Application of central composite design for simultaneous removal of methylene blue and Pb(2+) ions by walnut wood activated carbon

An experimental design study of photocatalytic activity of the Z-scheme silver iodide/tungstate binary nano photocatalyst

A binary AgI/ Ag2WO4 photocatalyst was fabricated and characterized by SEM, XRD, UV-Vis DRS, and FT-IR. It was then used to photodegrade sodium ceftriaxone (CTX) in an aqueous solution. The band gap energies of 2.95, 2.78, and 2.62 eV were obtained by the Kubelka-Munk model for Ag2WO4, AgI, and AgI/Ag2WO4 catalysts. The samples have pHPZC values of 6.9, 4.2, and 6.6, respectively. The synergistic photocatalytic activity of the coupled system depended on the AgI:Ag2WO4 mole ratio and grinding time (optimums:mole ratio of 4:1 and time 30 min). The experimental design was used for optimizing the conditions and a quadratic model well-processed the data based on the model F value of 131.87 > F0.05,14,13 = 2.55 and LOF F value of 0.78 < F0.05,10,3 = 8.78. The optimized RSM run included the irradiation time of 85 min, 3.5 mg/L of CTX sample at pH 9, and a catalyst dose of 1.0 g/L. Under the optimized conditions, about 63% of CTX molecules were photodegraded. In the study of the scavenging agents, the direct Z-scheme mechanism accumulated electrons in the CB-AgI and the holes in the VB-Ag2WO4 level, as stronger reducing and oxidizing centers than the accumulated electrons and holes of the type (II) heterojunction mechanism. Compared to a CTX oxidation potential of about 0.06 V, the direct Z-scheme mechanism is more favorable to reduce or oxidize it.

Application of response surface modeling optimization in UV spectrophotometric determination of 4-aminobenzoic acid by molecularly imprinted polypyrrole

Selective determination of 4-aminobenzoic acid (ABA) in pharmaceutical and human serum samples was performed by molecularly imprinted polypyrrole and ultraviolet (UV) spectrophotometry, based on precipitation polymerization. The molecularly imprinted polymer (MIP) was prepared using pyrrole functional monomer and ABA template molecules. The significant factors controlling the performance of the synthesized ABAMIP sorbent were screened and optimized using Plackett- Burman design (PBD) and central composite design (CCD), respectively. The model was used to obtain the optimal values of the significant response factors. The predicted MIP to NIP response ratio demonstrated an approximate deviation of 5 % from the experimental value. Under the obtained optimal conditions, the calibration curve showed a linear range of 0.05-2 mM with a correlation coefficient (r²) of 0.9920 and a limit of detection (LOD) of 0.0310 mM. The method recovery for the analyte was obtained 88.10-100.5 in the investigated real samples. The proposed ABA-MIP sorbent showed an acceptable selectivity in the presence of some pharmaceuticals.

Celecoxib Nanoformulations with Enhanced Solubility, Dissolution Rate, and Oral Bioavailability: Experimental Approaches over In Vitro/In Vivo Evaluation

Celecoxib (CXB) is a Biopharmaceutical Classification System (BCS) Class II molecule with high permeability that is practically insoluble in water. Because of the poor water solubility, there is a wide range of absorption and limited bioavailability following oral administration. These unfavorable properties can be improved using dry co-milling technology, which is an industrial applicable technology. The purpose of this study was to develop and optimize CXB nanoformulations prepared by dry co-milling technology, with a quality by design approach to maintain enhanced solubility, dissolution rate, and oral bioavailability. The resulting co-milled CXB composition using povidone (PVP), mannitol (MAN) and sodium lauryl sulfate (SLS) showed the maximum solubility and dissolution rate in physiologically relevant media. Potential risk factors were determined with an Ishikawa diagram, important risk factors were selected with Plackett-Burman experimental design, and CXB compositions were optimized with Central Composite design (CCD) and Bayesian optimization (BO). Physical characterization, intrinsic dissolution rate, solubility, and stability experiments were used to evaluate the optimized co-milled CXB compositions. Dissolution and permeability studies were carried out for the resulting CXB nanoformulation. Oral pharmacokinetic studies of the CXB nanoformulation and reference product were performed in rats. The results of in vitro and in vivo studies show that the CXB nanoformulations have enhanced solubility (over 4.8-fold (8.6 ± 1.06 µg/mL vs. 1.8 ± 0.33 µg/mL) in water when compared with celecoxib pure powder), and dissolution rate (at least 85% of celecoxib is dissolved in 20 min), and improved oral pharmacokinetic profile (the relative bioavailability was 145.2%, compared to that of Celebrex^®, and faster t_max 3.80 ± 2.28 h vs. 6.00 ± 3.67 h, indicating a more rapid absorption rate).

Nonthermal plasma-irradiated polyvalent ferromanganese binary hydro(oxide) for the removal of uranyl ions from wastewater

Nonthermal plasma (NTP) irradiation was employed to adjust the morphological structures and valence distribution of ferromanganese (Fe-Mn)-based binary hydro (oxide) to enhance the heterogeneous adsorption of uranyl ions. The output voltage and the liquid-plate distance played a more vital role among the NTP factors in the irradiation system in influencing the polyvalent Fe-Mn binary hydro (oxide) (poly-Fe-Mn). The formation of plates, flakes, and nanoscale nodules was specifically observed, which caused more pores and fractures in the poly-Fe-Mn binary hydro (oxide). The poly-Fe-Mn performed explicitly better in the adsorption of uranium ions in comparison with the counterpart of the Fe-Mn, which was appropriately fitted by the pseudofirst-order kinetic and Elovich models. Maximum equilibrium adsorption capacities of 663.92 and 923.45 mg/g were obtained for the Fe-Mn and poly-Fe-Mn binary hydro (oxides) toward U ions in the orthogonal design, respectively. The maximum monolayer adsorption capacity achieved by the fitting of the Langmuir model was 1091.10 mg/g. Both physisorption and chemisorption contributed to the heterogeneous process of the poly-Fe-Mn toward uranium ions. The employment of NTP irradiation changed the monolayer adsorption of the traditional Fe-Mn materials and diversified the reaction mechanisms between the interface of the Fe-Mn materials and uranium ions. The elements, including O, N, and U exhibited higher compatibility and overlapped in the samples. The highly effective capture of uranium ions from the solution by the poly-Fe-Mn binary hydro (oxide) was mainly related to the chemical deposition of O and N radicals.

Integrated Photocatalytic Oxidation and Adsorption Approach for the Robust Treatment of Refinery Wastewater Using Hybrid TiO2/AC

This study reports the removal of hydrocarbon (HC) pollutants from petroleum refinery wastewater by integrated photocatalytic oxidation and adsorption using a TiO2/AC hybrid material. The hybrid adsorbent/catalyst was prepared by the impregnation of TiO2 over AC and characterized by FTIR, SEM, EDX, and XRD analyses. Under the optimized reaction conditions of pH 3, 30 °C, and 1000 mg TiO2/AC per 500 mL of sample in 50 min, the integrated photocatalytic oxidation-adsorption achieved a net percentage removal of benzene, toluene, aniline, and naphthalene of 91% from model HC solutions. Under these conditions, for the treatment of real refinery wastewater, TiO2/AC caused a 95% decrease in chemical oxygen demand (COD). The integrated photocatalytic oxidation and adsorption using TiO2/AC showed a clear advantage over the individual adsorption and photocatalytic oxidation using AC and TiO2, whereby about the same level of removal of model HCs and a decrease in the COD of refinery wastewater was attained in 105 min and 90 min, respectively, utilizing larger adsorbent/catalyst dosages. GC-MS analysis revealed that during the integrated process of adsorption-photocatalytic oxidation, all the parent HCs and oxidation byproducts were completely removed from the refinery wastewater. Based on the outstanding performance, cost-effectiveness, and environmental greenness, the newly designed TiO2/AC via the integrated adsorption-photocatalytic oxidation can be counted as an effective alternative route for the large-scale processing of refinery wastewater.

Environmental remediation by tea waste and its derivative products: A review on present status and technological advancements

The rising consumption of the popular non-alcoholic beverage tea and its derivative products caused massive growth in worldwide tea production in the last decade, leading to the generation of huge quantities of waste tea residues every year. Most of these wastes are usually burnt or disposed in landfills without proper treatment which results in serious environmental issues by polluting water, air and soil. In the recent times, 'waste to wealth' is a fast-growing concept for environment friendly sustainable development. Utilization of the large amount of tea wastes for the production of low-cost adsorbents to reduce the expenses of water and wastewater treatment can be a sustainable way of management of these wastes which at the same time will improve circular economy also. This review endeavours to evaluate the potential of both raw and modified tea wastes towards the adsorption of pollutants from wastewater. The production of various adsorptive materials such as biochar, activated carbon, nanocomposites, hydrogels, nanoparticles from tea wastes are summarized. The advancements in their applications for the removal of different emerging contaminants from wastewater as well as potable water, air and soil are exhaustively reviewed. The outcome of the present review reveals that tea waste and its derivatives are appropriate candidates to be used as adsorbents that show tremendous effectiveness in cleaning the environment. This article will provide the readers with an in-depth knowledge on the sustainable utilization of tea waste as adsorbent materials and will assist them to explore this abundant cheap waste biomass for environmental remediation.

Activated Carbon as Superadsorbent and Sustainable Material for Diverse Applications

Activated carbon is a carbonaceous material with highly porous structure. Different functionalities can be introduced to its surface by various physical and chemical treatments. Various precursors can be used for the synthesis of activated carbon such as fossil fuels, agricultural wastes, and lignocellulosic wastes, etc. Number of papers have been reported in literature devoted to the synthesis, characterization, and various applications of activated carbon. Herein, in this review, special attention has been paid to the basic properties of activated carbon and its surface chemistry originated due to physical and chemical treatment. In addition, a general introduction to adsorption process, various adsorption isotherms, and adsorption kinetics is also included. A brief description of mechanism of adsorption onto activated carbon is also presented. At last, most probable applications of activated carbon such as adsorption of pollutants (e.g., dyes, heavy metal ions, pesticides, pharmaceutical waste products, and volatile organic organic), as catalyst support, anduse in food and pharmaceutical industries is also presented.

Development and Characterization of Activated Carbon from Olive Pomace: Experimental Design, Kinetic and Equilibrium Studies in Nimesulide Adsorption

The lack of adequate treatment for the removal of pollutants from domestic, hospital and industrial effluents has caused great environmental concern. Therefore, there is a need to develop materials that have the capacity to treat these effluents. This work aims to develop and characterize an activated charcoal from olive pomace, which is an agro-industrial residue, for adsorption of Nimesulide in liquid effluent and to evaluate the adsorption kinetics and equilibrium using experimental design. The raw material was oven dried at 105 °C for 24 h, ground, chemically activated in a ratio of 1:0.8:0.2 of olive pomace, zinc chloride and calcium hydroxide and thermally activated by pyrolysis in a reactor of stainless steel at 550 °C for 30 min. The activated carbon was characterized by Fourier Transform Infrared (FTIR) spectroscopy, X-ray Diffractometry (XRD), Brunauer, Emmett and Teller (BET) method, Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), density and zero charge potential analysis. The surface area obtained was 650.9 m² g⁻¹. The kinetic and isothermal mathematical models that best described the adsorption were PSO and Freundlich and the highest adsorption capacity obtained was 353.27 mg g⁻¹. The results obtained showed the good performance of activated carbon produced from olive pomace as an adsorbent material and demonstrated great potential for removing emerging contaminants such as Nimesulide.

Investigation of the Conditions for Preconcentration of Cadmium Ions by Solid Phase Extraction Method Using Modified Juglans regia L. Shells

BACKGROUND

Juglans regia L. shells as agricultural waste can be considered as alternative sorbents to minimize the problems associated with heavy metal pollution.

OBJECTIVE

In this study, J. regia shells (JRS) and JRS modified with hydrazine hydrate (JRS-HH) were used as sorbents and compared for the preconcentration of Cd(II) ions from aqueous solution.

METHODS

For the characterization of sorbents, scanning electron microscopy and energy dispersive X-ray (SEM/EDX) analysis and Fourier transform infrared (FTIR) spectroscopy were used. For preconcentration, the solid phase extraction (SPE) technique was used. Preconcentration studies were performed by column method and pH, eluent type and concentration, sample volume, flow rate, and interfering ions effect were studied to determine the optimum column parameters.

RESULTS

The limit of detection (LOD) of the sorbents (JRS and JRS-HH) are 0.31 and 0.18 µg/L, respectively. According to the Langmuir isotherm model for both sorbents, for JRS KL = 0.030 L/mg, R2 = 0.992, 0.016 L/mg, and for JRS-HH KL = 0.016 L/mg, R2 = 0.998 and maximum adsorption capacities of the sorbents were found to be as 29.6 and 65.7 mg/g, respectively. The mean recoveries and RSD values at a 95% confidence level (N = 6) for Cd(II) were 100.9% and 3.42, and 100.6% and 3.79, for the JRS and JRS-HH sorbents, respectively.

CONCLUSIONS

Using this method good results were obtained when compared with those in the literature and the proposed method was successfully applied to the analysis of the certificated reference material (NIST 1640).

HIGHLIGHTS

JRS are an effective and inexpensive sorbent for the preconcentration of metal ions when modified. Thus, low-cost agricultural wastes are both recovered and have an economic value.

Magnetically recyclable copper doped core-shell Fe3O4@TiO2@Cu nanocomposites for wastewater remediation

The smart magnetic nanocomposites have been doped to diminish the energy bandgap of the photocatalyst and to permit recovering of the photocatalyst after the wastewater treatment. The core-shell Fe3O4@TiO2 nanocomposite was synthesised by the hydrothermal method using titanium butoxide as a precursor. The nanocomposites were examined by XRD, VSM, UV-Vis, and TEM techniques. The energy band gap of core-shell Fe3O4@TiO2 nanocomposite is 3.5 eV. Doping of copper with a concentration of 1, 2, and 3 wt% into TiO2 shell was done to increase the performance of photocatalyst. The Fe3O4/PVP@TiO2@Cu photocatalyst was used for dye wastewater treatment. The energy bandgap decreased to 2.2 eV after copper doping into the TiO2 shell specified that copper-doped nanocomposite could be an outstanding photocatalyst. The photocatalytic activity was carried out using methylene blue(MB) and methyl orange (MO) under sunlight. About 65% of methylene blue and 85% of methyl orange degradation was done using Cu (3wt %) doped Fe3O4@TiO2 nanocomposite. These photocatalysts can be easily withdrawn with a magnetic field. The Fe3O4/PVP@TiO2@Cu photocatalyst has been demonstrated to be very functional or effective for the degradation of MB and MO dyes using solar illumination.

Implementation and Performance Evaluation of a Bivariate Cut-HDMR Metamodel for Semiconductor Packaging Design Problems with a Large Number of Input Variables

A metamodeling technique based on Bivariate Cut High Dimensional Model Representation (Bivariate Cut HDMR) is implemented for a semiconductor packaging design problem with 10 design variables. Bivariate Cut-HDMR constructs a metamodel by considering only up to second-order interactions. The implementation uses three uniformly distributed sample points (s = 3) with quadratic spline interpolation to construct the component functions of Bivariate Cut-HDMR, which can be used to make a direct comparison with a metamodel based on Central Composite Design (CCD). The performance of Bivariate Cut-HDMR is evaluated by two well-known error metrics: R-squared and Relative Average Absolute Error (RAAE). The results are compared with the performance of CCD. Bivariate Cut HDMR does not compromise the accuracy compared to CCD, although the former uses only one-fifth of sample points (201 sample points) required by the latter (1045 sample points). The sampling schemes and the predictions of cut-planes and boundary-planes are discussed to explain possible reasons for the outstanding performance of Bivariate Cut HDMR.

Solubilization and separation of o-toluidine and tricyclazole in sodium dodecyl sulfate micelles in micellar enhanced ultrafiltration

The solubilization laws of pollutants in micelles and their separation efficiency are very important in the successfully efficient application of micellar enhanced ultrafiltration (MEUF). The solubilization behavior of o-toluidine (OT) and tricyclazole (TC) into sodium dodecyl sulfate (SDS) micelles in MEUF was studied using nonlinear equation sets for concentration analysis, which resolved the issue on the overlap of absorption spectra of multicomponent compounds restricting the application of conventional ultraviolet (UV) spectroscopic method. The solubilization isotherms for both pollutants could be best explained by the Langmuir-Freudlich model (R²>0.99) followed by the modes of Langmuir and Freudlich, inferring the complexity of solubilization mechanism and solubilization advantage of monolayer over multilayer. The calculated thermodynamic parameters (ΔG⁰, ΔH⁰ and ΔS⁰) indicated that this process was endothermic and spontaneous. The solubilization of OT and TC well followed the pseudo second-order and pseudo first-order kinetics, respectively. The separation and recovery of SDS solubilizing these two pollutants were also investigated through lowering solution temperature to 2 °C followed by centrifugation. The best recovery rate of about 66% for SDS was achieved containing 10 and 5% of each initial amount of OT and TC, respectively, at near-neutral solution pH value. The recovery of SDS could decrease to some extent under alkaline and acidic conditions.

On the Suitability of Almond Shells for the Manufacture of a Natural Low-Cost Bioadsorbent to Remove Brilliant Green: Kinetics and Equilibrium Isotherms Study

Almond production generates a large number of coproducts, but the farmer's interest mainly focuses on the nutritional and commercial aspects of the kernel for getting the best return from their harvests. Thus, almond coproducts such as almond shells that represent more than 70% of biomass remain underexplored. In this work, the suitability of almond shell powder (ASP) as a natural low-cost adsorbent was evaluated in the adsorption of brilliant green dye (BG), which is known as a chemical pollutant. Brunauer-Emmett-Teller (BET) method, for the determination of specific surface area, Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) techniques were performed to characterize the ASP adsorbent. The batch adsorption kinetic study for the removal of BG dye was carried out by varying pH, temperature, initial concentration of the dye, bioadsorbent dose, and contact time. It was found that 98% of BG dye is removed under the following optimal experimental conditions: ASP bioadsorbent dose of 1 g/L at T = 25°C, pH = 6.8, and C 0 = 1 g/L, which proves that ASP can be used as an excellent low-cost bioadsorbent for the removal of BG dye from wastewater. The experimental isotherm data were analyzed using Freundlich and Langmuir models. The results show the best correlation with single-layer adsorption, and the adsorption kinetics seems to follow a pseudo-second-order model.

A new insight on enhanced Pb(II) removal by sludge biochar catalyst coupling with ultrasound irradiation and its synergism with phenol removal

The applicability of sludge biochar catalyst (SBC) coupling with ultrasound (US) irradiation for the simultaneous removal of Pb(II) and phenol was firstly investigated in this study. Results indicate that Pb(II) removal of SBC/US process was superior to that of SBC without US. The inhibitory order of the coexisting anions on Pb(II) removal was PO43- > HCO3- > NO3- > F- > SO42- > Cl-. Also, several coexisting metals ions inculding Cr(VI), Ni(II) and Cu(II) could be removed in a simultaneous manner with Pb(II). A high removal performance of Pb(II) by SBC/US process and its synergism with phenol oxidation had been successfully achieved. The simultaneous removal efficiencies of Pb(II) and phenol were high up to 95% within 60 min at optimum reaction conditions. Four kinds of Pb species inculding Pb0, PbCO3, PbO and Pb(OH)2 were formed during the reaction, whereas five kinds of transformation compounds of phenol such as 1,4-benzoquinone, acetic acid, formic acid, maleic acid and propionic acid were detected. Both HO and O2- contributed to the oxidation of phenol by SBC/US process, but HO was dominant radical. A reaction mechanism for the synergistic removal of Pb(II) and phenol by SBC/US process involving in four stages-namely adsorption, precipitation, reduction and Fenton-like oxidation processes was proposed. This study demonstrates that SBC/US process could be considered as a potential candidate for the remediation of real wastewaters containing Pb(II) and phenol.

Clay-activated carbon adsorbent obtained by activation of spent bleaching earth and its application for removing Pb(II) ion

BE/C-A750-1/1 is prepared by carbonizing SBE and then activating with KOH. BE/C-A750-1/1 has good adsorption capacity for Pb(II), and the adsorption capacity for Pb(II) is 206.65 mg/g. The harmful effects of coexisting cations are listed in ascending order: K⁺ < Na⁺ < Mg²⁺. Adsorption and desorption studies show that the adsorption capacity of BE/C-A750-1/1 for Pb(II) after adsorption and desorption 3 times is 183.62 mg/g. The adsorption mechanism mainly includes electrostatic attraction, ion exchange, physical adsorption, and chemical complexation. This suggests that activated BE/C may be a promising candidate for removing Pb(II) from industrial wastewater. Clay/carbon nanocomposites were prepared by carbonizing and activating the spent bleaching earth served as adsorbents for the efficient removal of Pb(II) from wastewater.

Highly branched triple-chain surfactant-mediated electrochemical exfoliation of graphite to obtain graphene oxide: colloidal behaviour and application in water treatment

The generation of surfactant-assisted exfoliated graphene oxide (sEGO) by electrochemical exfoliation is influenced by the presence of surfactants, and in particular the hydrophobic tail molecular-architecture. Increasing surfactant chain branching may improve the affinity for the graphite surfaces to provide enhanced intersheet separation and stabilisation of exfoliated sheets. The resulting sEGO composites can be readily used to remove of a model pollutant, the dye, methylene blue (MB), from aqueous solutions by providing abundant sites for dye adsorption. This article explores relationships between surfactant structure and the performance of sEGO for MB adsorption. Double-branched and highly branched triple-chain graphene-compatible surfactants were successfully synthesised and characterised by ¹H NMR spectroscopy. These surfactants were used to produce sEGO via electrochemical exfoliation of graphite, and the sEGOs generated were further utilised in batch adsorption studies of MB from aqueous solutions. The properties of these synthesised surfactants were compared with those of a common single-chain standard surfactant, sodium dodecyl-sulfate (SDS). The structural morphology of sEGO was assessed using Raman spectroscopy and field emission scanning electron microscopy (FESEM). To reveal the links between the hydrophobic chain structure and the sEGO adsorption capacity, UV-visible spectroscopy, zeta potential, and air-water (a/w) surface tension measurements were conducted. The aggregation behaviour of the surfactants was studied using small-angle neutron scattering (SANS). The highly branched triple-chain surfactant sodium 1,4-bis(neopentyloxy)-3-(neopentylcarbonyl)-1,4-dioxobutane-2-sulfonate (TC14) displayed enhanced exfoliating efficiency compared to those of the single-and double-chain surfactants, leading to ∼83% MB removal. The findings suggest that highly branched triple-chain surfactants are able to offer more adsorption sites, by expanding the sEGO interlayer gap for MB adsorption, compared to standard single-chain surfactants.

Treatment of water containing methylene by biosorption using Brazilian berry seeds (Eugenia uniflora)

Brazilian berry seeds (Eugenia uniflora) were used as an eco-friendly and low-cost biosorbent for the treatment of textile effluents containing methylene blue. Characterization techniques indicated that Brazilian berry seeds are constituted of irregular particles, mainly composed of lignin and holocellulose groups, distributed in an amorphous structure. Methylene blue biosorption was favorable at pH of 8, using a biosorbent dosage of 0.8 g L^-1. The equilibrium was reached in the first 20 min for lower M methylene blue concentrations and 120 min for higher methylene blue concentrations. Furthermore, the general and pseudo-second-order models were suitable for describing the kinetic data. Langmuir was the most adequate model for describing the isotherm curves, predicting a biosorption capacity of 189.6 mg g^-1 at 328 K. Biosorption was spontaneous (- 9.54 ≤ ΔG⁰ ≤ -8.06 kJ mol^-1) and endothermic, with standard enthalpy change of 6.11 kJ mol^-1. Brazilian berry seeds were successfully used to remove the color of two different simulated textile effluents, achieving 92.2% and 73.5% of removal. Last, the fixed-bed experiment showed that a column packed with Brazilian berry seeds can operate during 840 min, attaining biosorption capacity of 88.7 mg g^-1. The data here presented indicates that textile effluents containing methylene blue can be easily and successfully treated by an eco-friendly and low-cost biosorbent like Brazilian berry seeds.

Novel approach for effective removal of methylene blue dye from water using fava bean peel waste

Fava bean peels, Vicia faba (FBP) are investigated as biosorbents for the removal of Methylene Blue (MB) dye from aqueous solutions through a novel and efficient sorption process utilizing ultrasonic-assisted (US) shaking. Ultrasonication remarkably enhanced sorption rate relative to conventional (CV) shaking, while maintaining the same sorption capacity. Ultrasonic sorption rate amounted to four times higher than its conventional counterpart at 3.6 mg/L initial dye concentration, 5 g/L adsorbent dose, and pH 5.8. Under the same adsorbent dose and pH conditions, percent removal ranged between 70-80% at the low dye concentration range (3.6-25 mg/L) and reached about 90% at 50 mg/L of the initial dye concentration. According to the Langmuir model, maximum sorption capacity was estimated to be 140 mg/g. A multiple linear regression statistical model revealed that adsorption was significantly affected by initial concentration, adsorbent dose and time. FBP could be successfully utilized as a low-cost biosorbent for the removal of MB from wastewater via US biosorption as an alternative to CV sorption. US biosorption yields the same sorption capacities as CV biosorption, but with significant reduction in operational times.

Simultaneous removal of methylene blue and Pb2+ from aqueous solution by adsorption on facile modified lignosulfonate

In this paper, simultaneous removal of methylene blue (MB) and Pb²⁺ from the binary component system by an easily prepared cross-linked lignosulfonate bio-adsorbent (CLLS) was described. CLLS was characterized by FTIR, SEM/EDS and TGA. The influences of pH, temperature, contact time and initial MB and Pb²⁺ concentrations on the adsorption performance were investigated. The results demonstrated a good ability of CLLS to remove MB and Pb²⁺ simultaneously. Using of 1.0 g L^-1 loading, removal efficiency of MB and Pb²⁺ reached 98.0% and 97.8%, respectively, in the MB (100 mg.L^-1)-Pb²⁺ (50 mg.L^-1) system. Moreover, the adsorption isotherms and adsorption kinetics indicated that the results were fitting well with the Langmuir and pseudo-second-order model, respectively, for both MB and Pb²⁺. Based on the Langmuir model, the maximum adsorption capacity of MB and Pb²⁺ reached 132.6 and 64.9 mg g^-1, respectively, in the MB-Pb²⁺ system, which was much lower than that in the single component system (358.4 mg g^-1 100.9 mg g^-1 for MB and Pb²⁺, respectively). Hence, simultaneous adsorption of MB and Pb²⁺ onto CLLS was an antagonistic adsorption. In addition, an apart-sequential adsorption method was used to study the action of adsorption sites on CLLS for MB and/or Pb²⁺ with the help of an efficient self-made apparatus. Rudimental results showed that there would be three different kinds of adsorption sites on CLLS: MB-site, Pb²⁺-site and MB/Pb²⁺- shared sites. Furthermore, in the MB (100 mg.L^-1)-Pb²⁺(50.0 mg.L^-1) system, the simultaneous removal efficiency of MB and Pb²⁺ still maintained 91.8% and 85.0%, respectively, after 6 cycles.

Optimization of Ni(II) adsorption onto Cloisite Na+ clay using response surface methodology

The aim of this study was to investigate the adsorption of Ni(II) from aqueous solutions onto Cloisite Na⁺ clay. The effects of the initial concentration of Ni(II), adsorbent dose, pH, and temperature on adsorption capacity were studied using response surface methodology. A second-order regression model was determined based on the experimental results. Analysis of variance used to evaluate the individual and combined effects of process variables showed that initial Ni(II) concentration and adsorbent dose were more significant than solution pH and temperature. Moreover, the interaction effects of the initial concentration of nickel and the adsorbent dose, as well as the solution pH and adsorbent dose were significant. High coefficient of determination (R² = 0.93) and low probability values signify the validity of the model for predicting the adsorption capacity of Cloisite Na⁺ for Ni(II) ions. The optimal conditions for pH and adsorbent dose were found to be 6.9 and 0.21 g/L, respectively at a constant temperature of 25 °C and initial Ni(II) concentration of 50 mg/L. Under these conditions, the adsorption capacity of clay was found to be 31.43 mg/g. Moreover, the adsorption isotherms results indicated that these data could be best fitted to the Langmuir isotherm model (R² = 0.99). The Langmuir maximum adsorption capacity was estimated to be 32.05 mg/g for an adsorbent dose of 0.2 g/L at pH 7 and 25 °C. In conclusion, the results showed that Cloisite Na⁺ clay can be utilized as an effective adsorbent for the removal of Ni(II) from aqueous solutions.

Kinetic and equilibrium studies on the adsorption of Direct Red 23 dye from aqueous solution using montmorillonite nanoclay

In this research, the adsorption of the Direct Red 23 dye from synthetic textile wastewater using nanoclay was studied in a batch system. The properties of nanoclay were investigated by scanning electron microscope, Fourier transform infrared, and EDX analysis. The specific surface area of the nanoclay was determined using Sear's method. The results revealed that with increasing adsorbent dose and contact time and decreasing pH, ionic strength, and adsorbate concentration, dye removal efficiency has increased. Nanoclay could remove 99.4% dye from the solution containing 50 mg/L dye at 30 min. The results indicated that dye removal followed pseudo-second-order kinetic (R2 &gt; 0.99) and the Langmuir isotherm. According to the findings, nanoclay is an effective adsorbent for direct dye removal from wastewater.

Review of post-combustion carbon dioxide capture technologies using activated carbon

Carbon dioxide (CO₂) is the largest anthropogenic greenhouse gas (GHG) on the planet contributing to the global warming. Currently, there are three capture technologies of trapping CO₂ from the flue gas and they are pre-combustion, post-combustion and oxy-fuel combustion. Among these, the post-combustion is widely popular as it can be retrofitted for a short to medium term without encountering any significant technology risks or changes. Activated carbon is widely used as a universal separation medium with series of advantages compared to the first generation capture processes based on amine-based scrubbing which are inherently energy intensive. The goal of this review is to elucidate the three CO₂ capture technologies with a focus on the use of activated carbon (AC) as an adsorbent for post-combustion anthropogenic CO₂ flue gas capture prior to emission to atmosphere. Furthermore, this coherent review summarizes the recent ongoing research on the preparation of activated carbon from various sources to provide a profound understanding on the current progress to highlight the challenges of the CO₂ mitigation efforts along with the mathematical modeling of CO₂ capture. AC is widely seen as a universal adsorbent due to its unique properties such as high surface area and porous texture. Other applications of AC in the removal of contaminants from flue gas, heavy metal and organic compounds, as a catalyst and catalyst support and in the electronics and electroplating industry are also discussed in this study.

Hempseed Oil Quality Parameters: Optimization of Sustainable Methods by Miniaturization

Industrial Hemp, Cannabis sativa L., is characterized by low content of THC (<0.2%). An edible oil with excellent nutritional proprieties is obtained from cold pressing of hempseed. Since Hempseed oil is not reported in a Regulation yet, in order to ensure quality parameters, it is necessary to optimize standard methods (taken from the Regulation for EVOO). In this work, the standard method of quality parameters (free fatty acidity, peroxide number, and anisidine number) were miniaturized and optimized for Hempseed oil matrix. The miniaturized methods result in being sustainable, in environmental and economical perspectives, by using a smaller amount of chemicals (e.g., reagents, solvents), also reducing waste production and the sample needed in relation to the high cost of the Hempseed oil (60–70 €/L). The standard methods of miniaturization, carried out by using the Central Composite Design, allow for great saving of sample (5.35 g vs. 29 g) and reagents (up to 50%).

Removal of sulfamethoxazole antibiotic from aqueous solutions by silver@reduced graphene oxide nanocomposite

In the present study, the synthesizing of silver@reduced graphene oxide nanocomposite, through a facile precipitation method, is reported. In this method, in the synthesizing step, reduced graphene oxide was applied as a support, silver acetate as a precursor of Ag⁰, and sodium hydroxide as a medium for reducing procedure. Then synthesized particles were characterized by using transmission electron microscopy analysis, Fourier-transform infrared spectroscopy, field emission scanning microscopy/energy dispersive X-ray, and X-ray diffraction. Adsorbent potentials of the prepared nanocomposite were evaluated for sulfamethoxazole removal from polluted aqueous solutions via two different experimental methods, namely, "one-at-a-time" and "central composite design". The given results from the one-at-a-time method confirms that 0.007 g of silver@reduced graphene oxide nanocomposite can remove 88% (188.57 mg/g) of sulfamethoxazole from a 0.05 dm³ solution (initial concentration 30 mg/dm³) at pH = 5 after 3600 s' contact time. However, in the central composite design method, the optimum condition was 95% (79.17 mg/g) uptake of this drug from 0.05 dm³ of polluted solution with initial concentration of 30 mg/dm³ and pH = 7.5, using 0.018 g of the adsorbent in 3600 s. The main mechanism for sulfamethoxazole removal can be suggested as a suitable interaction between S atoms in functional groups in the drug and Ag atoms on the surface of nanoparticles. The pseudo-second-order patterns and Freundlich model described the empirical data isotherm and kinetics for the adsorption processes, respectively. The maximum adsorption capacity by experimental and theoretical isotherm methods (Langmuir) obtained 250 and 357 mg/g, respectively. Efficiency of the adsorbent in treatment of SMX from real samples displayed less hardness and electrical conductance samples have the maximum uptake percent while existence of nitrate ions in the solutions did not induce any negative effect on the removal of the SMX. All obtained results indicated loading of Ag nanoparticles on rGO nanosheets is an effective strategy for SMX uptake with high proficiency and shows great promise as pollutant adsorbent for environmental applications.

Hydroxamic acid mediated heterogeneous Fenton-like catalysts for the efficient removal of Acid Red 88, textile wastewater and their phytotoxicity studies

Heterogeneous Fenton-like catalyst and its industrial application are increasingly given importance for its non-selective mineralization of organic pollutants in broad pH range. Current study, utilized an aromatic hydroxamic acid derivative 2-hydroxypyridine-N-oxide (HpO), for the construction of iron-Hpo ligand catalyst supported on granular activated carbon (GAC). 8-Hydroxyquinoline and citric acid as non-hydroxamic aromatic and aliphatic Fenton-like catalysts were used for comparative evaluation of the efficiency with targeted catalyst (iron-HpO-GAC). This novel catalyst iron-HpO-GAC exhibits excellent efficiency in Acid Red 88 dye removal in the presence of hydrogen peroxide as oxidant at acidic, basic as well as at neutral conditions. Operational conditions for the catalytic oxidation including temperature, dye concentration, pH and catalyst dosage were systematically investigated and analyzed through kinetic studies. Thermodynamic analysis of the catalytic dye removal revealed that the system could oxidize pollutants faster with less activation energy requirement. Higher level of recyclability and stability of the catalyst with less iron leaching was achieved. Finally, the real time application of the catalyst was investigated through successful repeated treatment for actual industrial wastewater. The phytotoxicity assay (with respect to plant Phaseolus mungo) revealed that the degradation of Acid Red 88 and dye wastewater produced nontoxic metabolites which increases its potential application. This study emphasizes the viability of hydroxamate mediated efficient Fenton-like oxidation as a novel approach in designing economically viable pollutant removal technology.

Decolorization of crystal violet from aqueous solutions by a novel adsorbent chitosan/nanodiopside using response surface methodology and artificial neural network-genetic algorithm

A novel adsorbent of chitosan/nanodiopside nanocomposite (CS-NDIO) was synthesized as a green composite for the removal of crystal violet (CV) and characterized by techniques like XRD, FT-IR, BET, and FESEM analysis. The influence of parameters like molar ratios of CS to NDIO, initial pH of the solution, dosage of adsorbent, initial concentration of CV and contact time was investigated and evaluated by central composite design (CCD; 5 levels and 4 factors). Also, Hybrid model of (ANN) model with genetic algorithm (GA) optimization was applied to the experimental data get through CCD. The optimized molar ratio of CS-NDIO was found: 20/80. Optimal parameter choice for maximum CV adsorption process using CCD and ANN-GA were as follows: pH = 7.50 and 7.499, adsorbent mass: 0.0077 and 0.0077 g, CV concentration: 20.000 and 20.002 mg/L, and contact time: 25.00 and 25.00 min, respectively. The evaluation adsorption equilibrium and kinetic data were fitted with the Langmuir monolayer isotherm model (q_max: 104.66 mg g^-1 and R²: 0.9937) and pseudo-second order kinetics mechanism (R²: 0.9978). Thermodynamic parameters (R²: 0.9180, ΔH°: -74.93 kJ mol^-1, ΔG°: -12.89 kJ mol^-1, and ΔS°: 0.93 kJ mol^-1 K^-1) were calculated and indicating adsorption to be an exothermic and spontaneous process.

High Catalytic Activity of Lipase from Yarrowia lipolytica Immobilized by Microencapsulation

Microencapsulation of lipase from Yarrowia lipolytica IMUFRJ 50682 was performed by ionotropic gelation with sodium alginate. Sodium alginate, calcium chloride and chitosan concentrations as well as complexation time were evaluated through experimental designs to increase immobilization yield (IY) and immobilized lipase activity (ImLipA) using p-nitrophenyl laurate as substrate. To adjust both parameters (IY and ImLipA), the desirability function showed that microcapsule formation with 3.1%(w/v) sodium alginate, 0.19%(w/v) chitosan, 0.14 M calcium chloride, and 1 min complexation time are ideal for maximal immobilization yield and immobilized lipase activity. A nearly twofold enhancement in Immobilization yield and an increase up to 280 U/g of the lipase activity of the microcapsules were achieved using the experimental design optimization tool. Chitosan was vital for the high activity of this new biocatalyst, which could be reused a second time with about 50% of initial activity and for four more times with about 20% of activity.

Degradation of ciprofloxacin antibiotic by Homogeneous Fenton oxidation: Hybrid AHP-PROMETHEE method, optimization, biodegradability improvement and identification of oxidized by-products

The main purpose of this experimental study was to optimize Homogeneous Fenton oxidation (HFO) and identification of oxidized by-products from degradation of Ciprofloxacin (CIP) using hybrid AHP-PROMETHEE, Response Surface Methodology (RSM) and High Performance Liquid Chromatography coupled with Mass Spectrometry (HPLC-MS). At the first step, an assessment was made for performances of two catalysts (FeSO₄·7H₂O and FeCl₂·4H₂O) based on hybrid AHP-PROMETHEE decision making method. Then, RSM was utilized to examine and optimize the influence of different variables including initial CIP concentration, Fe²⁺ concentration, [H₂O₂]/[ Fe²⁺] mole ratio and initial pH as independent variables on CIP removal, COD removal, and sludge to iron (SIR) as the response functions in a reaction time of 25 min. Weights of the mentioned responses as well as cost criteria were determined by AHP model based on pairwise comparison and then used as inputs to PROMETHEE method to develop hybrid AHP-PROMETHEE. Based on net flow results of this hybrid model, FeCl₂·4H₂O was more efficient because of its less environmental stability as well as lower SIR production. Then, optimization of experiments using Central Composite Design (CCD) under RSM was performed with the FeCl₂·4H₂O catalyst. Biodegradability of wastewater was determined in terms of BOD₅/COD ratio, showing that HFO process is able to improve wastewater biodegradability from zero to 0.42. Finally, the main intermediaries of degradation and degradation pathways of CIP were investigated with (HPLC-MS). Major degradation pathways from hydroxylation of both piperazine and quinolonic rings, oxidation and cleavage of the piperazine ring, and defluorination (OH/F substitution) were suggested.

The preparation of carboxylic-functional carbon-based nanofibers for the removal of cationic pollutants

A simple route is presented to fabricate carboxylic-functional carbon-coated polyacrylonitrile nanofibers (oPAN@C) through preoxidation and hydrothermal carbonization. PAN fibers were firstly preoxidized to form aromatic ladder structure with the resistance to hydrothermal condition, in which more carboxyl groups were introduced on the fiber surface at the present of chitosan and citric acid. The oPAN@C composites exhibit a high adsorption capacity towards methylene blue (MB) and lead ion (Pb²⁺). The adsorption data matched the pseudo-second-order kinetic model and Langmuir model well with the maximum adsorption capacity (153.37 and 143.27 mg g^-1) for methylene blue and Pb²⁺, respectively. Moreover, oPAN@C could be regenerated easily by hydrochloric acid, and still remained high removal efficiency after 5 cycles. Therefore, oPAN@C fibers should have potential application in sewage treatment.

Photodegradation of methylene blue with PVA/PVP blend under UV light irradiation

Homogenous films of PVA/PVP blend (1:1) doped with different levels of methylene blue dye (MB) were prepared using the casting technique. The absorption spectra of doped PVA/PVP blend showed two absorption peaks due to the chromophor groups of MB while the pure PVA/PVP blend does not. The UV irradiation causes photodegradation of MB dye. The recovery of photodegraded MB is observed after keeping the sample 3h in atmospheric air. The value of the optical energy gap (E_g) decreases with increasing the doping levels with MB. The spectral distribution of absorption index (k) and refractive index (n) are determined from the reflection and transmission spectra in the spectral range 200-2500nm. The dependence of both n and k on wavelength of the incident light and the wt% content of MB in PVA/PVP blend is discussed. A normal dispersion observed at wavelength λ>370nm for pure PVA/PVP blend and λ>800nm for MB doped samples. The obtained results suggest the possible use of the studied system in many applications.