Elovich Models Research Articles

Removal of phenol from wastewater using Luffa cylindrica fibers in a packed bed column: Optimization, isotherm and kinetic studies

This research entails a comparison of the effectiveness of unmodified Luffa cylindrica fiber in a fully packed bed (RLCF) and NaOH-modified Luffa cylindrica fiber in another fully packed bed (MLCF) in the context of phenol removal from wastewater. Experimental data obtained through batch adsorption experiments were utilized to determine the most suitable model. It was observed that as the initial concentration of phenol increased from 100 to 500 mg/l, the maximum percentage removal increased from 63.5 to 83.1% for RLCF-PB and from 89.9 to 99.5% for MLCF-PB. The correlation coefficient (R2) was calculated for the Langmuir, Freundlich, Temkin, Harkin-Jura, Halsey, and Flory-Huggins models for both materials. The analysis revealed that the pseudo-second-order model was the most suitable, followed by the Elovich model, with the pseudo-first-order model being the least suitable. The Weber-Morris diffusion model suggested that pore diffusion was the rate-determining step, and diffusion at the border layer was determined to be endothermic, feasible, heterogeneous, and spontaneous. In summary, this study indicates that MLCF-PB is a promising material for the efficient removal of phenol from aqueous solutions.

Removal of paracetamol from aqueous solution with zinc oxide nanoparticles obtained by green synthesis from purple basil (Ocimum basilicum L.) waste

In this study, environmentally friendly zinc oxide nanoparticles (OB-ZnO NPs) were synthesized using Ocimum basilicum (OB) plant waste extract, and the removal of paracetamol (PCM) from pharmaceutical wastes with toxic effects on the ecosystem was investigated. The characteristic structure of synthesized OB-ZnO NPs was determined by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscope (SEM) and energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS), Zetasizer, thermogravimetry-differential thermal analysis (TGA-DTA), and UV-vis spectroscopy. The effect of the obtained OB-ZnO NPs on PCM removal was determined by batch adsorption tests. In the study in which 6 different kinetic and isotherm models were examined, error analysis functions were used to determine the most suitable model. Accordingly, the crystal structure of biosynthesized OB-ZnO NPs has a particle size of 30.39 nm, a surface area of 13.826 m2/g, and a pore volume of 0.0475 cm3/g. Since OB-ZnO NPs have a zeta potential of − 22.1 mV and a mass loss of 33% at about 750 °C, these NPs show that they are durable at high temperatures. When the PCM removal mechanisms with OB-ZnO NPs were examined, it was determined that the most suitable kinetic and isotherm model was the Elovich model with an R2 value of 0.989 and the Redlich-Peterson model with an R2 value of 0.999. In the study, which reached 23 mgPCM/gOB-ZnO NP removal efficiency, it was revealed that OB-ZnO NPs obtained from waste plants have the potential to be used in the removal of pharmaceutical wastes.Graphical abstract

Facile Preparation of Magnetic COF-on-COF for Rapid Adsorption and Determination of Sulforaphane from Cruciferous Vegetables

Sulforaphane (SFN) is a natural isothiocyanate compound widely abundant in cruciferous vegetables with multiple bioactive functions. However, traditional analytical methods for the extraction and determination of SFN are cumbersome, time-consuming, and low sensitivity with large amounts of organic solvents. Herein, novel magnetic COF-on-COFs (MB-COFs) were fabricated using Fe3O4 as a magnetic core and COFs-1 grown with COFs-2 as a shell, and they were used as efficient adsorbents of magnetic dispersive solid-phase extraction for rapid quantification of SFN in cruciferous vegetables by combining with HPLC-MS/MS. At the optimal ratio of COFs-1 to COFs-2, MB-COFs had a spherical cluster-like structure and a rough surface, with a sufficient magnetic response for rapid magnetic separation (1 min). Due to the introduction of Fe3O4 and COFs-2, MB-COFs exhibited outstanding extraction efficiencies for SFN (92.5–97.3%), which was about 18–72% higher than that of the bare COFs. Moreover, MB-COFs showed good adsorption capacity (Qm of 18.0 mg/g), rapid adsorption (5 min) and desorption (30 s) to SFN, and favorable reusability (≥7 cycles) by virtue of their unique hierarchical porous structure. The adsorption kinetic data were well fitted by the pseudo-second-order, Ritchie-second-order, intra-particle diffusion, and Elovich models, while the adsorption isotherm data were highly consistent with the Langmuir, Temkin, and Redlich–Peterson models. Finally, under the optimized conditions, the developed method showed a wide linear range (0.001–0.5 mg/L), high sensitivity (limits of quantification of 0.18–0.31 μg/L), satisfactory recoveries (82.2–96.2%) and precisions (1.8–7.9%), and a negligible matrix effect (0.82–0.97). Compared to previous methods, the proposed method is faster and more sensitive and significantly reduces the use of organic solvents, which can achieve the efficient detection of large-scale samples in practical scenarios. This work reveals the high practical potential of MB-COFs as adsorbents for efficient extraction and sensitive analysis of SFN in cruciferous vegetables.

Advancements in organic pollutant remediation: The role of nitrogen-doped rGO-CeO2 in photocatalytic efficiency enhancement

In this work, a novel nitrogen-doped reduced graphene oxide-ceria (N-doped rGO-CeO2) photocatalyst was successfully synthesized and exhibited a notable capability in degrading various organic pollutants. Among the synthesized samples, rGO-CeO2-900 N2 demonstrated the most efficient photocatalytic activity, achieving a 77.43% degradation rate for tetracycline (TC) fitting the modified Elovich model (R2 = 0.99). The CeO2 addition can increase defects and amorphous carbon species in rGO in Raman spectra. The rGO adding and N doping can contribute to more effective separation of photo-excited electrons/holes (e-/h+) and a faster rate of charge transfer via the results of photochemical tests. With the combination between rGO and CeO2, the N doped rGO-CeO2 catalyst gains certain anti-H+ ability in TC degradation and more·O2- can be generated under light, while the N doping can form an impurity level N 2p in CeO2 and create additional reactive sites on the rGO. This N doped rGO-CeO2 photocatalyst is well-suited for the harmless degradation and offers significant potential in wastewater treatment and pollution control.

γ-AlOOH decorated 3D-reduce graphene oxide: An effective adsorbent for removal of methylene blue and ciprofloxacin

Engineering and synthesis of high-efficiency adsorbent is imperative for water purification. Herein, γ-AlOOH nanoflakes were in-situ decorated onto 3D-reduced graphene oxide (3D-rGO) with the intention of augmenting the specific surface area and ameliorating the adsorption capacity of 3D-rGO in virtue of a facile one-step hydrothermal method. The detailed morphological and structural information of γ-AlOOH/3D-rGO nanocomposite were captured via various instruments. γ-AlOOH/3D-rGO exhibited outstanding removal efficiency towards methylene blue (MB) and ciprofloxacin (CIP) due to its abundant mesopores, increased specific surface area and 3D macro structure. The MB model could well describe the MB adsorption behavior and CIP adsorption process can be fitted by the Elovich model. Isotherm fitting results proclaim that MB adsorption and CIP adsorption followed the Langmuir model; and γ-AlOOH/3D-rGO possessed outstanding adsorption for MB and CIP with the maximum adsorption capacity of 930.0889 mg/g at 288 K and 353.9148 mg/g at 318 K, respectively. The MB and CIP adsorption onto γ-AlOOH/3D-rGO should be the results of the joint action of hydrogen bonds, π-π interaction and complexation. γ-AlOOH/3D-rGO also exhibited excellent reusability after five cycles owing to its 3D macro structure.

Dynamics and mechanisms of atrazine adsorption on biogas-residue biochar with citric acid modification

Atrazine is a widely used high-risk herbicide. Biogas-residue biochar (BC) is an adsorption material with low cost and great potential; however, its use is limited due to its poor surface properties. An understanding on the adsorption dynamics and mechanisms of the chemical modification of atrazine on biogas-residue biochar is very limited. Here, we examined the adsorption characteristics of atrazine on citric acid-modified BC (CA-BC) by conducting batch adsorption experiments followed by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS). The results showed that citric acid modification increased the surface area from 96.60 m2/g to 266.2 m2/g, decreased the pHzpc from 8.79 to 5.64, and effectively enhanced the adsorption capacity of CA-BC from 3.67 ± 0.31 mg g−1 to 5.94 ± 0.07 mg g−1. The adsorption kinetics and isotherm dynamics of atrazine on CA-BC were effectively fitted to the Elovich and Langmuir models, indicating that the adsorption process of CA-BC jointly involved physical and chemical adsorption. The dominant surface mineral of BC was whitlockite magnesian, which was dehydrogenated after modification and caused the development of its pore structure. The peaks corresponding to the oxygen-containing groups (hydroxyl and carboxyl groups) and cyclic structures increased after modification and decreased after adsorption. Based on these results, the adsorption mechanism of atrazine included microporous filling, electrostatic interactions and functional group interactions. Citric acid modification significantly enhanced the rate, maximal capacity, and stability of atrazine adsorption on biogas-residue biochar. Therefore, CA-BC could be considered an environmentally friendly material for controlling atrazine pollution. In general, our study provides a new approach for the high-value utilization of biogas residue and establishes a theoretical basis for improving the adsorption performance of atrazine using biogas residue biochar.

Evaluation of Chlorella vulgaris biosorption capacity for phosphate and nitrate removal from wastewater

High wastewater production rates during the past few decades are mostly attributable to anthropogenic activities. The main components leading to the nutrient enrichment of natural water bodies are such as nitrogen, phosphorus, and other minerals. The main focus of this research was to assess the ability of using Chlorella vulgaris algae, a potent and environmentally benign material, to eliminate phosphate and nitrate ions from wastewater. FTIR results showed that the biologically active molecules that facilitate the binding of phosphate and nitrate ions unto the C. vulgaris are C=C and N–H amid. The ideal equilibrium time for adsorption was 24 h with an optimum pH of 7 and the mass ratio of algae and different anions concentration was 80%. Freundlich isotherm model was the best-fitted isotherm. Moreover, the results of the experiment fit more closely with the pseudo-second-order kinetic model than other models. Elovich kinetic model data for both ions showed that the adsorption rate was much higher than the desorption rate. The growing popularity of biosorbents in treating wastewater has led to an improvement in their affordability and availability, and C. vulgaris may now represent an environmentally friendly choice from an environmental, and economic standpoint.

Activated carbon from single use surgical mask as an efficient adsorbent for 4-nitrophenol and 2,4-dicholorophenol from aqueous solution: adsorption kinetics, isotherms and thermodynamic study

ABSTRACT The activated carbon was prepared from single use surgical masks (SUSM) by hydrothermal method, resulting in a synthesised material termed SMAC. The physico-chemical properties of SMAC were analysed. The XRD pattern showed the amorphous nature, the FT-IR spectrum displayed the characteristic peaks of polypropylene, zeta potential analysis revealed the negative surface charge, SEM analysis showed the fibre morphology and XPS results confirmed the presence of oxygen, carbon and sulphur compounds. The adsorption properties were analysed using 4-nitrophenol (4-NP) and 2,4-dicholorophenol (2,4-DCP) from aqueous solution. The linear and nonlinear pseudo-first order, pseudo-second order, Elovich, intraparticle diffusion, external diffusion models and adsorption isotherms with linear and nonlinear Langmuir, Freundlich, and Temkin models were examined using adsorption data. The nonlinear kinetics and isotherm models have a better fit compared with linear models. The results were better fitted with pseudo-second order (0.9987 & 0.9962) and Elovich model (0.9964 & 0.9962) and described the adsorption process was leading by chemisorption fairly than physisorption. The Langmuir maximum adsorption capacity of SMAC for 4-NP and 2,4-DCP was 89.46 and 141.88 mg/g, respectively. Further, the thermodynamic study explained that the adsorption process of 4-NP and 2,4-DCP onto SMAC is an endothermic reaction. Among two regenerating agents (HCl & NaOH), 0.1 M NaOH was favoured for desorption of 4-NP (46%) and 2,4-DCP (40%) from SMAC. The recyclability studies showed that 67% and 64% of 4-NP and 2,4-DCP were removed after third cycle, respectively. The results conclude that the SMAC was an efficient adsorbent for phenols and economically viable.

Recycled activated carbon from plastic waste for effective oil removal from produced water

Recycled activated carbon (RAC) resultant from plastic waste was investigated as an adsorbent for removing cooking oil from contaminated water. RAC was prepared by pyrolysis and steam-activating plastic waste to develop porosity. SEM, TRM and BET analyses were used to describe RAC. Batch adsorption studies were conducted to optimize parameters like pH, dose, time, and concentration. Maximum oil removal of 97.5% occurred with 150 mg RAC dose at pH 5 and 25 °C. Kinetic data fitted pseudo-second-order (R2 =0.998) and Elovich models, indicating chemisorption. After 150 min, a state of equilibrium had been achieved with a 277.08 mg g-1 uptake. The adsorption fitted Sips (Langmuir and Freundlich models) isotherms well, indicating monolayer adsorption on a heterogeneous surface. Thermodynamic parameters showed endothermic spontaneous adsorption. RAC exhibited excellent reusability, retaining > 90% oil removal efficiency after 6 adsorption-desorption cycles using ethanol mix water (30% ethanol and 70% water) for regeneration which indicates the economic reusability of RAC. RAC from plastic waste demonstrated a high potential for removing cooking oil from contaminated water.

OPTIMIZATION AND COLUMN STUDY ON HEXAVALENT CHROMIUM REMOVAL USING HYDROXYAPATITE BEADS DERIVED FROM MOSAMBI FRUIT PEEL

This study elaborates on the preparation of hydroxyapatite particles from mosambi fruit peels by precipitation method. This hydroxyapatite was used as an adsorbent (AB) for the removal of Cr (VI) ion particles from wastewater. The adsorption was performed and optimized by desirability function to be pH 4, initial chromium concentration 200 mg/L, adsorbent dosage 0.425 g, and contact time 32.5 min, respectively using Response Surface Methodology (RSM). The Langmuir adsorption isotherm, pseudo-2nd-order, and Elovich model are well explained. Column experiments gave better results in the removal of Cr (VI) and this method is very effective for the treatment of industry effluent.

Synthesis of an iron-titanium-carbon composite from slag high in titanium for removing arsenic particles from drinking water

The objective is to develop a novel iron-titanium-carbon composite using titanium-rich slag as a precursor material. This composite should demonstrate efficient arsenic removal capabilities for water-based treatments. The straightforward photochemical method is used to create a microporous iron-titanium/carbon composite by milling titanium-rich slag with activated carbon at room temperature. XRD, SEM, EDX, and N2 adsorption/desorption were used to describe it. This microstructure sorbent has excellent composition, surface area, and pore structure suitable enough to intake As(V) ions from drinking water at pH 6 with the adsorption capability of 86 mg/g. Among the many adsorption isotherm types examined, the Langmuir isotherm had the best fit with R2:0.9879. The intake of As(V) into the produced composite was most aptly stated by the Elovich model (R2:0.9899), according to the kinetic investigations. Given that, the synthesized micro-composite exhibits long-term stability and reproducibility over several regeneration cycles. Our findings displayed that the synthesized iron-titanium/carbon composite is effectively convenient for the elimination of As(V) with the effectiveness of recuperation of 95%.

Avaliação do potencial de adsorção de rejeitos de mineração de ferro e seu efeito na germinação de raphanus sativus

ABSTRACT The objective of this work was to evaluate the physicochemical and adsorptive characterization of Fe tailing collected in the district of Brumadinho; and verify its effect on Raphanus sativus germination. The material was collected on the surface layer (0-20 cm) and disintegrated for pH, redox potential – Eh, electrical conductivity – EC, OM, cation exchange capacity – CEC, specific surface area – SSA and functional groups characterization. Adsorption studies were conducted using methylene blue (MB). The results of the adsorption studies were analyzed using kinetic models (Elovich, pseudo-first order – PFO and pseudo-second order – PSO) and isotherm models (Freundlich, Langmuir and Sips). The tailing has an acidic pH (5.60), negative ΔpH (-0.30) and low CEC (1.85 cmolc g-1). A high MB adsorption efficiency (96%) was verified. The Elovich model (0.9248<R2<0.9858) best represented the chemical kinetics, and the Freundlich model best describes the MB adsorption process in the tailing (R2 = 0.9609). The maximum adsorption capacity (qm) was equal to 15.08 mg g-1. The presence of Fe tailing positively influenced the germination of R. sativus seeds (73.8%), but stem and root growth were inferior when compared to seedlings cultivated in compost substrate. It is concluded that the material has favorable cationic adsorption capacity, which can benefit soil fertilization. However, R. sativus development was minor in Fe tailing substrate, probably due to low CEC, OM and nutrient availability.

Adsorption Kinetics of Tartrazine Dye on Activated Carbon Derived from Guava (Psidium guajava) Seeds

Azo dyes are widely used in various industries. However, many of these dyes are carcinogenic and reduce light penetration into aqueous systems, posing a threat to human health and hampering photosynthesis in aquatic environments. In this study, guava seeds were used to produce activated carbon by chemical activation with ZnCl2. The carbon was characterized and used as an adsorbent to remove tartrazine dye in aqueous medium. X-ray diffraction showed the formation of a material with disordered graphitic planes, typical of activated carbons. The equilibrium time for the dyeactivated carbon system was found to be 80 min by the Southwell plot method. The adsorbent removed 97.6% of the dye, representing an adsorbed concentration of 1.62 mg g−1 for an adsorbent dosage of 12 g L−1. The pseudo-second-order and Elovich kinetic models provided the best fit to experimental data, suggesting that chemisorption is the predominant mechanism, combined with the effect of surface heterogeneity. From an environmental point of view, the results suggest that the activated carbon produced is an efficient material for the treatment of industrial wastewater containing azo dyes.

Valorisation of energy plant Arundo donax cultivated in Serbia for biosorption of cobalt ions from an aqueous solution: Kinetic aspect

Metal ions can be eliminated from aqueous solutions using biosorbent, a substance made from plant biomass. This study investigated the potential use of Arundo donax stems as a cheap, natural biosorbent to remove cobalt ions (Co2+) from an aqueous solution. The biosorbent was characterized by the chemical composition analysis (cellulose, hemicellulose, and lignin), the point of zero charge (pHPZC), by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction analysis, and Fourier-transform infrared spectroscopy. According to the experimental data of kinetic studies, the equilibrium condition of Co2+ adsorption was attained 360 min after the biosorption started. The pseudo-first, pseudo-second, Elovich, and intra-particle diffusion models were used to model the kinetic experimental data. The best compliance was obtained with the pseudo-first order kinetic model, considering the highest value of the coefficient of determination R2 (0.996) and the lowest chi-square (?2) value (0.757). The findings of this study can be applied to the design of batch biosorption systems for the removal of Co2+ ions in real industrial systems.

Removal of methyl green dye using activated carbon prepared from corn cobs

Dyes released into hydrological systems in textile manufacturing, printing and other dyeing processes are hazardous and toxic to human and aquatic lives. Activated carbons have been remarkably used to treat dye contaminated waste water due to their large surface area and porosity, however regeneration and high cost have limited their applications. This study investigated the use of activated corn cobs (ACC) on the adsorption of methyl green dye from aqueous solution. The raw cobs were collected, crushed into particle size of about 600 μm and modified in-situ with KOH to prepare ACC which was characterized using some analytical techniques such as Fourier Transform Infra-Red (FTIR), Energy Dispersive X-ray (EDX) spectroscopy and Scanning Electron Microscopy (SEM). The absorbance of the dye solution was monitored at 620 nm with UV-Visible spectrophotometer. FTIR analysis showed the vibration frequency for C‒H, O‒H, C=O and C‒O stretches at 2950, 3400, 1710, and 1150 cm-1 respectively. SEM results revealed the ACC has a porous surface with heterogeneous pores which became compact after dye adsorption. EDX confirmed the presence of C, O, H and K in the adsorbent. The suitability of the pseudo-first, pseudo second and Elovich kinetic models for the sorption of methyl green onto ACC was examined. The equilibrium data were subjected to Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich isotherm models. The pseudo-second order kinetic model provided the best correlation and was found to be more statistically significant. Langmuir model was found to fit well based on the high values of the coefficient of regression R2 and low % standard error values. The monolayer adsorption capacity Qmax was found to be 85.83 mgg-1. Thermodynamic adsorption processes showed the spontaneous, endothermic and randomness of the systems with free energy change less than zero, enthalpy change (∆H) of 62.47 kJmol-1and entropy change (∆S) of 125.37 Jmol-1K-1.

Simultaneous optimization of production yield and sulfadiazine adsorption of MgFe2O4 loaded on prickly pear biochars using Box-Behnken design.

A major challenge that humans facing is the uncontrolled discharge of antibiotic-containing wastewater into the environment, accompanying with huge threats to human community. The utilization of cost-effective biomass-based adsorbents is considered a potential solution for the treatment of antibiotic wastewater. This study aims to optimize the synthesis of MgFe2O4 nanoparticles loaded on prickly pear biochar (PPB) with outstanding sulfadiazine adsorbability using response surface methodology. Thirteen materials (MgFe2O4-PPB) produced based on Box-Behnken design were tested to evaluate the impact of the main factors on the material preparation process, including ratio of MgFe2O4:PPB precursors, calcination temperature and calcination time. Under optimized conditions, i.e., MgFe2O4:PPB ratio 0.5, temperature 600 °C and time 1 h, the production yield of 46.5% and sulfadiazine removal percentage of 85.4% were obtained. Characterization of optimized MgFe2O4-PPB indicated the good porosity and functionality suitable for the adsorption of sulfadiazine. Elovich model showed the best description of kinetic process. Temkin model was considered to be an accurate description of the isotherm adsorption. Proposed mechanism for antibiotic adsorption onto MgFe2O4-PPB was described. We clarify cost-benefit analysis to asses the importance of MgFe2O4-PPB as well as the economic and environmental impacts of biochar-based composites.

Using titanium dioxide nanoparticle-deposited whey protein isolate amyloid fibrils to photocatalyze the degradation of methylene blue

BackgroundTitanium dioxide nanoparticles (TiO2NPs) have been widely used in photocatalytic reactions, but their tendency to aggregate reduces their photocatalytic activity. Recent studies have suggested that whey protein isolate amyloid fibrils (WPI-AFs) serve as promising catalyst carriers due to their structural stability and high surface area. This study is aimed at applying WPI-AFs to improve the dispersibility and photocatalytic activity of TiO2NPs. MethodsOne-dimensional composites, TiO2NP-deposited WPI-AFs (TiO2NP/WPI-AFs), were synthesized via the hydrothermal method. The concentration of TiO2NPs on WPI-AFs’ surface was determined through inductively coupled plasma optical emission spectroscopy (ICP-OES). TiO2NP/WPI-AFs were characterized via transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). In addition, the photocatalytic activities of bare TiO2NPs and TiO2NP/WPI-AFs were assessed by monitoring the degradation of methylene blue (MB) using UV-vis spectrophotometry. Significant findingsTiO2NP/WPI-AFs showed improved dispersibility and narrow band gap compared to TiO2NPs. The photocatalytic activity of TiO2NP/WPI-AFs was superior to that of bare TiO2NPs. The mechanism of TiO2NP/WPI-AFs photocatalyzed-MB degradation was examined by fitting the kinetic data with Langmuir–Hinshelwood and modified Elovich models. The results of activation parameters showed that TiO2NP/WPI-AFs lowers the activation energy, and the photocatalytic MB degradation is an endothermic and energetically unfavorable reaction.

Decontamination of Congo red dye from aqueous solution using nanoclay/chitosan-graft-gelatin nanocomposite hydrogel

In this study, bentonite nanoclay (BNC) impregnated chitosan-g-gelatin (CS-g-GEL/BNC) nanocomposite hydrogels were prepared with multi-features including being cost-effective, high-performance, biodegradable, and easy to separate for Congo red (CR) dye adsorption. Various characterization techniques, including FTIR, XRD, SEM, TGA, and EDX, were used to verify the successful formulation of the prepared hydrogels. The results revealed that the thermal stability of CS-g-GEL/BNC nanocomposite hydrogel was improved compared to CS-g-GEL hydrogel. CR dye also reached its equilibrium adsorption quickly and effectively at 60 min. When bentonite clay nanoparticles content was increased to 10 %, the removal efficiency increased to 70.41 %, which was significantly greater than 43.20 % for CS-g-GEL hydrogel. The maximum removal and adsorption capacity of 93.85 % and 453.87 mg/g was achieved at the optimal conditions of the adsorption process (pH = 9, an adsorbent dosage of 2 g/L, a temperature of 25 °C for 60 min, and a CR concentration of 100 mg/L). The results in thermodynamics indicated spontaneous adsorption from negative Gibbs free energy (ΔG°). Also, the analysis of the thermodynamics of the adsorption process resulted in an adsorption enthalpy (ΔH°) of − 21.8699 kJ/mol, which shows its spontaneous and exothermic nature at temperatures ranging from 25 °C to 45 °C. An equilibrium behavior of adsorption was successfully described using the Langmuir isotherm model. Compared with the pseudo-second-order, intra-particle, and Elovich models, the pseudo-first-order model gave a better description of the adsorption kinetics. CS-g-GEL/BNC nanocomposite hydrogels demonstrated enhanced reusability over five successive cycles, indicating potential application in adsorptive removal from aquatic environments contaminated with anionic dyes.

CTAB-modified peanut husk pre-treated with KMnO4 as an eco-friendly adsorbent for the uptake of Congo red in solution: adsorption and mechanism study.

A cationic surfactant (cetyltrimethylammonium bromide, CTAB)-modified peanut husk pretreated with potassium permanganate (KMnO4) was developed and applied as an adsorbent for the removal of Congo red (CR) in aqueous solution. The surface morphology and physicochemical characteristics of the adsorbent labelled as PNK-CTAB were assessed using well-established analytical techniques. The efficiency of PNK-CTAB was assessed via the batch adsorption method using distilled water, tap water and river water as aqueous medium. Results of the batch study showed that the adsorption capacity of PNK-CTAB could reach 70.5mgg-1 at 313K due to its improved surface properties and functionalities. Furthermore, the uptake of CR onto PNK-CTAB was found to be best described by the Elovich model thus suggesting adsorption on a heterogeneous surface, whereas fitting of intraparticle diffusion model indicated the significant role of mass transfer mechanism in the process. The equilibrium data was found to be well described by Langmuir, Temkin and Freundlich models albeit the latter was the best fit. Further analysis of the associated thermodynamics indicated the adsorption process to be endothermic, spontaneous in nature and likely mediated by physisorption processes. The excellent adsorption efficiency of PNK-CTAB toward CR within a wide pH range, negligible influence of some commonly occurring salts, good reusability efficiency, low cost (as confirmed by its cost analysis) and its ability to reduce the cytotoxicity of CR towards human embryonic kidney (HEK) 293 cells suggest the good prospects of this adsorbent for practical applications.

Potential bioremediation of lead and phenol by sunflower seed husk and rice straw-based biochar hybridized with bacterial consortium: a kinetic study

Environmental pollution is a global phenomenon and troublesome fact that poses a grave risk to all living entities. Via coupling carbonaceous feedstocks with outstanding microbial activity, kinetic experiments were established using the consortium of Proteus mirabilis and Raoultella planticola, biochar-derived sunflower seed husk (SHB) and rice straw (RSB), and their composites, which investigated at 30 °C (150 rpm) to eliminate 700 mg L−1 lead (120 h) and phenol (168 h) from synthetic wastewater. The derived biochars physicochemical properties of were studied. According to adsorption capacity (qe), consortium-SHB composites and consortium-RSB composites removed lead completely (70 mg g−1) within 48 h and 66 h, respectively. Besides, phenol was remediated entirely after 42 h and 48 h by both composite systems (69.90 mg g−1), respectively, comparing with bacterial consortium only or parent SHB and RSB. Moreover, four kinetic models were studied to describe the bioremediation process. Fractional power and Elovich models could be recommended for describing the adsorption kinetics for lead and phenol removal by the studied biomaterials with high correlation coefficient (R2 ≥ 0.91 for Pb2+ and ≥ 0.93 for phenol) and lower residual root mean square error (RMSE) and chi-square (X2). Overall, bacterial consortium-biochar composites exhibited greater remediation of lead and phenol than the sum of each single bacterial consortium and biochar systems; reflecting synergistic interaction of adsorptive capability of biochar and metabolic performance of bacterial consortium, as denoted by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The current study addressed the successful design of employing functional remediating consortium immobilized on waste biomass-derived biochar as a conducive alternative eco-sorbent and economic platform to detoxify organic and inorganic pollutants.