Removal of lead ions from wastewater using lanthanum sulfide nanoparticle decorated over magnetic graphene oxide

A chitosan-based sensing membrane for on-site and sensitive dual-channel portable detection and efficient adsorption of Pb2+ in groundwater

The presence of lead ion (Pb2+) in groundwater poses a serious risk to human health, even at low levels. Therefore, it is essential to develop a new strategy for both selective detection and effective removal of Pb2+ in groundwater, which has been rarely reported. Here, we developed a multi-functional chitosan-based fluorescent sensing membrane (CM-L/CG) by using a casting method for the sensitive/selective detection and removal of Pb2+ in groundwater. The CM-L/CG membrane can be integrated into the portable laser-induced fluorescence spectrometer (LIFs) for on-site detection of Pb2+, with a low detection limit of 1.02 ppb. Moreover, the CM-L/CG membrane demonstrates an outstanding 99 % removal rate and an adsorption capacity of 247.6 mg g-1 for Pb2+ and the adsorption process is mainly controlled by chemisorption. Importantly, the CM-L/CG membrane enables the real-time and on-site detection of Pb2+ in groundwater samples via a smartphone-based RGB (Red Green Blue) color analysis-assisted portable platform and portable LIFs-based platform, achieving acceptable results. This dual-functional fluorescent sensing membrane represents a breakthrough in environmental monitoring technology, offering a comprehensive solution for sensitive detection and efficient removal of Pb2+ from groundwater.

Ultrasonic-induced grafted lanthanum sulfide decorated multi-walled carbon nanotube onto bacterial cellulose applied for adsorption of pesticides in environmental waters

A new biosorbent was fabricated by modification of bacterial cellulose biopolymer grafted with lanthanum sulfide decorated carboxylated multiwall carbon nanotube (La2S3@MWCNT@BC). The sorbent was employed in a green alternative dispersive-solid phase extraction of a variety of 14 pesticides in environmental water samples. The analyses were performed using GC-µECD. The properties and structure of La2S3@MWCNT@BC nanocomposite were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and adsorption-desorption isotherms. The composition of the sorbent was also investigated to evaluate the adsorptive properties of its constituents. The impact of various parameters influencing extraction efficacies such as sorbent dose, adsorption time, sample pH, ionic strength, and desorption conditions was investigated. The method was validated by specificity, matrix effect % (-0.4 to -7.4), enrichment factor (4-10), limits of quantification (0.007-0.31 μg L-1), matrix-matched calibration linearity (0.01-200 µg L-1), determination coefficients (r2=0.9921-0.9998), and precision. The optimized method was applied for the analysis of multiclass pesticides in seven environmental and drinking waters and the recoveries were obtained in the 81-108 % range with RSDs of 2.5-4.7 %. This paper is the first report on the synthesis and use of La2S3@MWCNT@BC nanocomposite to extract pesticides from different water samples. The greenness of the procedure was evaluated by the AGREE protocols.

Adsorptive removal of heavy metals from aqueous solutions: Progress of adsorbents development and their effectiveness

Increased levels of heavy metals (HMs) in aquatic environments poses serious health and ecological concerns. Hence, several approaches have been proposed to eliminate/reduce the levels of HMs before the discharge/reuse of HMs-contaminated waters. Adsorption is one of the most attractive processes for water decontamination; however, the efficiency of this process greatly depends on the choice of adsorbent. Therefore, the key aim of this article is to review the progress in the development and application of different classes of conventional and emerging adsorbents for the abatement of HMs from contaminated waters. Adsorbents that are based on activated carbon, natural materials, microbial, clay minerals, layered double hydroxides (LDHs), nano-zerovalent iron (nZVI), graphene, carbon nanotubes (CNTs), metal organic frameworks (MOFs), and zeolitic imidazolate frameworks (ZIFs) are critically reviewed, with more emphasis on the last four adsorbents and their nanocomposites since they have the potential to significantly boost the HMs removal efficiency from contaminated waters. Furthermore, the optimal process conditions to achieve efficient performance are discussed. Additionally, adsorption isotherm, kinetics, thermodynamics, mechanisms, and effects of varying adsorption process parameters have been introduced. Moreover, heavy metal removal driven by other processes such as oxidation, reduction, and precipitation that might concurrently occur in parallel with adsorption have been reviewed. The application of adsorption for the treatment of real wastewater has been also reviewed. Finally, challenges, limitations and potential areas for improvements in the adsorptive removal of HMs from contaminated waters are identified and discussed. Thus, this article serves as a comprehensive reference for the recent developments in the field of adsorptive removal of heavy metals from wastewater. The proposed future research work at the end of this review could help in addressing some of the key limitations facing this technology, and create a platform for boosting the efficiency of the adsorptive removal of heavy metals.

Magnetic layered double hydroxide-based composites as sustainable adsorbent materials for water treatment applications: Progress, challenges, and outlook

Layered double hydroxides (LDHs) have shown exciting applications in water treatment because of their unique physicochemical properties, which include high surface areas, tunable chemical composition, large interlayer spaces, exchangeable content in interlayer galleries, and ease of modification with other materials. Interestingly, their surface, as well as the intercalated materials within the layers, play a role in the adsorption of the contaminants. The surface area of LDH materials can be further enhanced by calcination. The calcined LDHs can reattain their structural features upon hydration through the "memory effect" and may uptake anionic species within their interlayer galleries. Besides, LDH layers are positively charged within the aqueous media and can interact with specific contaminants through electrostatic interactions. LDHs can be synthesized using various methods, allowing the incorporation of other materials within the layers or forming composites that can selectively capture target pollutants. They have been combined with magnetic nanoparticles to improve their separation after adsorption and enhance adsorptive features in many cases. LDHs are relatively greener materials because they are mostly composed of inorganic salts. Magnetic LDH-based composites have been widely employed for the purification of water contaminated with heavy metals, dyes, anions, organics, pharmaceuticals, and oil. Such materials have shown interesting applications for removing contaminants from real matrices. Moreover, they can be easily regenerated and used for several adsorption-desorption cycles. Magnetic LDHs can be regarded as greener and sustainable because of several green aspects in their synthesis and reusability. We have critically reviewed their synthesis, applications, factors affecting their adsorption performance, and related mechanisms in this review. In the end, some challenges and perspectives are also discussed.

Removal of lead ions from wastewater using magnesium sulfide nanoparticles caged alginate microbeads

In this study, an adsorbent made of alginate (Alg) caged magnesium sulfide nanoparticles (MgS) microbeads were used to treat lead ions (Pb²⁺ ions). The MgS nanoparticles were synthesized at low temperatures, and Alg@MgS hydrogel microbeads were made by the ion exchange process of the composite materials. The newly fabricated Alg@MgS was characterized by XRD, SEM, and FT-IR. The adsorption conditions were optimized for the maximum removal of Pb²⁺ ions by adjusting several physicochemical parameters, including pH, initial concentration of lead ions, Alg/MgS dosage, reaction temperature, equilibration time, and the presence of co-ions. This is accomplished by removing the maximum amount of Pb²⁺ ions. Moreover, the adsorbent utilized more than six times with a substantial amount (not less than 60%) of Pb²⁺ ions was eliminated. Considering the ability of sodium alginate (SA) for excellent metal chelation and controlled nanosized pore structure, the adsorption equilibrium of Alg@MgS can be reached in 60 min, and the highest adsorption capacity for Pb²⁺ was 84.7 mg/g. The sorption mechanism was explored by employing several isotherms. It was found that the Freundlich model fits the adsorption process quite accurately. The pseudo-second-order model adequately described the adsorption kinetics.

Titanium lanthanum three oxides decorated magnetic graphene oxide for adsorption of lead ions from aqueous media

The current study presents a viable and straightforward method for synthesizing titanium lanthanum three oxide nanoparticles (TiLa) and their decoration onto the ferrous graphene oxide sheets to produce FeGO-TiLa as efficient magnetic adsorbent. Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and vibration sample magnetometer (VSM) were used to evaluate the physical and chemical properties of the produced nanocomposites. The FeGO-TiLa was used to enhance the removal of lead ions from aqueous solution. The FeGO-TiLa nanocomposite exhibited a much higher removal efficiency (93%) for lead ions than pure TiLa nanoparticles (81%) and magnetic graphene oxide (74%). The influence of FeGO-TiLa dosage, contact time, solution pH, solution temperature, and starting quantity on the lead ions was evaluated and adjusted. The investigations demonstrated that a pH 6 with 40 mg adsorbent resulted in >91% removal of lead ions at ambient temperature after 120 min. Isotherm models were used to analyze experimental results, and Langmuir model fitted the data well as compared Freundlich model with a maximum adsorption capacity of 109.89 mg g^-1. Kinetic and studies are performed the lead adsorption over FeGO-TiLa follow pseudo-second-order rate. Langmuir and Free energy suggested the lead ions uptake with FeGO-TiLa was monolayer and physical adsorption mechnaism, respectively. Finally, the FeGO-TiLa nanocompoiste can be used as an alternative adsorbent for water remediation.

Magnetic Beads of Zero Valent Iron Doped Polyethersolfun Developed for Removal of Arsenic from Apatite-Soil Treated Water

The drop immerses calcium chloride aqueous solution was utilized to prepare the zero valent iron-doped polyethersulfone beads (PES/ZVI) for the efficient removal of arsenic from apatite-soil treated waters. The proposed beads can assist in promoting uptake efficiency by hindering ZVI agglomeration due to a high porosity and different active sites. The PES/ZVI beads were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and vibrating sample magnetism (VSM). The main objective of this study was to investigate the function of new PES/ZVI beads with an increased removal efficiency for the remediation of arsenic ions from the apatite-soil treated waters. A maximum adsorption removal of 82.39% was achieved when the experiment was performed with 80 mg of adsorbent for a contact time of 180 min. Based on the results, a removal efficiency >90% was obtained after 300 min of shaking time with an arsenic concentration of 20 mg·L^-1. The experimental process was fitted with the Langmuir model due to the high R² (0.99) value compared to the Freundlich model (0.91) with an adsorption capacity of 41.32 mg·g^-1. The adsorption process speed was limited by pseudo-second-order (R² = 0.999) and the adsorption mechanism nature was endothermic and physical.

Integrated Electro-Ozonation and Fixed-Bed Column for the Simultaneous Removal of Emerging Contaminants and Heavy Metals from Aqueous Solutions

In the current study, an integrated physiochemical method was utilized to remove tonalide (TND) and dimethyl phthalate (DMP) (as emerging contaminants, ECs), and nickel (Ni) and lead (Pb) (as heavy metals), from synthetic wastewater. In the first step of the study, pH, current (mA/cm2), and voltage (V) were set to 7.0, 30, and 9, respectively; then the removal of TND, DMP, Ni, and Pb with an electro-ozonation reactor was optimized using response surface methodology (RSM). At the optimum reaction time (58.1 min), ozone dosage (9.4 mg L−1), initial concentration of ECs (0.98 mg L−1), and initial concentration of heavy metals (28.9 mg L−1), the percentages of TND, DMP, Ni, and Pb removal were 77.0%, 84.5%, 59.2%, and 58.2%, respectively. For the electro-ozonation reactor, the ozone consumption (OC) ranged from 1.1 kg to 3.9 kg (kg O3/kg Ecs), and the specific energy consumption (SEC) was 6.95 (kWh kg−1). After treatment with the optimum electro-ozonation parameters, the synthetic wastewater was transferred to a fixed-bed column, which was filled with a new composite adsorbent (named BBCEC), as the second step of the study. BBCEC improved the efficacy of the removal of TND, DMP, Ni, and Pb to more than 92%.

Enhanced remediation of lead (II) and cadmium (II) ions from aqueous media using porous magnetic nanocomposites - A comprehensive review on applications and mechanism

Lead and Cadmium, identified as toxic heavy metals, cause significant imbalance in the eco-system due to their tendency to bioaccumulate. Remediation of heavy metals by conventional adsorptive materials suffer demerits related to low efficiency or removal. Among the variety of adsorbent materials used in the adsorption process, metal oxides- and graphene oxide magnetic nanocomposites have gained a considerable attention. The use of nanomaterials may help to reduce this contamination, but after use, they are difficult to remove from water. An added magnetic property to nanomaterials facilitates their retrieval after use. The magnetic properties of these hybrid magnetic nanocomposites, coupled with unique characteristics of organic and inorganic elements, have found extensive application in water treatment technology. Detailed discussion on functionalisation of magnetic nanocomposites and the enhanced performance are presented. Magnetic graphene oxide-covalently functionalized-tryptophan was reported to have the highest adsorption capacity of 766.1 mg/g for remediation of lead (II) ions and graphene oxide exhibited the highest adsorption capacity of 530 mg/g for Cd (II) ions. The adsorption mechanisms for heavy metal ions on the surface of novel adsorbents, particularly lead and cadmium, using magnetic nanocomposites have been explained with reference to the isotherm models studied. The future scope of research in this area of research is proposed.

Magnetic sporopollenin supported polyaniline developed for removal of lead ions from wastewater: Kinetic, isotherm and thermodynamic studies

This study evaluated the synthesis of novel binary functionaladsorbent based on sporopollenin, magnetic nanoparticles, and polyaniline to produce MSP-PANI. The MSP-PANI was applied to enhance uptake of lead ions (Pb²⁺) from wastewater samples. The functionalities, surface morphology, magnetic properties, and elemental composition of the newly synthesized nanocomposite were investigated using Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), vibration sample magnetometer (VSM), and energy-dispersive X-ray spectroscopy (EDX), respectively. The experimental condition for the adsorption process was MSP/PANI ratio 1:1, pH ∼6, adsorbent dosage 40 mg, and contact time 90 min at room temperature. Under the proposed condition, lead ions removal were obtained as 83%, 88% and 95% for MSPE, PANI, and MSP/PANI, respectively. Based on the experimental and predicted data, the adsorption was corresponded to the psudo-second-order (R² = 0.999) kinetics model, and the adsorption equilibrium corresponded to the Langmuir model (R² = 0.996). Langmuir isotherm showed the maximum adsorption capacity of MSP-PANI for lead ions was 163 mg/g and followed the monolayer pattern. Hence, thermodynamic model under Van't Hoff equation suggested that the adsorption mechanism was physio-sorption with endothermic nature. Therefore, this research can help the researchers to use magnetic nanoparticles for lead removal in highly polluted areas.

Ammonia removal from industrial effluent using zirconium oxide and graphene-oxide nanocomposites

The present study developed and evaluated nano-adsorbents based on zirconium oxide and graphene oxide (ZrO₂/GO) as a novel adsorbent for the efficient removal of ammonia from industrial effluents. Fourier transform infrared (FTIR) spectroscopy, Field Emission Scanning Electron Microscope, Energy-dispersive X-ray Spectroscopy, and X-ray diffraction were used to evaluate and identify the novel adsorbent in terms of morphology, crystallography, and chemical composition. The pH (7), adsorbent quantities (20 mg), adsorbent contact time (30 min) with the sample, and initial ammonia concentration were all tuned for ammonia uptake. To validate ammonia adsorption on the ZrO₂/GO adsorbent, several kinetic models and adsorption isotherms were also utilized. The results showed that the kinetics of ammonia adsorption are of the pseudo-second order due to high R² (>0.99) value as compared first-order (R² = 0.52). The chemical behavior and equilibrium isotherm were analyzed using the isotherm models and Langmuir model provided high R² (>0.98) as compared Freundlich (>0.96). Hence, yielding a maximum uniform equilibrium adsorption capacity of 84.47 mg g^-1. The presence of functional groups on the surface of graphene oxide and ZrO₂ nanoparticles, which interact efficiently with ammonia species and provide an efficient surface for good ammonia removal, is most likely to be responsible.

Adsorption mechanism of Pb2+ in montmorillonite nanopore under various temperatures and concentrations

Adsorption of lead (Pb²⁺) onto the montmorillonite (Mt) surface is one of the key approaches to remove Pb²⁺ in geological and environmental engineering. Temperature and initial Pb²⁺ concentration are two essential factors that influence the adsorption capacity of Mt on absorbing Pb²⁺. However, the nanoscale governing mechanism of temperature and initial concentration on Pb²⁺ adsorbing of Mt is still unclear. This research performed comprehensively molecular dynamics (MD) simulations to investigate how temperature and initial concentration affect the dynamic Pb²⁺ adsorption of Mt nanopore. The Pb²⁺ removal ratio shows a two-stage variation with the increase of initial Pb²⁺ concentration. Temperature controls the maximum initial Pb²⁺ concentration for complete Pb²⁺ removal by changing the maximum adsorption energy of Mt. Temperature also influences the maximum adsorption capacity and Pb²⁺ removal ratio of Mt nanopore indirectly by changing diffusion and hydration state of Pb²⁺. The initial Pb²⁺ concentration corresponding to the maximum adsorption energy coincides with the maximum initial Pb²⁺ concentration determined by the Pb²⁺ removal ratio. Lower adsorption energy and higher level of hydration and diffusion make Pb²⁺ absorbing on Mt surface become more difficult, reducing the Pb²⁺ adsorbing capacity of Mt. The initial Pb²⁺ concentration influences adsorption capacity and Pb²⁺ removal ratio not only via altering the quantity of Pb²⁺ but also through controlling the adsorption energy of Mt, as well as the diffusion and hydration state of Pb²⁺. With the increase of initial Pb²⁺ concentration, the hydration of Pb²⁺ is weakened while the adsorption energy of Mt and diffusion of Pb²⁺ are enhanced.