Adsorption kinetics and thermodynamics of organophosphorus profenofos pesticide onto Fe/Ni bimetallic nanoparticles

Bimetallic Fe/Ni nanoparticles were synthesized and used for the removal of profenofos organophosphorus pesticide from aqueous solution. These novel bimetallic nanoparticles (Fe/Ni) were characterized by scanning electron microscopy, energy-dispersive X-ray analysis spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The effect of the parameters of initial pesticide concentration, pH of the solution, adsorbent dosage, temperature, and contact time on adsorption was investigated. The adsorbent exhibited high efficiency for profenofos adsorption, and equilibrium was achieved in 8 min. The Langmuir, Freundlich, and Temkin isotherm models were used to determine equilibrium. The Langmuir model showed the best fit with the experimental data (R ² = 0.9988). Pseudo-first-order, pseudo-second-order, and intra-particle diffusion models were tested to determine absorption kinetics. The pseudo-second-order model provided the best correlation with the results (R ² = 0.99936). The changes in the thermodynamic parameters of Gibb’s free energy, enthalpy, and entropy of the adsorption process were also evaluated. Thermodynamic parameters indicate that profenofos adsorption using Fe/Ni nanoparticles is a spontaneous and endothermic process. The value of the activation energy (E _a = 109.57 kJ/mol) confirms the nature of the chemisorption of profenofos onto Fe/Ni adsorbent.     

Removal of cadmium (II) from aqueous solution and natural water samples using polyurethane foam/organobentonite/iron oxide nanocomposite adsorbent

A novel polyurethane foam/organobentonite/iron oxide nanocomposite adsorbent was successfully prepared via in situ polymerization of toluene diisocyanate and polyol in presence of 5 wt% organobentonite/iron oxide. The obtained nanocomposite was characterized in detail, and the results revealed that the clay layers are exfoliated and/or intercalated in the polymer matrix forming a nanocomposite structure. The application of the prepared nanocomposite for adsorption of cadmium ions from aqueous solution was tested as a function of various experimental parameters using batch procedures. Adsorptive removal of Cd(II) onto the nanocomposite attained maximum at adsorbent content 1.5 g/L, pH 6, and the equilibrium was established within 60 min. Kinetic studies showed that the experimental data fit very well to pseudo-second-order model, and the adsorption process proceeds through three steps. It was found that external liquid film and intraparticle diffusion steps deeply affect the rate of Cd²⁺ ions adsorption onto the synthesized nanocomposite. Langmuir isotherm model fitted the adsorption data better than Freundlich with a maximum adsorption capacity (q _m) for Cd(II) equal to 78 mg/g under the specified experimental conditions. The synthesized nanocomposite afforded effective extraction for Cd²⁺ ions from natural water samples and excellent reusability feature. This study declares the potential efficiency of a new clay/polymer nanocomposite as alternative for wastewater remediation.     

A zinc oxide-coated nanoporous carbon adsorbent for lead removal from water: Optimization, equilibrium modeling, and kinetics studies

A zinc oxide-coated nanoporous carbon sorbent was prepared by acid modification and ZnO functionalization of mesoporous carbon. The synthesized materials, such as mesoporous carbon, oxidized mesoporous carbon and zinc oxide-coated nanoporous carbon, were characterized by nitrogen adsorption–desorption analysis, Fourier transform infrared spectra, scanning electron microscopy, and transmission electron microscopy. ZnO on oxidized mesoporous carbon gradually increased with increase in the number of cycles. Furthermore, the effects of agitation time, initial metal ions concentration, adsorbent dose, temperature and pH on the efficiency of Pb(II) ion removal were investigated as the controllable factors by Taguchi method. The value of correlation coefficients showed that the equilibrium data fitted well to the Langmuir isotherm. Among the adsorbents, zinc oxide-coated nanoporous carbon showed the largest adsorption capacity of 522.8 mg/g (2.52 mmol/g) which was almost close to that of the zinc oxide-coated (2.38 mmol/g), indicating the monolayer spreading of ZnO onto the oxidized mesoporous carbon. The results of the present study suggest that ZnO-coated nanoporous carbon can be effectively used for Pb(II) adsorption from aqueous solution, whereas a part of acidic functional groups may be contributed to binding the Pb(II) for the oxidized mesoporous carbon and mesoporous carbon. Kinetic studies indicated that the overall adsorption process of Pb(II) followed the pseudo-second-order model. The ZnO-coated nanoporous carbon was regenerated and found to be suitable of reuse of the adsorbent for successive adsorption–desorption cycles without considerable loss of adsorption capacity.     

http://dx.doi.org/10.1016/j.gsf.2015.11.003

Banded iron formations(BIFs) are major rock units having hematite layers intermittent with silica rich layers and formed by sedimentary processes during late Archean to mid Proterozoic time. In terrestrial environment, hematite deposits are mainly found associated with banded iron formations. The BIFs in Lake Superior(Canada) and Carajas(Brazil) have been studied by planetary scientists to trace the evolution of hematite deposits on Mars. Hematite deposits are extensively identified in Meridiani region on Mars. Many hypotheses have been proposed to decipher the mechanism for the formation of these deposits. On the basis of geomorphological and mineralogical studies, aqueous environment of deposition is found to be the most supportive mechanism for its secondary iron rich deposits. In the present study, we examined the spectral characteristics of banded iron formations of Joda and Daitari located in Singhbhum craton in eastern India to check its potentiality as an analog to the aqueous/marine environment on Mars. The prominent banding feature of banded iron formations is in the range of few millimeters to few centimeters in thickness. Fe rich bands are darker(gray) in color compared to the light reddish jaspilitic chert bands. Thin quartz veins(4 mm) are occasionally observed in the handspecimens of banded iron formations. Spectral investigations have been conducted in VIS/NIR region of electromagnetic spectrum in the laboratory conditions. Optimum absorption bands identified include 0.65, 0.86, 1.4 and 1.9 mm, in which 0.56 and 0.86 mm absorption bands are due to ferric iron and 1.4 and1.9 mm bands are due to OH/H_2O. To validate the mineralogical results obtained from VIS/NIR spectral radiometry, laser Raman and Fourier transform infrared spectroscopic techniques were utilized and the results were found to be similar. Goethite-hematite association in banded iron formation in Singhbhum craton suggests dehydration activity, which has altered the primary iron oxide phases into the secondary iron oxide phases. The optimum bands identified for the minerals using various spectroscopic techniques can be used as reference for similar mineral deposits on any remote area on Earth or on other hydrated planetary surfaces like Mars.     

Dye removal from aqueous solutions using novel nanocomposite hydrogel derived from sodium montmorillonite nanoclay and modified starch

A novel nanocomposite hydrogels (NCHs)-based polysaccharide was synthesized by incorporating Na-montmorillonite (NaMMT) nanoparticles (NPs) into poly acrylic acid and polyacrylamide grafted onto starch [P(AA–AAm)-g-starch] hydrogel. The conditions applied in this synthesis were optimized using the Taguchi orthogonal experimental design method. The characterization of NaMMT NPs/P(AA–AAm)-g-starch NCH was performed by Fourier transform infrared, thermogravimetric analysis, scanning electron microscopy/energy-dispersive X-ray, and atomic force microscopy analyses. The resulting optimized NCH showed improved pH-dependent swelling and enhanced safranin adsorption capacity compared to pure hydrogel and NaMMT NPs. Its adsorption process could be described very well by pseudo-second-order and Elovich kinetic models. The adsorption isotherm was followed by Freundlich isotherm models. The conclusion confirms the prospect of NCH as an effective adsorbent for the adsorption of dyes from aqueous solutions.     

The dynamics of cyanobacterial silicification: an infrared micro-spectroscopic investigation

The dynamics of cyanobacterial silicification was investigated using synchrotron-based Fourier transform infrared micro-spectroscopy. The changes in exo-polymeric polysaccharide and silica vibrational characteristics of individual Calothrix sp. filaments was determined over time in a series of microcosms in which the microbially sorbed silica or silica and iron load was increased sequentially. The changes in intensity and integrated area of specific infrared spectral features were used to develop an empirical quantitative dynamic model and to derive silica load-dependent parameters for each quasi-equilibrium stage in the biomineralization process.The degree of change in spectral features was derived from the increase in integrated area of the combined silica/polysaccharide region (Si-O/C-O, at 1150-950 cm⁻¹) and the Si-O band at 800 cm⁻¹, the latter representing specific silica bonds corresponding to hydrated amorphous SiO₄ tetrahedra. From the degree of change, a two-phase model with concurrent change in process was derived. In the first phase, a biologically controlled increase in thickness of the exo-polymeric polysaccharide sheath around the cell was observed. In phase two, a transition to an inorganically controlled accumulation of silica on the surface of the cyanobacterial cells was derived from the change in integrated area for the mixed Si-O/C-O spectral region. This second process is further corroborated by the synchronous formation of non-microbially associated inorganic SiO₄ units indicated by the growth of the singular Si-O band at 800 cm⁻¹. During silicification, silica accumulates (1) independently of the growth of the sheath polysaccharides and (2) via an increase in chain lengths of the silica polymers by expelling water from the siloxane bonds. IR evidence suggest that an inorganic, apparently surface catalyzed process, which leads to the accumulation of silica nanospheres on the cyanobacterial surfaces governs this second stage. In experiments where iron was present, the silicification followed similar pathways, but at low silica loads, the iron bound to the cell surfaces slightly enhanced the reaction dynamics.     

Mesoporous material Al-MCM-41 from natural halloysite

Aluminum-containing hexagonally ordered mesoporous silica (Al-MCM-41) with specific surface area of 509.4 m²/g was first synthesized using natural halloysite as source material by hydrothermal treatment, without addition of silica or aluminum regents. The samples were characterized by X-ray diffraction, transmission electron microscopy, N₂ adsorption–desorption measurements, and Fourier transform infrared spectra techniques. The results indicate that process parameters, including calcination temperature, pH value, n(SiO₂)/n(CTAB)/n(H₂O) ratio, and hydrothermal reaction time, show moderate effects on the preparation of Al-MCM-41. SiO₂/Al₂O₃ molar ratio could be effectively modulated by the calcination temperature for halloysite. Furthermore, we first clarified the structural evolution from natural halloysite to mesoporous material Al-MCM-41 at the atomic level.     

Equilibrium studies on removal of lead (II) ions from aqueous solution by adsorption using modified red mud

In the present experimental study, solid waste was used as an adsorbent and the effectiveness of the adsorbent was increased by novel treatment methods. Red mud, acid-treated activated red mud and iron oxide-coated acid-treated activated red mud were used for the removal of lead (II). The structural and functional groups were identified to confirm the removal of lead (II) by powder X-ray diffraction and Fourier transform infrared spectroscopy analyses. The enhancement of surface area was confirmed by Brunauer–Emmett–Teller analysis. Batch adsorption experiment was also conducted, and various parameters such as the effect of adsorbent dosage, pH, contact time and initial ion concentration were analyzed and reported. Adsorption equilibrium data were investigated using Langmuir, Freundlich and Dubinin–Radushkevich isotherm models with three parameters, and the rate of reaction was examined through kinetic models. The results indicate that in particular a novel modified form of red mud, namely iron oxide-coated acid-treated activated red mud was well fitted in lead (II) removal compared with reported adsorbents. The Langmuir isotherm shows that the maximum adsorption of adsorbate per gram was greater than other adsorbents (27.02 mg/g). In Freundlich isotherm, the Freundlich constant n values lie between 1 and 10 indicate the favorable adsorption. The calculated n values for normal red mud, acid-treated activated red mud and iron oxide-coated acid-treated activated red mud were found to be 1.9, 2.1 and 2.0 respectively. The correlation coefficient value was higher and the rate of reaction follows the pseudo-second-order kinetic model.     

Response surface methodology (RSM) optimization approach for degradation of Direct Blue 71 dye using CuO–ZnO nanocomposite

The present study highlights the synthesis of CuO–ZnO nanocomposite via facile hydrothermal method at 150 °C and autogenous pressure. The structural and textural features of prepared composite material was characterized by several characterization techniques such as X-ray powder diffraction, Fourier transform infrared spectroscopy, Scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The optimized prepared nanocomposite was utilized for photocatalytic degradation of aromatic Direct Blue 71 dye (DB71) under natural sunlight conditions. The catalytic activity results by CuO–ZnO nanocomposite were observed to be higher than the reagent-grade zinc oxide under visible light conditions. The response surface methodology protocol (RSM) with central composite design was optimized by different photodegradation operational parameters such as pH, dye concentration, catalyst amount, and reaction time. The optimized RSM results demonstrated that a quadratic polynomial model was found suitable to define the relation between the photocatalytic activity and operational parameters. Moreover, the observed high R ² value (0.9786) confirms a strong evaluation of experimental data. To achieve maximum DB71 degradation, optimized condition was found at 177.13 min of contact time, 3.93 solution pH, and 24.34 mg/L of dye concentration with 1.85 g/L of catalyst dose The identical optimum conditions resulted maximum 89.58% DB71 degradation.     

Characterization and efficacy of a new generation scavenger of heavy metal pollutant: a green method of remediation of wastewater

The presence of heavy metals in diverse forms in the environment (which is having a direct and continuous interface with the health of living beings) demands an efficient removal technique which would be cost effective, eco-friendly, easily operable and free of secondary waste. Hence, the useless and discarded leaves of Cissus rotundifolia have been valorized by utilizing it for the removal of heavy metal pollutant after its modification. The developed adsorbent is then characterized through X-ray diffraction study, scanning electron microscope analysis, Fourier transform infrared spectroscopy and application of mathematical models. The adsorption process was found to follow Langmuir isotherm model and pseudo-first-order kinetics. The intraparticle diffusion was found to be the rate limiting step. Besides being usable in batch method, this adsorbent is also applicable to fixed bed column technique, due to its faster kinetics, high hydrophilicity, and easy recovery with mild mineral acid (like 0.002 mol per liter of hydrochloric acid).     

Synthesis of poly(amidoamine)-graft-poly(methyl acrylate) magnetic nanocomposite for removal of lead contaminant from aqueous media

Poly(amidoamine)-graft-poly(methyl acrylate) magnetic nanocomposite was synthesized via radical polymerization of methyl acrylate onto modified magnetic nanoparticles followed by the functionalization of the methyl ester groups with poly(amidoamine) dendrimer. The resulting poly(amidoamine)-graft-poly(methyl acrylate) magnetic nanocomposite was then characterized by infrared spectroscopy, transmission electron microscopy, thermogravimetric analysis, scanning electron microscope and X-ray diffraction analysis. Its application as an adsorbent for the removal of Pb(II) ions was studied. The removal capability of the adsorbent was investigated in different pH values, contact time (kinetics) and initial concentration of lead. Moreover, adsorption isotherms were investigated to describe the mechanistic feature of this nanocomposite for adsorption. Accordingly, its high adsorption capacity (310 mg/g) and efficient adsorption toward lead ions in aqueous solution were shown. To further study of the chemistry behind the adsorption process, a comprehensive density functional theory-based study was performed, and a relatively strong interaction between metal ions and adsorbent was observed based on the calculated adsorption free energies.     

烃源岩中可溶有机质与粘土矿物结合关系——以东营凹陷沙四段低熟烃源岩为例

采用超临界抽提(SFE)新技术和氯仿抽提(CE)以及粘土分离等手段对东营凹陷沙四段低熟油烃源岩进行不同处理,得到3种粘土样品:(1)含有机质的粘土原样;(2)氯仿抽提去有机质的样品;(3)不同实验条件下超临界抽提后的样品。然后,分别对这3种粘土样品进行X射线衍射分析(XRD)和傅利叶转换红外光谱分析(FT-IR).研究发现烃源岩中可溶有机质除了吸附于矿物表面外,还吸附于粘土矿物尤其是蒙皂石层的层间,后者主要为碳数相对较低的饱和烃类。这一发现对认识沉积岩中可溶有机质对粘土矿物结构和特性的影响有着重要意义,对烃源岩评价和探讨泥质烃源岩烃类的初次运移提供了新思路。     

烃源岩中可溶有机质与粘土矿物结合关系——以东营凹陷沙四段低熟烃源岩为例

 采用超临界抽提(SFE)新技术和氯仿抽提(CE)以及粘土分离等手段对东营凹陷沙四段低熟油烃源岩进行不同处理,得到3种粘土样品:(1)含有机质的粘土原样;(2)氯仿抽提去有机质的样品;(3)不同实验条件下超临界抽提后的样品。然后,分别对这3种粘土样品进行X射线衍射分析(XRD)和傅利叶转换红外光谱分析(FT-IR).研究发现烃源岩中可溶有机质除了吸附于矿物表面外,还吸附于粘土矿物尤其是蒙皂石层的层间,后者主要为碳数相对较低的饱和烃类。这一发现对认识沉积岩中可溶有机质对粘土矿物结构和特性的影响有着重要意义,对烃源岩评价和探讨泥质烃源岩烃类的初次运移提供了新思路。     

Photocatalytic reduction of hexavalent chromium with commercial Fe/Ti oxide catalyst under UV and visible light irradiation

The photoreduction efficiency of toxic hexavalent chromium into non-toxic trivalent chromium was studied using local low-cost material and modern technology. The materials involved different iron–titanium oxide nanopowders synthesized via simple hydrothermal–hydrolysis process. X-ray diffraction and high-resolution transmission electron microscope were employed to study the structural properties of the as-prepared samples. The effects of molar ratio (Fe/Ti) and hydrothermal temperature on spectroscopic properties have been investigated using Fourier transform infrared FT-IR spectroscopy. The photocatalytic performance of hexavalent chromium was systematically studied at various conditions including initial concentration of Cr(VI), hydrothermal temperature and Fe/Ti ratios of mixed iron–titanium oxide powders. It has been found that the highest photoreduction efficiencies of Cr(VI) were 95.7 and 86.2% at initial concentrations 10 and 60 ppm of Cr(VI), respectively. The synthesized mixed Fe₂O₃–TiO₂ photocatalyst exhibited higher efficiency of about 88% under visible light irradiation. The as-prepared mixed oxide catalyst exhibited high photocatalytic conversion efficiency and recycling stability in comparison with different commercial catalysts.     

Investigating the removal of ethylbenzene from aqueous solutions using modified graphene oxide: application of response surface methodology

This research focused on the application of response surface methodology (RSM) for the removal of ethylbenzene by the graphene oxide grafted with polymethyl vinyl ketone and aniline (GO-MVK-ANI) from wastewater. The adsorbent was prepared through polymerization of graphene oxide with methyl vinyl ketone using ammonium persulfate initiator and further modification by aniline. The synthesized material was characterized via Fourier transform infrared resonance spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and Brunauer–Emmett–Teller analysis. RSM was used to minimize the number of experiments and investigate the effect of three selected parameters (contact time, initial pH and adsorbent dose) on the removal efficiency of ethylbenzene. Additionally, the affecting parameters were optimized based on the selected target (ethylbenzene removal efficiency). The results show that 73% ethylbenzene could be adsorbed with initial ethylbenzene concentration of 20 mg/l under the optimum conditions (the contact time of 11 min, pH of 5.64 and adsorbent dose of 3.75 g/l). In this paper, high R ²-value (97.18%) for ethylbenzene removal and a good agreement with adjusted R ²-value (94.65%) indicated that the model was successful and the results demonstrated a reasonable proportion of the experimental and the predicted results.     

Synthesis,characterization of CdS/rectorite nanocomposites and its photocatalytic activity

CdS/rectorite nanocomposite was synthesized via a cation-exchange reaction followed by a sulfurization process. The obtained samples were characterized by using X-ray diffraction (XRD), fourier transform infrared spectra (FTIR), transmission electron microscope (TEM), UV-Vis diffuse reflectance spectra (DRS), and thermal analysis. The measured results indicate that CdS species in the composites exist in the form of pillars and nanoparticles, the crystallized CdS particles are in the hexagonal symmetry. The photocatalytic activities of the pillared nanocomposite were enhanced significantly comparing with the bare rectorite and the pure CdS. Moreover, the photostabilities of the obtained nanocomposites are also better than that of the pure CdS due to the hosts retard the photocorrosion of the CdS.     

多种铁改性和未改性生物炭对模拟地下水中六价铬的去除

为了研究不同类型的生物炭对模拟地下水中去除Cr（Ⅵ）的影响，选用杨木、柳木、桃木和松木为原料，分别在300℃和600℃热解温度下，制备不同粒径、经氯化铁改性的和未改性的20种生物炭，设计了一系列批实验，探究不同种类的生物炭对模拟地下水中Cr（Ⅵ）的去除效果；并采用傅里叶变换红外光谱（FTIR）和X射线近边吸收光谱（XANES）研究了生物炭去除Cr（Ⅵ）的机理。结果表明：在300℃下热解制成的改性生物炭，对Cr（Ⅵ）去除率均达到了99.0%以上；和粒径2 mm的生物炭相比，粒径<0.5 mm的生物炭对Cr（Ⅵ）有更好的去除效果；拟一级动力学方程较好地描述了300℃热解温度下杨木铁改性生物炭（FeCl3BC300Y）对Cr（Ⅵ）的去除过程。XANES分析结果表明，FeCl3BC300Y中的铬以三价的形态（Cr（Ⅲ））存在，FTIR分析表明羟基和羧基参与了Cr（Ⅵ）的去除。生物炭通过氧化还原和络合作用去除Cr（Ⅵ）。铁改性生物炭有望作为可渗透反应墙的填充材料，成为修复Cr（Ⅵ）污染地下水的新型材料。     

Adsorption to goethite of extracellular polymeric substances from Bacillus subtilis

Extracellular polymeric substances (EPS) are heterogeneous biopolymers produced by Gram-negative and Gram-positive bacterial cells. Adsorption of EPS to minerals can alter the substrata physico-chemistry and influence initial bacterial adhesion processes via conditioning film formation, but the effects of solution chemistry on uptake of EPS remain poorly understood. In this study, the adsorption to goethite (α-FeOOH) of EPS isolated from the early stationary growth-phase culture of Bacillus subtilis was investigated as a function of pH and ionic strength (I) in NaCl background electrolyte using batch studies coupled with Fourier transform infrared spectroscopy and size-exclusion high-performance liquid chromatography. Proteins, particularly those of higher molar mass, and phosphorylated macromolecules were adsorbed preferentially. Increasing solution I (1-100 mM NaCl) or pH (3.0-9.0) resulted in a decrease in the mass of EPS adsorbed. Batch studies and diffuse reflectance infrared Fourier transform spectra are consistent with ligand exchange of EPS phosphate groups for surface hydroxyls at Fe metal centers. The data indicate that both electrostatic and chemical bonding interactions contribute to selective fractionation of the EPS solution. Proteins and phosphate groups in phosphodiester bridges of nucleic acids likely play an important role in conditioning film formation at Fe oxide surfaces.     

A novel approach for textile dye degradation by zinc,iron–doped tin oxide/titanium moving anode

The present contribution reports a moving iron (Fe), zinc (Zn)–doped tin oxide/titanium (SnO₂/Ti) anode-based system designed and operated for the electro-oxidation of methyl orange dye effluent. Electrochemical oxidation of the dye was carried out at a current density of 1.8 A/dm² for 120 min. Similar experiments were repeated with pure SnO₂-based static and moving anode-based systems and the Fe, Zn-doped SnO₂ static anode-based electro-oxidation system. Post oxidation, the surface of the electrodes was critically examined by scanning electron microscopy. Dye samples were analysed at regular intervals during the electro-oxidation process by chemical oxygen demand and colour removal measurements and characterized by UV–Vis spectroscopy and Fourier transform infrared spectroscopy at the end of the oxidation process. The obtained results elucidate the superiority of Fe, Zn-doped SnO₂/Ti moving anode-based system for methyl orange dye effluent electro-oxidation. The moving anode prevents passive layer formation and decreases polarization resistance. Doping of Fe and Zn provides the anode-enhanced mechanical strength and electrocatalytic activity. The combined effects of axial anode movement and doping are responsible for improved performance of the moving anode system reported in this contribution.     

Application of nanoadsorbents for removal of lead from water

Enormous increase in the application of various heavy metals including lead for commercial and non-commercial purposes has also led to their enhanced occurrence in the effluents from industries and domestic discharge creating substantial environmental concerns. The existing techniques for removal of these contaminants such as reverse osmosis and ion exchange suffer a few disadvantages and hence, thrust to develop efficient techniques for the removal have been ever increasing. Adsorption based on the use of nanoadsorbents is promising being cost effective and based on the ease of operation. The present work furnishes a detailed overview on nanoadsorbents for removal of lead from water. The various nanoadsorbents covered in the analysis include alumina, anatase, carbon nanotubes, chitosan, copper, iron and zinc oxide, magnetite, nanoclay and zirconium nanoparticles. The review also gives an insight into the synthesis and characterization of nanoadsorbents followed by guidelines on optimum operating parameters to be used in the removal process for maximizing the extent of removal. The typical optimum conditions established based on the critical analysis of literature are pH ≤ 6, contact time ≥60 min and optimum adsorbent dose dependent on the nanomaterials. Comparison of different nanoparticles revealed that titanium oxide and hematite nanoparticles are the best, giving 100% removal efficiency for lead ions. The sequestration was mainly dependent on adsorbent dose that has to be kept optimum to yield adequate surface area and number of adsorption sites. Overall, nanoadsorbents have been established to yield efficient removal of lead from water.