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Environmental Chemistry Research Laboratory, Department of Chemistry, University of Allahabad, Allahabad-211 002, Uttar Pradesh, India E-mail : mcc46@rediffmail.com Fax : 91-53-22541786 The aim of this article is to provide updated, concise yet accurate information about nanotechnology and magnetic nanoparticles in the fields of high societal impact such as environment and biomedicines based on scientific literatures and authoritative reports. The article also includes some visions of potential of applications of nanotechnology, whilst keeping the discussion at the realistic level. This article has been written with the purpose of supporting and enhancing the knowledge of college students, non-governmental organizations, trade unions and industrial workers, as well as other working groups in learning about the nanotechnology and magnetic nanoparticles and its potential in these diverse areas of applications. The authors' intention is to provide those groups forming a balanced view of nanotechnology and magnetic nanoparticles, so to promote a constructive dialogue about this emerging technology. Other aspects of this discussion, such as potential environmental risks of nanoparticles, health and safety aspects, and challenges related to nanotechnology has been also covered in this article.

Water pollution has become a worldwide threat as the natural water resources are shrinking day by day. Emergent actions are needed to conserve water stocks to fulfill the sustainable development goals. Herein, we have prepared activated carbon-doped magnetic nanocomposites (AC@CoFe2O4) with environment friendly approach and characterized for FTIR, XRD, SEM, EDS, BET surface area, and pHzpc. AC@CoFe2O4 nanocomposite was applied for the decolorization of toxic food dyes (rhodamine B and tartrazine) from wastewater. Effect of ultrasonic waves, pH, contact time, surfactants, temperature, and analysis of real wastewater systems were studied. Adsorption isotherm, kinetics, and thermodynamics of the experiment were calculated for the present removal process. The effect of ultrasonication shows that the maximum removal percentage for RhB was found to be 92% and for tartrazine, it was found to be 86% at 60 min. Ultrasound-assisted adsorption and degradation revealed good results because of the formation of highly active ·H and ·OH radicals in the liquid through the decomposition of water molecules by the formation of hot spots under ultrasonic waves. Highest decolorization of 69% was obtained for RhB with anionic surfactant SDS and climax decolorization of tartrazine was acquired in case of CTAB as 60.5%. Analysis of real wastewater samples shows that the decolorization of RhB was found to be ~ 91% from well-water and ~ 95% removal of tartrazine was observed from submersible water on AC@CoFe2O4 nanocomposites. The decolorization best fitted (R2 < 0.988) with Langmuir model and value of Langmuir climax decolorization efficiency (Q0) was found to be 142.68 and 435.72 mg/g for RhB and tartrazine, respectively. Kinetic analysis revealed that adsorption follows pseudo-second-order equation. The dye-loaded AC@CoFe2O4 nanocomposites were recycled by 0.1 M HCl or NaOH and regenerated AC@CoFe2O4 nanocomposites were used up to five rounds with better adsorption efficiency.

Monitoring small amount of endocrine disrupting chemical, estradiol (E2) residue in environmental and biological samples is extremely important because of its possible connections to breast and prostate malignancies and gastrointestinal disorders. The newly synthesized graphene-coated silver nanoparticles (GN@Ag) decorated on graphitic carbon nitride (g-C

Present work demonstrates the synthesis, characterisation and application of a novel hybrid nanocomposite GO@Fe3O4-MnO2 for adsorption and catalytic degradation of dyestuff malachite green and tartrazine from wastewater. The nanocomposite GO@Fe3O4-MnO2 was characterised by FT-IR, XRD, SEM-EDS and pHzpc. Effects of various optimising parameters such as contact time, solution pH, surfactants, light, adsorbent dose, ultrasonication and coexisting ions were investigated. The removal efficiencies of malachite green and tartrazine were observed as high as 99.9% and 98% under direct sunlight, respectively. The adsorption kinetics follows the pseudo-second order model (R2 = 0.99) where k2 for malachite green and tartrazine were 0.0097 and 0.0011 g mg−1 min−1, respectively, that means adsorption was controlled by chemisorption. Equilibrium adsorption isotherm of these dyes was analysed in the context of Langmuir and Freundlich models, and the maximum adsorption capacity for Langmuir isotherm was found to be 8.0 and 5.1 mg g−1 for malachite green and tartrazine, respectively. The percentage removal was initially low, but when the ultrasound was irradiated, the removal percentage (96% for malachite green and 98% for tartrazine) was drastically increased because of the formation of highly active •H and •OH radicals in the water through the decomposition of water molecules by the formation of hot spots. On treatment with H2O2, advance oxidation processes were observed with high remediation percentage (99.5% for malachite green and 98% for tartrazine) of dye. The synthesised GO@Fe3O4-MnO2 was finally used for the treatment of dyes from real water samples. The used nanocomposite was separated using an external magnet and recycled with 0.1 N HCl or 0.1 N NaOH as desired.

The application of nanomaterials for water treatment has gained impetus in recent years. Nano-adsorbents offer significant decontamination potential due to their unique characteristics. Present study deals with synthesis and application of alumina nanoparticles for removal of an anionic dye, Orange G (OG) from aqueous solutions. The properties of synthesized nanoparticles were investigated by FTIR, TG/DTA, XRD, TEM, SEM, EDX and N2 adsorption-desorption techniques. The effect of various important parameters on dye removal was examined and adsorption was found to be highly pH dependent and maximum removal of 98.4% was observed at pH 2.5. The presence of interfering anions such as SO42−, PO43−, and C2O42− was found to be limiting factor of the adsorption process. The kinetic results demonstrated that the sorption process was described by pseudo-second-order model. Mechanism of adsorption process was also interpreted with the help of diffusion models and the results exhibited that external diffusion governed the overall sorption process. The Langmuir model yielded a good fit for the experimental data with high adsorption capacity (93.3 mg/g at 303 K). The evaluated thermodynamic parameters ΔG°, ΔH° and ΔS°, proposed that adsorption of OG was spontaneous, feasible, and exothermic under investigated conditions. Desorption experiments confirmed that the exhausted adsorbent can be successfully regenerated and can be effectively reused up to four successive cycles with almost the same sorption capacity resulting in reducing cost of treatment. The adsorption performance of alumina nanoparticles was also tested by using real wastewater and results indicated that nano alumina is proficient for the treatment of multi-solute system also. Keywords: Alumina nanoparticles, Isotherm, Kinetics, N2 adsorption-desorption, Regeneration, TGA/DTA

The release of recalcitrant dyes into the biosphere is a threat because of pollution and environmental health issues. Adsorption using commercial activated carbon has been effective in industrial dye-loaded effluent remediation to some acceptable extent. However, commercial activated carbon suffers from limitations related to cost, relatively lower adsorption capacity, fewer microporous and mesoporous networks in comparison with other competing adsorbents, and reduced adsorption efficiency after regeneration. Here we review the recent developments in applying microwave irradiation, ultrasonication, ionic liquids and nanoscience for the preparation, activation, and physical, chemical and biological functionalization of novel and more potent adsorbents such as metal, mineral, carbon and polymer-based nanoparticles for dye removal. We observed that microwave and ultrasound irradiation and the use of ionic liquids are highly beneficial for the preparation of adsorbent materials; those adsorbents display enhanced porous structures and morphologies that account for much larger surface areas for faster adsorption interactions. Graphene-based, magnetic, cellulose-based and nanocomposite adsorbents are more selective and thermally more stable, faster in dye adsorption kinetics, have higher adsorption capacities for many dyes and can be regenerated for reuse without significant decrease in adsorption capacity. The scales of fabrication of green adsorbents do not go beyond the kilogram scale.

Early detection and diagnostics are essential for the cure of cancer which has high mortality rate globally. In recent decades, various methods such as mammography, computed tomography (CT) scan, magnetic resonance imaging (MRI), polymerase chain reaction (PCR), molecular imaging, endoscopy and electrochemical methods have been adopted to detect cancerous cells. All of the above-mentioned techniques have their own pros and cons, hence, there is a need of reliable and sensitive tool for pre diagnostics of cancer biomarkers. To overcome various drawbacks of traditional methods, nanotechnologies emerged out to be highly advantageous for early cancer diagnostics by detecting cancer biomarkers in their lower limits. Electrochemical biosensors are very useful tools due to their small size, portability, easy to use, requirement of small sample volume and cost effectiveness. Electrochemical biosensors can also detect low levels of target cancer biomarkers in biological fluids. Further, the use of nanomaterials in electrochemical biosensor provides high surface area, good biocompatibility, high electrical conductivity, low cost and fast analysis. Therefore, electrochemical nanobiosensors are getting increased attention for the early detection of cancer biomarkers in clinical medicines. In this review, recent advancements made in last decade (2011–2021) and modifications made in the field of electrochemical biosensors on integrating with nanoscale materials-based hybrid frameworks have been reviewed. The application of electrochemical techniques and their detection modes in cancer biomarkers detection has been focused. Further, biological, technical and clinical challenges as well as future outlook have been also discussed.

Application of agrochemicals in farming sector to control insects and pests; and use of synthetic organic dyes to color the products are increasing continuously due to the rapid growth of industries. During the application process many industries releases toxic agrochemicals and dyes in to the aquatic environment and on land without the proper treatment. Due to their toxicity the disposal of such chemicals is of utmost importance. Biochar offers the ability to remediate these substances from environmental matrices because of their high sorption ability of pollutants from water and soil. This review highlights the development and advancement of biochar-based treatment for abatement of agrochemicals and synthetic organic dyes, involving its technical aspects and the variables connected with removing these kinds of pollutants. Several optimization parameters like temperature, pH, chemical concentration, biochar properties, time, and co-existing ions have been elaborated. Literature survey shows that most of the researches on biochar application have been conducted in the batch mode. Hence there is an urgent need to apply this beneficial technique for the remediation of pollutants at the larger scale in the real water and soil samples. A comprehensive summary on sorption kinetics and adsorption isotherms with regards to pollutant removal is also presented. This review also covers the cost analysis of various techniques where biochar has been used as an adsorbent. Thus this review makes an easy roadmap for the further development in biochar and biochar based composites and expansion of these demanding areas of research in biochar and their applications.

In the present study, we successfully synthesized graphitic carbon nitride (g-C3N4) and functionalized with copper coordinated dithiooxamide metal organic framework (Cu-DTO MOF) to form g-C3N4/Cu-DTO MOF nanocomposite. The synthesized g-C3N4 and g-C3N4/Cu-DTO MOF nanocomposite were thoroughly characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDX) and transmission electron microscopy (TEM). The TEM analysis of g-C3N4/Cu-DTO MOF composite material shows the successful immobilization of Cu-DTO MOF particles on the platform of g-C3N4 flakes. The electrochemical sensing performance of g-C3N4 and g-C3N4/Cu-DTO MOF nanocomposite modified electrodes were compared through sensitive determination of an endocrine disruptor i.e., 4-(4-isopropoxy-benzenesulfonyl)-phenol (BPSIP) using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The detection limit was estimated to be 0.02 µM and sensitivity to be 0.5675 µAµM-1cm−2 for the proposed g-C3N4/Cu-DTO MOF nanocomposite based BPSIP sensor through DPV that are better as compared to g-C3N4 based sensor. Therefore, it was found that the nanocomposite based sensor has better sensing ability and was successfully applied for the determination of BPSIP in river water sample.

In this paper, the efficiency of biosorbent prepared from Mikania micrantha to remediate a hazardous dye Alizarin Red S from aqueous phase was investigated. Morphological and constitutional characteristics of the biosorbent were studied by performing SEM and FTIR. The adsorption equilibrium was modeled with the Langmuir and Freundlich isotherm. The maximum monolayer adsorption capacity was found to be 46.51 mg g−1 at 50 °C. The isotherm data were better fitted to Freundlich model indicated heterogeneous nature of the adsorbent. The negative values of ∆G° and positive value of ∆H° demonstrated that the adsorption of Alizarin Red S onto Mikania micrantha were spontaneous and endothermic in nature, respectively. Positive value of ∆S° advocated the randomness at solid–liquid interface.

Copper coordinated dithiooxamide metal-organic framework (Cu-DTO MOF) was synthesized and applied for the removal of tartrazine from aqueous solutions. The properties of Cu-DTO MOF were extensively examined through different instrumentation techniques including Fourier transform infra red spectroscopy (FTIR), X- ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), energy dispersive X-ray analysis (EDX), atomic force microscopy (AFM), N2 adsorption-desorption for surface area analysis, thermo-gravimetric analysis (DTA/TGA/DTG) and zeta potential analysis (pHZPC). The effects of various process parameters such as pH, temperature, ionic strength, contact time and initial dye concentration were systematically studied. The interpretation of sorption kinetic data suggest that pseudo-second order model represents data more appropriately. Moreover, consideration of intraparticle diffusion model suggested that both film diffusion and pore diffusion phenomenon dictate the adsorption process. The equilibrium isotherm data agrees well with Freundlich model and the highest adsorption capacity of the synthesized MOF for removal of tartrazine was found to be 309.2 mg/g at 323 K. Thermodynamic parameters like change in free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) were also calculated and it was observed that the sorption process was spontaneous and endothermic in nature. Desorption study recommended that the regenerated adsorbent can be effectively used without significant loss in adsorption capacity upto five cycles.

Water pollution by industrial sector is a great problem which hampers the sustainable development goals. Dye containing water effluent poses vast challenge to clean water before its discharge in to the surrounding ecosystem. Herein, we prepared humic acid functionalized Fe3O4 nanosorbents through an eco-friendly route and applied for decolorization of carcinogenic dye from water. The nanosorbents was characterized by AFM, BET surface area analyzer, FTIR, SEM-EDX, TEM, TGA/DTG, VSM and XRD. Adsorption experiments were conducted by taking the appropriate amount of dye in different sources of water under ultrasonication. Adsorption process was controlled by chemisorption in nature making pseudo-second-order model most suitable. Multilayer adsorption was taking place on the active sites of nanosorbents showing applicability of Freundlich isotherm model with highest adsorbed amount of 199.986 mg g−1 at 323 K. Rise in temperature favors the remediation of colored effluent thus positive value of ΔH° (74.234 kJ mol−1) and negative value of ΔG° shows endothermic and spontaneous nature of adsorption system. Cationic surfactant CTAB favors the adsorption ( 48%) because of the micelle formation at the surface of nanosorbents. Decolorization from real water samples shows that the adsorption of malachite green was 97, 90, 91, 87, and 86% for Ganga river water, tap water, well water, hand pump water and submersible water, respectively. The used Fe3O4/HA nanosorbents was easily recycled from water samples through 0.1 M HCl and nanosorbents was used up to five cycles with greater percentage of removal at 85%.

The potential of Lantana camara L. in raw (LR) and modified form (LM) for adsorptive removal of two basic dyes, namely Rhodamine B (RB) and methylene blue (MB), from aqueous solution has been investigated. The adsorbent was characterized by various analytical techniques. The results obtained indicate that adsorption of the dyes strongly depends on pH, initial dye concentration, contact time, and presence of surfactant in batch mode and on flow rate and bed depth in column mode. Kinetic studies revealed that removal of the dyes was governed by pseudo-second-order kinetics and a film diffusion mechanism controls the overall rate of the sorption process. The equilibrium adsorption data were interpreted using various isotherm models, and the data were best fit by the Freundlich isotherm model. Modified adsorbent displayed improved adsorption capacity for RB and MB of 34.24–147.05 mg/g and 23.25–111.12 mg/g, respectively, at 30 °C. Thermodynamic parameters indicated that the dye removal process was spontaneous, endothermic, and chemical in nature. The highest desorption efficiency of spent adsorbent was achieved using sulfuric acid (1 M). The results show that LM has considerable potential for removal of RB and MB from aqueous solution.

Adsorptive potential of an agricultural waste, oat hull for the removal of a dye, Malachite Green from aqueous solutions was investigated. The adsorbent was characterized by FTIR, XRD, SEM, and BET. Batch adsorption experiments were conducted to examine the sorption behavior of MG at different adsorbent particle sizes, solution pH, initial dye concentration, contact time and temperature. Optimum conditions were investigated as adsorbent particle size ~ 150 μm; initial pH, 8.0, contact time, 80 min and at 313 K. The study of sorption kinetics was found to be more consistent with pseudo second-order model and film diffusion mechanism was interpreted as rate limiting step. The adsorbate–adsorbent interaction as a function of temperature was assessed and the data fitted better in Freundlich model. The adsorption capacity increases with increasing temperature and maximum Langmuir's adsorption capacity was found to be 83 mg/g at 313 K. Thermodynamic studies indicated that the process of removal of MG was spontaneous in nature. The efficacy of the batch sorption process was further investigated by column experiments. Factors like effect of flow rate and bed depth were examined in column mode. The column sorption data was mathematically treated with bed depth service time (BDST) and Thomas models. The above findings recommend that oat hulls can be successfully used for the decoloration of MG contaminated wastewater.

In this study, a novel bimetallic Fe–Zn nanoparticle was synthesized via a coprecipitation method and applied for the adsorptive removal of carcinogenic dye malachite green (MG) and Congo red (CR) in water. The synthesized bimetallic Fe–Zn nanoparticles were characterized by TEM, XRD, FTIR, and SEM with an attached EDX, a BET surface area analyzer, and by determining pH zpc . Batch adsorption experiments were conducted to evaluate the adsorption process by varying the optimization parameters such as the solution pH, time, and initial dye concentration. The process was initially very rapid, and the maximum adsorption was observed within 60 min of contact time. The kinetics of removal were tested with a pseudo-first order, a pseudo-second order, and an intra-particle diffusion model and showed the best agreement with the pseudo-second order model. Adsorption data were modeled with Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherms and had a good fit with the Langmuir isotherm model. The Langmuir maximum adsorption capacity for MG and CR was found to be 21.74 and 28.56 mg/g, respectively. The adsorption process was endothermic with positive values of Δ H ° of 62.73 and 69.65 kJ/mol for MG and CR, respectively, and was spontaneous, as the Δ G ° value was negative for all of the samples. A positive Δ S ° value indicates increased disorder at the solid–solution interface during the adsorption of the MG and CR dyes. An attempt was made to regenerate the MG- and CR-loaded bimetallic Fe–Zn nanoparticles with suitable eluents and the regenerated bimetallic Fe–Zn nanoparticles were reused seven and six times with removal levels higher than 70% for the adsorption of MG and CR, respectively.

In the present study, SnFe 2 O 4 @activated carbon magnetic nanocomposite was synthesized via co-precipitation route. The as-prepared magnetic nanocomposite was characterized by BET surface area analyzer, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), vibrating sample magnetometer (VSM), and through the determination of pH zpc . The performance of magnetic nanocomposite was further evaluated for its potential in adsorptive removal of cationic dye, crystal violet (CV). The effect of various parameters such as initial dye concentration, contact time, pH, and temperature were also investigated. The adsorption equilibrium data were analyzed by Langmuir, Freundlich, and Dubinin–Radushkevich isotherm models and Langmuir model found to be the most appropriate one. The maximum sorption capacity for the removal of CV was calculated as 158.73 mg/g at 323 K. The adsorption kinetics was analyzed using pseudo-first order, pseudo-second order, and intra-particles diffusion models. Adsorption kinetics reveals better agreement with pseudo-second order model. Investigation of thermodynamic parameters suggests endothermic and spontaneous nature of dye removal process. All these results revealed that the as-prepared magnetic nanocomposite has a remarkable potential for the removal of CV from aqueous solution.

In this paper, the ability of activated carbon obtained from Alligator weed (AAW) to remove tartrazine from aqueous solutions was investigated. The as-prepared AAW was characterized by SEM, FTIR, BET surface area analyzer, and through the determination of pH zpc . The effect of different operational parameters like pH, initial concentration of tartrazine, contact time, and temperature on the sorption behavior was studied in batch mode. The adsorption of tartrazine was favored in acidic medium. The kinetic data were examined using various models viz. pseudo-first order, pseudo-second order, and intra-particle diffusion models. The fitness of the experimental data with pseudo-second order model was evident from the values of correlation coefficient ( R 2 > 0.99). The adsorption equilibrium was modeled with the Langmuir and Freundlich isotherm expressions. The isotherm data were better fitted to Freundlich model which indicates heterogeneous nature of the adsorbent. The Freundlich adsorption capacities ( K F ) were found to be 107.56, 131.67 and 183.4 mg g −1 at 30, 40 and 50 °C, respectively. The negative values of Δ G ° and positive value of Δ H ° demonstrated that the adsorption of tartrazine onto AAW were spontaneous and endothermic in nature, respectively. The regenerated AAW can be reused 4 times for the adsorption of tartrazine.

In present work takovite, anionic clay was synthesized by urea hydrolysis method and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermo gravimetric analysis (TGA-DTA). Using this anionic clay, the interaction of Cu(II) was studied in aqueous solutions in a batch system to study the effect of various parameters such as initial concentrations (5–25 mg L − 1 ), adsorbent dose (1–10.0 g/L), temperature (303–323 K), pH (3–7) and contact time (15–120 min.). The percentage removal increased with the increase in takovite dose, while the percentage removal decreased with increasing of initial concentrations of Cu(II). The synthesized takovite adsorbed 98.54% of Cu (II) from the synthetic waste water within 120 min at neutral pH, 7.0. The equilibrium studies show that adsorption follows Langmuir isotherm at all temperatures (303–323 K). Kinetic and thermodynamic studies were performed on different initial concentrations of Cu(II). Kinetic studies showed that the data followed pseudo-second order kinetic model. Negative values of Gibb's free energy change (∆G°), positive value of enthalpy change (∆H°) and negative value of entropy change (∆ S°) shows that the adsorption was feasible, spontaneous, and endothermic in nature. Used takovite can be easily regenerated by 0.1 M NaHCO 3 .

The continuous discharge of heavy metals into the near water bodies causes great harm to the human and aquatic ecosystem. Several adsorbent have been developed and applied for effective removal of metal ions from water. In this paper nitrilotriacetic acid (NTA) functionalized Fe3O4 nanoparticles (Fe3O4-NTA) were developed by coprecipitation method with iron salt and NTA, shown to be effective removal of Cu(II) ions from aqueous solution. The functionalized nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR), X ray diffractometer (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), Brunauer–Emmett–Teller Surface area analyzer (BET), and pHzpc. The various effecting factors of Cu(II) ions adsorption from aqueous solution such as contact time, adsorbate dose, and pH were investigated. The kinetics models such as pseudo-first-order, pseudo-second-order, Elovich, and intra-particles diffusion were applied on experimental Cu(II) adsorption. The kinetic data showed pseudo-second-order model was found to be better agreement with correlation coefficient, R2 = 0.997–0.999 at 60–12 mg L−1. The equilibrium adsorption data modeled with Langmuir, Freundlich, and Dubinin–Radushkevich isotherms found to be better fitted with Langmuir reveal the monolayer adsorption of Cu(II) ions on the surface of Fe3O4-NTA with maximum adsorption capacity of 34.63, 38.8 and 40.24 mg L−1 at 298, 303 and 308 K, respectively. The positive value of ΔH° (35.127 kJ mol−1) and ΔS° (176.031 kJ mol−1 K−1) indicates the endothermic nature of Cu(II) adsorption onto Fe3O4-NTA. The negative value of ΔG° (7.365–8.005 kJ mol−1) indicates spontaneous nature of adsorption.

The present communication addresses the applicability of acid-modified wheat husk for the adsorptive removal of an anionic dye, Acid Orange 10 (AO-10) from aqueous solutions. The adsorbent was characterized by FTIR and SEM. The adsorption reached equilibrium within 30 min, and the percentage removal increased with contact time, adsorbent dosage, and ionic strength. Low pH condition enhances AO-10 sorption. The experimental data for kinetic study agrees with pseudo-second-order model. Detailed investigation of experimental kinetic data indicates that overall sorption rate is governed by film diffusion mechanism. The adsorption behavior followed a Freundlich adsorption isotherm with high correlation coefficient and low χ2 values. The maximum adsorption capacity was found to be 31.25 mg/g. The results of thermodynamic study demonstrated that the adsorption process was spontaneous and exothermic in nature. Desorption studies revealed that the adsorbent could be reused for two successive trials without...

Superparamagnetic Fe 3 O 4 nanoparticles were synthesized by co-precipitation method and characterized for TEM, XRD, FTIR, TGA/DTG, BET surface area, VSM, SQUID, and through the determination of pH zpc . The Fe 3 O 4 magnetic nanoparticles were used for the removal of Ni(II) from aqueous solutions. The removal of Ni(II) is strongly dependent on pH of the medium with enhanced adsorption as the pH turns from acidic to alkaline side. The process was very fast initially and the maximum adsorption was observed within 35 min of contact time. The kinetics of the removal, tested with pseudo-first-order, pseudo-second-order and intra-particles diffusion model, showed better agreement with pseudo-second-order rate kinetics (k 2 = 6.740 × 10 − 7 to 8.023 × 10 − 9 g mg − 1 min − 1 ). The adsorption data was modeled with Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin isotherms and yielded good fit with the Freundlich isotherm model. The nanoscale Fe 3 O 4 particles have considerable Langmuir adsorption capacity to Ni(II) removal in the range of 209.205 to 362.318 mg g − 1 . The adsorption process was endothermic with a positive value of ΔH (101.209 kJ mol − 1 ) and spontaneous in nature (ΔG: − 13.338 to − 17.266 kJ mol − 1 ). The results have established good potentiality of the Fe 3 O 4 nanoparticles to remove Ni(II) from aqueous solutions.

Preparation of the activated carbon biosorbents from Lantana camara weed by sulphuric acid activation was carried out. Laboratory prepared activated carbon was used as adsorbents for the removal of an acidic dye tartrazine from aqueous solutions. Liquid-phase adsorption experiments were conducted and the maximum adsorption capacity of activated carbon was determined. The effects of various process parameters, i.e., temperature, pH, initial tartrazine concentration, contact time on the adsorption capacity of activated carbon were investigated. The kinetic models for tartrazine adsorption onto activated carbon were studied. Freundlich isotherm (KF, 98.401 L g−1) showed better fit than Langmuir isotherm (Q0, 90.900 mg g−1) for the activated carbon. The rates of adsorption were found to confirm the pseudo-second-order kinetics with good correlation. The separation factor (RL) revealed the favorable nature of the isotherm of the tartrazine-activated carbon system. The values of activation parameters such as free energy (ΔG°, −10.346 to −10.983 kJ mol−1), enthalpy (ΔH°, 22.976 kJ mol−1) and entropy (ΔS°, 154. 555 J mol−1 k−1) were determined, respectively, indicating that the adsorption was spontaneous, endothermic and favorable process in nature.

Wastewater contaminated with chromium(VI) ions was released in the aquatic environment during different industrial processes and is considered dangerous, since chromium(VI) is a powerful epithelial irritant and a human carcinogen. It is therefore required to develop new materials that can effectively used to remove metallic species from liquid phase. In this perspective layered double hydroxides (LDHs) with Co/Bi = 3 were synthesized via urea hydrolysis method. The as-prepared LDH material was further characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). The adsorption behavior of Cr (VI) was studied at different initial concentrations (100–500 mg/L), contact time (15–120 min), pH (2.0–12.0), temperature (298–318 K) and adsorbent dose (0.1–0.5 g) by batch equilibrium technique. Adsorption experiments indicate that the maximum adsorption capacity of Cr(VI) reached to 277.7 mg/g on the optimum adsorption conditions (dosage of 0.1 g, contact time for 120 min., pH at 7 and temperature at 283 K). The kinetic data agrees well with pseudo-second order ( R 2 = 0.995). The adsorption isotherm study reveals that experimental data fitted well in both Freundlich and Redlich–Peterson model. The study of thermodynamic parameters indicated that adsorption of Cr(VI) is spontaneous and exothermic in nature. Desorption study recommends that adsorbent can be easily regenerated by 0.1 M NaHCO 3 .

The adsorption behavior of methylene blue on as-synthesized alumina nanoparticles has been investigated. The adsorbent was characterized by Fourier transform infrared spectroscopy (FTIR), TG/DTA/DTG, X-ray diffractrometry and scanning electron microscopy. N2 adsorption–desorption measurements were carried out to analyze the porous structure and surface area of the adsorbent and results revealed that the adsorbent is mesoporous with a specific surface area of 76 m2 g−1. Batch experiments indicated that solution pH, initial dye concentration, contact time, temperature and the presence of ions had prominent impact on the dye removal process. The sorption kinetic data were found to be in accordance with pseudo-second order kinetics. The mechanistic interaction of the adsorbate–adsorbent system was also interpreted with the help of Weber–Morris model and the Boyd model and it was found that the adsorption process is controlled by a film diffusion mechanism. The investigation of adsorption isotherms suggested that the data fitted Langmuir isotherm model. The values the thermodynamic parameters for the process of removal were determined and the negative values change in free energy, ΔG0, indicated the spontaneous nature of the sorption process. A high desorption efficiency of 90.11% indicated a possible regeneration of the adsorbent. The adsorbent displayed almost the same adsorption capacity even after three cycles of regeneration bringing down the cost of treatment.

In recent years, microbial degradation and bioremediation approaches of polychlorinated biphenyls (PCBs) have been studied extensively considering their toxicity, carcinogenicity and persistency potential in the environment. In this direction, different catabolic enzymes have been identified and reported for biodegradation of different PCB congeners along with optimization of biological processes. A genome analysis of PCB-degrading bacteria has led in an improved understanding of their metabolic potential and adaptation to stressful conditions. However, many stones in this area are left unturned. For example, role and diversity of uncultivable microbes in PCBs degradation is still not fully understood. Improved knowledge and understanding on this front will open up new avenues for improved bioremediation technologies which will bring economic, environmental and societal benefits. This article highlights on recent advances in bioremediation of PCBs in soil. It is demonstrated that bioremediation is the most effective and innovative technology which includes biostimulation, bioaugmentation, phytoremediation, rhizoremediation etc. and acts as a model solution for pollution abatement. More recently, transgenic plants and genetically modified microorganisms have proved to be revolutionary in the bioremediation of PCBs. Additionally, other important and aspects such as pretreatment using chemical/physical agents for enhanced biodegradation are also addressed. Efforts have been made to identify challenges, research gaps and necessary approaches which in future can be harnessed for successful use of bioremediation under field conditions. Emphases have been given on the quality/efficiency of bioremediation technology and its related cost which determines its ultimate acceptability.

Density and dynamic viscosity of binary mixtures of water and tartrazine have been measured over the entire concentration regime in the temperature range (293.15–333.15 K) at 5 K intervals. A Mettler Toledo, DE45 delta range density meter and an automated Anton Paar microviscometer were used for the measurements of density and viscosity respectively. A peltier based thermostat is incorporated in both instruments for the regulation of temperature with a precision of ±0.1 K. Temperature dependent density has been utilized for evaluation of thermal expansivity and heat capacity ratio. Temperature dependence of density and thermal expansivity for this system have been described by an empirical second-order quadratic polynomial equation and viscosity data were analysed by a simple linear equation. The results have been critically discussed in terms of specific and molecular interactions.

Keeping in view the importance of thermophysical studies of ionic liquid + polymer systems, thermal expansivity of binary mixtures of 1-butyl-3-methylimidazolium hexafluorophosphate + poly(ethylene glycol) has been evaluated from variation in density with temperature, in order to investigate the extent and magnitude of specific and molecular level interactions. A slight monotonic decrease in expansivity values was observed throughout the concentration regime of 1-butyl-3-methylimidazolium hexafluorophosphate + poly(ethylene glycol). Study reveals the presence of complex electrostatic interaction involving both attractive and repulsive forces actively involved in the mixture.

Citric acid coated magnetite nanoparticles (Fe 3 O 4 -Cit) have been synthesized for the removal of cadmium from aqueous solutions. As-prepared Fe 3 O 4 -Cit was characterized by using Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometer (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and through the determination of pH zpc . Several factors effecting the adsorption of Cd(II) ions on the surface of Fe 3 O 4 -Cit such as pH, temperature and contact time were investigated. The Cd(II) ions adsorption equilibrium on the Fe 3 O 4 -Cit were obtained by 35 min at the optimized pH 5. Kinetic study shows the Cd(II) adsorption onto Fe 3 O 4 -Cit follow the pseudo-second order kinetic model with R 2 > 0.997 at 308 K. The adsorption data was satisfactorily explained by Langmuir and Freundlich isotherm models. The experimental data found to be suitable linearity with Langmuir isotherm having maximum adsorption capacity ( q m ) values in mg g −1 10.81, 11.45 and 12.56 at the 298 K, 303 K and 308 K, respectively. The correlation coefficient R 2 = 0.997 fully supports the favorability of Langmuir isotherm in adsorption process. The negative values of Δ G °, −5.68, −6.31 and −6.95 kJ mol −l throughout the temperature at 298 K, 303 K and 308 K are indicating the feasibility of adsorption process on to Fe 3 O 4 -Cit was spontaneous in nature.

Adsorption of an anthraquinone dye Alizarin Red S onto biosorbent of Lantana camara has been studied on aqueous solutions. The batch adsorption experiments were conducted using simulated aqueous solutions and the effects of initial dye concentration, pH of solution, contact time and temperature were investigated. The prepared biosorbent was characterized using FTIR, SEM, elemental analysis and through the determination of pHzpc. The equilibrium data were modeled with Langmuir and Freundlich isotherms. Freundlich model fitted very well with the equilibrium adsorption data and this provided evidence of multilayer adsorption of the dye molecules onto the active sites on the biosorbent. The kinetic studies revealed that the process was quite rapid and more than 90 % of equilibrium capacity was achieved within 80 min. The rates of adsorption were found to confirm to the pseudo-second-order kinetics with good correlations (R 2 > 0.99). The thermodynamic studies showed that the Alizarin Red S-biosorbent system is spontaneous, exothermic and favourable in nature.

Measurements of density and dynamic viscosity of binary mixtures of water + sodium dodecylbenzenesulphonate (SDBS) solutions have been carried out over the entire concentration regime in the temperature range (298.15 K to 333.15 K) at 5 K intervals. The densities were measured by using a Mettler Toledo, DE45 delta range density meter, based on electromagnetically induced oscillations of a U-shaped glass tube. An automated Anton Paar microviscometer was used for the measurement of dynamic viscosities. Both the instruments have an automatic temperature control system maintained by Peltier effect. Temperature dependent densities were satisfactorily correlated with a second order quadratic polynomial equation and dynamic viscosities were correlated with Arrhenius equation. Various useful thermodynamic parameters viz. thermal expansion coefficient and apparent molar volume have been calculated from density data. The results are critically discussed in terms of interactions. The work mainly focuses on environmental consideration and significance of thermodynamic and transport properties data of ubiquitous environmental pollutant (SDBS) and their utilisation in the improvement of design and calculation methods for its treatment and separation processes to minimize its toxicity and environmental hazards.

Heavy metals released from industrial activities pose a significant threat to the environment and public health due to their reported toxicity even at trace levels. Although there are several available methods to treat or remove heavy metals from water and wastewater, the research focuses on development of technological solutions which sound environmental friendly and economically feasible, able to reduce the costs and maximize the efficiency. In this framework, the biosorption process, which uses cheap and non-pollutant materials, may be considered as an alternative, viable and promising, technology for heavy metal and metalloid ions sequestration and ultimately removal technology in the waste water treatment. However, there is as yet little data on full-scale applications for the design and testing of adsorption units using single biosorbents and their combinations to sequester heavy metal ions from multi-metal systems. Immediate research and development is hence earnestly required in this specific direction to further make progress this blooming technology and widen its scope of application to real situations needing heavy metal pollution remediation. This review provides a comprehensive appraisal of the equilibrium modeling of a number of biosorption processes as well as the structural, chemical and morphological modifications and activation of biosorbents. Further the relative merits of the methods used to recover sequestered heavy metal ions and regenerate biosorbents through desorption routes and their future applications are discussed.

The kinetics, adsorption isotherms, thermodynamics and spectroscopic analyses of the removal of the anthraquinone dye, Alizarin Red S by adsorption onto mustard husk were studied. Batch adsorption experiments were conducted using synthetic aqueous solutions and the effects of initial dye concentration, initial pH of solution, adsorbent dose and temperature were investigated. The mustard husk adsorbent was characterized using Fourier transform infrared spectroscopy, scanning electron microscopy and through the determination of pH zpc . The equilibrium adsorption data fitted very well to the Freundlich model and this provided evidence of multilayer adsorption of the dye molecules onto the active sites on the biosorbent. The kinetic studies showed that the process was quite rapid and 90% of equilibrium capacity was achieved within 80 min. The process followed the pseudo-second-order kinetic model with a k 2 value of 0.094 g/mg min for an Alizarin Red S concentration of 25 mg/L. Positive Δ H ° and negative Δ G ° were indicative of the endothermic and spontaneous nature, respectively, of Alizarin Red S removal by adsorption onto mustard husk biomass.

Water pollution by anthropogenic activities is proving to be of critical concern as the heavy metals affect aquatic organisms and can quickly disperse to large distances. This poses a risk to both human health and the aquatic biota. Hence, there is a need to treat the wastewater containing toxic metals before they are discharged into the water bodies. During recent years, magnetic nanoparticles came to the foreground of scientific interest as a potential adsorbent of novel wastewater treatment processes. Magnetic nanoparticles have received much attention due to their unique properties, such as extremely small size, high surface-area-to-volume ratio, surface modifiability, multi functionality, excellent magnetic properties, low-cost synthesis, and great biocompatibility. The multi-functional magnetic nanoparticles have been successfully applied for the reduction of toxic metal ions up to ppb level in waste-treated water. This chapter highlights the potential application of magnetic nanoparticles for the removal of heavy metals.

Environmental Chemistry Research Laboratory, Department of Chemistry, University of Allahabad, Allahabad-211 002, Uttar pradesh, India E-mail : sushbanerjee9@gmail.com Fax : 91-532-2541786 In this work, the performance of a nanocrystalline LSCF composite as a cathode material was investigated. The cathode LSCF composite was successfully synthesized via gel-combustion route. The synthesized LSCF composite material was characterized for microstructural and electrochemical performance by SEM, XRD, BET, FTIR, TGA-DTA, and impedance spectroscopy. The prepared LSCF material shows the high surface area of 68 m2/g. The XRD analysis reveals the nanocrystalline structure of synthesized material. FTIR spectra confirm the formation of mixed metal oxide at high temperature. TGA/DTA analysis reveals that the synthesized LSCF composite is highly stable at high temperatures. The impedance measurement suggested that as-synthesized LSCF composite material can be used as cathode in the fabrication of IT- OFCs.

Environmental Chemistry Research Laboratory, Department of Chemistry, University of Allahabad, Allahabad-211 002, Uttar Padesh, India E-mail : ravindragautam1987@gmail.com, mcc46@rediffmail.com Manuscript received online 15 February 2015, accepted 28 April 2015 Superparamagnetic Fe3O4 nanoparticles with diameter of ~7 nm were prepared by a colloidal method, without employing surfactants and using precursors like FeCl3·6H2O, FeSO4·7H2O, deionized water and using NH4OH solution (29% vol.) as precipitating agent. The synthesized product was characterized by X ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy attached with energy dispersive X-ray (SEM-EDS), Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett- eller (BET) surface area, thermogravimetric analysis (TGADTG), and atomic force microscopy (AFM). The hysteresis loops of the magnetite nanoparticles were measured using a superconducting quantum interference device (SQUID) and the results showed a superparamagnetic behavior at room temperature. &nbsp

Advanced oxidation processes constitute important, efficient, promising, catalytic, and environmentally friendly materials designed for the remediation of recalcitrant pollutants from industrial effluents. Commonly, the advanced oxidation processes are based on the in situ generation of highly reactive radical species (•OH) generation, which plays a significant role in the catalytic degradation and decontamination of wastewater. In recent decades, major achievements have been made in advanced oxidation process–based techniques, which include ozonation, sonochemical degradation, electrochemical remediation, heterogeneous catalysis, Fenton’s oxidation, and photo-Fenton’s oxidation. In this chapter, the principles, chemical performances, reaction mechanisms, advantages, and applications of advanced oxidation processes in the degradation of some organic compounds are provided.

Monitoring and separating metal ions in water samples is a challenge to analysts and environmental engineers due to their toxicity and carcinogenicity on humans and animals. Various technologies such as membrane filtration, bioremediation, coagulation, precipitation, adsorption, and advanced oxidation processes have been utilized to decontaminate the heavy metals from aquatic systems. In recent years, separation technology supported on graphene-based nanostructure materials has received considerable attention. This chapter highlights the review of literature dealing with the application of graphene-based materials to the separation and preconcentration of metal ions and metalloids in water samples. The high surface area to volume ratio graphene or graphene oxide doped with inorganic and organic moieties have gained much attention. The graphene-based magnetic nanoparticles have been widely utilized for the removal of heavy metals from aqueous systems as they can be easily separated and regenerated with an external magnet. The magnetic extraction method is not only convenient, economical, and highly efficient but it also overcomes problems with conventional solid-phase extraction as the adsorbent–adsorbate system gains equilibrium within a shorter time as compared with conventional techniques. However, there is urgent need to conduct experiments regarding their use in column studies and on industrial scales.

Rapid industrialization, haphazard urbanization, and tremendous growth in population have discharged huge amounts of environmental contaminants into aquatic ecosystems such as ponds, lakes, rivers, and estuaries, affecting millions of people worldwide. Thus management of contaminants has become a major environmental issue. Nanotechnology plays a vital function in the remediation of pollutants from water and wastewater. During the recent few decades the scientific community is developing novel nanomaterials which can be efficiently utilized for water treatment. Nanoscale materials of mixed-metal oxides, such as magnetic nanomaterials, layered double hydroxides, metal organic frameworks, bimetallic nanoparticles, nanocatalysts, and graphene-based nanocomposites, have been widely developed and utilized for the separation and purification of hazardous pollutants from aqueous solutions because of their high surface area to volume ratio, high physicochemical stability, biocompatibility, and efficient regeneration of utilized nanoadsorbents. These nanomaterials have been widely used in the degradation, treatment, and remediation of aqueous environmental contaminants such as phenols, heavy metals, metalloids, anionic and cationic dyes, pharmaceuticals, and organic pollutants from wastewater before their discharge into the nearby water bodies. Nowadays, it has become a hot topic to develop novel nanoscale materials and evaluate their removal performance for environmental contaminants under varying experimental conditions. Adsorption–desorption of pollutants from aqueous media to the interface of nanoadsorbents has been evaluated as a crucial technique and has been modeled to get favorable optimization conditions by mathematical equations. A lot of attempts have been made to understand the removal of pollutants using kinetic rate equations. In this chapter, an overview on the recent advances made in the field of nanomaterials is presented.

Pollution by metal and metalloid ions is one of the most widespread environmental concerns. They are non-biodegradable, and, generally, present high water solubility facilitating their environmental mobilisation interacting with abiotic and biotic components such as adsorption onto natural colloids or even accumulation by living organisms, thus, threatening human health and ecosystems. Therefore, there is a high demand for effective removal treatments of heavy metals, making the application of adsorption materials such as polymer-functionalized nanocomposites (PFNCs), increasingly attractive. PFNCs retain the inherent remarkable surface properties of nanoparticles, while the polymeric support materials provide high stability and processability. These nanoparticle-matrix materials are of great interest for metals and metalloids removal thanks to the functional groups of the polymeric matrixes that provide specific bindings to target pollutants. This review discusses PFNCs synthesis, characterization and performance in adsorption processes as well as the potential environmental risks and perspectives.

Contamination of aquatic environments has become an important problem during the last couple of decades, and when the contaminant persists in the water beyond its permissible limits it may cause some harmful and toxic effects, sometimes posing mutagenic and carcinogenic risks to aquatic organisms and humans. Environmental scientists are continuously developing low-cost and high-efficiency tools for the monitoring and remediation of aquatic pollutants. Many technologies, such as coagulation, flocculation, membrane filtration, photo-Fenton oxidation, electrochemical reduction, and adsorption, have been designed and developed for the removal of heavy metals and organic pollutants from aqueous solutions. This chapter highlights emerging technologies for the efficient separation and purification of environmental contaminants from aquatic systems.

Magnetically recyclable nanophotocatalysts have gained much attention during the last few years because of their high surface area, low band gap, high efficiency, economic viability, and excellent recyclability. Iron oxide–based cores and coatings via various types of semiconductor materials have been successfully tested as photocatalysts for the treatment and remediation of dyes, chlorophenols, nitrophenols, DDT, DDE, arsenic, and chromium from water and wastewater under the presence of visible or UV light. In this chapter, the synthesis, characterization, and application of magnetically separable photocatalysts have been presented. The photocatalytic degradation mechanisms of various pollutants present in wastewater have been critically discussed.