Kinetics, equilibrium, statistical surface modeling and cost analysis of paraquat removal from aqueous solution using carbonated jujube seed

Enhanced adsorption and photocatalytic degradation of tetracycline antibiotics through novel I-Bi/Bi2WO6@MWCNTs heterostructure composite photocatalyst

Bismuth-based photocatalysts proved to have remarkable photoactivity for antibiotic degradation from water. However, the two significant challenges of bismuth-based photocatalysts are the fast charge recombination rate and higher energy band gap. This study successfully synthesised a novel I-Bi/Bi2WO6/MWCNTs (C-WBI) heterostructure composite photocatalysts with shorter energy band-gap and higher charge production capability through interfacial amidation linkage. The photochemical characterization of C-WBI confirms that the interfacial linkage between MWNCTs and I-Bi/Bi2WO6 (WBI) significantly boosted the charge production capacity and broadened visible-light harvesting (508 nm), resulting in improved photocatalytic activity. As anticipated, optimized 7%C-WBI shows remarkable adsorption and photocatalytic activity for TC removal compared to pristine WBI (2.27 times) under visible light. TC removal was enhanced to 96.75% from 71.58% (WBI) at mild operating conditions of pH 8, photocatalyst loading of 20 mg, and an initial TC concentration of 20 mg/l. Adsorption equilibrium was best fitted to Langmuir isotherm and pseudo-first-order kinetics with R2 of 0.998 and 0.997, respectively. In contrast, the photodegradation of TC is best described by pseudo-first-order kinetics with a correlation coefficient of 0.99 and a reaction rate of kobs of 0.0205 min-1. The effect of co-existing ions (Cl-, SO₄2⁻ and HCO₃⁻) reveals that the presence of Cl- notably inhibited the photocatalytic reaction rate, reducing it to 0.0161min⁻1. Quenching experiments identified •O₂⁻ and h⁺ radicals as key contributors to TC degradation, accounting for 63.02% and 60.8%, respectively. Furthermore, 7%C-WBI demonstrated outstanding reusability (82.05%) over 5 consecutive cycles with no obvious changes, thereby confirming the stability of the synthesised composite photocatalysts.

Adsorptive avidity of Prussian blue polypyrrole nanocomposite for elimination of water contaminants: a case study of malachite green and isoniazid

Persistent water contaminants include a variety of substances that evade natural cleaning processes posing severe risks to ecosystems. Their adsorptive elimination is a key approach to safer attenuation. Herein we present the design and development of Prussian blue incorporated polypyrrole (PPY/PB) hybrid nanocomposite as a high-performance adsorbent for the elimination of malachite green (M.G.), isoniazid (INH) and 4-nitrophenol (4-NP) water contaminants. The nanocomposite synthesis was favored by strong dopant-polymer interactions, leading to a PPY/PB material with enhanced electro-active surface area compared to pristine PPY. The structure-activity response of the nanocomposite for the adsorption of target contaminants was unveiled by evaluating its maximum adsorption capacities under environmentally viable conditions. In-depth analysis and optimization of adsorption influencing factors (pH, temperature, and adsorbent dose) were performed. Using equilibrium studies, kinetic model fitting, aided with FTIR analysis, a multi-step mechanism for the adsorption of target contaminants on the nanocomposite was proposed. Furthermore, the PPY/PB nanocomposite also acts as a catalyst, enabling contaminant elimination following a synergistic scheme that was demonstrated using 4-NP contaminant. The synergetic adsorption and catalytic degradation of 4-NP using PPY/PB as adsorbent and catalyst was demonstrated in the presence of NaBH4 as a reducing agent in absence of light. In summary, this work highlights the targeted design of adsorbent, its optimization for adsorptive avidity, and the synergistic role of adsorption trapping in the catalytic degradation of persistent contaminants.

Low-cost materials as vehicles for pesticides in aquatic media: a review of the current status of different biosorbents employed, optimization by RSM approach

Water contamination by pesticides is increasing dramatically due to population growth and the extensive use of pesticides in agriculture, leading to grave environmental and health concerns. Thus, efficient processes and the design and development of effective treatment technologies are required due to the enormous demand for fresh water. The adsorption approach has been widely used to remove organic contaminants such as pesticides because of its performance, less expense, high selectivity, and simplicity of operation compared to other treatment technologies. Among alternative adsorbents, biomaterials abundantly available for pesticide sorption from water resources have attracted the attention of researchers worldwide. The main objective of this review article is to (i) present studies on a wide range of raw or chemically modified biomaterials potentially effective in removing pesticides from aqueous media; (ii) indicating the effectiveness of biosorbents as green and low-cost materials for removing pesticides from wastewater; and (iii) furthermore, report the application of response surface methodology (RSM) for modeling and optimizing adsorption.

Plant extracts as an eco-friendly approach to remove paraquat from aqueous solution

Nowadays, water pollution by herbicides is known as a global concern. Paraquat (PQ) (1-1-methyl-4,4-bi-pyridinium-dichloride) is a chip with high performance, which is being widely used herbicide to remove weeds from agricultural and natural ecosystems. PQ can contaminate water sources due to its high solubility in water. Human death by poisoning effects of PQ has been reported in several countries. Therefore, the side effects of PQ are a global challenge. This study aimed to investigate the bioremediation of PQ by plant extracts, as a low-cost, nontoxic, and natural absorbent to remove PQ from aqueous solutions in different conditions. In this regard, the extracts of common purslane (portulaca oleracea), florist kalanchoe (kalanchoe blossfeldiana), and jade plant (crassula portulaca) were used as adsorbents. For this purpose, the effect of various parameters such as contact time, initial concentration of PQ solution, temperature, pH, and amount of extract was investigated. The results of present study showed that P. oleracea extract and C. portulaca extracts have higher adsorption efficiency than k. blossfeldiana extract. The highest PQ removal was obtained by P. oleracea extract (79.04%) and C. portulaca extract (78.72%) at pH = 11, the adsorbent content of 0.2 mg L-1, and the lowest absorption of PQ (50.6%) was obtained by K. blossfeldiana extract. The highest PQ removal by plant extract was observed at 30 min for P. oleracea and C. portulaca, and at 15 min for k. blossfeldiana extract. Moreover, surface absorption capacity increased with increasing plant extract concentration, decreasing PQ concentration and decreased with increasing temperature. Finally, it can be concluded that plant extract can help to remove PQ from the aqueous solution.

Statistical physics modeling study of an environmentally friendly and efficient adsorbent derived from the brown macroalgae Bifurcaria bifurcata for the removal of Bisphenol A

The brown macroalgae Bifurcaria bifurcata was valued and used to develop a carbonaceous material activated by H2SO4 (AC-BB@H2SO4), with the goal of assessing its adsorption ability against Bisphenol A (BPA). During the adsorption experiments, the effects of the adsorbent dose, solution pH, and contact time were examined, and the results were m = 0.4 g/L, pH = 8.3, and t = 120 min, with an elimination yield of 91.6 %. With comparatively high R2 values, the pseudo-second-order kinetic model perfectly fitted the experimental data. Langmuir's model was found to be the best appropriate for describing the adsorption equilibrium of BPA on AC-BB@H2SO4. The thermodynamic findings show that BPA adsorption on AC-BB@H2SO4 was spontaneous, favorable, and endothermic in nature. Even after six cycles of reuse, regeneration testing demonstrated that our adsorbent could eliminate BPA by >50 %. The BPA adsorption mechanism's statistical physics control parameters were determined and analyzed. BPA's adsorption energies were <40 kJ/mol, indicating that the interactions between BPA and AC-BB@H2SO4 were governed by physical forces (i.e., hydrogen bonding and van der Waals and electrostatic interactions). All of these intriguing findings indicate that our carbonaceous material might have direct ramifications in the field of wastewater treatment, notably for the clearance of BPA, which is difficult to biodegrade.

Modeling of adsorptive removal of azithromycin from aquatic media by CoFe2O4/NiO anchored microalgae-derived nitrogen-doped porous activated carbon adsorbent and colorimetric quantifying of azithromycin in pharmaceutical products

Herein, it was aimed to optimize the removal process of Azithromycin (Azi) from the aquatic environment via CoFe2O4/NiO nanoparticles anchored onto the microalgae-derived nitrogen-doped porous activated carbon (N-PAC), besides developing a colorimetric method for the swift monitoring of Azi in pharmaceutical products. In this study, the Spirulina platensis (Sp) was used as a biomass resource for fabricating CoFe2O4/NiO@N-PAC adsorbent. The pores of N-PAC mainly entail mesoporous structures with a mean pore diameter of 21.546 nm and total cavity volume (Vtotal) of 0.033578 cm3. g-1. The adsorption studies offered that 98.5% of Azi in aqueous media could remove by CoFe2O4/NiO@N-PAC. For the cyclic stability analysis, the adsorbent was separated magnetically and assessed at the end of five adsorption-desorption cycles with a negligible decrease in adsorption. The kinetic modeling revealed that the adsorption of Azi onto the CoFe2O4/NiO@N-PAC was well-fitted to the second-order reaction kinetics, and the highest adsorption capacity was found as 2000 mg. g-1 at 25 °C based on the Langmuir adsorption isotherm model at 0.8 g. L-1 adsorbent concentration. The Freundlich isotherm model had the best agreement with the experimental data. Thermodynamic modeling indicated the spontaneous and exothermic nature of the adsorption process. Moreover, the effects of pH, temperature, and operating time were also optimized in the colorimetric Azi detection. The blue ion-pair complexes between Azi and Coomassie Brilliant Blue G-250 (CBBG-250) reagent followed Beer's law at wavelengths of 640 nm in the concentration range of 1.0 μM to 1.0 mM with a 0.94 μM limit of detection (LOD). In addition, the selectivity of Azi determination was verified in presence of various species. Furthermore, the applicability of CBBG-250 dye for quantifying Azi was evaluated in Azi capsules as real samples, which revealed the acceptable recovery percentage (98.72-101.27%). This work paves the way for engineering advanced nanomaterials for the removal and monitoring of Azi and assures the sustainability of environmental protection and public health.

Pb(II) Ion Removal Potential in Chemically Modified Ziziphus joazeiro Barks

In this study, five types of modified Ziziphus joazeiro barks were investigated for the removal of Pb(II) ions from aqueous solutions. The samples tested were natural barks, natural powder, washed with water, ethanol at 80% (EE) and 0.5 N NaOH. Batch kinetics experiments were performed under the conditions: 24−25 °C, pH 5.5−5.8, 102 mg·L−1 Pb(NO3)2, 100 rpm and 0.1 g of adsorbent, and analyses of pHpzc and Fourier transform infrared spectroscopy. All adsorbents tested showed potential to remove Pb(II) ions, but the adsorbent washed by 0.5 N NaOH obtained the highest experimental performance (25.5 mg·g−1 at 30 min), while the EE had the least performance (20.4 mg·g−1 at 60 min), and maximum removals of 99.9%. The kinetic models pointed to a probable chemisorption due to the best fit of pseudo-second order and Elovich, and Boyd’s model, suggesting that intraparticle diffusion limits the adsorption until the initial minutes of contact. The Langmuir isotherm fitted better to the experimental data for the NaOH adsorbent, with maximum adsorption capacity equal to 62.5 mg·g−1, although the Temkin model partially fitted, both suggesting the occurrence of chemisorption. The adsorption process is reversible (>81% at 20 min) and hence the adsorbents can be recycled and the Pb(II) ions recovered.

Nanoporous Carbon from Oil Palm Leaves via Hydrothermal Carbonization-Combined KOH Activation for Paraquat Removal

In this study, nano-porous carbon was completely obtained from oil palm leaves (OPL) by hydrothermal pretreatment with chemical activation, using potassium hydroxide (KOH) as an activating agent. Potassium hydroxide was varied, with different ratios of 1:0.25, 1:1, and 1:4 (C: KOH; w/w) during activation. The physical morphology of nano-porous carbon has a spongy, sponge-like structure indicating an increase in specific surface area and porosity with the increasing amount of KOH activating agent. The highest specific surface area of OPL nano-porous carbon is approximately 1685 m²·g^-1, with a total pore volume of 0.907 cm³·g^-1. Moreover, the OPL nano-porous carbon significantly showed a mesoporous structure designed specifically to remove water pollutants. The adsorptive behavior of OPL nano-porous carbon was quantified by using paraquat as the target pollutant. The equilibrium analyzes were explained by the Langmuir model isotherm and pseudo-second-order kinetics. The maximum efficiency of paraquat removal in wastewater was 79%, at a paraquat concentration of 400 mg·L^-1, for 10 min in the adsorption experiment. The results of this work demonstrated the practical application of nano-porous carbon derived from oil palm leaves as an alternative adsorbent for removing paraquat and other organic matter in wastewater.

Cotton Cord Coated with Cyclodextrin Polymers for Paraquat Removal from Water

The contamination of hazardous agrochemical substances in water caused essential trouble for humans and the environment. The functional textile was used as an effective adsorbent for paraquat removal from an aqueous solution. The coating of anionic cyclodextrin polymer, issued from the cross-linking between 1,2,3,4-butanetetracarboxylic acid and β−cyclodextrin in the presence of poly (vinyl alcohol), on the cotton cord, was firstly investigated. Their physicochemical characteristics were also characterized by gravimetry, acid–base titration, ATR-FTIR, ¹³C NMR, TGA, and stereo-microscopy. The BDP5 system revealed 107.3% coating yield, 1.13 mmol/g COOH groups, and 95.1% paraquat removal for 25 mg/L of initial concentration. The pseudo-second-order model was appropriate for kinetics using 6 h of contact time. Langmuir isotherm was suitable with the maximum adsorption of 30.3 mg/g for paraquat adsorption. The weight loss was 10.7% and 7.8%, respectively, for water and 5% v/v of HCI in ethanol after 120 h of contact time. Finally, the reusability efficiency stayed at 88.9% after five regeneration.

Adsorption of Cationic Contaminants by Cyclodextrin Nanosponges Cross-Linked with 1,2,3,4-Butanetetracarboxylic Acid and Poly(vinyl alcohol)

Cationic organic pollutants (dyes and pesticides) are mainly hydrosoluble and easily contaminate water and create a serious problem for biotic and abiotic species. The elimination of these dangerous contaminants from water was accomplished by adsorption using cyclodextrin nanosponges. These nanosponges were elaborated by the cross-linking between 1,2,3,4-butanetetracarboxylic acid and β-cyclodextrin in the presence of poly(vinyl alcohol). Their physicochemical characteristics were characterized by gravimetry, acid-base titration, TGA, 13C NMR, ATR-FTIR, Raman, X-ray diffraction, and Stereomicroscopy. The BP5 nanosponges displayed 68.4% yield, 3.31 mmol/g COOH groups, 0.16 mmol/g β-CD content, 54.2% swelling, 97.0% PQ removal, 96.7% SO removal, and 98.3% MG removal for 25 mg/L of initial concentration. The pseudo-second-order model was suitable for kinetics using 180 min of contact time. Langmuir isotherm was suitable for isotherm with the maximum adsorption of 120.5, 92.6, and 64.9 mg/g for paraquat (PQ), safranin (SO), and malachite green (MG) adsorption, respectively. Finally, the reusability performance after five regeneration times reached 94.1%, 91.6%, and 94.6% for PQ, SO, and MG adsorption, respectively.

Comparison of Paraquat Herbicide Removal from Aqueous Solutions using Nanoscale Zero-Valent Iron-Pumice/Diatomite Composites

Paraquat is the most important herbicide of the bipyridyl group. The aim of the present study was to compare the removal of paraquat herbicide from aqueous solutions using nanoscale zero-valent iron-pumice/diatomite composites. In this study, nZVI was supported with diatomite and pumice. Scanning electron microscopy (SEM) analysis, X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectrometry (FTIR), and specific surface area tests (BET) were used to evaluate the properties of nanoadsorbents. The residual concentration of paraquat in aqueous solution was detected by high-performance liquid chromatography (HPLC). Then, the effects of different variables including the pollutant concentration, contact time, temperature, adsorbents (D-nZVI and P-nZVI) dose, and pH, were investigated in a lab scale batch system. The results showed that the optimal pH for both processes was 3.74. In optimal conditions, the efficiencies of D-nZVI and P-nZVI were 92.76% and 85.28%, respectively. In addition, isotherm and adsorption kinetics studies indicated that P-nZVI follows the Langmuir and Freundlich isotherm models, and D-nZVI follows the Langmuir isotherm model, and both processes follow pseudo-second-order kinetics. The results indicated that the synthesized nanoparticles were suitable for removing paraquat from aqueous solutions. Both adsorbents were found to be very effective in removing similar compounds at ambient temperature in a short time.

Adsorption of Paraquat by Poly(Vinyl Alcohol)-Cyclodextrin Nanosponges

The contamination of hydrosoluble pesticides in water could generate a serious problem for biotic and abiotic components. The removal of a hazardous agrochemical (paraquat) from water was achieved by adsorption processes using poly(vinyl alcohol)-cyclodextrin nanosponges, which were prepared with various formulations via the crosslinking between citric acid and β-cyclodextrin in the presence of poly(vinyl alcohol). The physicochemical properties of nanosponges were also characterized by different techniques, such as gravimetry, thermogravimetry, microscopy (SEM and Stereo), spectroscopy (UV-visible, NMR, ATR-FTIR, and Raman), acid-base titration, BET surface area analysis, X-ray diffraction, and ion exchange capacity. The C10D-P2 nanosponges displayed 60.2% yield, 3.14 mmol/g COOH groups, 0.335 mmol/g β-CD content, 96.4% swelling, 94.5% paraquat removal, 0.1766 m2 g-1 specific surface area, and 5.2 × 10-4 cm3 g-1 pore volume. The presence of particular peaks referring to specific functional groups on spectroscopic spectra confirmed the successful polycondensation on the reticulated nanosponges. The pseudo second-order model (with R2 = 0.9998) and Langmuir isotherm (with R2 = 0.9979) was suitable for kinetics and isotherm using 180 min of contact time and a pH of 6.5. The maximum adsorption capacity was calculated at 112.2 mg/g. Finally, the recyclability of these nanosponges was 90.3% of paraquat removal after five regeneration times.

Magnetic porous biochar with nanostructure surface derived from penicillin fermentation dregs pyrolysis with K2FeO4 activation: Characterization and application in penicillin adsorption

Magnetic porous biochars (MC_HCl, MC_HAc) with nanostructure on surfaces were prepared from penicillin fermentation dregs by pyrolysis with K₂FeO₄ activation and used in penicillin adsorption. MC_HCl and MC_HAc had high BET surface areas of 672 and 735 m²/g, respectively; mainly be attributed to the activation of K₂FeO₄ as well as acid pickling. Saturation magnetizations of MC_HCl and MC_HAc were 75.29 and 42.45 emu/g, respectively; the magnetism was mainly derived from the Fe₃O₄ and Fe₃C in magnetic biochars. MC_HCl had nano sticks of ~ 80 nm and MC_HAc had petal-like slice of ~ 30 nm on surfaces. The maximum adsorption capacities of penicillin on MC_HCl and MC_HAc were 196 and 322 mg/g at 308 K, respectively. The adsorptions of penicillin on MC_HCl and MC_HAc were consistent with pseudo primary kinetics and the Langmuir adsorption isotherm model, and thermodynamic analysis indicated that the adsorption mechanism included physical and chemical adsorption.

Ceramic hydroxyapatite foam as a new material for Bisphenol A removal from contaminated water

Ceramic hydroxyapatite foam (CF-HAP) was prepared by combining slip-casting and foaming methods. The prepared CF-HAP was characterized by scanning electron microscopy (SEM), physisorption of N₂, Fourier transforms infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The results of the specific surface area and SEM analyses revealed that the used shaping method provides CF-HAP with a wide range of porosity including macro and mesopores. Based on FTIR and XRD analyses, the CF-HAP is similar to pure well-crystallized hydroxyapatite. The adsorption results revealed that 94% of the BPA with a concentration of (40 mg/L) was effectively removed from the water and that the maximum adsorption capacity was higher in acidic than in basic medium. The thermodynamic studies indicated that the adsorption reaction was spontaneous and endothermic in nature. The adsorption capacity increased with the temperature and the BPA is chemisorbed on the ceramic foam. The isotherm data fitted slightly better with the Liu than with the Freundlich and Langmuir models suggesting that the adsorption was homogeneous and occurred only in the monolayer. The adsorption process depends largely on the BPA concentration and the results fitted well with the pseudo-first-order model. This confirms that the interaction between the BPA and the CF-HAP was mainly chemical in nature. The FTIR analysis of the used and fresh CF-HAP showed that all the hydroxyl and phosphorus bands characteristic of the hydroxyapatite shifted after adsorption of Bisphenol A. This suggests that the adsorption of Bisphenol A occurred in the sites of the hydroxyapatite. Therefore, it can be concluded that the CF-HAP has the potential to be used as an adsorbent for wastewater treatment and purification processes.

Carbon tubes from biomass with prominent adsorption performance for paraquat

Paraquat (PQ) pollution has become an increasing seriously threat to the ecological environment. Thus, it is vital to study novel adsorption materials capable of removing PQ. Modified carbon tubes (MCT-600) were prepared by carbonizing the seed hair fibers of Metaplexis japonica at 600 °C and further modifying with nitric acid. The MCT-600 was found to possess a regular morphology, a good graphitization degree and an abundance of carboxyl functional groups. Moreover, this materil exhibits excellent adsorption performance for paraquat (PQ), such as a fast adsorption rate (adsorption equilibrium within 20 min), large adsorption capacity (218.61 mg g^-1) and good regeneration ability (reused more than 5 times). The adsorption process for PQ onto MCT-600 was found to be well matched to a Langmuir isotherm and pseudo-second-order kinetics model. Owing to its unique surface properties, green raw material source and simple preparation process, MCT-600 shows potential as an outstanding candidate for PQ removal from water.

Marine alga "Bifurcaria bifurcata": biosorption of Reactive Blue 19 and methylene blue from aqueous solutions

In this study, we have investigated the removal efficiency of two organic pollutants: methylene blue (MB) and Reactive Blue 19 (RB19) dyes by using a brown marine alga abundantly available on the Moroccan coastlines called Bifurcaria bifurcata (Bif-Bcata). During the experiments that were conducted in batch mode, we have studied the effect of some parameters such as pH, Bif-Bcata mass, contact time, and initial dye concentration in order to optimize the most suitable biosorption conditions. The biosorption tests on Bif-Bcata showed that the equilibrium is reached after 15 min for both dyes MB and RB19. The optimal pH values are 5.6 and 1.0 for MB and RB19, respectively. Kinetic studies revealed that the biosorption of both dyes follows the pseudo-second-order model. The biosorption isotherms demonstrated that the Langmuir model is the most appropriate to describe the biosorption equilibrium for both dyes MB and RB19 with maximum biosorption capacities reaching 2744.5 mg/g for MB and 88.7 mg/g for RB19. According to these results, it is clear that Bif-Bcata can be considered a promising biomaterial to be used as an effective biosorbent for the elimination of cationic and anionic dyes from textile effluents.

Graphene oxide/polydimethylsiloxane composite sponge for removing Pb(ii) from water

An efficient adsorbent to remove Pb(ii) from water was prepared by treating polydimethylsiloxane (PDMS) sponge with polyvinyl alcohol and then coating the sponge with graphene oxide (GO). The GO-PDMS sponge was highly hydrophilic, easily handled during and after use, and easily recycled. The kinetics and isotherms of Pb(ii) sorption onto the GO-PDMS sponge were investigated by performing batch sorption tests. The kinetics of Pb(ii) sorption onto the GO-PDMS sponge indicated that sorption equilibrium occurred rapidly (within 60 min) and that the sorption data could be described using a pseudo-second-order model. Maximum Pb(ii) sorption onto the GO-PDMS sponge occurred at pH > 5. Increasing GO loading on the PDMS sponge increased the amount of Pb(ii) that could be sorbed. The isotherm for Pb(ii) sorption onto the GO-PDMS sponge was non-linear and was well described by the Langmuir isotherm model, indicating that Pb(ii) sorption onto the GO-PDMS sponge was homogeneous and occurred through sorption of a monolayer of Pb(ii). The GO-PDMS sponge, used as a filter, removed Pb(ii) efficiently from water. The Pb(ii) removal efficiencies were more than 50% and the maximum was 85%.

Nitrogen doped graphitic porous carbon from almond shells as an efficient persulfate activator for organic compound degradation

Here, we have developed a simple and efficient low-temperature process for doping N into graphitic porous carbon to prepare a catalyst: N-GPC.

Selected pharmaceuticals removal using algae derived porous carbon: experimental, modeling and DFT theoretical insights

Porous carbon from Laminaria digitata algae activated using NaOH (PCLD@NaOH) was prepared by a chemical activation approach and has been tested for the adsorption of ketoprofen and aspirin molecules. The prepared PCLD@NaOH was characterized using XPS, FTIR, Raman, N2-physisorption, SEM, acidic/basic character (Boehm), and pHPZC. The batch adsorption of ketoprofen and aspirin was investigated under different parameters. The adsorption kinetics on PCLD@NaOH were well described by the Avrami-fractional kinetic model and the equilibrium data by Liu isotherm model. The adsorption capacity of aspirin (970.88 mg g-1 at 25 °C) was higher than ketoprofen (443.45 mg g-1 at 25 °C). The thermodynamic values indicate that the adsorption of ketoprofen and aspirin is exothermic and spontaneous. These results were in good agreement with DFT calculation that shows that the aspirin molecule presents high reactivity, electrophilicity, and softness compared to the ketoprofen molecule. Finally, the response surface methodology was used to optimize the removal efficiency of ketoprofen and aspirin.

Reusable bentonite clay: modelling and optimization of hazardous lead and p-nitrophenol adsorption using a response surface methodology approach

In this work, bentonite clay (BC) calcined at 500 °C was used as an adsorbent (BC-500) for the adsorption of Pb²⁺ and p-nitrophenol.