Initial Solution Concentration Research Articles

Biosorption studies on arsenic (III) removal from industrial wastewater by using fixed and fluidized bed operation

Previously, activated carbon was used as adsorbent for the removal of heavy metals at batch scale and the reported removal efficiency was up to 25 % (while in our technique the efficiency is up to 75%). The large industries operate with continuous processes and discharge large amount of wastewater containing heavy metals. No research was published for continuous operation using fluidized bed adsorption column till now. The novelty of this study is on the mode of operation (continuous operation at large scale under fixed and fluidized bed conditions), Biosorbent activated carbon (AC), and maximum efficiency of arsenic removal (i.e. 75 %). The Biosorbent activated carbon prepared from waste agriculture material. Industrial wastewater consists of many inorganic and organic pollutants which are discharged into water bodies resulting the serious health problems. Now a days, concentration of arsenic has much increased as compared to the permissive concentration level (25mg/L). Therefore, there is need to reduce this concentration up to threshold value (10μg/L). The use of biosorbents for arsenic removal from wastewater has global significance due to its widespread availability and low cost. Biosorption of Arsenic strongly depends on the initial metal concentration, contact time, speed of stirring, pH and temperature. The maximum arsenic as (III) removed at pH-7.5 is 70%, it was improved to 83% by agitation in batch experiments. While in continuous mode experiments (Fixed bed) the bed height and flow rates were varied. At the Fluidized bed experiments, the maximum As (III) removed was 75%. The effects of several factors such as pH, initial solute concentration, biosorbents dose, has been revaluated in this paper. The low cost, easily available biosorbent AC is recommended for removal of arsenic from contaminated wastewaters to bring them in compliance.

Valorization of Silybum marianum seed shells waste as biosorbent for basic fuchsin dye removal from water: kinetics, isotherms, and thermodynamic studies

Over the last decades, the valorization of agro-industrial wastes into adsorbents has received a lot of attention due to the low-cost, high performance and sustainability factors. This work aims to valorize Silybum marianum seed shells (SMSS) as biosorbent for the removal of basic fuchsin dye (BF) from water. The prepared biosorbent from SMSS was characterized to check the morphological and structural proprieties using several techniques including FTIR, XRD, SEM, TGA-DTA, and BET. It was found that SMSS has a fibrous semi-amorphous structure typical of lignocellulosic materials. The study also investigated the impact of numerous operational parameters on basic fuchsin biosorption efficiency, including particle size, biosorbent mass, stirring speed, initial dye concentration, temperature, and pH of solution. Additionally, the research explored the influence of natural water matrices on dye removal. The adsorption performance was found to be higher at basic pH values, reaching 97.50%. The adsorption process was analyzed using different kinetic models, and it was found that the process follows a pseudo-second-order model. The experimental data was thoroughly scrutinized using the Freundlich and Langmuir isotherm models. The results confirm that Langmuir model fits well the BF dye adsorption on SMSS surface. The thermodynamic study revealed that the adsorption process of BF dye onto SMSS was endothermic. Overall, SMSS shows great adsorption ability which might be a good candidate for real wastewater treatment, by considering low-cost and availability of the original waste.

ABSORBTION KINETICS OF CARBON DIOXIDE BY LITHIUM CARBONATE AQUEOUS SOLUTION

The kinetics of absorption (chemisorption) of carbon dioxide by an aqueous solution of lithium carbonate at a temperature of 293 K and in the pressure range 8.0·103 – 3.2·104 Pa was studied. Lack of inhibition of the reaction by dissolving carbon dioxide, i.e. the occurrence of the reaction in the kinetic region was proven by conducting experiments to establish the dependence of the process rate on the intensity of stirring the solution. The voltage supplied to the stirrer motor was determined, starting from which the kinetic curves of CO2 absorption merged with each other, i.e. the rate of CO2 absorption ceased to depend on the intensity of mixing - the so-called maximum absorption rate. The effect of lithium carbonate concentration on the absorption rate was studied at a constant carbon dioxide pressure of 1.6·104 Pa. It was found that the initial reaction rate was practically independent on the initial concentration (zero order reaction). However, as the reaction product accumulated, it slowed down: the zero order of the reaction passed into the first. The dependence of the reaction rate on carbon dioxide pressure was determined at the same initial concentration of lithium carbonate solution 0.2027 M and different pressures. It was found that with increasing pressure the rate of the process increased linearly. First order on carbon dioxide concentration was observed. To explain the observed patterns, a diagram of the reaction mechanism is proposed, from which the kinetic equation was derived. The effective absorption rate constants were calculated. Based on the proposed reaction mechanism, the inhibition of absorption by the reaction product is explained. Its addition shifts the absorption-chemical equilibrium, thereby reducing the concentration of hydrogen ions. The resulting kinetic equation can serve as the basis for calculating and optimizing the operation of industrial carbon dioxide absorbers.

Magnetophoresis of paramagnetic metal ions in porous media.

We report a numerical investigation of the magnetophoresis of solutions containing paramagnetic metal ions. Using a simulated magnetic field of a superconducting magnet and the convection-diffusion model, we study the transport of transition metal salts through a porous medium domain. In particular, through a detailed comparison of the numerical results of magnetophoretic velocity and ion concentration profiles with prior published experiments, we validate the model. Subsequent to model validation, we perform a systematic analysis of the model parameters on the magnetophoresis of metal ions. Magnetophoresis is quantified with a magnetic Péclet number Pem. Under a non-uniform magnetic field, Pem initially rises, exhibiting a local maximum, and subsequently declines towards a quasi-steady value. Our results show that both the initial and maximum Pem values increase with increasing magnetic susceptibility, initial concentration of metal solutes, and ion cluster size. Conversely, Pem decreases as the porosity of the medium increases. Finally, the adsorption of metal salts onto the porous media surface is modeled through a dimensionless Damkohler number Daad. Our results suggest that the adsorption significantly slows the magnetophoresis and self-diffusion of the paramagnetic metal salts, with a net magnetophoresis velocity dependent on the kinetics and equilibrium adsorption properties of the metal salts. The latter result underscores the crucial role of adsorption in future magnetophoresis research.

Formation and Physicochemical Properties of Freeze-Dried Amyloid-Like Fibrils From Pinto Bean Protein: Amyloid-Like Fibrils From Pinto Bean Protein.

Amyloid nanofibrils are long and thin strands with cross β structures associated by hydrogen bonds. These structures can be formed under suitable conditions commonly at low pH and high temperatures. Fibrillated pinto bean protein isolate (FPBPI) was made by heating pinto bean protein at 85°C in an acidic condition while gently stirring at initial protein solution concentrations of 4 mg/mL, 13 mg/mL, and 21 mg/mL. Freeze-dried FPBPI's physicochemical, structural, and thermal characteristics were assessed, and they were compared with a native pinto bean protein isolate (PBPI) as a control. An increase in Congo red spectral absorption at 544 nm was observed following the fibril formation process. The largest concentration of freeze-dried fibrillated protein exhibited the highest Congo red spectral absorption. Fibrillar proteins' Fourier transform infrared (FTIR) spectrograms with lower wave numbers were seen than the native protein. For native PBPI, transmission electron microscopy (TEM) images were globular in shape, but they changed to long and curly morphologies in fibrillated proteins. FPBPI has a lower melting enthalpy than native protein when measured by differential scanning calorimetry (DSC). With the rising initial protein content, the enthalpy rose. Concurrently, semicrystalline structure for native and fibrillated pinto bean proteins was revealed by X-ray diffraction (XRD) findings. As the original protein concentration grew, so did the crystallinity intensity. Water-holding capacity (WHC) and oil-holding capacity (OHC) of freeze-dried FPBPI were higher than those of native protein. So, fibrillation of pinto bean protein helped it to serve as a good thickener in food industries.

Influence of activators on spent coffee grounds as biosorbent for chromium

Global production of Cr (VI) can reach 44 million metric tons annually, of which 49% is released into the environment. Developments in the industry are to blame for this. There are numerous ways to defend against the damaging impact that heavy metals have on the environment. The presence of Cr (VI) metal causes environmental problems because it can endanger the physical and ecosystem balance of aquatic fauna in river flows. Exposure to Cr (VI) causes health problems such as liver, lung and kidney damage. Adsorption is a straightforward, affordable, and user-friendly technique. The adsorbent utilized is derived from biomass waste, specifically SCG, but its potential as an adsorbent still needs to be developed. The purpose of this work was to examine the impact of activators on activated SCG and its capacity to adsorb Cr (VI) metal. Nitric acid and Bromide acid activators were used to activate 25 g of SCG for 1, 2, and 3 hours. Adsorbent to activator ratios are 1:4, 1:5, and 1:6. Cr (VI) solution was started at a concentration of 100 mg/L, and the adsorption process was stirred at a rate of 300 rpm. In the adsorption process, a ratio of 1:6 is best, along with the best activator, which is HNO3, solution pH 4, contact time of 120 minutes, and initial solution concentration of 20 mg/L. OH is the major functional group in all adsorbents.

Investigation of the solid oxidizer effect on the metal geotechnology efficiency

Purpose. The research is aimed at increasing the useful component content in a pregnant solution during in-situ leaching (ISL) using a solid oxidizer and increasing the ferric iron concentration in the leaching solution based on laboratory research. Methods. Laboratory research is performed on a specially developed model electrolyzer for obtaining comparative data on divalent iron oxidation to trivalent iron and the change in the useful component content in a pregnant solution. Firstly, tests are conducted with a basic leaching solution, then on the oxidation of the leaching solution with a solid oxidizer in the form of a lead dioxide plate. Tests are conducted by changing sulphuric acid concentration within 5-50 g/l, amount of divalent iron ions in the solution from 0.5 up to 4.0 g, lead dioxide plate surface area from 19 to 76 cm2. The leaching time is up to 10 hours. Findings. The results of laboratory research on determining the oxidation degree of divalent iron ions and change in the oxidation-reduction potential (ORP) depending on the sulphuric acid concentration and on the initial concentration of divalent iron ions in the initial solution are presented. With a change in the sulphuric acid concentration from 5 to 50 g/l, the oxidation value of divalent iron ions increases from 26.5 to 96.5%, and with an increase in the initial solution concentration of divalent iron, the oxidation degree of divalent iron naturally decreases from 95.2 to 58.8%. In the initial leaching solution, the divalent solution concentration is 312 mg/l, and that of the trivalent solution is 288 mg/l. After oxidation with a solid oxidizer, the divalent and trivalent iron concentrations are 56 and 392 mg/l, respectively. In the course of further laboratory research using core materials from a uranium deposit, it has been revealed that when leaching with a basic solution, the uranium content in the pregnant solution is 19.36 mg/l, and when leaching with a solution after oxidation with a solid oxidizer, it is 27.9 mg/l, which is by 8.54 mg/l more. Originality. New dependences have been determined of the oxidation degree of divalent iron ions to trivalent one on the sulphuric acid concentration and on the initial concentration of divalent iron ions, as well as the useful component content in the pregnant solution on the leaching time when using a solid oxidizer. Practical implications. Using of a solid oxidizer, it is possible to increase the trivalent iron concentration in the leaching solution and the useful component content in the pregnant solution compared with the basic technology, thereby reducing the time of mining uranium reserves. Proposed technology is environmentally friendly, with low capital costs.

Synthesis of chitosan based new material for recovery of Pt (IV)

In this study a new type of adsorbent bead precursor was reached using chitosan and pretreated clay. The pretreated clay was produced from the clay of the "Tsogt-Ovoo" deposit in the Umnugovi province of Mongolia. It was produced by acid and heat treatment to remove its mechanical impurities. The mixtures of chitosan and pretreated clay were taken with various ratios (8:1, 8:2, and 8:3) for chemical processing to obtain a chitosan-based adsorbent bead for recovery of (Pt(IV)) from aqueous solution. It was examined that the adsorption capacity of the adsorbent bead when the chitosan and pretreated clay mass ratio 8:2 was the highest for platinum ion (Pt (IV)). The adsorption properties of Pt (IV) were studied depending on the solution pH, contacting time, temperature, initial concentration of platinum ion solution, and amount of adsorbent material. The adsorption efficiency was the highest (93.29%) when the initial concentration of the platinum ion was 50 mg/l at the following condition; pH=3, temperature 250C, time 3 hours, and the amount of the adsorbent material 0.1 g. It represents that the chitosan clay bead can be applied for the recovery of platinum (Pt (IV)) from aqueous solution.

Regulating microstructure and improving precipitation hardening response of fine-grained Mg-RE-Ag hot-extruded alloy by extreme short-time heat treatment

The difficulty in exerting beneficial effects of fine grains, high number density nano-precipitates as well as weakened texture simultaneously is currently the bottleneck limiting the development of high performance (high strength, high plasticity, and isotropic) age-hardenable Mg-RE alloys. The key difficulty is that the generation of excessive dynamic precipitates is always accompanied by the formation of fully dynamic recrystallized ultrafine grains during thermal deformation, causing a significant depletion of solutes within the entire matrix and finally seriously weakening the subsequent aging nano-precipitation. In this work, the process of extreme short-time (2 min) heat treatment (ESHT) followed by peak aging treatment is applied to an ultrafine-grained weak-textured Mg-RE-Ag as-extruded alloy with numerous dynamic precipitates. The precipitation hardening response is dramatically increased (ΔHV = 37.2 HV) and the yield strength is increased by nearly 50 MPa. This is attributed to the fact that concentration of main solutes in matrix is greatly increased within only 2 min of heat treatment promoting the precipitation of nano-precipitates (prismatic β′ and basal γ′′) in the absence of excessive grain growth. The large difference between the initial and equilibrium solute concentrations, the extremely short distance required for solute diffusion within sub-microscale grains, and the effective pinning of grain boundaries by excess dynamic precipitates are responsible for the unusual microevolution during the ESHT. In addition, the formation of precipitation-free zones (PFZs) is attributed to ‘uphill’ diffusion during aging, and novel γ′′-PFZs and β′-PRZs are found. The ESHT followed by peak aging treatment provides a new way to simultaneously exert the beneficial effects of fine grains and high number density nano-precipitates.

An Analysis of the Factors Influencing Cadmium Removal in Aquatic Environments by Chlorella vulgaris-Derived Solids

Chlorella vulgaris is an inexpensive microalga that could be employed for environmental remediation, but further investigations are needed to assess its suitability and optimal treatment methodology. With this aim in mind, this study focused on the raw biomass and the biochar and hydrochar obtained from it, analyzing their physicochemical properties and testing them to capture cadmium from an aqueous environment. The adsorption/absorption tests assessed the effect of adsorbent dosage, pH, Cd concentration, and contact time, and the results were analyzed through a structural equation model. Biochar and hydrochar performed similarly and better than the raw biomass, with the highest Cd removal observed at an adsorbent dosage of 0.8 g L−1, an initial concentration of Cd solution of 30 mg L−1, a pH of 6, and a contact time of 30 min. The adsorption isotherm data for Cd could be well-described by the Langmuir and Temkin models. The results from the structural equation modeling revealed that the variables material type, dosage, and concentration all contributed to Cd removal in water, with time mediating these effects.

Experimental Investigation of Lanthanum-Modified Reinforced Composite Material for Phosphorus Removal

Adsorption stands as an economically viable, efficient, recyclable, operationally straightforward, cost-effective, and low-sludge method extensively employed for phosphorus removal. In an effort to enhance the adsorption capabilities of the adsorbent, this study employs the rare-earth metal lanthanum in conjunction with the group’s previously researched high-efficiency composite industrial residue phosphorus removal materials (EPRC) for modification, thereby generating lanthanum-modified reinforced composite phosphorus removal materials (La-EPRC). Subsequently, the novel material undergoes static modification, followed by experimental investigations into static and dynamic adsorption for phosphorus removal. Static adsorption experiments reveal optimal phosphorus removal efficiency when the initial phosphorus solution concentration is 20 mgP/L, with a La-EPRC particle dosage of 3 g/250 mL and a temperature of 25 °C. The removal efficiency of phosphorus particles is above 90% within the pH range of 4 to 10. Common coexisting anions in water, including Cl−, SO42−, HCO3−, and CO32−, demonstrate minimal impact on the efficacy of phosphorus removal. La-EPRC demonstrates a robust adsorption stability in both water and hot water environments. In a 2.5 mol/L NaOH solution, effective desorption of La-EPRC particles is observed, facilitating material regeneration. The raw materials for La-EPRC are easily accessible and cost-effective, imparting significant potential for widespread applications.

Naringin processing using GAS antisolvent technique and in vivo applications

Naringin is a flavanone glycoside with various pharmacological activities, including neuroprotective and antipsychotic-like effects. However, it has poor solubility in water and oral bioavailability. This study aims to investigate the influence of gas antisolvent operational parameters (pressure, temperature, antisolvent flow rate, and initial concentration of solute) on particle diameter using a 24 Central Composite Design. Naringin particles produced were analyzed for dissolution rate and then applied to ketamine-induced hyperlocomotion in mice. Results for run with C= 5 mg∙mL−1, P = 12 MPa, T = 308 K, CO2 flow rate= 15 mL.min−1 showed amorphous particles while run with C= 10 mg.mL−1, P = 8 MPa, T = 318 K, CO2 flow rate= 15 mL.min−1 kept the crystalline structure of naringin. In vivo assays showed promising results for run with crystalline particles, probably due to the increased bioavailability, and amorphous particles had similar effects to commercial naringin because of the recrystallization when in contact with the aqueous medium.

Zirconium based metal-organic framework as highly efficient and acid-stable adsorbent for the rapid removal of Sr2+ and Cs+ from solution

Herein we present acid stable [Zr6(µ3-O)4(µ3-OH)4(OBA)4(OH)3(H2O)3(Me2NH2)]n (OBA = 4,4-oxy bis(benzoic acid)) (Zr(OBA) MOF) with the presence of cationic dimethyl ammonium groups were charge balanced with anionic Zr(OBA)nn– that is effective for removing Sr2+ and Cs+. This MOF shows distribution coefficients and record-high absorption capacities (Qm) of 353 mg/g for Sr2+ and 432.91 mg/g for Cs+ at pH 4, 112.75 mg/g for Sr2+ and 141.24 mg/g for Cs+ under 4 M HNO3 circumstances, and 221.5 mg/g for Sr2+ and 253.77 mg/g for Cs+ from simulated seawater. It was demonstrated that a significant excess of complex cations had no substantial influence on the removal of Sr2+ and Cs+ from simulated seawater and nuclear waste, which have been included with Sr2+ and Cs+. The Langmuir isotherm was well suited for Sr2+ and Cs+ adsorption onto MOF, confirming the existence of monolayer adsorption. This finding was made possible by investigating the Langmuir, Freundlich, and Temkin adsorption isotherms. The results of the experiments agree very well with pseudo-second-order kinetic studies, which leads one to believe that chemisorption is the primary mechanism. The measurement of zeta potential has indicated an electrostatic connection between the negatively charged surface of the MOF and positively charged Sr2+/Cs+ at various pH values. This interaction demonstrates that the adsorption capacity is relatively high. SEM-EDS elemental mapping, IR, and XPS analysis confirm the presence of Sr2+ and Cs+ on MOF - of Zr(OBA)@Sr and Zr(OBA)@Cs MOF after adsorption studies. Sr2+/Cs+ exchanged MOF were improved in order to get a clear image of the ion exchange process, and the binding energies of −87.31 for Zr(OBA)@Sr and −113.75 kJ/mol for Zr(OBA)@Cs, respectively. The dose, initial concentration of metal ions, pH solution, contact time, and other ions of Na+, K+, Ca2+, and Mg2+ that were already present affected the adsorption of Sr2+ and Cs+. Recycle studies of Zr(OBA) MOF show 80 % recovery of Sr2+ and Cs+ even after eight cycles.

Исследование эффективности очистки воды от ионов аммония прокалённым сорбентом из золошлаковых отходов

Experimental studies of sorption on water treatment from ammonium ions by a calcined sorbent based on ash-and-slag waste from thermal power engineering have been carried out. The calcined sorbent was obtained by calcining samples of ash-and-slag from coal combustion at the Novocherkassk State District Power Plant at a temperature of 600 оC for 30 min. The sorption capacity of a sorbent with a dose of 2.0 g per 50 mL of a model solution, a stirrer speed of 200 rpm, pH 7, and sorption time from 10 to 180 minutes was studied. The influence of the initial concentration of model solutions with the content of ammonium ions 5, 20, 50 and 100 mg/L on the amount of adsorption and treatment efficiency was studied. The highest treatment efficiency of 60% was obtained for an initial concentration of ammonium ions in a solution of 20 mg/L. Processing of experimental data was carried out according to the models of pseudo-first, pseudo-second-order and intra-particle diffusion kinetics. The best description of the experimental data was obtained using the pseudo-first order model, which has the highest value of the coefficient of determination. The adsorption equilibrium in the system ammonium ions – calcined sorbent was studied for the initial concentration of ammonium ions in solution: 5, 20, 30, 50, 100, 200, 300 mg/L. Processing of experimental data on equilibrium was carried out on the basis of two-parameter adsorption isotherms: Langmuir, Freindlich and Temkin. The value of the coefficient of determination according to the Langmuir isotherm is the largest R2 = 0.9904. Dependences between the cleaning efficiency at adsorption equilibrium and the initial concentration of ammonium ions in solution for the system ammonium ions – calcined sorbent are obtained. With an increase in the initial concentration of ammonium ions in the solution, the treatment efficiency at low initial concentrations increases, and decreases with increasing concentration.

A novel hierarchical 0D/3D NH2-MIL-101(Fe)/ZnIn2S4 S-scheme heterojunction photocatalyst for efficient Cr(VI) reduction and photo-Fenton-like removal of 2-nitrophenol

In this work, we designed a new hierarchical 0D/3D NH2-MIL-101(Fe)/ZnIn2S4 (NM-101(Fe)/ZIS) S-scheme heterojunction photocatalyst using a simple oil bath technique, in which nanometer-sized NM-101(Fe) are extensively scattered on the surface of ZIS microspheres. In contrast to an acidic environment, the optimal 10% NM-101(Fe)/ZIS can remove 94% of Cr(VI) in 60 min under neutral circumstances, the apparent rate constant is 24.6 and 3.26 times that of NM-101(Fe) and ZIS, respectively. This is due to the hierarchical 0D/3D heterostructure and the unique S-scheme photogenerated carrier transfer path, which successfully encourage the separation of photogenerated carriers while simultaneously enhancing redox ability. Specially, an efficient photo-Fenton-like system was developed using Fe3+ in NM-101(Fe) in conjunction with external H2O2 for entirely eliminating the refractory 2-nitrophenol pollutant in 120 min. It has an apparent rate constant that is 5.63 and 3.99 times that of pure NM-101(Fe) and ZIS. In order to better meet the demands of practical wastewater treatment, the impact of various photocatalyst doses, initial solution concentrations, coexisting ions and pH values on its photocatalytic activity were investigated. Finally, this work provides an idea to construct unique 0D/3D S-scheme heterostructure and effective photo-Fenton-like system for photocatalytic water purification.

Experimental investigation of ice slurry viscosity

This work attempted to conduct an experimental study which demonstrates the effect of the initial concentration of solute on the apparent viscosity of ice slurry in a horizontal circular pipe. The study was conducted on ice slurry based on propylene glycol, varying from 5 to 24% with different ice mass fractions varying from 5 to 25%. During the experiments, the initial concentration of the propylene glycol, ice concentration, and flow rate was modified as parameters. The flow tests were performed on laminar flows. The results of the investigation revealed that the ice slurry behaved like a non-Newtonian fluid, while it sometimes behaved like a Newtonian fluid. The rheological behavior of the ice slurry is reflected by its viscosity. For the shear-thickening behavior, the apparent viscosity increases with increasing the shear rate, and for the shear-thinning behavior, the viscosity decreases with increasing the shear rate, while for the Newtonian behavior, the viscosity remains almost constant. Then it was revealed that the viscosity of the mixture became too high for low shear rates at high ice mass fractions by increasing the concentration of the solute. The power law was used to establish a relationship between the apparent viscosity and the indexes of flow and consistency of ice slurry.

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.

The Development and Synthesis of a CdZnS @Metal–Organic Framework ZIF-8 for the Highly Efficient Photocatalytic Degradation of Organic Dyes

The development of photocatalysts for organic degradation is a hot research topic. In this study, CdZnS was selected as the carrier, and ZIF-8 was combined with it to explore the photocatalytic performance of the composite. In addition, the compound material, CdZnS@ZIF-8, was used as a photocatalyst for the decomposition of methylene blue dye, and the performance of pure CdZnS and pure ZIF-8 was compared. The photocatalytic efficiency of CdZnS@ZIF-8 was significantly higher than that of the other two. In the experimental reaction, the amount of catalyst was 0.04 g, the pH value was 7, the initial concentration of methylene blue aqueous solution was 20 mg/L, and the degradation of methylene blue in 50 mL aqueous solution could reach 99.5% under visible light irradiation for 90 min, showing excellent photocatalytic efficiency in the visible light range. It demonstrated excellent photocatalytic function in the visible light region, and the electron transfer phenomenon at the interface occurred in the het-junction and the separation of the photo-generating electron–hole as an electron acceptor of ZIF-8 further promoted the photocatalytic effect.

Adsorption of Antibiotic Drug on the Surface of Humic Acid Modified Magnetite Nanoparticles: Kinetics, Isotherm and Thermodynamic Studies

The present study reports the synthesis of humic acid-modified magnetite nanoparticles for adsorption behaviour towards the ofloxacin drug. Several analytical and spectroscopic techniques were used to characterize the synthesized surface modified magnetite nanoparticles. In order to determine the highest possible adsorption capacity of these coated nanoparticles, the effects of various influencing variables such as pH of the solution, contact time, initial concentration of adsorbate solution, amount of adsorbent and temperature were also investigated using batch adsorption method. Adsorption isotherm and kinetic analysis for the adsorption of ofloxacin drug from aqueous solution were studied simultaneously. The kinetics and isotherm studies demonstrated good agreement with the pseudo-second-order kinetics model and Langmuir model of isotherm, respectively. Thermodynamic analysis of the adsorption of ofloxacin on the surface of humic acid modified magnetite nanoparticles displayed negative values of Gibb’s free energy change, positive values of enthalpy as well as entropy change, resulting that the adsorption process was spontaneous and endothermic in nature. A comparative study of percentage drug removal efficiency of humic acid functionalized magnetite nanoparticles with the reported adsorbents has also been reported. This study revealed that the humic acid-modified magnetite nanoparticles showed remarkable adsorption capacity and thus could be used as an effective adsorbent for the removal of ofloxacin from aqueous solution.

Adsorption of Diclofenac from Aqueous Solution by Amine-Functionalized Poly (Acrylonitrile-Co-Acrylic Acid) Microparticles Adsorbent

In this study, the synthesis of poly(acrylonitrile) (PAN) and poly(acrylonitrile-co-acrylic acid) (poly(ACN-co-AAc)) was carried out via redox polymerization, using sodium bisulphate (SBS) and potassium persulphate (KPS) as initiators. Subsequently, the resulting poly(ACN-co-AAc) was functionalized with ethanolamine (ETA) and ethylenediamine (EDA) to utilize as adsorbents for the removal of diclofenac from an aqueous solution. Both unfunctionalized and functionalized poly(ACN-co-AAc) were characterized using Fourier-Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscope (SEM), Thermogravimetric Analysis (TGA), and Brunauer-Emmett-Teller (BET) analysis. The effects of pH, initial concentration of diclofenac solution, contact time, and adsorbent dosage were investigated during the adsorption process. The isotherm data were best fitted by the Langmuir model, indicating a mono-layered adsorption mechanism. The maximum adsorption capacities obtained from the Langmuir equation were higher for ETA-functionalized poly(ACN-co-AAc) at 120.5 mg/g, as compared to EDA-functionalized poly(ACN-co-AAc) at 80.6 mg/g. The experimental kinetic results showed that the pseudo-second-order model was a good fit for describing the adsorption rate of diclofenac for both ETA-functionalized poly(ACN-co-AAc) and EDA-functionalized poly(ACN-co-AAc), with R2 values of 0.9930 and 0.9906, respectively. This suggests that the chemisorption process is more favourable for the adsorption of diclofenac when using both types of adsorbents.