Potential of Activated Groundnut Shells as a Natural Adsorbent for Removal of Lead (II) Ions Metals from Aqueous Solution

Performance evaluation of natural iron-rich sandy soil as a low-cost adsorbent for removal of lead from water

Magnetic metal organic frameworks (MOFs) composite for removal of lead and malachite green in wastewater

<div> <p>Low cost agricultural waste adsorbents can be viable alternatives to activated carbon for the treatment of contaminated wastewater. Sugarcane Bagasse, an abundant agriculture waste in Egypt, was used in the present study to prepare activated carbon. Batch adsorption experiments were conducted to study its effectiveness to remove cationic dye methylene blue from aqueous solution. The effects of initial dye concentrations, agitation time, solution pH and temperature on methylene blue dye removal were investigated. The optimum pH value for the maximum percentage removal of the dye was 7. Adsorption isotherms were determined and modeled with Redlich–Peterson, Langmuir and Freundlich equations at 20ºC.The kinetic data were analyzed using Pseudo-first order, pseudo-second order. The mechanism of the adsorption process was determined from the intraparticle diffusion model. Thermodynamic parameters such as standard enthalpy (ΔH°), standard entropy (ΔS°) and free energy (ΔG°) were determined.  The equilibrium data were best fitted to the Redlich–Peterson isotherm model .The adsorption kinetics was found to follow the pseudo-second-order kinetic model with good correlation coefficient. The positive ΔH<sup>◦</sup> value indicated that the adsorption process was endothermic in nature. The results revealed sugarcane bagasse activated carboncould be employed as a low-cost alternative adsorbent in wastewater treatment. </p> </div> <p> </p>

The main polluting agents of the environment are different anthropogenic activities; among them, industries are the primary one. Lead (Pb2+) is an extremely toxic metal ion and is the main raw material of lead–acid batteries. The present study focuses on adsorptive removal of lead from battery manufacturing industrial effluent by sweet lemon (Citrus limetta) peel biochar (SLPB). The removal efficiency was about 97.11% at optimum contact time of 160 min with optimum dosage of 3.5 g L−1 at constant temperature. The optimum pH and temperature were recorded to be 5 and 55 oC with their maximum adsorption capacities of 55.67 and 53.89 mg g−1, respectively. The process obeyed second-order kinetics favoring chemisorption over physisorption. The adsorbent was also characterized by SEM–EDX, XRD, BET and FTIR to validate the results obtained. The results were justified by the functional groups present and changes in morphology of the biochar after treating wastewater. Further, adsorption process preferred Freundlich (r2 = 0.98) adsorption isotherm in comparison with Langmuir (r2 = 0.95) adsorption isotherm. The adsorption process demonstrated that the removal process was multilayered and heterogeneous with maximum adsorption capacity (qmax) of 2840.91 mg g−1 which was higher than most of the values obtained from other materials. Thus, the study concluded that SLPB might be used to overcome the pollution level of metals in our water bodies to maintain the quality of water bodies.

The present study explores the ability of activated carbon prepared from sulphuric acid-treated cottonseed cake (SCSC) by chemical activation with sulphuric acid for the removal of Pb(II) from an aqueous solution. Batch experiments were carried out by varying several conditions such as contact time, solution pH, adsorbent dose and temperature along with commercial activated carbon (CAC). According to the experimental results, the equilibrium time and optimal pH range were found to be 3 h and 4.0–6.0, respectively. The equilibrium data were analysed based on the Freundlich, Langmuir, Redlich–Peterson and Dubinin–Radushkevich isotherms using nonlinear regression analysis and fit well with the Langmuir model. Based on the Langmuir isotherm, the adsorption capacity was found to be 115.86 mg/g for SCSC, which was substantially (5.3 times) greater than that of CAC (21.69 mg/g) at 300 K. The thermodynamic investigations indicated that the adsorption reactions were spontaneous and exothermic in nature. The results of the kinetic study showed that the adsorption of Pb(II) could be described by the pseudo-second-order equation, suggesting that the adsorption process is presumably chemisorptions with film diffusion. A single-stage batch adsorber was designed for different adsorbent dose using the Langmuir equation.

Treatment of wastewater from heavy metal pollutants still remains a serious challenge for some developing countries without centralized waste water systems. The study examines the potentials of raw and nano composite from Spondias mombin seed as an adsorbent for removal of lead (II) ions from contaminated water. Instrumental techniques such as scanning electron microscopy (SEM), Fourier Transform Infrared Spectrophotometer (FTIR), and Atomic absorption Spectrophotometer (AAS) were used to characterize the absorbents. The study analyzed the effect of various factors including absorbent dosage (0.2 – 1.0g), lead concentration (100-300 mg), contact time (30-180 min), pH (2-10) and temperature (30-50°C) respectively, on the absorption of pb2+ ions. The experimental findings revealed that the adsorbents have high absorption capacity and high percentage removal for the removal of pb2+ ions from aqueous solutions. Absorption isotherm kinetic models and thermodynamic studies were applied to access the absorption mechanism of lead (II) ion removal. The Langmuir absorption isotherm and pseudo-second-order model were found to fit the equilibrium data for nano composite while Freundlich isotherm and pseudo-first-order fitted the equilibrium data for raw fruit. According to the results obtained, a linear model was generated which indicated good predictability and the results agreed with the experimental data. The contact time and absorbent dosage were predicted to have a positive effect on the absorption process. However, after the investigation on the efficiency of raw and nano composite of Spondias mombin fruit on the removal of lead (II) ion from aqueous solutions as the impact of different variables were investigated. The study showed that the raw and modified adsorbents can be considered effective adsorbent for the removal of lead metal ions from wastewater by varying some basic parameters. The physiochemical properties of the absorbent were analyzed and the results obtained confirmed the adsorption potentials of the raw and nano composite. The removal efficiencies of both adsorbents on the Pb2+ ion were strongly dependent on their contact time, initial metal ion concentration, absorbent dosage, pH and temperature. The Langmuir isotherm model was well fitted to the experimental data, indicating that the two absorbents were effective in removing Pb2+ ions from aqueous solutions with low absorption energy. The experimental data of Pb2+ ions adsorption by raw and nano composit adsorbents studied were fitted with the pseudo-first-order and pseudo-second-order kinetic model respectively, revealing that adsorption occurs by physiosorptions and chemisorptions technique. The thermodynamic data showed that the adsorption process was exothermic, spontaneous and feasible in nature. Therefore, this work exposed the possible removal of lead (II) ions by raw and nano composite from agro waste of Spondias mombin from wastewater, which is generally a low cost agro waste.

This study has the objective to evaluate the lead(II) removal capacity of hydroxyapatite powder synthesized by microwave as an alternative method to decrease production time and cost. Hydroxyapatite (HA) was synthesized by a microwave-assisted precipitation method using calcium nitrate and ammonium hydrogen phosphate as calcium and phosphorus sources, respectively. X-ray diffraction and Fourier transform infrared results clearly revealed that the resulting powder was HA with high purity and crystallinity. The obtained powder was used for the removal of lead(II) from aqueous solutions. The effects of pH, amount of adsorbent, initial lead(II) concentration, and contact time were studied in batch experiments. In the adsorption experiments, maximum lead(II) retention was obtained at pH6. Adsorption equilibrium was established after 40min. It was found that the adsorption of lead(II) on HA was correlated well (R (2) = 0.958) with the Freundlich equation for the concentration range studied. Both ion exchange and adsorption process were thought to exist in the removal process. This study indicates that easily and rapidly synthesized HA by microwave-assisted precipitation method could be used as an efficient adsorbent for removal of lead(II) from aqueous solutions.

Green and efficient agro-waste-based activated carbon has been prepared utilizing peanut shells for adsorptive elimination of an industrial dye, methylene blue, and lead from polluted water. The carbonaceous biomass obtained from peanut shells was chemically activated using either NaOH, ZnCl2, or steam and characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, and N2 adsorption and desorption studies. The adsorption process was optimal for methylene blue at alkaline pH, while pH 4.5 was optimal for Pb (II) adsorption. The adsorption takes place through pseudo-second-order kinetic, and the rate-governing step of the adsorption procedure are intraparticle diffusion and film diffusion. Furthermore, the thermodynamics of the adsorption process has been studied, and the obtained Gibbs free energy (ΔG°) values are negative (− 35.90 to − 43.59 kJ mol−1) indicating the spontaneous adsorption of the investigated pollutants on the prepared activated carbon. As per the correlation coefficient, the obtained results were best fit by the Langmuir isotherm with maximum adsorption capacity of 303.03 mg g−1 for methylene blue and 130.89 mg g−1 for Pb (II). The activated carbon successfully removed methylene blue and Pb (II) with %removal exceeding 95%. The mechanisms of interaction of Pb (II) with the activated carbon is a combination of electrostatic interaction and ion exchange, while methylene blue interacts with the activated carbon via π–π interaction, hydrogen bonds, and electrostatic interaction. Thus, the prepared activated carbon has been employed to decontaminate wastewater and groundwater samples. The developed agro-waste-based activated carbon is a promising, cost-efficient, green, and accessible tool for water remediation.

Removal of basic and acid dyes from aqueous solutions by a waste containing boron impurity

In this work, cobalt-methylimidazolate framework has been used as an adsorbent in the removal of Pb(II) from acid mine drainage in adsorption batch system. X-ray diffraction, Fourier-transform infrared spectroscopy, Brunauer-Emmet-Teller and transmission electron microscope were used for structural, morphological, and surface characteristics of cobalt-methylimidazolate framework. The concentration of heavy metal ions in water samples was measured by inductively coupled plasma optical emission spectrometry. Different experimental factors/variables (such as contact time, dosage, and pH) affecting the adsorption of Pb(II) from acid mine drainage were optimized by response surface methodology based on central composite design. Under optimized experimental parameters, the maximum adsorption capacity of Pb(II) was found to be 105mgg-1. The nature of the adsorption process was investigated using Langmuir and Freundlich isotherm models. The obtained data best fitted Langmuir isotherm model suggesting a homogeneous adsorption process. Furthermore, the adsorption mechanism was investigated using five kinetic models, that is, pseudo-first order, pseudo-second order, intraparticle diffusion and Elovich model. The adsorption data fitted better to pseudo-second-order followed by intra-particle diffusion kinetic models suggesting that the adsorption mechanism is dominated by both chemical and physical adsorption processes. The adsorbent could be regenerated up to 8 cycles and it was successfully used in the removal of lead in real acid mine drainage samples.

Removal of Pb2+ ions by raw corn silk (Zea mays L.) as a novel biosorbent

The possibility of using waste cotton and cotton/polyester yarns to remove lead and chromium ions from polluted water was investigated in this work. Structural, morphological, and adsorption properties of yarns were determined by iodine sorption, water retention scanning electron microscopy, Fourier transform infrared spectroscopy, and streaming potential method for determination of an isoelectric point. It was found that the presence of polyester component negatively affects adsorption capacity, through the reduced porosity of cotton/polyester yarn surface, increased surface, and structural crystallinity. Relatively fast adsorption of lead and chromium ions from binary mixture onto cotton and cotton/polyester yarns follows the pseudo-second order kinetic, while equilibrium data fitted better with the Langmuir isotherm model, with maximal adsorption capacity from 259.0 to 824.7 μg/g. Although, cotton yarn shows slightly higher maximal adsorption capacities, both cotton and cotton/polyester yarns can be utilized as cheap and highly efficient adsorbents for removal of lead and chromium ions from water.

The purpose of this study was to prepare activated carbon from an agricultural solid waste and assess its effectiveness in adsorptive removal of lead from aqueous solution. Activated carbon was prepared from coconut coir and its characteristics were compared with that of a commercial bituminous coal-based activated carbon. The coconut coir activated carbon possessed higher surface and micropore areas, micropore volume and average pore diameter, and well developed meso-and micropores. Adsorption of lead from aqueous solution by the coconut coir activated carbon was examined. Batch adsorption test showed that extent of adsorption was dependent on lead concentration, contact time, pH and activated carbon dose. Adsorption was low at acidic pH and increased up to pH 5, with marginal increase up to pH 6. Equilibrium adsorption was attained in 2.5 h. Lead adsorption followed pseudo-second order kinetics. Equilibrium lead adsorption data for the coconut coir activated carbon and commercial activated carbon were described by the Langmuir and Freundlich isotherm models. Coconut coir activated carbon showed higher lead adsorption capacity [7.75 (Langmuir) and 3.63 (Freundlich)] compared with the commercial activated carbon [7.55 (Langmuir) and 1.87 (Freundlich)]. Coconut coir activated carbon is a suitable substitute for commercial activated carbon in the adsorptive removal of lead from water.

Adsorptive removal of Lead from water by the effective and reusable magnetic cellulose nanocomposite beads entrapping activated bentonite

In this study, adsorption potential of soya bean adsorbent for lead (Pb) and arsenic (As) has been assessed in order to consider its suitability for purification of wastewater containing heavy metals. The main focus of study was on Pb and As. Batch experiments were performed to study the adsorption of Pb and As on soya bean absorbent. The effect of various experimental parameters (adsorbent dose, contact time, temperature and pH) was studied, and optimal conditions were determined. The effect of adsorbent dose on the biosorption of Pb and As from aqueous solution was studied at 37 °C by varying the adsorbent amount from 1 g/100 ml to 4 g/100 ml. Highest amount of Pb and As was adsorbed at sorbent amount of 3 g/100 ml. The optimum pH for removal of As and Pb was found to be 2.0 and 4.0 ± 0.26. Maximum biosorption of Pb and As was achieved at 37 °C. The maximum percentage removal of Pb and As was attained at 60 min of shaking time. Langmuir and Freundlich isotherm models were utilized for equilibrium studies. It was found that biosorption by soya bean adsorbent was exothermic in nature. The thermal degradation analysis suggested that the degradation occurs in two steps and adsorbent is thermally stable.