parameters including initial pH, adsorbent dose, contact time and temperature were studied in batch adsorption experiments. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and point of zero charge (pHpzc) analysis were used to characterise the adsorbent material. Aflatoxins' adsorption equilibrium was achieved in 15 min, with highest adsorption at alkaline pH (6-8), while ochratoxin has not shown any significant adsorption due to surface charge repulsion. The experimental equilibrium data were tested by Langmuir, Freundlich and Hill isotherms. The Langmuir isotherm was found to be the best fitted model for aflatoxins, and the maximum monolayer coverage (Q0) was determined to be 8.4, 9.5, 0.4 and 1.1 ng mg(-1) for AFB1, AFB2, AFG1 and AFG2 respectively. Thermodynamic parameters including changes in free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) were determined for the four aflatoxins. Free energy change and enthalpy change demonstrated that the adsorption process was exothermic and spontaneous. Adsorption and desorption study at different pH further demonstrated that the sorption of toxins was strong enough to sustain pH changes that would be experienced in the gastrointestinal tract. This study suggests that biosorption of aflatoxins by dried banana peel may be an effective low-cost decontamination method for incorporation in animal feed diets.

This study was aimed to assess the adsorption and leaching potential of imidacloprid pesticide in column and field soil. To visibly understand these actions and factors affecting them, the experiments were carried out under laboratory and field conditions. Adsorption study was divided into kinetic and equilibrium sections. The evaluation of kinetic data was done through pseudo first and second order models. It was found that kinetic adsorption of imidacloprid on soil followed pseudo second order with rate constant value of 4.333 mg/g/h. Langmuir and Freundlich isotherms were used to explain equilibrium adsorption, from these isotherms it was evaluated that Freundlich isotherm was obeyed well with adsorption capacity of 2.190 - 4.573 mol/g. Leaching study was performed in laboratory using column made of poly-vinyl chloride having 30 cm length. Known amount of imidacloprid pesticide was applied to column left for adsorption and then eluted with 500 mL water in five equal portions. These water portions and soil of column which was divided into three sections were analyzed by HPLC. The result revealed that the concentration of imidacloprid was decreased from 0.481 ppm in first portion of water to 0.327 ppm in last portion of water while 0.783 ppm in first section of column soil to 0.038 ppm in last section of column soil. In field the leaching power of imidacloprid was observed up to 60 cm depth, its concentration decreased with soil depth. It was 3.311 ppm in first portion of soil and 0.357 ppm in last portion of soil. The leaching potential of imidacloprid pesticide up to 60 cm soil depth was due to less organic matter, sandy texture, alkaline pH, and low cation exchange capacity.

Fluoride in drinking water above permissible level is responsible for human being affected by skeletal fluorosis. In this study, Amberlite XAD-4™ has been modified by introducing amino group onto the aromatic ring for its application in fluoride remediation. Characterization of the modified resin was made by, FT-IR and elemental analysis (CHNS) techniques. The pH 9 was optimum value for quantitative sorption of fluoride in both batch and column experiments. The desorption of fluoride was achieved by using 10% HCl. The batch and column sorption studies of fluoride with modified resin were carried out to evaluate sorption isotherms too. Thus equation isotherms such as Langmuir, Freundlich, and Dubinin–Radushkevich (D–R) were successfully used to model the experimental data. The sorption capacity of modified Amberlite XAD-4 resin was found as 5.04 × 10 −3 mol g −1 . From the D–R isotherm parameters, it has been evaluated that the uptake of fluoride by modified resin occurs through ion exchange adsorption mechanism. The study will contribute toward the removal of fluoride from the aqueous environment as well as in the field of analytical and environmental chemistry.

The adsorption of methyl parathion from aqueous solutions by the low-cost and abundant adsorbent mango kernel was studied in a batch adsorption system. The adsorption was studied as a function of pH, contact time, initial pesticide concentration, adsorbent dose, and temperature. A maximum adsorption of 98% ± 1% was achieved. Physicochemical characterization of the adsorbent was carried out by EDXRF, BET, and CHNS analysis. Freundlich, Langmuir, and Dubinin-Radushkevich isotherms were employed to evaluate the adsorption capacity of the adsorbent. Lagergren, Morris-Weber, and Reichenberg equations were employed to study the kinetics of the adsorption process. Thermodynamic parameters Δ H, Δ S, and Δ G were computed. The developed adsorption method was applied to real environmental samples.

The present study describes the Pb(2+) sorption potential of newly synthesized tetraester calix[4]arene (TC4) based resin from aqueous media. The TC4 resin was synthesized through diazotization reaction of TC4 with Amberlite XAD-4 in the presence of sodium nitrite in acidic medium. The TC4 resin was characterized by using different analytical techniques such as FT-IR, elemental analysis and scanning electron microscopy (SEM). The Pb(2+) removal ability of the resin from the aqueous environment has been evaluated by both batch adsorption as well as column studies. The experiments have been conducted involving the determination of effect of pH, adsorbate concentration, adsorbent dosage, contact time and temperature. Moreover, on the basis of kinetic studies, the pseudo-first-order and pseudo-second-order adsorption kinetics were calculated. The thermodynamic parameters of lead adsorption were also calculated. Equation isotherms such as Langmuir (L), Freundlich (F), and Dubinin-Radushkevich (D-R) were successfully used to model the experimental data. From the D-R isotherm parameters, it was considered that the uptake of Pb(2+) by TC4 resin is ion exchange mechanism. From the results it has been found that the TC4 resin is a versatile adsorbent for the removal of Pb(2+) from the aqueous environment. The study also confers its impact on human health, reinstate of polluted sites and other fields of material science.

The sorption efficiency of chickpea husk of black gram variety (BGH), for the removal of organophosphorous pesticides (OPPs), i.e. triazophos (TAP) and methyl parathion (MP) from aqueous media has been investigated. Optimization of operating sorption parameters, i.e. particle size, sorbent dose, agitation time, pH, initial concentration of sorbates, and temperature has been studied. The sorption data fitted well to Freundlich, Langmuir and Dubinin–Radushkevich (D–R) sorption isotherms. The maximum sorption capacities of BGH for TAP and MP were calculated to be 3.5 ± 0.45 and 10.6 ± 0.83 mmol g −1 by Freundlich, 0.0077 ± 0.021 and 0.025 ± 0.0094 mmol g −1 by Langmuir and 0.48 ± 0.037 and 0.15 ± 0.077 mmol g −1 by D–R isotherms respectively, employing 0.2 g of sorbent, at pH 6, 90 min agitation time and at 303 K. Application of first order Lagergren and Morris–Weber equations to the kinetic data yielded correlation coefficients, close to unity and showed partial intra-particle diffusion. The negative values of thermodynamic parameters, i.e. Δ H (kJ mol −1 ), Δ S (J mol −1 K −1 ) and Δ G (kJ mol −1 ) indicate the exothermic and spontaneous nature of the sorption process. The sorbed pesticides were recovered by sonication with methanol, making the regeneration and reutilization of the sorbents promising. The investigated sorbent exhibited potential applications in water decontamination, treatments of industrial and agricultural waste waters and thus productively demonstrated viable use of agricultural waste material.

This study describes the use of banana peel, a commonly produced fruit waste, for the removal of Cd(II) from environmental and industrial wastewater. The banana peel was characterized by FT-IR and scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX) analysis. The parameters pH, contact time, initial metal ion concentration and temperature were investigated and found to be rapid ( approximately 97% within 10 min). The Langmuir adsorption isotherm was used to describe partitioning behavior for the system at room temperature. The value of Q(L) was found to be (35.52 mg g(-1)) higher than the previously reported materials. The binding of metal ions was found to be pH-dependent with the optimal sorption occurring at pH 8. The retained species were eluted with 5 mL of 5 x 10(-3)M HNO(3) with the detection limit of 1.7 x 10(-3)mg L(-1). Kinetics of sorption followed the pseudo-first-order rate equation with the rate constant k, equal to 0.13+/-0.01 min(-1). Thermodynamic parameters such as Gibbs free energy at 303K (-7.41+/-0.13 kJ mol(-1)) and enthalpy (40.56+/-2.34 kJ mol(-1)) indicated the spontaneous and endothermic nature of the sorption process. The developed method was utilized for the removal of Cd(II) ions from environmental and industrial wastewater samples using flame atomic absorption spectrophotometer (FAAS).

In the present studies chemically and thermally treated watermelon peels (TWMP) have been utilized for the removal of methyl parathion (MP) pesticide from water. The effect of process variables such as pH of solution, shaking speed, shaking time, adsorbent dose, concentration of solution and temperature have been optimized. Maximum adsorption (99 ± 1%) was achieved for (0.38–3.80) × 10−4 mol dm−3 of MP solution, using 0.1 g of adsorbent in 20 ml of solution for 60 min agitation time at pH 6. BET and SEM analysis have been carried out for the characterization of TWMP. Adsorption data has been analyzed by Freundlich, Langmuir and Dubinin–Radushkevich (D–R) adsorption isotherms. Lagergren, Morris–Weber and Reichenberg equations have been used for kinetic studies of adsorption process. Thermodynamic parameters ΔH, ΔS and ΔG have been calculated. Positive value of ΔH and negative value of ΔG show endothermic and spontaneous nature of adsorption respectively. The developed adsorption method has been employed to surface water samples with percent removal 99% ± 1.

The removal of Cd(II) using polystyrene foam chemically modified with 2,2′-bipyridine has been investigated. The modified polystyrene foam has been characterized by FT-IR spectroscopy, thermogravimetry, elemental analysis and scanning electron microscopy. The solid was employed as a Cd(II) adsorption from aqueous solutions at room temperature. The effects of several variables (pH, shaking speed, agitation time, metal concentration and presence of other ions in the medium) have been studied using batch technique. Flame atomic absorption spectrometry was used to determine the Cd(II) ion concentration in the filtrate after the adsorption process. Maximum sorption ⩾90% was achieved at pH 7 after 30 min of shaking time. Sorbed metal ions have been desorbed with 5 ml of 2 M HNO 3 with the detection limit of 16.7 ng ml −1 . The Langmuir, Freundlich and D–R isotherm equation were used to describe partitioning behavior of the system at room temperature. Kinetic and thermodynamic behavior of modified polystyrene foam for Cd(II) ion removal was also studied. Br − , PO 4 3− , Pb 2+ , Ni 2+ and Cr(VI) suppress the sorption to some extent. The possible sorption mechanism of Cd(II) ions onto modified sorbent is also discussed. Method was utilized to remove Cd(II) ions from aqueous media.

A new simple sensitive differential pulse polarographic (DPP) method was investigated for the determination of acrylamide (AA) directly in a neutral aqueous solution. The AA showed a well-defined and well-resolved peak in pure aqueous LiCl at −1.84 V in the potential range from −1.6 V to −1.97 V at nitrogen pressure of 0.5 kg cm −2 . Among the various electrolytes studied, the AA showed good DPP response in the presence of LiCl and tetra methyl ammonium iodide, while it showed poor response in the presence of tetra butyl ammonium hydroxide and tetra butyl ammonium bromide due to their strong adsorption on the surface of electrode which hindered its reduction. The effect of LiCl concentration, the cyclic voltammetric response and the drop time study showed that AA exhibited an irreversible adsorptive electrochemical behavior. The good electrochemical response in pure aqueous medium suggested that hydrogen bonding might be involved which may favor the electrode reaction. Under optimized conditions, the peak current was linear in the entire concentration range from 0.2 mg L −1 to 20 mg L −1 with the correlation coefficient of R 2 = 0.9998. The method showed good reproducible results with R.S.D. of 0.3% ( n = 16). The detection limit (LOD) was 27 μg L −1 . The influence of various interfering agents was also studied. The method was applied successfully for the quantification of AA in water samples without any interference effect from alkali metals.

Tannery wastewater collected from a local leather industry in Peshawar, Pakistan was subjected to DC electrolysis in a simple cell having two static sheet electrodes and stirring assembly after proper dilution and adjustment to desired conditions. One percent HNO 3 and 1% NaHCO 3 were used as electrolytes and pH adjusters. The latter salt also worked as sodium source for anodic deposition of Na 2 Cr 2 O 7 . Various combinations of electrodes were tested and conditions optimized for best electrode couple with increased recovery and removal of chromium in the form of Cr(OH) 3 and/or Na 2 Cr 2 O 7 at cathode and anode, respectively. The recovery of 99% chromium was achieved after 2 h electrolysis at a cell potential of 1.0 V, pH 5.0 and stirring rate of 500 rpm using Pb sheet as anode and Cu sheet as cathode. The most interesting and novel finding of this work was the recovery of the mentioned salt(s) alone at Cu cathode or Pb anode or collectively at both electrodes by proper control of pH. Such treatment not only minimizes the environmental water pollution, but results in the formation of useful products employed for recycling purpose in tannery or other related industry to make the process economical.

Moringa oleifera pods Lamarck (Drumstick or Horseradish) is a multipurpose medium or small size tree from sub-Himalayan regions of north-west India and indigenous to many parts of Asia, Africa, South America, and in the Pacific and Caribbean Islands. Its pods (MOP) have been employed as an inexpensive and effective sorbent for the removal of organics, i.e., benzene, toluene, ethylbenzene and cumene (BTEC) from aqueous solutions using HPLC method. Effect of different parameters, i.e., sorbent dose 0.05-0.8g, 25cm(-3) agitation time 5-120min, pH 1-10, temperature 283-308K and concentration of sorbate (1.3-13)x10(-3), (1.1-11)x10(-3), (0.9-9)x10(-3), (0.8-8)x10(-3)moldm(-3), on the sorption potential of MOP for BTEC have been investigated. The pore area and average pore diameter of the MOP by BET method using nitrogen as a standard are calculated to be 28.06+/-0.8m(2)g(-1) and 86.2+/-1.3nm respectively. Freundlich, Langumir and Dubinin-Radushkevich (D-R) sorption isotherms were employed to evaluate the sorption capacity of MOP. Sorption capacities of BTEC onto MOP have been found to be 46+/-10, 84+/-9, 101+/-4, 106+/-32mmolg(-1) by Freundlich, 8+/-0.1, 9+/-0.1, 10+/-0.3, 9+/-0.1mmolg(-1) by Langumir and 15+/-1, 21+/-1, 23+/-2, 22+/-3mmolg(-1) by D-R isotherms respectively, from BTEC solutions at 303K. While the mean energy of sorption process 9.6+/-0.3, 9.2+/-0.2, 9.3+/-0.3, 9.5+/-0.4kJmol(-1) for BTEC is calculated by D-R isotherm only. Rate constant of BTEC onto MOP 0.033+/-0.003, 0.030+/-0.002, 0.029+/-0.002, 0.027+/-0.002min(-1) at solution concentration of 1.3x10(-3), 1.1x10(-3), 0.9x10(-3) and 0.8x10(-3)moldm(-3) and at 303K have been calculated by employing Lagergren equation. Thermodynamic parameters DeltaH -8+/-0.4, -10+/-0.6, -11+/-0.7, -11+/-0.7kJmol(-1), DeltaS -22+/-2, -26+/-2, -27+/-2, -29+/-3Jmol(-1)K(-1) and DeltaG(303K) -0.9+/-0.2, -1.9+/-0.2, -2.3+/-0.1 and -2.6+/-0.2kJmol(-1) were also estimated for BTEC respectively at temperatures 283-308K. The negative values of DeltaH, DeltaS and DeltaG suggest exothermic, stable (with no structural changes at solid-liquid interface) and spontaneous nature of sorption process under optimized conditions. MOP has been used extensively to accrue and then to preconcentrate benzene, toluene and ethylbenzene in wastewater sample.

Sorptive potential of selected agricultural waste materials i.e. rice (Oryza sativa) bran (RB), bagasse fly ash (BFA) of sugarcane (Saccharum officinarum), Moringa oleifera pods (MOP) and rice husk (RH) for the removal of methyl parathion pesticide (MP) from surface and ground waters has been investigated. Optimization of operating parameters of sorption process, i.e. sorbent dose, agitation time, pH, initial concentration of sorbate, and temperature have been studied. The sorption data fitted to Freundlich, Langmuir and Dubinin-Radushkevich (D-R) sorption isotherms. The maximum capacities of RB, BFA, MOP and RH for MP were calculated to be 3.6+/-0.8, 5.3+/-1.4, 5.2+/-1.5 and 4.7+/-1.0 mmolg(-1) by Freundlich, 0.39+/-0.009, 0.39+/-0.005, 0.36+/-0.004 and 0.35+/-0.008 mmolg(-1) by Langmuir and 0.9+/-0.08, 1.0+/-0.10, 1.0+/-0.10 and 0.9+/-0.07 mmolg(-1) by D-R isotherms respectively, employing 0.1g of each sorbent, at pH 6, 90 min agitation time and at 303 K. Application of first order Lagergren and Morris-Weber equations to the kinetic data yielded correlation coefficients, close to unity. Thermodynamic parameters of sorption process, i.e. DeltaH, DeltaS and DeltaG were computed and their negative values indicated the exothermic and spontaneous nature of sorption process. The pesticide may be stripped by sonication with methanol, making the regeneration and reutilization of sorbents promising. The sorbents investigated exhibited their potential applications in water decontamination, treatment of industrial and agricultural waste waters.

The ability of sawdust (treated and untreated) waste, a waste material derived from the commercial processing of cedrus deodar wood for furniture production, to remove/preconcentrate Cd(II) ions from aqueous solution was determined. Sorption was found to be rapid (approximately 97% within 8 min). The binding of metal ions was found to be pH dependent, optimal sorption accruing at around pH 4-8. Potentiometric titrations of sawdust revealed two distinct pK(a) values, the first having the value similar to carboxylic groups (3.3-4.8) and second comparable with that of amines (8.53-10.2) with the densities 1.99 x 10(-4) and 7.94 x 10(-5), respectively. Retained Cd(II) ions were eluted with 5 ml of 0.1 mol l(-1) HCl. Detection limit of 0.016 microg ml(-1) was achieved with enrichment factors of 120. Recovery was quantitative using sample volume of 600 ml. The Langmuir and D-R isotherm equations were used to describe partitioning behavior for the system at different temperatures. Kinetic and thermodynamic behavior of sawdust for Cd(II) ions removal was also studied.

Molecularly imprinted particles embedded composite cryogel discs specific for alpha-cypermethrin and beta-cypermethrin were prepared. Two different types of imprinted particles were embedded into cryogel to prepare composite cryogels specific for two isomers of cypermethrin simultaneously. Adsorption studies revealed that MIP is extremely selective for alpha-cypermethrin and beta-cypermethrin with outstanding adsorption capacity. A sensitive analytical method comprising MISPE coupled with GC-MS has been developed to quantify trace levels of alpha-cypermethrin and beta-cypermethrin in real water matrices. The polymer showed fast kinetics and follows a pseudo-second-order kinetic model very well (R-2 = 0.9999). It shows excellent capacity towards alpha-cypermethrin and beta-cypermethrin with a higher total number of binding sites (N-t - 96 mu mol g(-1) for alpha-cypermethrin and 95 mu mol g(-1) for beta-cypermethrin). The MIP showed selectivity over the homologues of alpha-cypermethrin and beta-cypermethrin with imprinting factor (IF) 11.2, 10.0, 1.04 and 1.20 for alpha-cypermethrin, beta-cypermethrin, deltamethrin and permethrin, respectively. The developed MISPE method followed by GC-MS enhanced the sensitivity and selectivity of the assay. This method was successfully applied to samples of lake water for the determination of alpha-cypermethrin and beta-cypermethrin simultaneously. Moreover, the synthesized MIP can be easily regenerated and repeatedly used without loss of efficiency.

A simple and reliable method has been developed using packing waste material (Styrofoam) containing dithizone as a chelating agent, to concentrate ultratrace amounts of cadmium ions in aqueous solutions. After characterization, the static sorption behavior of Cd(II) ions onto modified sorbent has been investigated. The sorption has been optimized with respect to the pH, shaking speed and contact time between the two phases. Maximum sorption has been achieved from solution of pH 6–8 after 8 min of shaking time. Sorbed metal ions are desorbed with 5 ml of 0.2 M EDTA solution with the preconcentration factor of 40. The kinetics and thermodynamics of sorption are studied in detail. The kinetics follows the first order rate equation with the rate constant k , equal to (3.46 ± 0.17 min −1 ). The variation of equilibrium constant, K c , with temperature between 15 and 40 °C yields values of Δ H = 80.94 ± 4.95 kJmol −1 , Δ S = 290 ± 15.3 JmolK −1 and Δ G is between −3.96 and −10.88 kJmol −1 . The sorption data studied in the concentration range of 8.88 × 10 −7 mol l −1 to 4.44 × 10 −4 mol l −1 Cd(II) ions follows Langmuir, Freundlich, and Dubinin-Radushkevich isotherms at all temperatures investigated. The monitoring of the influence of diverse ions on the sorption of Cd(II) ions has revealed that only Pb(II) ions suppress the sorption to some extent. The possible sorption mechanism of cadmium(II) ions onto impregnated sorbent is also discussed. The sorption procedure is utilized to preconcentrate cadmium ions prior to their determination in human blood and pipe tobacco samples by atomic absorption spectrometry using direct and standard addition methods.

A simple and reliable method has been developed using polymeric material containing phthalic acid as a chelating agent to concentrate ultratrace amounts of lead ions in aqueous solutions. After characterization by CHN, IR, and thermal studies, the static and dynamic sorption behavior of Pb(II) ions onto new synthetic resin has been investigated. The sorption has been optimized with respect to pH, shaking speed, and contact time between the two phases. Maximum sorption is achieved from solution of pH 5–8 after 10 min agitation time. The lowest concentration for quantitative recovery is 5.8 ng cm−3 with a preconcentration factor of ∼850. The kinetics of sorption follows the first-order rate equation with the rate constant k = 0.58 ± 0.04 min −1 . The variation of the equilibrium constant K c with temperature between 10 and 50 °C yields values of ΔH, 52.4 ± 1.65 kJ mol −1 , ΔS, 186 ± 5.21 J mol −1 K −1 , and Δ G 303 K , − 4.15 ± 0.002 kJ mol −1 . The sorption data of Pb(II) ions in the concentration range from 2.41 × 10 −6 to 1.44 × 10 −4 mol L −1 follows the Langmuir, Freundlich, and Dubinin–Radushkevich (D–R) isotherms at all temperatures investigated. The sorption of Pb(II) ions onto synthesized resin in the presence of common anions and cations has also been measured. The possible sorption mechanism of Pb(II) ions onto phthalic acid modified XAD-16 is also discussed. The sorption procedure is utilized to preconcentrate Pb(II) ions prior to their determination in automobile exhaust particulates by atomic absorption spectrometry using direct and standard addition methods.

A simple, inexpensive method based on solid-phase extraction (SPE) on sawdust from Cedrus deodera has been developed for speciation of Cr(III) and Cr(VI) in environmental water samples. Because different exchange capacities were observed for the two forms of chromium at different pH-Cr(III) was selectively retained at pH 3 to 4 whereas Cr(VI) was retained at pH 1-complete separation of the two forms of chromium is possible. Retained species were eluted with 2.5 mL 0.1 mol L(-1) HCl and 0.1 mol L(-1) NaOH. Detection limits of 0.05 and 0.04 microg mL(-1) were achieved for Cr(III) and Cr(VI), respectively, with enrichment factors of 100 and 80. Recovery was quantitative using 250 mL sample volume for Cr(III) and 200 mL for Cr(VI). Different kinetic and thermodynamic properties that affect sorption of the chromium species on the sawdust were also determined. Metal ion concentration was measured as the Cr(VI)-diphenylcarbazide complex by UV-visible spectroscopy. The method was successfully applied for speciation of chromium in environmental and industrial water samples.

In this study, core-shell molecularly imprinted polymer selective for endosulfan I and II was prepared by copolymerization of Fe3O4@SiO2-methacrylamide composites and N,N'-methylene-bis-acrylamide. The synthesized polymer was thoroughly characterized by FT-IR, TGA, and SEM. The adsorption properties of the MIP and NIP were demonstrated by equilibrium rebinding experiments, pseudo-second-order kinetic model, LF-isotherm and Scatchard analysis. The competitive recognition studies were performed with endosulfan I and II and structurally similar compounds: aldrin, dieldrin and heptachlor. The imprinting factors (IF) of endosulfan I and II were found to be 10.1 and 9.1, respectively, which were much higher than the imprinting factors (IF) of other cyclodienes. The imprinted polymer was then coated on stainless steel wire to develop an easy and simple laboratory made solid phase microextraction device for selective extraction of endosulfan I and II from water samples of environmental importance. Also the main parameters influencing coating of fiber and microextraction procedure were investigated and optimized using Plackett-Burman and Central Composite designs. The developed method was thoroughly validated for its linearity, selectivity, precision and accuracy. The developed MISPME method's linearity ranged from 7 to 5×10(3)ngl(-1) (R(2)=0.999) and from 10 to 5×10(3)ngl(-1) (R(2)=0.999) for endosulfan I and II, respectively. The limits of detection for endosulfan I and II were found to be 2ngl(-1) and 3ngl(-1), respectively. However, the limits of quantification for endosulfan I and II were 7ngl(-1) and 10ngl(-1), respectively.

The molecularly imprinted polymer (MIP) selective for di(2-ethylhexyl) phthalate (DEHP) an environmental endocrine disruptor was prepared by suspension polymerization using methacrylamide as functional monomer and N,N'-methylene-bis-acrylamide as cross-linker. The imprinted polymer was employed for solid-phase extraction of DEHP from water samples of environmental importance and characterized by FT-IR and SEM. The adsorption properties of the imprinted polymer were demonstrated by equilibrium rebinding experiments, Pseudo-second-order kinetic model, Sips isotherm and Scatchard analysis. The reusability of MIP was checked for at least six repeated batch adsorption cycles and the results showed almost no deterioration in the adsorption capacity. The competitive recognition studies were performed with DEHP and structurally similar compounds; dimethyl phthalate (DMP), diethyl phthalate (DEP), and dibutyl phthalate (DBP). The imprinting factor (IF) of DEHP was found to be 12.86 which was much higher than the imprinting factors (IF) of other phthalates. A method constituted by molecularly imprinted solid-phase extraction (MISPE) with GC-FID was developed for DEHP analysis in water samples under very simple conditions. Sample loading and desorption conditions were also optimized. The MISPE method's linearity ranged from 0.035 to 3.0 μg ml⁻¹ with r² = 0.9998. Intra-assay, interassay precision and accuracy ranged from 0.0168% to 1.017%, 1.130% to 4.799% and 94.98% to 99.35%, respectively. The LOD and LOQ were found to be 0.011 and 0.035 μg ml⁻¹, respectively. Synthesized MIP was employed in MISPE for cleaning up the spiked river water samples prior to gas chromatographic analysis. The river samples were found to contain DEHP in the range of 1.4 × 10⁻³ to 0.349 μg ml⁻¹.

Biosorption of divalent metal ions, i.e. Pb(II), Cd(II), Zn(II) and Cu(II) onto rice husk activated (RHA) is investigated over pH range (1–10) via batch adsorption technique. The chemical and thermal activation of rice husk with 0.1 M HNO 3 and 1 M K 2 CO 3 at 473 K enhanced the removal efficiency of RHA (35 ± 2.1–99 ± 0.5%, 33 ± 1.2–97 ± 0.6%, 32 ± 1.3–96 ± 0.8% and 28 ± 1.8–95 ± 0.9% before and after treatment, respectively). The surface area analysis of RHA by BET (Brunauer, Emmett and Teller) nitrogen adsorption method provided pore area and average pore diameter to be 542 ± 2.3 m 2 g −1 and 1076 ± 5.6 nm respectively. SEM and FTIR analyses of RHA were carried out to determine the surface morphology and functional groups involved in metal binding mechanism, respectively. The adsorption equilibrium was well described by Freundlich, Langmuir and Dubinin–Radushkevish (D–R) isotherm models by employing (4.8–48, 8.9–89, 15.3–153 and 15.7–157) × 10 −5 M solution concentrations of sorbates, respectively, at equilibrium time of 20 min at pH 6 and onto 0.2 g of sorbent. The kinetics of mass transfer and intra-particle diffusion for metal ions sorption onto RHA were studied with Lagergren and Morris–Weber kinetic models. The numerical values of thermodynamic parameters indicated the exothermic nature, spontaneity and feasibility of the sorption process. The desorption study of metal components from RHA surface was carried out with 0.1 M HCl. The sorption mechanism developed illustrates the strong interactions of sorbates with the active sites of the sorbent coupled with efficient and environmentally clean exploitation of rice waste product.

A simple and sensitive method based on solid phase extraction (SPE) on acetyl acetone modified XAD-16 has been established for separation of Cr (III) and Cr (VI) from and industrial water samples. Two forms of chromium showed different exchange capacities at different pH values, viz. Cr (III) selectively retained at pH 5-7 whereas Cr (VI) retained at pH 1. Hence complete separation of the two forms of chromium is possible. Retained species were eluted with 5 mL of 2 mol L(-1) HNO(3) and 2 mol L(-1) NaOH. The detection limit of 0.02 and 0.014 microg mL(-1) was achieved for Cr (III) and Cr (VI), respectively, with an enrichment factor of 100 and 140. Various kinetic and thermodynamic parameters were also determined. The metal ion concentration was measured by atomic Absorption Spectroscopy. The possible retention mechanism is also discussed. The method was successfully applied for the speciation of chromium in industrial water samples.

The removal of selected pesticides such as carbofuran (CF) and methyl parathion (MP) using low-cost abundant sorbent chestnut shells from aqueous solutions has been investigated in the present study. The sorption parameters, i.e., contact time, pH, initial pesticide solution concentration and temperature have been studied. Maximum percent sorption (99+/-1%) was achieved for (0.38-3.80) x10(-4) and (0.45-4.5) x10(-4) mol dm(-3) of MP and CF pesticide solutions respectively, using 0.4 g of sorbent in 100 ml of solution for 30 min agitation time at pH 6. The Freundlich, Langmuir and Dubinin-Radushkevich (D-R) models have been applied, and their constants for methyl parathion and carbofuran, sorption intensity 1/n (0.55+/-0.02 and 0.54+/-0.04), multilayer sorption capacity C(m) (28.3+/-0.5 and 16.4+/-0.7) x10(-3) mol l(1-1/n)dm(3/n)g(-1), monolayer sorption capacity Q (22.5+/-0.5 and 10.8+/-0.3) x10(-6) mo lg(-1), binding energy, b (2.9+/-0.2 and 5.2+/-0.5) x10(4) dm(3)mol(-1), and sorption energy E (11.2+/-0.1 and 11.5+/-0.2 kJ mol(-1)) have been evaluated respectively. Lagergren, Morris-Weber and Reichenberg equations were employed to study kinetics of sorption process. Thermodynamic parameters DeltaH (-5.09+/-0.1 and 22.8+/-0.4 kJ mol(-1)), DeltaS (-4.33+/-0.0003 and 0.09+/-0.001 kJ mol(-1)K(-1)) and DeltaG((303K)) (-2.9 and -3.8 kJ mol(-1)) have been calculated for methyl parathion and carbofuran, respectively. The developed sorption procedure has been employed to environmental samples.

The sorption potential of chemically and thermally treated rice husk (RHT) for the removal of 2,4-dichlorophenol (DCP) from aqueous solutions has been investigated. Sorption of DCP by rice husk was observed over a wide pH range of 1-10. The effect of contact time between liquid and solid phases, sorbent dose, pH, concentration of sorbate and temperature on the sorption of DCP onto rice husk has been studied. The pore area and average pore diameter of RHT by BET method are calculated to be 17+/-0.6 m2g-1 and 51.3+/-1.5 nm, respectively. Maximum sorption (98+/-1.2%) was achieved for RHT from 6.1x10(-5) moldm(-3) of sorbate solution using 0.1g of rice husk for 10 min agitation time at pH 6 and 303K, which is comparable to activated carbon commercial (ACC) 96.6+/-1.2%, but significantly higher than chemically treated rice husk (RHCT) 65+/-1.6% and rice husk untreated (RHUT) 41+/-2.3%. The sorption data obtained at optimized conditions was subjected to Freundlich, Langmuir and Dubinin-Radushkevich (D-R) isotherms. Sorption intensity 1/n (0.31+/-0.01) and sorption capacity multilayer C(m) (12.0+/-1.6 mmolg(-1)) have been evaluated using Freundlich sorption isotherm, whereas the values of sorption capacity monolayer Q (0.96+/-0.03 mmolg(-1)) and binding energy, b, (4.5+/-1.0)x10(4)dm(3)mol(-1) have been estimated by Langmuir isotherm. The Langmuir constant, b, was also used to calculate the dimensionless factor, R(L), in the concentration range (0.6-6.1)x10(-4) moldm(-3), suggesting greater sorption at low concentration. D-R sorption isotherm was employed to calculate sorption capacity X(m) (2.5+/-0.07 mmolg(-1)) and sorption energy E (14.7+/-0.13 kJmol(-1)). Lagergren and Morris-Weber equations were employed to study kinetics of sorption process using 0.2g of RHT, 25 cm(3) of 0.61x10(-4)moldm(-3) sorbate concentration at pH 6, giving values of first-order rate constant, k, and rate constant of intraparticle transport, R(id), (0.48+/-0.04 min(-1) and 6.8+/-0.8 nmolg(-1)min(-1/2), respectively) at 0.61x10(-4)moldm(-3) solution concentration of DCP, 0.1g RHT, pH 6 and 2-10min of agitation time. For thermodynamic studies, sorption potential was examined over temperature range 283-323 K by employing 6.1x10(-4)moldm(-3) solution concentration of DCP, 0.1g RHT at pH 6 and 10 min of agitation time and values of DeltaH (-25+/-1 kJmol(-1)), DeltaS (-61+/-4 Jmol(-1)K(-1)) and DeltaG(303K) (-7.1+/-0.09 kJmol(-1)) were computed. The negative values of enthalpy, entropy, and free energy suggest that the sorption is exothermic, stable, and spontaneous in nature.