Initial Adsorbate Concentration Research Articles

Ion Exchange Properties of Crosslinked and Carboxylated Peanut (Arachis Hypogaea L.) Testa Extract

After polymerization via polycondensation of catechin units in the acetone extract of peanut (arachis hypogaea L.) testa (PTE) using phosphorus oxychloride (POCl3) as a crosslinking agent, POCl3-crosslinked PTE (Crosslinked-PPTE) was functionalized by etherification (PC-PTE) using monochloroacetic acid (MCAA) in the presence of an alkali according to the method of Williamson ether synthesis. Subsequent to characterization by Fourier Transform Infrared spectroscopy (FTIR) as well as physical properties, Crosslinked-PPTE was assessed for cation exchange capacity (CEC) and pH at point of zero charge (ZPHC) following demonstrated capacity to remove heavy metal ions in single and multi-elements aqueous solutions by Atomic Absorption Spectrometry (AAS) technique while functionalized (carboxymethylated) Crosslinked-PPTE (PC-PTE) was further characterized by degree of substitution (DS). FTIR absorption bands due to -C-O-P=O, -P=O, P-O-C- and R-O-P-OH stretching vibrations were seen at 1350/1250, 1244/1246, 997/993 cm-1 respectively. Asymmetric and symmetric stretching vibrations of the -C=O of a COOH, Ar-O-C- of an aromatic ether as well as -P-O-C - of an aromatic PO43-, R-P=O of a -PO43-, -R-O-P- and R-O-P-OH of a PO43- ester created by crosslinked and carboxymethylated PTE respectively were seen at 1743, 1377, 1278, 1190, 1062 and 823 cm-1. The results obtained showed that 0.6 was the DS of PC-PTE while 6.72 meq/g and 3.57 defined the CEC and pH (zpc) respectively of Crosslinked-PPTE. Quantitative removal of Fe2+, Ni2+, Pb2+, Cu2+ and Zn2+ in laboratory simulated metal ion wastewater (LSW) to the levels of 84.4, 81.7, 76.5, 72.0 and 75.1% respectively was achieved using Crosslinked-PPTE resin in batch adsorption experiments in which the efficiency was found to depend significantly on the temperature and pH of the water as well as initial adsorbate concentration and contact time but partially on the amount of adsorbent used was observed to be independent of the speed of stirring of the wastewater. Stable, Matakana and fine powder crosslinked-PPTE which is insoluble in water and common laboratory solvents holds great potential in the purification of heavy metal ions polluted water

Efficient Uptake of Angiotensin-Converting Enzyme II Inhibitor Employing Graphene Oxide-Based Magnetic Nanoadsorbents

This paper reports a high efficiency uptake of captopril (CPT), employing magnetic graphene oxide (MGO) as the adsorbent. The graphene oxide (GO) was produced through an oxidation and exfoliation method, and the magnetization technique by the co-precipitation method. The nanomaterials were characterized by FTIR, XRD, SEM, Raman, and VSM analysis. The optimal condition was reached by employing GO·Fe3O4 at pH 3.0 (50 mg of adsorbent and 50 mg L−1 of CPT), presenting values of removal percentage and maximum adsorption capacity of 99.43% and 100.41 mg g−1, respectively. The CPT adsorption was dependent on adsorbent dosage, initial concentration of adsorbate, pH, and ionic strength. Sips and Elovich models showed the best adjustment for experimental data, suggesting that adsorption occurs in a heterogeneous surface. Thermodynamic parameters reveal a favorable, exothermic, involving a chemisorption process. The magnetic carbon nanomaterial exhibited a high efficiency after five adsorption/desorption cycles. Finally, the GO·Fe3O4 showed an excellent performance in CPT removal, allowing future application in waste management.

Fe (II) Ions’ Adsorption Kinetics and Thermodynamics on Lagenaria siceraria Stem Nano Carbon

As severe a threat to the environment as global warming is heavy metal contamination. Nano carbon from Lagenaria siceraria Stem fiber has been used to examine the removal of Fe(II) ions from aqueous solution. It employs batch adsorption methods. We looked into the effects of contact time, initial adsorbent concentration, dose, and solution pH. The equilibrium adsorption data were connected with the Langmuir, Freundlich, Dubinin-Radushkevich, and Redlich-Peterson isotherm models. The adsorption procedure was advantageous, according to the isotherm analyses of RL values. The evaluation of thermodynamic parameters H0 , S0 , and G0 . The data show that the adsorption was endothermic in nature and spontaneous. Pseudosecond-order, Elovich model, and intra-particle diffusion models were used to investigate the kinetics of adsorption. A pseudo-second-order adsorption reaction is suggested by kinetic investigations. This work demonstrates that intra-particles were crucial to the mechanism governing the adsorption of Fe(II) ions. For the removal of Fe(II) ions from aqueous solution, the Activated Lagenaria siceraria Stem Nano Carbon has a high adsorption capacity and adsorption rate. Key words : Adsorption, Fe(II) ions, kinetics, Activated Lagenaria Si

Removal of Zinc (II) ions from industrial wastewater by adsorption on to activated carbon produced from pine cone

Recently heavy metal pollution is consider among the most essential environmental issues. Due to their impact, the removing of heavy metals from the environment is a high demanding concern. Heavy metals adsorption is a new technology for wastewater treatment that contain different selected heavy metals types. This study aim to adopted adsorbents with low cost application, in this technique a pine cones used as plant wastes adsorbents in Industrial wastewater treatment by implemented batch technique adsorbent dosage and adsorbate initial concentration). The plant waste sample of (pine cone) was used to test its efficiency which that provide the optimum performance in removing heavy metals and other pollutants (Turbidity, TSS and TDS). Activated carbon produced from Pine cones Turkish Pine (ACPC) was adopted as an adsorbent for the Zinc ions removal from wastewater with industrial pollutants. Surface analysis was preform to measure the pore size distribution and specific surface area of the activated carbon produced from pine cone. Optimal parameters, pH, equilibrium time, adsorbent dosage, temperature and mix speed were investigated. Using Langmuir, Freundlech and Elvich isotherm models, equilibrium data were evaluated. Langmuir isotherm model provided the highest fit to the equilibrium data.

Recovery of tetrodotoxin from pufferfish viscera extract by amine-functionalized magnetic nanocomposites.

Tetrodotoxin (TTX) has been widely used in pharmacology, food poisoning analysis, therapeutic use, and neurobiology. In the last decades, the isolation and purification of TTX from natural sources (e.g., pufferfish) were mostly based on column chromatography. Recently, functional magnetic nanomaterials have been recognized as promising solid phases for the isolation and purification of bioactive compounds from aqueous matrices due to their effective adsorptive properties. Thus far, no studies have been reported on the utilization of magnetic nanomaterials for the purification of TTX from biological matrices. In this work, an effort has been made to synthesize Fe3O4@SiO2 and Fe3O4@SiO2-NH2 nanocomposites for the adsorption and recovery of TTX derivatives from a crude pufferfish viscera extract. The experimental data showed that Fe3O4@SiO2-NH2 displayed a higher affinity toward TTX derivatives than Fe3O4@SiO2, achieving maximal adsorption yields for 4epi-TTX, TTX, and Anh-TTX of 97.9, 99.6, and 93.8%, respectively, under the optimal conditions of contact time of 50 min, pH of 2, adsorbent dosage of 4 g L-1, initial adsorbate concentration of 1.92 mg L-1 4epi-TTX, 3.36 mg L-1 TTX and 1.44 mg L-1 Anh-TTX and temperature of 40 °C. Interestingly, desorption of 4epi-TTX, TTX, and Anh-TTX from Fe3O4@SiO2-NH2-TTX investigated at 50 °C was recorded to achieve the highest recovery yields of 96.5, 98.2, and 92.7% using 1% AA/ACN for 30 min reaction, respectively. Remarkably, Fe3O4@SiO2-NH2 can be regenerated up to three cycles with adsorptive performance remaining at nearly 90%, demonstrating a promising adsorbent for purifying TTX derivatives from pufferfish viscera extract and a potential replacement for resins used in column chromatography-based techniques.

Uklanjanje boje bemacid red adsorpcijom na piljevini i karbonizovanoj piljevini

Today, huge amounts of coloured wastewater, released into ecosystems are a big problem, because they have harmful effects on humans, the environment, as well as the aquatic environment. One of the common treatments for removing dyes from wastewater is the adsorption process, with an emphasis on the use of cheap adsorbents. Therefore, the subject of this paper is the possibility of removing the anionic dye bemacid red (BR) on wood biomass sawdust and carbonized sawdust. The experiments examined the equilibrium contact time, the effect of initial pH, the effect of adsorbent dose, as well as the effect of the initial adsorbate concentration on the process of adsorption. By applying linear kinetic models, it was found that the adsorption process follows a pseudo-second-order kinetic model. It was found that pH does not have a significant effect on adsorption onto carbonized sawdust. By examining the effect of the initial adsorbent dose, it was found that optimal adsorption requires twice the mass of sawdust compared to carbonized sawdust. The use of linear adsorption isotherms shows better agreement with the Freundlich model for both adsorbents. The maximum adsorption capacity for sawdust is 30.18 mg/kg, while for carbonized sawdust it is 74.60 mg/kg. Use of sawdust and carbonized sawdust can be an effective adsorbent for removing the dye bemacid red from wastewater, which is confirmed by the experiment on a real sample of wastewater. The obtained efficiency of dye removal from real wastewater for sawdust is 42.9 %, and for carbonized sawdust 95.1 %.

Use of calcined camel bones for water fluoridation of five boreholes in the Maradi region, Niger

The presence of fluorides in drinking water has become a major concern worldwide due to their chronic carcinogenic behavior for humans. The development of easily accessible and environmentally friendly disposal strategies is therefore a challenge for scientists. Camel bones calcined at different temperatures and then activated with HCl at different concentrations were used for the removal of fluorides ions from an aqueous solution. The effect of activate concentration, initial adsorbate concentration, contact time and adsorption process were studied. In addition to these previous parameters, the influence of co-existing ions on the adsorption capacity of fluorides ions was investigated. The optimal dose on calcined and activated camel bones is 16g / L with a maximum adsorption capacity of 0.63 mg / g. After optimization of this parameter an application on natural waters was realized. The study showed that the calcined and activated dromedary or camel bone is a promising adsorbent for the removal of fluorides ions from fluoridated or contaminated or drinking water.

Adsorptive removal of hazardous crystal violet dye onto banana peel powder: equilibrium, kinetic and thermodynamic studies

In this study, banana peel powder (BPP) was used to remove carcinogenic crystal violet (CV) dye from aqueous solution. The BPP adsorbent was characterized by Fourier-Transform Infrared (FTIR) spectroscopy and Scanning Electron Microscopy (SEM). In batch sorption experiments, the maximum removal of CV was recorded 93% at optimum levels of operating parameters, i.e., pH 7.0, adsorbent dosage 0.1 g, contact time 10 min, initial adsorbate concentration 90 ppm and temperature 20 C o . The kinetics of the adsorption process was found best to follow the pseudo first order model with high value of R 2 (0.9999) and low values of error functions. The Langmuir isotherm model was the best fit with high R 2 (0.9552) low values of error models. The plots of Freundlich and D-R isotherms confirmed the feasibility ( n = 1.3109 L g − 1 ) and the physisorption nature ( E s = 0.1107 kJ mol − 1 ) of the process respectively. The negative values of thermodynamic parameters ( Δ G & Δ H ) revealed that the adsorption was spontaneous and exothermic in nature respectively. The results of the desorption study showed that 91% of the adsorbent was regenerated. The novelty of the present research is that no work has been reported till date to remove crystal violet dye by using banana peel specifically. The high adsorption and desorption efficiencies (>90%) suggest that BPP possesses characteristics to be used as an effective, fast and low-cost adsorbent for adsorption of CV dye from industrial effluents. HIGHLIGHTS Adsorption technique was employed to remove crystal violet dye by using banana peel powder. The hydroxyl ( OH − ) & carboxylate ( OH − ) groups on adsorbent surface provided excellent binding with adsorbate molecules. Equilibrium attainment in 10 min at neutral pH. 93% adsorption and 91% desorption.

Selective recovery of lanthanum from magnesium-containing solution via phosphoric acid modified kaolin prepared by a simple mechanochemical process

As the world's demand for rare earths soars, the supply of rare earths is in danger of being depleted. The recycling rate of rare earth is only 1 % of all rare earth. Therefore, the recovery of rare earth is crucial and challenging. A phosphoric acid modified kaolin (P-K) was prepared by a simple mechanochemical method, and the selective recovery of rare earth element lanthanum (La) was studied. The P-K was characterized and analyzed by SEM, EDS, and FT-IR. Additionally, the different modification conditions of P-K preparation such as milling speed, time, and mass ratio of H3PO4/kaolin on La adsorption were investigated, and the effects of operating conditions such as solution initial pH, adsorption time, and adsorbent concentration on La adsorption were studied. The adsorption behavior of La by P-K was consistent with the Langmuir isothermal adsorption model with a saturated adsorption capacity of 18.55 mg/g, and the adsorption kinetics accorded with the pseudo-second-order kinetic model. Additionally, La in the mixture of La and magnesium (Mg) can be selectively adsorbed through P-K, while the adsorption rate of Mg is almost 0. P-K load with La could be eluted by 0.03 mol/L HCl, and the elution rate of La can reach 99.9 %. As a result, this study demonstrates a method for the recovery of La from rare earth wastewater.

2-Methylimidazole-modifi ed Iron Metal-organic Framework as an Effi cient Methylene Blue Adsorbent

Metal organic frameworks have a wide range of applications in the fi eld of environmental remediation. In this study, Fe-BDC/Fe-2MI composites were synthesized by one-pot solvothermal method. By studying the adsorption performance of methylene blue (MB) in wastewater, it was confi rmed that Fe-BDC/Fe-2MI has excellent adsorption properties. When the initial molar ratio of FeCl3 .6H2O: H2BDC: 2-MI is 1:1.5:10, the adsorbent has the best adsorption performance. At the same time, the effects of different pH (2-10), temperature (303-323K) and initial concentration of adsorbate (30-90mg/L) on the adsorption capacity were further explored. It was found that when pH=6.0, T=303K was favorable for Fe-BDC/Fe-2MI to adsorb MB. The adsorption process conformed to the Langmuir isotherm adsorption model, indicating that it was a monolayer adsorption which was a good adsorption process. Thermodynamic parameters show that the adsorption process is a spontaneous exothermic reaction. These results demonstrated that Fe-BDC/Fe-2MI composites possess potential practical application value.

Comparative adsorption study of mango (<em>Mangifera indica</em>) leaves and neem (<em>Azadirachta indica</em>) leaves, as an adsorbent for dye removal

The study attempted to evaluate and compare the adsorption capacity (Methylene Blue removal) of non-conventional adsorbents prepared from Neem (<em>Azadirachta indica</em>) leaf and Mango (<em>Mangifera Indica</em>) leaf and Langmuir model or Freundlich model were analyzed. The leaves from Neem and Mango were collected, cleaned, dried (115°C) and powdered. The physiochemical properties were studied. Methylene blue dye was used as the pollutant since it is a frequently used dye for adsorption studies. A series of batch experiments were carried to evaluate the adsorption capacity of Neem leaf adsorbent and mango leaf adsorbent with different dosages and different initial adsorbate concentrations (100, 150, 200 and 250 mg/L). Neem leaf showed the highest adsorption capacity of 83%. The adsorption capacity of the Mango leaves was around 79%. Adsorbent dose and adsorption rate have a positive relation. Adsorption rate increases with adsorbent dose and decreases with increases of adsorbate initial concentration. Langmuir isotherm showed a high coefficient of determination. Both Langmuir separation factor (RL) and Freundlich constant (nF) suggest the favorable adsorption of the dye onto the adsorbents. The results indicated that both neem and mango leaves have an attractive property to remove dye from water. Therefore, both can be used as alternative green adsorbents for pollutant removal.

Functionalized graphene oxide-zinc oxide hybrid material and its deployment for adsorptive removal of levofloxacin from aqueous media

This work reports on the synthesis of aspartic acid-functionalized graphene oxide-zinc oxide, as a functional porous material, and its potential to mitigate levofloxacin (LFXN). The adsorbent was characterized by various techniques, including ultraviolet–visible (UV–Vis), Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM). The average crystallite size of the prepared composite was about 17.30 nm. Batch adsorption studies were carried out to elucidate the adsorption process for LFXN. Different parameters, including contact time, LFXN initial concentration, adsorbent concentration, pH, temperature, and ionic strength were studied. The mechanism and kinetics were studied by fitting the data to Freundlich and Langmuir isotherms, pseudo-first-order and pseudo-second-order kinetic models, respectively. The isotherm data was better fitted to Langmuir isotherm (R2 = 0.999) as compared to the Freundlich model. The maximum adsorption capacity obtained at equilibrium was 73.15 mg/g. For kinetic studies, Pseudo first order was better fitted with R2 = 0.87797, confirming the physisorption process. Thermodynamics parameters revealed that the process was exothermic and spontaneous at low temperatures. The adsorption mechanism was studied and the impregnation of LFXN in the adsorbent was confirmed by FTIR studies. This research proved that the designed GO/Asp-ZnO was a novel and promising adsorbent for the removal of LFXN with an efficiency of 95.12% at 30 mg/L LFXN by 0.6 g/L adsorbent in 24 h at pH = 7 and T = 25 °C.

Highly Efficient Adsorption of Tetracycline Using Chitosan-Based Magnetic Adsorbent.

Herein, tetracycline adsorption employing magnetic chitosan (CS·Fe3O4) as the adsorbent is reported. The magnetic adsorbent was synthesized by the co-precipitation method and characterized through FTIR, XRD, SEM, and VSM analyses. The experimental data showed that the highest maximum adsorption capacity was reached at pH 7.0 (211.21 mg g-1). The efficiency of the magnetic adsorbent in tetracycline removal was dependent on the pH, initial concentration of adsorbate, and the adsorbent dosage. Additionally, the ionic strength showed a significant effect on the process. The equilibrium and kinetics studies demonstrate that Sips and Elovich models showed the best adjustment for experimental data, suggesting that the adsorption occurs in a heterogeneous surface and predominantly by chemical mechanisms. The experimental results suggest that tetracycline adsorption is mainly governed by the hydrogen bonds and cation-π interactions due to its pH dependence as well as the enhancement in the removal efficiency with the magnetite incorporation on the chitosan surface, respectively. Thermodynamic parameters indicate a spontaneous and exothermic process. Finally, magnetic chitosan proves to be efficient in TC removal even after several adsorption/desorption cycles.

Optimized adsorption and effective disposal of Congo red dye from wastewater: Hydrothermal fabrication of MgAl-LDH nanohydrotalcite-like materials

• MgAl-LDH was synthesized ideally using the hydrothermal method. • MgAl-LDH exhibited excellent adsorption capacity for CR dye compared with previously prepared LDH compounds and other sorbents. • The experimental adsorption data adequately fit the Langmuir isotherm model. • Pseudo-second-order kinetic model best represents the adsorption data. • The interaction mechanism of CR to the MgAl-LDH surface was strengthened by electrostatic attraction. The effectiveness of Congo red (CR) adsorption from aqueous solutions onto MgAl-layered double hydroxide (MgAl-LDH) nanosorbents was examined in this study. MgAl-LDH was synthesized using the hydrothermal method, and physicochemical characterization was performed via powdered X-ray diffraction, high-resolution transmission electron microscopy, Fourier transform infrared analysis, and zeta potential measurements. For optimum adsorption of CR onto the synthesized MgAl-LDH nanosorbent, the adsorption process was employed in batch experiments. Adsorption parameters, such as the adsorbent dosage, solution pH, contact time, and initial adsorbate concentration, vary with the adsorption kinetics and isotherm mechanism. The results of the batch experiments indicated rapid adsorption of CR dye from aqueous solutions onto MgAl-LDH during the first 30 min until equilibrium was achieved at 180 min with a dye concentration of 50 mg/100 mL and MgAl-LDH adsorbent dosage of 0.05 g. The experimental adsorption data fit adequately with the monolayer coverage under the Langmuir isotherm model ( R 2 = 0.9792), and showed the best fit with the pseudo-second-order kinetic model ( R 2 = 0.996). The change in zeta potential confirmed the effective adsorption interaction between the positively charged MgAl-LDH and the negatively charged CR molecules with electrostatic interactions. This work is distinguished by the successful hydrothermal preparation of MgAl-LDH in the form of homogenous nanoscale particles (∼100 nm). The prepared MgAl-LDH showed a high adsorption capacity toward anionic CR dye with a maximum adsorption capacity of 769.23 mg/g. This capacity is higher than those reported for other adsorbents in previous research.

Adsorptive Removal of Copper (II) Ions from Aqueous Solution using Acid and Thermally Activated Iron Oxide Sand

Heavy metal pollution of water bodies is a common problem in Zambia, whose economy depends on copper mining. Removal of Cu2+ ions from the solution via adsorption using iron oxide ore was investigated. The composition of the adsorbent was determined by XRF and ICP-OES. Iron oxide had predominantly Fe2O3 at 60 % with less than 3% of SiO2 and Al2O3. The Cu2+ ion concentrations were measured before and after adsorption using Atomic Absorption Spectroscopy (AAS). The effects of initial concentration, pH, acid activation, and thermal activation of the adsorbent on adsorption were investigated. A decrease in the adsorption of Cu2+ ions with an increase in the initial concentration of adsorbate (Cu2+) was observed. The adsorption of Cu2+ ions on acid-activated Iron oxide compared to thermally activated iron oxide ranged from 83-73%, respectively. Adsorption of Cu2+ ions was pH dependent with an optimum pH of 7. Acid activation of the adsorbent had better absorptivity since acids cause mineral dissolution, which increases the surface area and porosity of the adsorbent. Iron Oxide adsorbents have the potential to the removal of Cu2+ ions from aqueous solutions. Keywords: Adsorption, Copper ions, Heavy metals, Iron oxide, Pollution.

Synthesis of a Novel Adsorbing Agent by Coupling Chitosan, β-Cyclodextrin, and Cerium Dioxide: Evaluation of Hexavalent Chromium Removal Efficacy from Aqueous Solutions

The present study aimed at synthesizing a novel adsorbing agent by coupling chitosan, β-cyclodextrin, and cerium dioxide (Chit/β-CyD/Ce). Its efficiency towards the removal of hexavalent chromium from aqueous solutions was studied and compared to an adsorbent comprising of only chitosan and cerium dioxide. Batch water purification experiments in varying experimental conditions (initial adsorbent concentration 5–100 mg/L, adsorbate concentration 0.1–2 g/L, pH 2–11, and temperature 15–50 °C) were carried out to evaluate the effectiveness of both adsorbents. In all the experimental cases, the Chit/β-CyD/Ce adsorbent exhibited the higher efficacy. The optimum operating conditions were found to be at an initial adsorbent concentration of 2 g/L, pH = 3, and temperature of 50 °C, with the Chit/β-CyD/Ce adsorbent being able to fully remove Cr(VI) from solutions with up to 50 mg/L Cr(VI) at these conditions. The adsorption of hexavalent chromium onto both adsorbents occurs in a multilayer pattern of a heterogeneous surface following the Freundlich isotherm model. Furthermore, the adsorption process was exothermic and obeyed the pseudo-second-order kinetic model, thus indicating the occurrence of chemisorption. Finally, FTIR, XRD, and SEM analyses were performed to characterize the synthesized adsorbents and verify the adsorption process.

Rapid Removal of Toxic Remazol Brilliant Blue-R Dye from Aqueous Solutions Using Juglans nigra Shell Biomass Activated Carbon as Potential Adsorbent: Optimization, Isotherm, Kinetic, and Thermodynamic Investigation.

Recently, the treatment of effluent by agricultural waste biomass has significantly attracted wide interest among researchers due to its availability, efficacy, and low cost. The removal of toxic Remazol Brilliant Blue-R (RBBR) from aqueous solutions using HNO3-treated Juglans nigra (walnut) shell biomass carbon as an adsorbent has been examined under various experimental conditions, such as initial pH, adsorbate concentration, adsorbent dosage, particle size, agitation speed, and type of electrolyte. The experiments are designed to achieve the maximum dye removal efficiency using the response surface methodology (RSM). The optimum pH, adsorbent dosage, and particle size were found to be 1.5, 7 g L−1, and 64 μm, respectively for maximum decolorization efficiency (98.24%). The prepared adsorbent was characterized by particle size, Brunauer–Emmett–Teller (BET) surface area, pore volume, zero-point charge (pHzpc), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy/energy dispersive X-ray spectroscopy (FE-SEM/EDX), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Based on fitting the experimental data with various models, the isotherm and kinetic mechanism are found to be more appropriate with Langmuir isotherm and pseudo-second-order kinetics. The adsorption mechanism can be described by the intra-particle diffusion model, Bangham, and Boyd plots. The overall rate of adsorption is controlled by the external film diffusion of dye molecules. The maximum monolayer adsorption capacity, (qmax) 54.38 mg g−1 for RBBR dye, was obtained at a temperature of 301 K. From a thermodynamic standpoint, the process is endothermic, spontaneous, and the chemisorption process is favored at high temperatures. Desorption studies were conducted with various desorbing reagents in various runs and the maximum desorption efficiency (61.78% in the third run) was obtained using the solvent methanol. Reusability studies demonstrated that the prepared adsorbent was effective for up to three runs of operation. The investigation outcomes concluded that walnut shell biomass activated carbon (WSBAC) is a cost-effective, eco-friendly, and bio-sustainable material that can be used for synthetic dye decolorization in aqueous media.

Facile adsorptive removal of dyes and heavy metals from wastewaters using magnetic nanocomposite of zinc ferrite@reduced graphene oxide

• Incorporation of ZnFe 2 O 4 onto rGO improves the adsorption efficiency of rGO. • Pb (II) and MB dye were efficiently adsorbed onto the synthesized MrGO. • Adsorption of Pb(II) and MB onto MrGO follow Langmuir isotherm and PSO kinetic models. • The synthesized MrGO nanocomposite have been used for 5 consecutive cycles. Graphene-based nanomaterials can be tailored as green and excellent adsorbents for wastewater treatment. Herein, reduced graphene oxide was synthesized by a modified Hummer’s method and decorated with zinc ferrite nanoparticles for the efficient adsorptive removal of lead, and methylene blue dye from aqueous solutions. The characteristics of the nanocomposite adsorbent (ZnFe 2 O 4 @rGO, MrGO) were ascertained by various physicochemical tools including: X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Field Emission scanning electron microscopy with energy dispersive X-ray spectrometry (FESEM-EDX), X-ray photoelectron spectroscopy (XPS), Zeta potential, and Vibrating sample magnetometer (VSM) analysis. Various parameters, influencing the adsorptive removal of pollutants, were thoroughly explored and optimized including the mass of adsorbent, initial concentration of adsorbate, and medium pH. The synthesized MrGO nano-adsorbent exhibited excellent adsorption capacities towards model pollutants of lead ions and methylene blue dye of 89.8 and 119.0 mg g −1 , respectively. A plausible mechanism of pollutants’ removal on the synthesized nanocomposite was attributed mainly to the vacancy defects and oxygen bearing functional groups of the MrGO nanoparticles’ surfaces. The adsorption isotherms conformed to the Langmuir, rather than the Freundlich, model and followed the PSO kinetic model suggesting a chemisorption process via pollutants monolayers on the MrGO nanoparticles’ surfaces. The synthesized MrGO nanocomposite was excellently stable and reusable for five consecutive cycles; and therefore, it can be a promising adsorbent for the effective removal of pollutants of heavy metals and dyes for environmental remediation purposes.

Nitrate removal from aqueous solution using watermelon rind derived biochar-supported ZrO2 nanomaterial: Synthesis, characterization, and mechanism

• WM was synthesized from watermelon rind. • WM@ZrO 2 was about 3.84 of WM. • WM@ZrO 2 exhibited an adsorption capacity of 15.196 mg g −1 . • WM@ZrO 2 was favorable for more affinity towards nitrate. • WM@ZrO 2 had a good regeneration capacity in five cycles. Recently, biochar has attracted tremendous research interest for environmental applications. In this study, biochar-derived watermelon rind (WM) was produced via optimal pyrolysis at 500 °C for 2 h, and then improved the adsorption capacity by Zirconium oxide nanoparticles (ZrO 2 NPs). The WM@ZrO 2 was characterized using X-ray diffraction (XRD), Scanning electron microscopic - Energy-dispersive X-ray spectroscopy (SEM-EDS), and Fourier transform infrared (FTIR). The adsorptive capacities of synthesized ZrO 2 NPs were investigated for nitrate as a function of pH, adsorbent dosage, contact time, initial adsorbate concentration, and pyrolysis temperature in the batch experiment. The results showed that a Langmuir isotherm and a pseudo-second-order kinetics model were the best-fit for experimental nitrate data in its non-linear form as correlation coefficients (R 2 ) were 0.985 and 0.998, respectively. The maximum adsorption capacity for the Langmuir isotherm model was 15.196 mg g −1 . The proposed mechanism, including electrostatic attraction and ligand exchange, played a dominant role in nitrate adsorption. After testing with the real domestic wastewater, the removal of nitrate for WM@ZrO 2 was achieved at 78 %, which was equivalent to the adsorption capacity of 8.1 mg g −1 of adsorbent. Overall, the WM@ZrO 2 is proposed as a promising, effective, and environmentally friendly adsorbent in removing nitrate from an aqueous solution.

Fabrication of a magnetite hydroxyapatite nanocomposite for the removal of Paraquat dichloride: Adsorption studies

Paraquat dichloride (PQ) is a broad-spectrum herbicide that is widely employed in traditional agricultural practices due to its fast activity, minimal expense and resulting in high productivity. But its uncontrolled and inappropriate usage with subsequent discharge has resulted in contamination of water bodies. It is known to pose serious threat to human well-being and to the aquatic community on account of its toxic nature. Adsorption on account of its ease of operation, cost-effectiveness and environment friendliness is recognized as one of the best tertiary treatment methods and hence can be recommended for the eradication of PQ from aqueous water bodies. The utilization of adsorbent materials with reasonable and eco-accommodating attributes is a possible answer for getting safe water. To maintain sustainability, a nanocomposite of hydroxyapatite and magnetite (NC) was fabricated and its adsorption potential for the eradication of PQ was evaluated. NC was characterised using FTIR and XRD methods. Batch adsorption studies were carried out to evaluate the extent of adsorption. For the adsorption of PQ onto NC, the effects of operating parameters such as pH, adsorbent dose, initial adsorbate concentration, contact time, and temperature were also investigated. The Langmuir model best fit the adsorption data, and the maximum adsorption capacity for PQ at 25 °C was 416.67 mg/g. The dynamics of the process were best explained by a pseudo-first order kinetic model. According to kinetic studies, equilibrium was reached within 130 min of contact time in which approximately 90 % of PQ was eradicated. Adsorption of PQ onto NC was found to be a favourable, spontaneous, and exothermic reaction by thermodynamic analysis. The present study thus demonstrates the effectiveness of fabricated nanocomposite for the eradication of PQ from aqueous solution.