Pseudo First-order Model Research Articles

Oxidative pyrolysis for enhanced-CO2 adsorption capacity in biosolid-derived biochar

The study conducts the adsorption kinetic analysis of biosolid-derived biochar produced from pyrolysis and oxidative pyrolysis. The adsorption kinetic analysis is performed at three different temperatures. The characteristics of the adsorption and diffusion mechanisms are evaluated by applying adsorption kinetic models and diffusion mechanism models. The pseudo-first-order model (PFO) and the pseudo-second-order model (PSO) reveal that the CO2 adsorption process of the biosolid can be categorised as physisorption with activation energy below 40 kJ/mol. The CO2 adsorption capacities of the biochar produced at 700°C, 800°C, and 900°C are 6.3, 7.9, and 6.4 mg/g at 45°C, respectively. In contrast, the biochar produced from oxidative pyrolysis shows a CO2 adsorption capacity of 7.5 mg/g at 45°C. Film and intraparticle diffusions are primary rate-limiting factors of the adsorption process. The biochar samples maintain 84-85% of their adsorption capacities after five cyclic tests. The present study demonstrates the CO2 adsorption capacity of biosolid-derived biochar produced from different conditions of pyrolysis, providing an energy-efficient and sustainable solution to CO2 adsorption with solid adsorbents.

Green synthesis of silver nanoparticles using Lepidium sativum seed mucilage as a bioreductant/capping agent for efficient antibacterial and photocatalytic activities

Contamination of aquatic resources with organic dyes and pathogenic bacteria ranks among the most serious threats to human survival and the environment. The current work investigated L. sativum seed mucilage as a reducing and capping agent for Ag NPs. From UV–vis spectroscopy, the characteristic surface plasmon resonance peak and the band gap energy of as-fabricated NPs were 440 nm and 2.07 eV, respectively. SEM revealed irregular-shaped NPs with an average diameter of 73.85 nm and EDX disclosed Ag along with C, O, and Si from mucilage’s biomolecules. The antibacterial and antibiofilm results showed higher inhibitory effects against the Gram-positive (B. cereus) than the Gram-negative (E. coli, and E. aerogenes) bacteria. The biosynthesized NPs were impressive in degrading methylene blue (MB, 89.45 %) and methyl orange (MO, 84.78 %) under optimized conditions viz., dye solution (20 ppm), photocatalyst dose (5 mg), light intensity (UV index of 10 +), and irradiation time (120 min). The kinetic data strongly supported the pseudo-first order model with maximum adsorption capacities of 787.40 and 724.64 mg/g for MB and MO, respectively as determined through the Langmuir isotherm model. The photocatalyst exhibited sufficient stability even after six repeated cycles, highlighting its suitability for industrial and commercial applications.

Chitosan extracted from the feather of Dosidicus gigas crosslinked with glutaraldehyde for use as a 99Mo adsorbent

The production of Technetium-99 m (99mTc) is important for cancer diagnosis. The solvent extraction is the most widely used method to obtain 99mTc; however, due to the evaporation of the polluting solvent into the environment, a radiochemical separation using a chromatographic column system based on adsorbent materials would be cleaner and more efficient.In this study, squid feather (Dosidicus gigas) chitosan (SFC) polymers have been synthesized and crosslinked with glutaraldehyde solutions at concentrations of 50, 40 and 25 % to study the adsorption of 99Mo with the aim of test a promising material to produce 99mTc in the chromatographic column of the 99Mo/99mTc generator. Likewise, the same methodology of synthesis was performed using a commercial chitosan (CC) as a control. Deacetylation degree was measured obtaining 74.15 % and 77.65 % for the SFC and CC polymers, respectively. The molecular weight obtained was 990.72 kDa for SFC and 722.72 kDa for CC and the characterization of the biopolymers was performed with FTIR, SEM, XRD, TGA y FT Raman techniques. Equilibrium time, adsorbent mass and pH effect were evaluated as factors that influence the adsorption process of 99MoO4-2. The zero load point (pHPZC) analysis confirmed the positive charge of the crosslinked polymers, improving the adsorption capacity of 99MoO4-2 at low pH values between 2 and 4, following a pseudo-first order model. With respect to the adsorption isotherms, they exhibit maximum values of 99MoO42- of 482 mg g−1 SFCG40 and 502 mg g−1 CCG25 with a better fit to the Langmuir theoretical model.

“Sunlight-Driven Catalytic Degradation of MB Dye and Multi-Cycle Re-usability Analysis of Cu2-xSe Nanoparticles”

One of the best ways to remove organic dyes based contaminant from water resources and industrial waste water is the sunlight driven photo-catalytic degradation method. The theme of the present investigation is the photocatalytic degradation of methylene blue (MB) dye using economically produced Cu2-XSe nanoparticles (NPs) catalyst under solar radiations. The Cu2-XSe NPs crystallized in the cubic structural phase with an average crystallite size around 19 nm. The direct band gap was found to be 2.1 eV. The PL spectra and corresponding CIE diagram show the Cu2-xSe NPs emitted yellow color. The SEM micrographs show that the small grains staked over others to form large grains or patches. The FTIR and EDX spectra confirmed the formation of Cu2-XSe NPs. The obtained optimum photocatalytic degradation efficiency for Cu2-XSe NPs is 90.3%. for first cycle analysis. The pseudo-first order and second order models were used to analyze the kinetic data of Cu2-XSe NPs for varying concentrations. The multiple-cycle degradation analysis by catalyst of MB dye in one day spam for continuous four cycles were also analysed and discussed. The sun light driven multi-cycle catalytic degradation confirms the re-usability of Cu2-xSe NPs for the treatment of industrial waste water and other contaminated water bodies for the survival of aquatic life and for saving environment.

Sensor parameters and adsorption behaviour of rhodamine-based polyacrylonitrile (PAN) nanofiber against dichloromethane vapour

This study is focused on the determination of sensor and adsorption parameters ofrhodamine-based polyacrylonitrile (PAN) nanofiber during the dichloromethane vapour exposure due to a very limited investigation of the rhodamine-based PAN nanofiber sensor. Quartz crystal microbalance (QCM) measurement system is employed to monitor the sensor response to dichloromethane vapour. This nanofiber sensor demonstrates a highly sensitive, stable, reproducible response and concentration dependence behaviour. A good stability, with an excellent recovery occurred. Sensor parameters such as the limit of detection (153 ppm), the limit of quantification (465 ppm), the sensitivity (0.0215 Hz/ppm), response (2 s) and recovery (3 s) times are determined using QCM measurement results. Pseudo first-order and Elovich adsorption models have proved that dichloromethane vapours are adsorbed bythis nanofiber sensor andthe amount of vapour adsorption rate is increased when the concentration of dichloromethane vapour increases.Owing to its achieved sensor parameters, high adsorption feature and simple fabrication process with a low cost, this proposed sensing device is expected to be a promising alternative for monitoring dichloromethane vapour sensing application at room temperature.

Chemical aging of biochar-zero-valent iron composites in groundwater: Impact on Cd(II) and Cr(VI) co-removal

Biochar (BC), zero-valent iron (ZVI), and their composites are promising materials for use in permeable reactive barriers, although further research is needed to understand how their properties change during long-term aging in groundwater. In this study, BC, ZVI and their composites (4BC-1ZVI) were subjected to the chemical aging tests in five media (deionized water, NaCl, NaHCO3, CaCl2 and a mixture of CaCl2 and NaHCO3 solutions) for 20 days. After treatment, the microscopic analysis and performance tests for the co-removal of Cd(II) and Cr(VI) were carried out. The results indicated that the removal of Cd(II) by aged 4BC-1ZVI followed a pseudo-second-order model, whereas the removal of Cr(VI) was better fitted with a pseudo-first order model. The aging mechanism of 4BC-1ZVI was primarily governed by iron corrosion/passivation, the reduction of soluble components, and the formation of carbonate minerals. Less Fe3O4/ γ-Fe2O3 was formed during aging in deionized water, NaCl and CaCl2 solutions. The corrosion products, Fe3O4/ γ-Fe2O3, FeCO3 and α/γ-FeOOH, were observed after aging in NaHCO3 and a mixture of NaHCO3 and CaCl2 solutions. The decrease in the soluble components of biochar led to a decrease in cation exchange, while carbonate minerals contributed to Cd(II) precipitation. This work provides insights into the aging processes of BC-ZVI composites for long-term groundwater remediation applications.

Evaluation of Adsorption Ability of Lewatit® VP OC 1065 and Diaion™ CR20 Ion Exchangers for Heavy Metals with Particular Consideration of Palladium(II) and Copper(II).

The adsorption capacities of ion exchangers with the primary amine (Lewatit® VP OC 1065) and polyamine (Diaion™ CR20) functional groups relative to Pd(II) and Cu(II) ions were tested in a batch system, taking into account the influence of the acid concentration (HCl: 0.1-6 mol/L; HCl-HNO3: 0.9-0.1 mol/L HCl-0.1-0.9 mol/L HNO3), phase contact time (1-240 min), initial concentration (10-1000 mg/L), agitation speed (120-180 rpm), bead size (0.385-1.2 mm), and temperature (293-333 K), as well as in a column system where the variable operating parameters were HCl and HNO3 concentrations. There were used the pseudo-first order, pseudo-second order, and intraparticle diffusion models to describe the kinetic studies and the Langmuir and Freundlich isotherm models to describe the equilibrium data to obtain better knowledge about the adsorption mechanism. The physicochemical properties of the ion exchangers were characterized by the nitrogen adsorption/desorption analyses, CHNS analysis, Fourier transform infrared spectroscopy, the sieve analysis, and points of zero charge measurements. As it was found, Lewatit® VP OC 1065 exhibited a better ability to remove Pd(II) than Diaion™ CR20, and the adsorption ability series for heavy metals was as follows: Pd(II) >> Zn(II) ≈ Ni(II) >> Cu(II). The optimal experimental conditions for Pd(II) sorption were 0.1 mol/L HCl, agitation speed 180 rpm, temperature 293 K, and bead size fraction 0.43 mm ≤ f3 < 0.6 mm for Diaion™ CR20 and 0.315-1.25 mm for Lewatit® VP OC 1065. The maximum adsorption capacities were 289.68 mg/g for Lewatit® VP OC 1065 and 208.20 mg/g for Diaion™ CR20. The greatest adsorption ability of Lewatit® VP OC 1065 for Pd(II) was also demonstrated in the column studies. The working ion exchange in the 0.1 mol/L HCl system was 0.1050 g/mL, much higher compared to Diaion™ CR20 (0.0545 g/mL). The best desorption yields of %D1 = 23.77% for Diaion™ CR20 and 33.57% for Lewatit® VP OC 1065 were obtained using the 2 mol/L NH3·H2O solution.

Adsorption parameters optimization of spent coffee ground biochar for methylene blue removal using response surface methodology

This study investigates the potential of spent coffee ground biochar (SCGB) as a sustainable and cost-effective adsorbent for the removal of methylene blue (MB), a hazardous dye commonly used in the textile and printing industries. A response surface methodology (RSM) approach with central composite design (CCD) was employed to systematically investigate the effects of key process parameters, including adsorbent dosage, solution pH, contact time and temperature, on MB removal efficiency. The analysis revealed that adsorbent dosage and temperature as critical factors influencing MB removal, with a linear model providing a strong correlation. Optimal conditions for MB removal were determined to be 0.99 g of SCGB, 30 min of contact time, 30 °C temperature, and a solution pH of 7. Under these conditions, MB removal reached 99.99%, with a desirability of 1.000. The experimental results closely matched the predicted values, differing by only 0.02%, thus validating the accuracy of the model. Kinetic studies indicated a rapid adsorption process, well-described by both pseudo-first and pseudo-second order models. Isotherm analysis confirmed the applicability of the Freundlich model, suggesting favorable adsorption with increasing MB concentration. The high adsorption capacity of SCGB is attributed to its carbonaceous and porous structure, highlighting its potential as an effective adsorbent for dye removal in wastewater treatment applications.

Mixed ligand iso-reticular MOFs as integrated photo-catalytic adsorbents for the removal of bromo-phenol blue: Kinetics, thermodynamics and mechanistic study

The designing of mixed linker MOFs with identical framework structures and different chemical components provides opportunities for enhancing their inborn adsorption and photo-degradation performances. Herein, we synthesized zinc, copper, manganese, and cobalt-based iso-reticular MOFs via the solvothermal method using 2,5-furan dicarboxylic acid and 1,2-bis(4-pridyl) ethylene as green ligands. The synthesized MOFs were applied for the adsorption-assisted photo-catalytic decontamination of bromophenol blue (BPB) from wastewater without using any co-catalyst under visible light irradiation. Note-worthily, Cu-MOF (BUT-206-Cu) exhibits high adsorption capacity (299 mg/g) and removal efficiency (97 %), mainly owing to the high surface area (280 m2/g), opened porous structure, additional defective sites, efficient energy transfer, and excellent stability in aqueous, and acidic environments resulting from the strong co-ordination environment of the copper cations. The impact of key factors, including initial pH and concentration of the dye solution, on the adsorption and degradation efficiency of BUT-206-Cu was investigated. Moreover, trapping experiments and EPR results revealed that OH• and h+ were the main active species in the photocatalytic degradation of BPB. Adsorption and degradation kinetics of BPB were observed to obey pseudo-second-order and pseudo-first order models, respectively. The thermodynamics study revealed that the adsorption of BPB fitted the Langmuir model, and values of the ΔGads, ΔHads, and ΔSads revealed that the adsorption process is spontaneous, physical, and exothermic and leads to increased randomness in the system. BUT-206-Cu exhibited excellent reusability for up to five cycles, indicating its potential as an environmentally friendly integrated photocatalytic adsorbent for removing BPB from wastewater.

Adsorption dynamics of Eriochrome Black dye removal using raw and ultrasonicated Pithecellobium seed biomass: ANN modeling and mechanisms

Utilization of Ultrasonic modified Pithecellobium dulce seed biomass, proved the efficacy in Eriochrome black dye remediation. The study investigates the sorption dynamics of Eriochrome Black (EB) dye removal using raw and ultrasonicated Pithecellobium seed biomass combined with Artificial Neural Network (ANN) modeling for the elucidation of underlying mechanisms. To improve the adsorption performance, Pithecellobium dulce biomass has been subjected to ultrasonication. The characterization of modified seed adsorbent revealed the adsorptive properties of biomass for the removal process. Varying impacts of dye adsorption were studied revealing the optimal parameters to be pH of 5, temperature of 303 K, contact time of 40 min-Ultrasonicated Pithecellobium dulce (UPDB) biomass; 80 min – Raw Pithecellobium dulce biomass (RPDB), and dose of 5 g/L and 2.5 g/L for RPDB and UPDB respectively. Isotherm and Kinetic analysis revealed the Freundlich and pseudo-first order models to be best fitting for the current system. Ultrasonicated seed biomass exhibited enhanced adsorption capacity of 126.9 mg/g compared to 83.8 mg/g for raw seed biomass. Thermodynamic investigation infers the spontaneity and exothermic nature of adsorption process. The ANN model for the prediction of eriochrome black dye adsorption onto ultrasonic modified Pithecellobium dulce seed biomass exhibited better correlation coefficient of 0.9559 indicating the better prediction of trained model for dye removal process. Thus, ANN model provides a better prediction of the relation between operational factors and dye removal.

Surface coupling of molecularly imprinted polymers as strategy to improve sulfamethoxazole removal from water by carbons produced from spent brewery grain

This work aims to assess the surface coupling of molecularly imprinted polymers (MIP) on carbon adsorbents produced from spent brewery grain, namely biochar (BC) and activated carbon (AC), as a strategy to improve selectivity and the adsorptive removal of the antibiotic sulfamethoxazole (SMX) from water. BC and AC were produced by microwave-assisted pyrolysis, and MIP was obtained by fast bulk polymerization. Two different methodologies were used for the molecular imprinting of BC and AC, the resulting materials being tested for SMX adsorption. Then, after selecting the most favourable molecular imprinting methodology, different mass ratios of MIP:BC or MIP:AC were used to produce and evaluate eight different materials. Molecular imprinting was shown to significantly improve the performance of BC for the target application, and one of the produced composites (MIP1-BC-s(1:3)) was selected for further kinetic and equilibrium studies and comparison with individual MIP and BC. The kinetic behaviour was properly described by both the pseudo-first and pseudo-second order models. Regarding equilibrium isotherms, they fitted the Freundlich and Langmuir models, with MIP1-BC-s(1:3) reaching a maximum adsorption capacity (qm) of 25 ± 1 μmol g-1, 19 % higher than BC. In comparison with other seven pharmaceuticals, the adsorption of SMX onto MIP1-BC-s(1:3) was remarkably higher, as for the specific recognition of this antibiotic by the coupled MIP. The pH study evidenced that SMX removal was higher under acidic conditions. Regeneration experiments showed that MIP1-BC-s(1:3) provided good adsorption performance, which was stable during five regeneration-reutilization cycles. Overall, this study has demonstrated that coupling with MIP may be a suitable strategy to improve the adsorption properties and performance of biochar for antibiotics removal from water, increasing its suitability for practical applications.

Characterization and Adsorption Capacity Evaluation of ZnCl2 Impregnated Cassava Peel Carbon for Removal of Fe, Ca, Mg and Zn ions in Wastewater from Cassava processing Industry

The objective of this paper was to prepare, characterize and evaluate the adsorption capacity of cassava peel carbon (CPC) impregnation with ZnCl2 salt for the removal of Fe, Ca, Mg and Zn ions in wastewater derived from cassava processing which has been noted to be problematic in terms of management. CPC and cassava peel activated carbon (CPAC) at 1:3, 2:3, and 1:1 impregnation levels were placed in fixed bed adsorption columns to determine metal ion adsorption capacities of the carbon materials after 120, 240, 360 and 480-minute contact times. Langmuir and Freundlich isotherm models were used in assessment of adsorption of the carbon materials, while pseudo-first and second order models were used to validate the adsorption kinetics of Fe, Ca, Mg and Zn. Pore space development was also monitored using scanning electron microscope (SEM) imagery. Results SEM images revealed hexagonal honeycomb surface structure at 2:3 impregnation level and spongy configuration at 1:1 ZnCl2 impregnation level. The correlation coefficient of Langmuir isotherm was observed to be between 0.86 to 1, indicating that the adsorbent is very good in adsorption of the metals, however, Freundlich isotherm is found to be unfavorable in describing CPAC’s capacity in adsorbing zinc ion contaminant. The pH of the carbon materials was observed to have increased while the bulk density reduced with increasing level of impregnation. Conclusively, CPC and CPAC materials are well suited to Langmuir isotherm as well as pseudo-second order model, implying that adsorption occurs well in a monolayer form on the surface material surface.

Modified starch as a component of environmentally friendly polymer adsorbents − from synthesis and characterization to potential application in the removal of toxic C.I. Basic Yellow 2 dye

Increasing global degradation of the aquatic environment is forcing the search for new and low-cost adsorbents of reduced toxicity, derived from natural and renewable sources. To meet these expectations, a new approach to adsorbent fabrication was developed.The study aimed to synthesize, characterize, and apply environmentally friendly adsorbents based on poly(ethylene glycol dimethacrylate-co-vinyl acetate) (EGDMA-VA) with unmodified/modified starch (St). The first step proposed a new mechanochemical method of starch modification using thiourea (T) and potassium dihydrogen phosphate (P). Then, the functionalized starch was used to obtain polymeric microspheres. The final step involves their application for the removal of toxic C.I. Basic Yellow 2 (BY2) dye. The pristine materials and adsorbents were characterized by ATR/FT-IR and XPS, DSC, SEM/EDX, porous structure, particle size distribution, tendency to swell, and pHpzc.Adsorption batch studies of BY2 as a function of time (1–60 min), initial dye concentration (1–25 mg/L, pH=8.3), temperature (298–328 K), and competing electrolyte (5–15 g/L Na2SO4) and surfactant (0.1–0.5 g/L CTAB) presence were carried out. The kinetic studies were analyzed using pseudo-first order, pseudo-second order, and intraparticle diffusion models. The equilibrium studies revealed that the Freundlich isotherm model (kF=5.62–6.56 mg1-1/n L1/n) described BY2-adsorbents systems rather than Langmuir, Temkin or Dubinin-Radushkevich. Thermodynamic parameters (ΔG°, ΔH°, and ΔS°) pointed to the exothermic nature of adsorption and its spontaneousness. Importantly, the starch-modified microspheres were regenerated, too.

Synthesis of a novel chitosan-TiO2 nanocomposite as an efficient adsorbent for the removal of methylene blue cationic dye from wastewater

This study investigates the efficacy of chitosan-TiO2 nanocomposites (CS-TiO2) as an efficient adsorbent for removing Methylene blue (MB) cationic dye from wastewater. The synthesis of chitosan-TiO2 nanocomposites (CS-TiO2) involved the co-polymerization and crosslinking of Chitosan biopolymer (CS) with titanium dioxide (TiO2). The CS-TiO2 nanocomposites involved their structure, morphology, and characteristics through the utilization of several analytical methods such as FTIR, XRD, SEM, TEM, TGA, UV-visible, DLS, and XPS. The removal of MB dye examined in different concentrations of chitosan exhibits an increase as the pH of the solution increases; the maximum value was attained at pH 6 and 120 minutes of contact time. The optimal dosage of CS-TiO2 nanocomposites for adsorbing methylene blue (MB) was found to be between 0.10 mg/L and 0.20 mg/L. The experimental data was evaluated using the thermodynamic process, Dubinin-Radushkevich, Langmuir, and Freundlich isotherm models. The data were examined using various kinetic models and found to be consistent with pseudo-first order, pseudo-second order, and Intraparticle diffusion kinetics models. Desorption and reuse after adsorption of MB onto CS-TiO2 nanocomposite was investigated using different desorbing agents like NH4OH/NH4Cl or NaOH. These results indicate that CS-TiO2 nanocomposite is a highly effective and cost-effective adsorbent for removing MB dyes from contaminated water.

Efficient adsorption removal of anionic dyes by waste PET-derived MIL-101(Cr)

Adsorption can be used as a pollutant removal method to solve the increasingly serious problem of synthetic dye pollution and metal organic framework (MOF) is considered as a novel adsorbent for its unique structure. However, the high cost and high toxicity during the synthesis procedure of MOFs like MIL-101(Cr) limited their potential on the large-scale production and application. In this paper, waste PET plastic was depolymerized to prepare terephthalic acid (TPA) as an organic linker to synthesize MIL-101(Cr). Besides, Hydrofluoric acid (HF) was not added during the synthesis to avoid poisonous pollution. MIL-101(Cr) was applied to the adsorption of anionic dyes reactive red 2 (RR2) and reactive blue 19 (RB19). The batch experiments exhibited kinetic data best fitted the pseudo-first-order model (PFO) with the adsorption capacity of 662.87 (RR2) and 863.67 mg g-1 (RB19). The isotherm adsorption data fitted well with the Freundlich isotherm, indicating formation of multilayer coverage over the surface of MIL-101(Cr). The highest regeneration rate of MIL-101(Cr) at the fourth cycle was 91.18 and 91.44 % after RR2 and RB19 adsorption. X-ray photoelectron spectroscopy (XPS) technique and Fourier Transform Infrared (FTIR) spectroscopy both indicated the possible adsorption mechanism of MIL-101(Cr) toward RR2 and RB19 could be attributed to electrostatic interactions, hydrogen bonding, and the π-π stacking. This work proposed a novel method using waste plastics as raw materials to synthesize eco-friendly pollutant adsorbent, which had an enlightening effect on pollutant treatment.

Methylene Blue Adsorption Kinetics Investigation by Coconut Shell Activated Carbon Adsorbent Using Fractional Power, Avrami and Bangham Models

Methylene blue is not easily biodegradable, and its persistence in water can contribute to long-term contamination if not properly treated. Numerous adsorption kinetic study successes were achieved utilizing activated carbons of coconut shell, especially the Pseudo-First and Pseudo-Second order models with little/no regards to the unique behavior described by the Avrami, Bangham and the Fractional Power kinetic models. The parameters in those models are determined to describe the sorption mechanism. Avrami model fitting results suggests a complex adsorption process, which does not follow the first-order kinetic. Obtained results show that the Fractional Power model best described the Coconut Shell-Activated Carbon Methylene blue bio-sorption process at constant adsorption capacity of 15937.8 mg/g. Findings show that Bangham kinetic model does not fit the experimental data for Methylene blue sorption from aqueous solution. Methylene blue exposure issues like gastrointestinal discomfort, skin and eye irritation, and imbalances in the populations of various species in aquatic ecosystems due to impacts on their growth, reproduction and survival, may be solved using a very effective adsorbent, such as the Coconut Shell -Activated Carbon used here.

Synthesis and characterisation of novel beta-cyclodextrin based Fe3O4 nanocomposite: adsorption behaviour and photocatalytic dye degradation studies

ABSTRACT Novel Beta-Cyclodextrin-based Fe3O4 nanocomposite has been synthesised through copolymerisation by incorporating Fe3O4 nanoparticles into the polymer matrix. Ultraviolet-Visible (UV-Visible) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, Thermogravimetric (TGA) analysis, Point of Zero Charge, X-ray diffraction (XRD), and Scanning electron microscopy (SEM) analysis have been used to characterise the Fe3O4 Nanoparticles and β-CDHs@Fe3O4 nanocomposite. The synthesised β-CDHs@Fe3O4 nanocomposite has been utilised for the adsorption of methylene blue (MB) dye from aqueous solutions. The maximum percentage removal of MB dye at optimum pH 7 and was found to be 98.51%. The adsorption capacity (qe) of β-CDHs@Fe3O4 nanocomposite has been found to be 268.09 mg/g at optimum dosages 1.2 g/L, pH 7, temperature 25°C, concentration 100 mg/L and an agitation speed of 200 rpm. Adsorption data have been fitted with three isotherm models namely Langmuir, Freundlich, and Temkin, and it was found to be the best fit with the Langmuir isotherm model. Kinetic studies like the pseudo-first order, pseudo-second order, and intra-particle diffusion model were also performed to study the adsorption mechanism. Further, thermodynamic studies demonstrate that the reaction was exothermic and spontaneous. Photocatalytic degradation of MB dye under visible light has also been studied, and 79.01% degradation of the dye was observed. Also, desorption of the nanocomposite was performed, and it was found to be reusable up to 5 times with 90% dye-desorption in the fifth cycle.

Phosphorus recovery from ultrafiltered membrane wastewater by biochar adsorption columns: The effect of loading rates

The present study used bench scale columns filled with biochar for phosphorous (P) recovery from real ultrafiltered wastewater. No studies are available about the potentiality of biochar using ultrafiltered real wastewater. Therefore, this study aimed to assess phosphate (PO43−) recovery by biochar-packed columns employing real treated wastewater from an ultrafiltration process. Three flow rates were tested, specifically 0.7, 1.7 and 2.3 L h−1, to gain insights into the optimal working conditions. Results revealed that the maximum amount of PO43− recovery (namely, 3.43 mg g−1 biochar) can be achieved after 7 h by employing the highest tested flow rate. Furthermore, the phosphorus exchange capacity (PEC) was inversely correlated with the feeding flow rate (FFR), with PEC values equal to 35, 25 and 9 % for FFR of 0.67, 1.7 and 2.3 L h−1, respectively. The pseudo-first order model best approximated the adsorption kinetics, thus suggesting that the adsorption of phosphate by biochar depends on its concentrations (i.e. physiosorption mechanism).

Investigating biotic and abiotic degradation of emerging contaminants in surface water-sediment batch systems

Four emerging compounds including estrone, progesterone, sulfamethoxazole and trimethoprim were investigated for their degradation in water/sediment systems exposed to a variety of biotic and abiotic conditions. Both the water and sediment were sampled from River Yamuna. The experiments were conducted in batch mode for 40 days. The degradation kinetics were described using a pseudo first-order reaction model. Among the four exposure conditions, bio-photodegradation led to higher removal of emerging contaminants. Comparing photodegradation in sterile surface water and distilled water showed the impact of interfering ions on the photochemical reactions thereby slowing the reaction. All the four target compounds underwent rapid degradation in batch 4, consisting of distilled water exposed to sunlight. The identification of transformation products suggested degradation pathways except for estrone, for which only one transformation product was identified. The study also detected the transformation products in Yamuna surface water samples confirming the presence of the proposed degradation pathways in the environment.

Адсорбционное извлечение аминов из водных растворов

Aquatic biological resources are an important part of the ecosystems of our planet, since they are involved in economic turnover as a source of food. The composition of water, including waste water from enterprises, has a direct impact on the state of aquatic biological resources. To extract and concentrate metals from solutions, hydrometallurgical processes are used – extraction and sorption. Their implementation is possible with the use of special substances – extractants and in a number of processes – sorption materials (Solvent Impregnated Resins (SIR’s) and Levextrel’s) with a mobile phase of the extractant, combining the properties of sorbents and extractants. Despite the advantages of the latter, such as high kinetic parameters, lack of swelling and high values of mechanical strength, they are characterized by the disadvantages of extraction methods – the entrainment of the extractant into the aqueous phase in dissolved and emulsion forms. Under static conditions, the possibility of purification of aqueous solutions containing primary or tertiary amine by adsorption on carbon materials (activated carbon NWC, carbon NWC-T modified with carbon nanotubes, CS-PTFE modified with polytetrafluoroethylene), as well as on styrene-divinylbenzene nonionic copolymer Porolas-T and a natural shell rock adsorbent was studied. The kinetics of adsorption of аmines Primene-JMT and TOA from aqueous solutions by these adsorbents has been studied by the method of a limited volume of solution. Of the known pseudo-first order, pseudo-second order and Elovich models, the pseudo-second order model describes kinetic data more adequately (R2&gt;0.99). The values of the distribution coefficients and the rate constants of adsorption of Primene-JMT and TOA are determined. A block diagram of adsorption purification of aqueous solutions from amines is proposed, the implementation of which will reduce the toxicity of waste solutions and return some of the expensive extractant to circulation.