Removal Of Lead Ions Research Articles

Enhanced Adsorption of Aqueous Pb(II) by Acidic Group-Modified Biochar Derived from Peanut Shells

Using peanut shells, a sustainable agricultural waste product, as its raw material, the acid group-modified biochar (AMBC) was prepared through phosphoric acid activation, partial carbonization, and concentrated sulfuric acid sulfonation for efficient removal of lead ion from aqueous solutions. Characterization techniques such as N2 isothermal adsorption–desorption, SEM, XRD, FT-IR, TG-DTA, and acid–base titration were utilized to fully understand the properties of the AMBC. It was found that there were high densities of acidic oxygen-containing functional groups (-SO3H, -COOH, Ph-OH) on the surface of the AMBC. The optimal adsorption performance of the AMBC for Pb(II) in water occurred when the initial concentration of Pb(II) was 100 mg/L, the pH was 5, the dosage of the adsorbent was 0.5 g/L, and the contact time was 120 min. Under the optimal conditions, the removal ratio of Pb(II) was 76.0%, with an adsorption capacity of 148.6 mg/g. This performance far surpassed that of its activated carbon precursor, which achieved a removal ratio of 39.7% and an adsorption capacity of 83.1 mg/g. The superior adsorption performance of AMBC can be caused by the high content of acidic oxygen-containing functional groups on its surface. These functional groups facilitate the strong binding between AMBC and Pb(II), enabling effective removal from water solutions.

Enhanced adsorption of lead (II) ions onto cellulose nanoparticles/chitosan composite based on loofah sponge: kinetic and thermodynamic studies

AbstractThe purpose of this work is to study the efficiency of lead ions removal via adsorption onto created solid nanomaterials. Three solid adsorbents were synthesized as cellulose nanoparticles (CN) extracted from plant loofah sponge using alkali treatment and acid hydrolysis techniques, chitosan beads (CZ), and cellulose nanoparticles/chitosan beads composite (CZC). The generated solid adsorbents were investigated using TGA, N2 adsorption/desorption, ATR-FTIR spectroscopy, SEM, TEM, XRD, and pHPZC. Based on our findings, CZC had a pHPZC of 7.2, a larger specific surface area (645.3 m2/g), and a total pore volume (0.372 cm3/g). The batch adsorption of lead ions was well-fitted by pseudo-second order, Elovich, Langmuir, Temkin, and Dubinin-Radushkevich on all the samples. Cellulose nanoparticles/chitosan composite had the highest Langmuir adsorption capacity (221.104 mg/g) at 47°C, 120 min as shaking time, 2 g/L as adsorbent dose, and pH 6.5. Nitric acid had the highest desorption percentage (92%). The thermodynamic investigation revealed that lead ion adsorption is endothermic, favorable, spontaneous, and physisorption. Our findings showed that CZC has a high adsorption capacity and rapid kinetics, indicating its potential for employment in water treatment.

Removal of lead ions onto potassium-type fine-grained zeolite prepared from dry or wet milling treatment

Potassium-type zeolite (KZ) was prepared from coal fly ash by hydrothermal activation treatment using potassium hydroxide solution and potassium-type fine-grained zeolite was prepared by dry milling (KZ-D) or wet milling (KZ-W). The effects of the different treatments on the Pb2+ adsorption performance were assessed. KZ-W resulted in a much smaller particle diameter (0.61 ± 0.12 µm) than KZ-D (1.4 ± 0.48 µm) and KZ (6.5 ± 0.49 µm). KZ-W also realized a higher pore volume, mean pore diameter, and specific surface area, than KZ-D and KZ. Additionally, KZ-W realized a greater Pb2+ adsorption capacity (242.6 mg/g) than KZ (195.3 mg/g) or KZ-D (188.9 mg/g). The adsorption phenomena were fitted to the Freundlich and Langmuir models to clarify the Pb2+ adsorption mechanism, and then both models showed a good fit to the experimental data (the correlation coefficients of 0.914–0.996 for Freundlich model and 0.897–0.981 for Langmuir model). Additionally, the ion exchange capability, elemental distribution, and binding energy before and after adsorption were analyzed. The results indicated that the physicochemical characteristics of the tested adsorbent surface affected the Pb2+ adsorption capacity in the aqueous phase. According to kinetics, the pseudo-second-order model matched the experimental data (the correlation coefficients of 0.996–0.999). The samples also demonstrated selective adsorption of Pb2+ in a binary solution. The results demonstrated that KZ-W can effectively remove Pb2+ from the aqueous phase and that it may be a useful tool for preventing contamination of water bodies.

Hydroxyapatite-magnetite nanocomposites: Synthesis and superior adsorption properties for lead ion removal, with insights into intraparticle diffusion, kinetic modeling, and phase dependency

Multifunctional superparamagnetic magnetite/hydroxyapatite (Fe3O4/Ca10(PO4)6(OH)2 or MHAp) nano-composites were synthesized via a facile two-step co-precipitation method at room temperature. These magnetic nano-composites underwent heat treatment at various temperatures ranging (400°, 600°, and 900 °C), which were subsequently utilized as nanosorbents for removing Pb2+ ions. The XRD data revealed that both the magnetite and hydroxyapatite synthesized were in a pure phase. In the Fe3O4/HAp composites, there was an augmentation in the intensity peak of hydroxyapatite observed up to 600 °C. However, at 900 °C, a calcium iron phosphate phase emerged, and magnetite (Fe3O4) transitioned into the hematite (Fe2O3) phase. Elevating the heat treatment enhanced the crystallinity of the developed Fe3O4/HAp composites while diminishing the surface area. The prepared nanocomposites exhibited high adsorption efficiency across a wide pH range, with an optimal pH of 5.5. Notably, the adsorption rate of Pb2+ reached 94 % within the first 5 min, with complete metal adsorption progressively at 60 min. The kinetic and isotherm analysis of the adsorption process revealed that pseudo-second-order model and Langmuir model agreed well with the adsorption process. Also, FAH0 demonstrated the highest adsorption capacity (263.2 mg/g) for Pb2+ ions. Furthermore, the Fe3O4/HAp composite NPs exhibited remarkable recyclability even after five cycles of reuse; retaining an efficiency of over 96 %, and allowing for easy separation without a significant loss of adsorption efficiency. The results of the current desorption study underscore the promising practical applications of these nano-composites in decontaminating aqueous media.

Removal of lead ions from aqueous solution by modified nanocellulose.

Heavy metals significantly impact the environment due to their non-biodegradable, toxic, and carcinogenic behaviors. Lead contaminants impose severe health impacts on humans and the water environment. Therefore, eco-friendly and efficient lead ion removal practices such as nanotechnology are an urgent requirement for the abatement of lead pollution. In the present study, nanocellulose was synthesized from the cotton straw residue using chemical methods and modified with titanium dioxide to form a nanocomposite. The nanocomposite synthesized was characterized by using FTIR, XRD, FESEM, and BET. FTIR results noticed peaks at 1648.43 and 1443.57cm-1 for cellulose and Ti-O-Ti bonding at 505.02cm-1. The nanocomposite was noticed to be disordered and irregular in shape. The nanocomposite has particle sizes of 83nm. The nanocomposite crystalline particle had 65% anatase and 32% rutile phases observed from the XRD result. BET results show that the surface area of nanocellulose increases after surface modification from 25.692 to 42.510 m2/g. The adsorption capacity of the nanocomposite was 0.552mg/g was noticed. The Elovich kinetic and Baudu isotherms are the best-fitted models for lead ion adsorption. Thermodynamic parameters resulted in Gibbs free energy decreasing with temperature. This study revealed that modified cellulosic adsorbents efficiently absorbed lead ions derived from cotton straws.

Removal efficiency, metal uptake, and breakthrough curve of aqueous lead ions removal using olive stone waste

Olive industries generate olive stone waste (OSW), which is recognized as an organic contaminant. Jordan is one of the Mediterranean Sea countries that produces a large amount of these residues. Waste from olive stones could serve as a biosorbent. One of the most hazardous heavy metals produced in a variety of industries, including the production of paint and batteries, is lead ions. The purpose of this work is to remove lead ions using olive stone waste as a biosorbent by adsorption techniques. The effects of initial concentration, pH, adsorbent concentration, and contact time are covered in the first section of the adsorption parameters, which is comprised of batch studies. In the second section, the breakthrough curve study was carried out using a fixed bed adsorption column. Findings said that the ideal pH for highest removal efficiency was occurred at 6.8 acidity and the most promising removal efficiency, at 25 ± 2 °C and 1 g of adsorbent for every 0.25 L of solution, hit 82.5 % of the initial concentration of 9 mg/L while 1 g of adsorbate was adsorbed in 1.9 mg of adsorbent. The breakthrough study indicated that after 110 h of operation a 150 L of treated solution attained with maximum removal efficiency of 90 % for lead ions initial concentration of (18 mg/L).

Application of Noug (Guizotia abyssinica cass.) stalk activated carbon for the removal of lead (II) ions from aqueous solutions

Due to the rise of industries worldwide, huge amounts of pollutants including heavy metals are released into the surroundings. Disposal of effluents containing heavy metals in higher concentrations without proper treatment is common in industries; lead is one of them. This study aims to determine and optimize the efficiency of Noug (Guizotia abyssinica Cass.) stalk porous carbon (NSAC) for the elimination of lead (II) from aqueous solutions. For studying the adsorption characteristics of Noug stalk activated carbon (NSAC) an adsorbate of lead (II) ions was used. The interaction and effect of the following parameters on Pb(II) adsorption were investigated using Design Expert version 7.0 software (central composite design) to determine the optimum adsorption condition: pH, initial concentration of Pb(II) ion, adsorbent dose, and contact time. The optimized condition for the elimination of lead (II) using Noug stalk porous carbon (98.77 %) was achieved at pH [4.87], initial concentration of Pb(II) [84.66 mg/L], adsorbent dose [18.43 g/L], and contact time [2.04 h]. The pseudo-second-order kinetics and the Langmuir isotherm model which had a maximum adsorption capacity of 89.25 mg/g, provided the best-fit models for Pb(II) adsorption, with R2 values of 0.99 and 0.98, respectively. Efficient elimination of Pb(II) from wastewater can be performed through the use of NSAC. Future research should delve more into column adsorption under continuous wastewater flow.

In vitro and in vivo screening of bacterial species from contaminated soil for heavy metal biotransformation activity

Heavy metals (HMs) are widely used in various industries. High concentrations of HMs can be severely toxic to plants, animals and humans. Microorganism-based bioremediation has shown significant potential in degrading and detoxifying specific HM contaminants. In this study, we cultivated a range of bacterial strains in liquid and solid nutrient medium containing different concentrations of different HMs to select and analyze bacteria capable of transforming HMs. The bacterial strains most resistant to selected HMs and exhibiting the ability to remove HMs from contaminated soils were identified. Then, the bacterial species capable of utilizing HMs in soil model experiments were selected, and their ability to transform HMs was evaluated. This study has also generated preliminary findings on the use of plants for further removal of HMs from soil after microbial bioremediation. Alcaligenes faecalis, Delftia tsuruhatensis and Stenotrophomonas sp. were selected for their ability to grow in and utilize HM ions at the maximum permissible concentration (MPC) and two times the MPC. Lysinibacillus fusiformis (local microflora) can be used as a universal biotransformation tool for many HM ions. Brevibacillus parabrevis has potential for the removal of lead ions, and Brevibacillus reuszeri and Bacillus safensis have potential for the removal of arsenic ions from the environment. The bacterial species have been selected for bioremediation to remove heavy metal ions from the environment.

Lemon peel activated carbon: A sustainable solution for lead ion removal from E-waste bioleachate

In the investigation of sustainable materials, this study explores the viability of employing Lemon Activated Carbon (LAC) for the bio-adsorption of lead ions from e-waste bio-leachate. The novelty of this work lies in the comprehensive analyses of LAC characteristics, including particle size, surface area, zeta potential, and surface morphology. The morphology and adsorption capacity were measured using scanning electron microscope (SEM) and atomic absorption spectroscopy (AAS), confirming the efficacy of LAC in removing lead ions from the bio-leachate solutions. The surface area analysis unveiled that LAC, with a surface area of 603.7 m²/g achieved through thermal activation, exhibited competitive lead ion adsorption capacity despite its lower surface area compared to commercial-activated carbon (990 m²/g). Additionally, both LAC and CAC displayed pseudo-second-order kinetics for adsorption, with the Langmuir isotherm model fitting well (R2 = 0.9879) for LAC. The amorphous nature of LAC confirmed by X-ray diffraction (XRD) analysis and FTIR spectroscopy revealed functional surface groups, highlighting their suitability for lead ion adsorption. LAC comprised 75.82% carbon and exhibited maximum lead ion adsorption at pH 6. The optimized operating parameters achieved 89.16% lead ion removal from bio-leachate. These findings highlight the innovative utilization of lemon peel-derived activated carbon as a sustainable and environmentally friendly solution for mitigating the impacts of e-waste bio-leachate, thus contributing to the advancement of environmental remediation techniques.

Versatility of p-Imidazolemethylcalix[4]arene-attached silica resin for the removal of lead and cadmium ions from wastewater

ABSTRACT Water pollution is a global concern due to the unregulated discharge of various pollutants into aquatic environments without proper treatment. A prominent contributor to environmental degradation and adverse health effects is the unmitigated discharge of heavy metal ions within industrial effluents. The present study revealed the synthesis of p-imidazolemethylcalix[4]arene-based resin (4) and its application as an adsorbent for the removal of toxic metals, i.e., Pb2+and Cd2+, from aqueous media. The synthesis of resin (4) proceeded through well-known organic synthetic procedures and was characterised by different analytical techniques, i.e., FT-IR, SEM and elemental analyses. However, the adsorption process monitored by using UV-Vis spectrophotometer. The adsorption behaviour of resin (4) was evaluated through batch experiments, and different parameters, such as pH, adsorbent dosage and contact time, were optimised. The experimental results were evaluated by the Langmuir and Freundlich isotherm models. Moreover, kinetic and thermodynamic studies were also performed to evaluate the data. The maximum adsorption of toxic metals, 98% and 96%, respectively, for Pb2+and Cd2+ was observed at pH 7 with 30 mg of resin (4) after 1 h at ambient temperature. The results were also compared with those of other reported materials, and it could be concluded that resin (4) has great potential for minimising the risk of environmental water pollution. This novel resin demonstrates exceptional versatility in its capacity to effectively capture a wide range of heavy metal ions present in wastewater, thereby offering a comprehensive solution to a pressing environmental concern. The specific molecular structure of p-Imidazolemethylcalix[4]arene enables selective and efficient adsorption of heavy metal ions, surpassing conventional methods in terms of both effectiveness and versatility. The synthesis and characterisation of this unique resin, coupled with its demonstrated efficacy in heavy metal ion removal, represent a significant advancement in the field of environmental remediation.

Fe3O4/Graphene Oxide/Chitosan Nanocomposite: A Smart Nanosorbent for Lead(II) Ion Removal from Contaminated Water.

A new graphene oxide (GO) nanocomposite that contains chitosan, a biological polymer, combined with a magnetic nanoparticle inorganic material (Fe3O4) was successfully prepared and applied for the adsorption of Pb(II) from aqueous solutions. The structural and morphological properties of the GO/Fe3O4/CS (GFC) nanocomposites were characterized by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Influent factors for Pb(II) adsorption, including the contacting time, pH of the working medium, working temperature, and adsorbent dosage on the adsorption efficiency, have been optimized. Under optimized conditions, the adsorption isotherm results indicated that the Langmuir model provided a better description for the adsorption of Pb(II) onto the GFC nanosorbent than the Freundlich model. The maximum adsorption capacity (qmax) was 63.45 mg g-1. The pseudo-second-order kinetic model (R2 = 0.999) was fitted with the experimental results, implying that the adsorption of Pb(II) onto GFC is a chemical process. The thermodynamic studies demonstrated the exothermic nature of the adsorption process. Another advantage of the GFC nanosorbent for Pb(II) removal is its capability to be easily recovered under the use of an external magnet and subsequently regenerated. Our work demonstrated that the removal efficiency was stable after several regeneration cycles (i.e., approximately 12% reduction after four successive adsorption-desorption cycles), implying that the GFC nanosorbent exhibits satisfactory regeneration performance. Therefore, with high removal efficiency, high adsorption capacity, and stable reusability, the GFC nanocomposite is a remarkable application potential adsorbent for the in situ treatment of Pb(II) ion-containing aqueous solutions.

Magnetic and PEG-crosslinked poly(methyl acrylate) functionalized with triethylenetetramine for removal of lead ions from contaminated water

A new magnetic polymer adsorbent with high swellability was prepared based on a PEG-crosslinked poly(methyl acrylate) via ATRP technique. FT-IR, TGA, CHN, FE-SEM, EDX, XRD, VSM, BET, and DLS measurements were used for the characterization of the prepared adsorbent. After replacing terminal bromines with triethylenetetramine chelating agent, the adsorption process of lead ions led to the removal of these ions from aqueous solutions. The removal of lead ions was investigated using ICP-OES technique. At pH = 7, the equilibrium adsorption capacity increased significantly and reached 37 mg/g at a contact time of 60 min. The adsorption capacity increased with increasing adsorption temperature (up to 40 °C) and initial concentration of lead ions (up to 70 mg/L), while it decreased with increasing adsorbent dose. The Freundlich isotherm better described the process of adsorption of lead ions by the prepared adsorbent. The adsorption kinetic was in greater agreement with pseudo-second-order model. The prepared adsorbent performed much better in adsorbing lead ions compared to cobalt and mercury ions. By performing the adsorption–desorption process three times, it was found that the adsorbent has high reusability. Overall, high swelling behavior and ease of magnetizability are two prominent features of the newly prepared adsorbent.

Preparation of poly(lactic acid) (PLA)/poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV)/graphene oxide (GO) polymeric composites for the selective removal of lead ions (Pb(II)) in water

AbstractLead pollution in water has risen globally, due to industrialization and globalization. In this study, this problem was addressed by preparing poly (lactic acid) (PLA)/poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV)/graphene oxide (GO) composites and addressing their effectiveness in absorbing water, and adsorbing Pb(II) ions in water. In water absorption studies, increasing the GO content to above 1 wt.% (3 and 5 wt.%) resulted in the degradation of the composites. All blends, and composites with 1 wt.% GO loading showed good water intake properties, with the composites having the highest. Pb (II) ion intake analyses showed that all the materials adsorb Pb(II) ions significantly in 24 h contact time, but the composites with 1 wt.% GO loadings adsorbed the greatest (81.3%–86.5%). For the effect of pH on adsorption, the adsorption of Pb(II) ions increased with an increase in pH from acidic to basic. This was attributed to the abundance of hydroxyl ions in basic media, that will not compete with Pb(II) ions for adsorption sites. Conclusions were that the 49.5/49.5/1 w/w PLA/PHBV/GO composite was the most optimal adsorbent of Pb(II). This composite could be used in industrial water purification processes like membranes, to remove lead ions from water while conserving the environment.Highlights Melt mixed PLA/PHBV/GO composites for removing lead ions from water. 1 wt.% GO contents in the composites sufficiently absorbed water. 3 and 5 wt.% GO contents resulted in the hydrolytic degradation of composites. Contact time is directly proportional to the degree of lead ion adsorption. Basic pH media resulted in the optimal adsorption of lead ions from water.

Influential biosorption of lead ions from aqueous solution using sand leek (Allium scorodoprasum L.) biomass: kinetic and isotherm study

AbstractIn this study, a zero-cost, naturally effective adsorbent, sand leek (Allium scorodoprasum L.), was used for the effective removal of lead ions from an aqueous solution. This natural adsorbent was characterized by FT-IR, SEM–EDX, and PZC analyses. Batch studies were conducted at one factor at a time to explore maximum removal efficiency in terms of pH, initial lead(II) ion concentration, contact time, adsorbent dosage, and temperature for efficient adsorption. The maximum lead(II) ion uptake capacity for SAC was obtained at pH 4.5, initial lead(II) ion concentration at 1000 mg/L, operation time of 1440 min, adsorbent dosage of 10 g, and temperature of 25 °C. The adsorption data were well-fitted by the Freundlich isotherm model, with an R2 value of 1.000, indicating a good fit. The kinetic study revealed that the adsorption of lead(II) ions followed a pseudo-first-order kinetic model, with an R2 value of 0.9746. Furthermore, the thermodynamic parameters including Gibbs-free energy change (ΔG°), enthalpy change (ΔH°), and entropy change (ΔS°) were calculated to demonstrate that the adsorption of lead(II) ions onto natural adsorbent was endothermic and spontaneous.

A review of current practices on lead ions removal from different aqueous streams

Toxic heavy metals like Lead are destructive to humans and the environment when existing above their threshold limits. Several conventional lead abatement methods are used in wastewater treatment plants to restore the ecology, food supply, and human and animal health. Many tactics are used to remove harmful Pb metals, like ion exchange, chemical precipitation, membrane filtration, and coagulation. These have a few principal approaches for removing metal ions from used water. Rapid developments in tailor-made materials science have proved to remove Lead metal using ion exchange resins, zeolite, polymeric membranes, and ionic liquids due to their low cost, surface accessibility, and unique benefits. This review paper has studied the detailed benefits and shortcomings of removing lead ions from wastewater using numerous materials, processes of production, possibly destructive properties on public health, and potential hybrid routes. In addition, this work observes the present advancements and developments in lead mitigation tools using different techniques for the past five years. Furthermore, this research review opens up to study of other materials' diverse applications in removal processes.

Synthesis and characterization of graphene oxide (GO) for the removal of lead ions in water

The synthesis and characterization of graphene oxide (GO) for water related applications has become an increasing area of research. GO was prepared via Hummer's method, and analysed for structure, morphology, thermal stability, and the ability to remove heavy lead ions from solution. In FTIR analyses, hydroxyl, carboxyl and ester groups were found to be on the structure of GO. XRD showed the interlayer spacing to have increased from graphite to graphene oxide, whereby the average crystallite size of GO was 16.13. Then SEM confirmed the morphology of GO to be exfoliated and wrinkled, with stacked layers. In TGA, EG degraded in a single step, while GO degraded in three distinct steps. When using AAS to analyse the Pb (II) ion intake properties of GO, it showed a maximum adsorption of 98.1% for 600 ppm lead ion solution. The Freundlich isotherm model was consistent with this adsorption, meaning that adsorption took place on a heterogenous surface, on a multilayer basis. The value of n for this isotherm was 0.1474, implying a dominant chemical adsorption. A significant contribution was done to the structure of GO, with its metal adsorption properties clearly portrayed.

Organo-inorganic hybrid IPN sourced porous carbons and their lead decontamination perspectives

The present communication is about generation of porous carbons through sacrificial template route, from organo-inorganic hybrid interpenetrating polymer networks (IPN's) and their use as a remediation tool for the removal of lead ions from contaminated water. The hybrid IPN's between phenol-formaldehyde (PF) polymer and silica were formed through sequential IPN formation route, in which, silica network was formed first through sol-gel process involving tetraethoxysilane (TEOS) dispersed in phenolic resin followed by thermal crosslinking of the later. The resulting PF/SiO2 IPNs were transformed to C/SiO2 composites through carbonization at 1000 °C under inert atmosphere with silica contents ranging from 10 to 70 %. The silica phase was sacrificed through hydrogen fluoride (HF) leaching to obtain porous carbons, which were further chemically activated with KOH. The derived porous carbons had hierarchical open pore geometry with majority of the pores belonging to the meso category. The carbons were employed to scavenge lead (Pb2+) ions from aqueous effluents and a maximum uptake of 177.3 mg of Pb2+ ions per gram of the adsorbent, was achieved with the present carbons. The adsorption was studied with standard adsorption models, such as Langmuir and Freundlich, of which a better compliance with Langmuir model was noted. Adsorption between the PFSiC carbons and Pb2+ ions obeyed second order kinetics.

Synthesis of ZnO nanopowder using zinc Zamak dross and adsorption of Pb

In this study, zinc oxide nanopowder (ZnONPDs) was successfully recovered from zinc die casting alloys’ (ZAMAK) dross using a facile dissolution and pH-controlled precipitation approach for removal of lead (II) ions from aqueous solutions. XRD patterns showed that ZnONPDs, calcined at 240°C, exhibited a hexagonal unit cell structure with an average crystallite size of 36.46 nm. FE-SEM micrographs revealed that the ZnONPDs are spherical and hexagonal in shape. TEM images showed the morphology and particle size of synthesized ZnONPDs with an average size of 23.81 nm. XRF and EDS analyses confirmed the high purity of the prepared ZnONPDs. The BET surface area of ZnONPDs was 33.85 m²/g. Adsorption experiments exhibited the maximum removal of Pb2+ ions 100% at the optimal conditions (25 ppm Pb2+ ions, 20 min contact time, 30 mg adsorbent per 100 ml of solution). The pH and zeta potential confirmed that a pH range from 5 to 9 was optimal for the adsorption study. The zeta potential within this range indicated a high level of stability for the particles in the suspensions, effectively preventing flocculation and agglomeration. XPS results conclusively demonstrated the successful adsorption of Pb onto the surface of ZnONPDs. The ZnONPDs synthesized in this study were shown to be promising candidates for use in adsorption processes, indicating that they could be highly useful in wastewater treatments removing toxic metal ions.

Preparation of magnetic composite based on chitosan/carbon nanotubes for reactive blue 198 and lead (II) ion removal

This study involved synthesizing a magnetic composite material of chitosan and carbon nanotubes using the freeze-drying process. The composite was created by mixing chitosan (CS), carbon nanotubes (CNT), and Fe3O4 in different ratios (w/w) (1.2:0.3:0.5, 1.2:0.5:0.3, 1.2:0.6:0.2 and 1.2:0.7:0.1). Results showed that the most porous structure was achieved with a ratio of 1.2:0.5:0.3 for CS:CNT:Fe3O4 (w/w). Various analytical methods such as FT-IR, SEM, XRD, and TGA were employed to determine the characteristics of the composite. The composite material was tested for its ability to adsorb Pb2+ heavy metal ions and reactive blue 198 (RB198) at concentrations ranging from 25 to 100 ppm. The study also investigated the effects of adsorbent amount, pH, and equilibrium time on the adsorption performance of the material.

Improving household water treatment: using zeolite to remove lead, fluoride and arsenic following optimized turbidity reduction in slow sand filtration

Despite the United Nations 2030 agenda, large number of both urban and rural dwellers in low-income countries continue to lack access to improved water. Thus, increased effort is required towards enhancing low-cost drinking water treatment technologies especially for developing countries. Slow sand filter (SSF) is one of the most commonly used low-cost and efficient technologies for treating household drinking water. However, effectiveness of SSF is substantially affected by very high turbidity and relatively large amounts of dissolved heavy metals. To enhance removal of both turbidity and heavy metals, this study optimized sand bed depth (SBD) of SSF and investigated the potential of natural zeolite from Uganda for removal of lead, arsenite (As(III)) and fluoride ions from water. To remove lead ions, the zeolite was used in its natural form. However, to remove As(III) and fluoride, the natural zeolite was modified using hexadecyltrimethylammonium bromide solution. Removal of high turbidity was found to require a large optimal SBD. Furthermore, efficiency of treating synthetic turbid water increased with increasing initial turbidity. Variation of final turbidity with SBD was found to be best described by an exponential function. Optimal SBDs on top of an underdrain gravel layer of 0.2 m were 453, 522, 561, and 580 mm for turbidity of 60, 80, 100, and 120 NTU, respectively. Optimized SBD used achieve at least 95% efficiency in removing suspended particles from water with turbidity 120 NTU was found to save up to 35% of the total cost for acquiring sand volume required by a conventional SSF. For a particular zeolite mass, removal efficiencies of lead, As(III) and fluoride generally increased with increasing contact time. Removal efficiencies of lead, As(III), and fluorides were also shown to increase with increasing zeolite mass. Lead removal efficiencies using natural zeolite were 75 and 98% under 20 and 40 min, respectively. Removal of As(III) using modified zeolite mass was 91% within contact time of 10 min. Adsorption of fluoride on modified zeolite was 80% within 5 min. Adsorption of lead, As(III), and fluorides indicated promising potential of natural zeolites from Uganda for treating polluted water.