Adsorption Isotherm Equation Research Articles

Recovery of Low-Concentration Tungsten from Acidic Solution Using D318 Macroporous Resin.

Tungsten is a crucial strategic metal that plays a significant role in various fields, such as the defense industry, fine chemicals, and the preparation of new materials. During the practice of numerous tungsten smelting processes, a large amount of acidic wastewater containing low concentrations of WO3 is generated. The adsorption method, known for its simplicity, effectiveness, and ease of operation, represents the most promising approach for tungsten recovery and is vital for the sustainable development of the tungsten industry. In this study, D318 macroporous resin was used as an adsorbent to investigate its effectiveness in adsorbing WO3 from acidic solutions. Static adsorption experiments revealed that the adsorption capacity of D318 resin for WO3 was 683 mg·g-1. Kinetic analysis indicated that the controlling step for the adsorption of WO3 from acidic solutions by D318 resin was intraparticle diffusion. Thermodynamic analysis demonstrated that the adsorption process was endothermic and could occur spontaneously. By fitting the isothermal adsorption equation, it was found that the Langmuir model was more suitable for describing the adsorption process of WO3 on D318 resin in acidic solutions. The results of dynamic adsorption experiments showed that under optimized conditions, the dynamic adsorption capacity for WO3 was 529 mg·g-1; when using NaOH as the desorbent for cyclic desorption, the desorption rate for WO3 was 98.21%. XPS and SEM-EDS testing and analysis confirmed that D318 macroporous resin exhibited excellent adsorption performance for tungsten in acidic solutions.

Mass Transfer Kinetics of Volatile Organic Compound Desorption from a Novel Adsorbent

The adsorption isotherms and intraparticle mass transfer coefficients of a novel adsorbent with various VOCs at different temperatures during the desorption process are investigated. Firstly, the adsorption isotherms of an HCP-5 adsorbent with o-xylene and ethyl acetate systems were determined at temperatures ranging from 30 to 160 °C, and the data were fitted using the Langmuir adsorption isotherm equation. Subsequently, a mathematical model for the fixed-bed desorption breakthrough of VOCs was established. By combining with fixed-bed desorption breakthrough experiments, the intraparticle mass transfer coefficients of o-xylene and ethyl acetate during the desorption process at different temperatures were obtained through the least squares method. This study revealed that the intraparticle mass transfer coefficients of o-xylene and ethyl acetate during the desorption process were basically equal. The intraparticle mass transfer coefficients increased and then decreased with temperature during the desorption process. Compared with the adsorption process, the contribution of surface diffusion inside the adsorbent pores to intraparticle mass transfer decreased during the desorption process, leading to a significant decrease in the intraparticle mass transfer coefficients, which were approximately one-twentieth of those during the adsorption process.

Controllable Synthesis of Magnetic Composite Derived from MIL-88D and Study on Adsorption Properties of Cu2+

In this paper, MIL-88D (Fe) with spindle shape was prepared by the hydrothermal synthesis method, a metal oxide with a new structure was obtained by calcination at different temperatures as a precursor, and a magnetic iron oxide composite was prepared successfully. At the same time, it was used as an adsorption material for the adsorption of heavy metal ions Cu2+. The influence of the initial pH value and adsorption time on the adsorption effect was investigated, the adsorption kinetics and adsorption isotherm were further fitted, and the adsorption mechanism was preliminarily analyzed. The results show that the magnetic iron oxide composites have a good adsorption capacity for Cu2+. The pH value is an important parameter that affects the adsorption effect. The adsorption of Cu2+ by magnetic iron oxide composites reached adsorption equilibrium in 30 min. The adsorption of Cu2+ by magnetic iron oxide composites conforms to the second-order reaction kinetics and Langmuir adsorption isotherm equation, which indicates that the adsorption process mainly occurs through chemisorption and typical single-molecular-layer adsorption.

Development of a limestone-based ballasted material for enhanced co-removal of turbidity and fluoride from coal mine water: An efficacy study

The rapid progression of coal mining technology in recent years has resulted to the discharge of mine water with excessively high levels of turbidity and fluoride, presenting a complex contamination issue. This study develop an innovative limestone-based ballasted material, integrating it with ballasted flocculation technology. The synergistic effects of surface flocculation and adsorption have enabled the simultaneous and efficient removal of high concentrations of turbidity and fluoride. The influence of various parameters, including the dosage of the coagulant, flocculant, ballasted material, and the stability under long-term continuous operation, on the performance of this new technology was investigated. Findings indicate that an increase in the dosage of the coagulant, polyaluminum chloride (PAC), positively affects the removal of turbidity and fluoride ions, with an optimal dosage of 60 mg/L. The addition of polyacrylamide (PAM) showed that both conventional and ballasted coagulation techniques exhibit an initial increase followed by a decrease in turbidity removal efficiency, and an ascending trend in fluoride removal efficiency, with an optimal PAM dosage of 1.0 mg/L. The dosage of the new ballasted material was determined based on the initial water turbidity and fluoride concentrations, an increase in its dosage led to a progressive reduction in effluent turbidity and a corresponding increase in fluoride removal. A 30-day continuous operation confirmed the stability of the new process, with a treatment cost of approximately 2.67 $/t. The pseudo-first-order kinetic model and the Langmuir adsorption isotherm equation provided satisfactory fits to the treatment data, suggesting that both conventional and ballasted coagulation involve a combination of surface adsorption and intraparticle diffusion mechanisms for the removal of turbidity and fluoride.

Excellent inhibition performance of an imidazole based ionic liquid on steel-N80 in 15 % hydrochloric acid medium

Imidazoline phenyl thiourea iodized n-butane quaternary ammonium salt (IMSQ) is synthesized from oleic acid, diethylenetriamine, iodinated n-butane, and n-phenylthiourea. The corrosion inhibition performance is studied by electrochemical test. The experimental findings underscored a pronounced positive correlation between the concentration of IMSQ and its corrosion inhibition efficacy on N80 steel. Notably, at a concentration of 0.07 mM, IMSQ attained a corrosion inhibition efficiency of 99.1 %, exhibiting exceptional protective capability for N80 steel in hydrochloric acid environments. By studying the adsorption isotherm equation, it is judged that the type of adsorption includes physical adsorption and chemical adsorption. The characterization analysis results indicate that IMSQ can adsorb on the surface of steel-N80, providing effective protection for the metal.

Evaluation of green corrosion inhibitors of chitosan oligosaccharide derivatives for CO2 corrosion inhibition on 20# carbon steel

Two chitosan oligosaccharide derivatives, VCOS and GCOS, were synthesized and explored as corrosion inhibitors, the synergistic inhibition effect of KI and VCOS was also studied. Their structures were elucidated using Fourier Transform Infrared Spectroscopy and Nuclear Magnetic Resonance. The inhibition efficacy of VCOS+KI and GCOS on 20# steel within an 80℃, 3 wt% NaCl, CO2-saturated solution system was investigated employing various techniques, including gravimetric measurement, electrochemical analysis, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and molecular dynamics simulations. The results reveal that the inhibition efficiency of VCOS is relatively low when it acts alone. When VCOS and KI are combined, they have a good synergistic effect, and the synergistic parameter is the highest at 6.209. In the weight loss experiment, the corrosion inhibition efficiency increased with the concentration of the corrosion inhibitor. The inhibition rates of VCOS+KI and GCOS were 90.5 % and 90.2 %, respectively. The adsorption on 20# steel conformed to the Langmuir isotherm adsorption equation. The measurement results of SEM, Energy Dispersive Spectroscopy, and AFM show that VCOS+KI and GCOS adsorbed on the surface of carbon steel to form a dense inhibitor film, which effectively protected the metal substrate. According to the polarization test results, both VCOS+KI and GCOS are mixed-type inhibitors primarily exhibiting anodic inhibition, with inhibition efficiencies reaching 98.9 % and 95.1 %, respectively. Electrochemical impedance spectroscopy tests showed that with increasing inhibitor concentration and immersion time, Rct increased and Cdl decreased, resulting in a gradual increase in inhibition efficiency and the formation of a dense and stable inhibitor film. The results indicate that VCOS+KI and GCOS are non-toxic, water-soluble, and environmentally friendly inhibitors with good anti-corrosion performance.

Influence of corn stalk and corn stalk biochar application on the strategy of phosphorus sorption and release in brown earth

AbstractThe characteristics of soil phosphorus (P) fixation and release have a critical impact on the availability of P and the risk of environmental loss. Investigation of the effects of corn stalk and corn stalk biochar on the P adsorption–desorption characteristics of brown earth can provide a theoretical basis for the rational return of crop stalk to the field and improving the availability of soil P. The Langmuir adsorption isotherm equation provided a better fit than the Freundlich equation for the curve of soil P adsorption and equilibrium solution P concentration. Biochar application increased the maximum adsorption capacity (MAC) and maximum buffer capacity (MBC) of the soil for P by 8.5% and 17.2%, respectively. Corn stalk and its biochar reduced the P adsorption saturation (DPS) by 41.8% and 31.9%, respectively, but increased the amount of readily desorbable P (RDP) by 39.7% and 154.4%, respectively. The application of corn stalk and its biochar improved the soil P desorption rate at substrate P concentrations of less than 5 mg L−1, whereas significant reductions in the soil P desorption rate were observed between 5 mg L−1 and 30 mg L−1, and no significant effects were observed at P concentrations over 40 mg L−1. In addition, the total P and Olsen‐P contents of the soil were significantly associated with the P adsorption–desorption process (p < .05). Therefore, corn stalk and corn stalk biochar can enhance the capacity of soil for P adsorption, with a stronger effect observed for biochar than for corn stalk, and the rate of P desorption from treated soil is dependent on P concentration in the soil solution.

Exploring the circular prospects of cashew nutshells and avocado seeds as potential adsorbents for onboard natural gas storage

Natural gas (NG), known for its eco-friendly energy attributes, faces challenges such as low volumetric density, leakage susceptibility, and explosion risks during storage and transport. To narrow this gap, this study reports on the potential of bio-based adsorbents from cashew nut shells (CNS) and avocado seeds (AVS) as an alternative approach for the onboard storage of NG. CNS and AVS were characterized to determine moisture content, volatile matter content, ash content, and fixed carbon content. Additionally, the study determined the optimal loading of activating agents to produce activated carbons (ACs). ACs were produced through a dual process involving simultaneous chemical activation and carbonization. In the chemical activation phase, a sample of either cashew nut shells (CNS) or avocado seeds (AVS) was impregnated with phosphoric acid at various ratios. Subsequently, the properties of the ACs, including surface area, pore volume, and X-ray diffraction (XRD), were evaluated. The NG adsorption capacity of the ACs was assessed, and Freundlich and Langmuir isotherm adsorption equations were derived to elucidate the NG adsorption behavior on the ACs. The results revealed that the proximate analysis of CNS and AVS showed low moisture content (6.48% and 8.91%), high volatile matter (80.21% and 73.09%), low ash content (1.48% and 4.71%), and high fixed carbon (13.65% and 15.59%), indicating suitability for AC formulations. During synthesis, adding phosphoric acid to AVS or CNS in a 1:1 ratio resulted in significantly larger surface areas and pore volumes in the produced ACs. X-ray diffraction analysis of the ACs produced from CNS or AVS with phosphoric acid added at a 1:1 ratio indicated a broad diffraction background and a predominantly amorphous structure. The performance of the ACs in the adsorption of NG demonstrated that ACs produced from 1:1 mixtures of CNS with phosphoric acid and AVS with phosphoric acid exhibited higher adsorption capacities, 0.038 g/g and 0.031 g/g, respectively, at a low pressure of 5 bar, showcasing a novelty of this study. Furthermore, the Freundlich equation test yielded a constant R² exceeding 0.9, with positive adsorption intensity and adsorption capacity values, indicating a favorable fit for the model. In contrast, the Langmuir equation test resulted in a constant R² exceeding 0.9, but the adsorption capacity exhibited negative values, leading to inconclusive explanations. These findings affirm that bio-wastes can be an effective source of adsorbents for onboard natural gas storage , suggesting a means to reduce the take-dispose model and promote a circular economy in the energy sector.

An in vitro study of metformin adsorption to activated charcoal

Introduction Metformin is a biguanide used to manage patients with type 2 diabetes mellitus. However, metabolic acidosis with an elevated lactate concentration and death caused by metformin overdoses are toxicological concerns. Although activated charcoal has been widely used for gastrointestinal decontamination in cases of acute poisoning, there is no evidence regarding its efficacy in treating metformin overdoses. We therefore evaluated the adsorptive capacity of activated charcoal for metformin in vitro. Methods Activated charcoal (specific surface area: 1,080 m2/g) mixed with various concentrations of metformin solution was dissolved in simulated gastric and intestinal fluids at 37° Celsius. The suspension was then filtered and the metformin concentration in the filtrate was determined using high-performance liquid chromatography. The maximum adsorptive capacity for metformin was calculated using the Langmuir adsorption isotherm equation. Results The amount of metformin adsorbed per gram of activated charcoal ranged from 0.7 to 8.1 mg/g at pH 1.2, and from 8.4 to 48.2 mg/g at pH 6.8. The corresponding maximum adsorptive capacities were 10.6 mg/g and 55.9 mg/g respectively. Discussion The maximum adsorptive capacity of activated charcoal for metformin was similar to that of its capacity for other poorly adsorbed substances. This is likely because metformin is water-soluble and has high polarity—factors that correlate with poor adsorption on activated charcoal. Conclusions The maximum adsorption of metformin by activated charcoal was low. Therefore, activated charcoal may not be effective for treating patients with metformin overdose.

A Method for Evaluating Coalbed Methane Reservoir Productivity Considering Drilling Fluid Damage

In the process of coalbed methane development, drilling fluid and fracturing fluid cannot achieve absolute compatibility with formation. The incompatibility between the working fluid and reservoir will lead to the intrusion of working fluid into the reservoir and cause reservoir pollution. This is a very common phenomenon. There is a large amount of pulverized coal in the coal seam, and the intrusion of working liquid will be combined with the pulverized coal to form cement to block the seepage space in the reservoir. Since pressure relief and fracturing fluid backflow will be performed at the first time after fracturing, the intrusion range of the working fluid is small, generally reaching 10 m to 50 m. Compared with a conventional gas reservoir or shale gas reservoir, the working fluid loss during CBM development will seriously affect the subsequent production project and even make the gas well lose production capacity. On the other hand, in order to avoid this phenomenon, measures such as acidification or volumetric fracturing are sometimes used to improve the seepage environment near the well and near the fracture. The purpose of this study is to quantitatively evaluate the impacts of working fluid filtration and reservoir reconstruction on production. In this study, a single well productivity evaluation model and sensitivity analysis method considering drilling fluid filtration loss, fracturing fluid filtration loss, reservoir reconstruction and other processes is proposed. The formation mechanism of fluid loss during drilling and fracturing is described, and the productivity evaluation model considering fluid loss is combined with the Langmuir isothermal adsorption equation, steady-state diffusion law, Darcy’s seepage law and Duhamel convolution formation. Combined with the distribution of actual gas reservoir flow characteristics, the sensitivity of single well productivity to gas reservoir porosity, gas reservoir permeability, coal seam adsorption coefficient, working fluid filtration loss and reservoir reconstruction measures are analyzed. Through the analysis and fitting of the actual production data on site, the relationship curve can better fit the field production data, and the evaluation results are in line with the drilling and fracturing conditions at that time and the subsequent production conditions, with small errors. The obtained method is suitable for predicting the productivity of fractured vertical wells in different working conditions and provides a basis for the development and productivity prediction of CBM reservoirs in China and in international cooperation.

Study of The Inhibition Corrosion of Aluminum Metal Using Peppermint Oil in An Acidic Medium

This study included the study of the efficiency of peppermint oil inhibition of aluminum corrosion in acidic medium HCl at concentrations (0.5, 1, 1.5, 2 M) on the corrosion rate in the presence and absence of the inhibitor peppermint oil at different concentrations (1000, 2000, 3000, 4000 ppm).In order to study the effect of changing the temperature (303, 313, 323, 333 K) on the corrosion rate in the absence and presence of the inhibitor, different concentrations of the inhibitor were chosen in addition to the acid concentration (1M). The experiments were carried out using the weight loss method to calculate the erosion rate. The expected heat of adsorption enthalpy was (-29.913 KJ/mol), with a negative sign indicates that the process is exothermic. The value of the free energy of adsorption ranged from (11.086-15.067 KJ/mol. (The results showed that Freundlich adsorption isotherm equation is the best fit to examine the adsorption process, also a scanning electron microscope. Showed the surface of aluminum before and after corrosion according to the results of the study, it was found that the used inhibitor reduces corrosion in acidic media. Its anti-corrosion efficacy also improves with increasing inhibitor concentration and with decreasing temperature.

Development of a Multicomponent Adsorption Isotherm Equation and Its Validation by Modeling.

Researchers have made significant efforts over the past few decades to understand adsorption by developing various simple adsorption isotherm models. However, though many contaminants usually occur as multicomponent mixtures in nature, multicomponent adsorption isotherms have received limited attention and remain an area of inadequate research. We have presented here in a new multicomponent adsorption isotherm model, named the Jeppu Amrutha Manipal Multicomponent (JAMM) isotherm, that can alleviate this problem. We first developed the JAMM multicomponent isotherm using our experimental data sets of arsenic and fluoride competitive adsorption on activated carbon. We then tested the JAMM multicomponent isotherm for a case study of cadmium and zinc competitive adsorption. Next, we further assessed the JAMM isotherm using another competitive adsorption case study of copper and chromium. Through extensive validation studies and error analysis, the JAMM isotherm was able to demonstrate its efficacy in predicting the adsorption behavior in several multicomponent adsorption systems accurately. The main advantage of JAMM isotherm over other multicomponent isotherms is that it utilizes and leverages the single-component adsorption parameters to simulate multicomponent isotherms. The proposed JAMM analytical isotherm model furthermore incorporates the interaction between the components, a mole fraction parameter, and a heterogeneity index, providing a more comprehensive modeling framework for multicomponent adsorption. The mole fraction term was introduced for the distribution of adsorption sites based on the relative number of molecules of each component. An additional term for interaction coefficient was introduced for the representation of interactions. During the validation of JAMM with three experimental case studies with negligible, small, and high competition systems of adsorbates, impressive predictions were exhibited, with the average normalized absolute percentage error as 6.05% and average R2 as 0.86, highlighting the model's robustness, versatility, and reliability. We propose that the new JAMM isotherm modeling framework might profoundly help in chemical engineering, environmental engineering, and materials science applications by providing a potent tool for analyzing and predicting multicomponent adsorption systems.

Physical origin of adsorption heat and its significance in the isotherm equation

Adsorption heat is a cornerstone concept underpinning almost all the existing theoretical isotherms for porous media. Yet, it remains elusive what this concept stands for and what are the physical sources for it. Here, a rigorous thermodynamic formulation is derived for the adsorption process with the aid of the law of mass action, leading to an expression of adsorption heat as the external chemical potential difference between two adjacent adsorbate layers. The interaction between adsorbent and adsorbates like van der Waals is theoretically identified as the intermolecular source for the change of adsorption heat. Thereby, adsorption heat is formulated as a spatially varied function of the distance to adsorbent surfaces. This adsorption heat function facilitates the establishment of a two-parameter sorption isotherm equation. The equation can be theoretically converted to two widely used adsorption isotherm equations, namely Brunauer–Emmet–Teller (BET) and Guggenheim-Anderson-de Boer (GAB) equations, and shows excellent performance in capturing experimental isotherm data of a wide array of materials. The comparative analysis demonstrates that the derived two-parameter isotherm equation outperforms the two-parameter BET equation and the three-parameter GAB equation in most cases. Such performance verifies the generality of the derived isotherm equation, thus further confirming the validity of the derived formulation of adsorption heat.

Influence of chemical activation on the ability of Transcarpathian clinoptilolite to adsorb direct dyes

Significant quantities of wastewater are generated in dyes synthesis processes and in technologies involving their use, which are toxic to living organisms, making the purification of industrial wastewater from organic colouring substances a pressing issue nowadays. The aim of this study was to investigate the prospects of using natural clinoptilolite from the Sokyrnytske deposit and its activated forms in the purification processes of wastewater from direct dyes. Natural clinoptilolite was activated by treatment with 5% H2SO4 and HCl aqueous solutions and heating at 300°C for two hours. The impact of activation conditions on the structural adsorption properties of clinoptilolite has been determined using a comprehensive thermal analysis method. The adsorption of the direct violet dye by natural and activated clinoptilolite has been investigated using spectrophotometric methods at pH 7 and a light wavelength of 550 nm, corresponding to the maximum value of light absorption coefficient. According to the results of thermal analysis, activated clinoptilolite samples exhibited a more developed specific surface area and a higher presence of hydroxyl groups, which can serve as active adsorption sites on the surface. The results of the violet dye adsorption have corresponded to the monomolecular Langmuir theory, indicating the energetic homogeneity of the adsorption centres. By linearizing the Langmuir adsorption isotherm equation, adsorption characteristics of natural and activated clinoptilolite with a 5% HCl aqueous solution relative to the direct violet dye have been determined. Activated clinoptilolite has shown increased sorption capacity (9.53 mmol/kg) compared to natural clinoptilolite (2.28 mmol/kg). The improvement in adsorption characteristics of activated clinoptilolite has been explained by its partial dealumination, resulting in the appearance of meso- and macropores capable of retaining dye molecules. The use of a 30% H2SO4 aqueous solution in activation processes and heating above 400°C has caused mineral degradation, confirmed by electron images of its surface. Practical value of the study lies in the recommendation to apply activated clinoptilolite in the purification processes of wastewater from organic pollutants

Effect of microwave pretreatment on lignocellulosic degradation of corn cob

Lignocellulosic biomass is a widespread and renewable alternative to fossil resources from which valuable products such as biofuels and chemicals can be obtained. The usual biotechnological way of lignocellulose processing involves pre-treatment of biomass and enzymatic hydrolysis of complex carbohydrates (cellulose and hemicellulose) to simple sugars. The aim of this study was to examine the effect of microwave pretreatment on lignocellulosic degradation of corn cob. Biomass will be treated in a microwave oven (Bosch Serie 2, Germany) using hydrogen peroxide, under different conditions (pH and treatment time). After treatment, the solid fraction was subjected to enzymatic hydrolysis using the commercial enzyme CellicCTec2 (Novozymes, Denmark). The effect of the treatment was determined by determining the surface area of cellulose and lignin (based on the equation of Langmuir adsorption isotherm for adsorption of Congo red and Azure B, respectively), and the crystallinity index (iodine adsorption method). Enzymatic hydrolysis of biomass was monitored using spectrophotometric methods to determine the concentration of reducing sugars (DNS method), total hexose sugars (Antron method) and total pentose sugars (Orcinol method). The results of the treated samples were compared with the untreated ones in order to determine the most efficient treatment conditions for the degradation of lignocellulosic biomass.

Optimizing ciprofloxacin removal using ion exchange resin: Exploring operational parameters and assessing toxicity

The present study investigates the adsorption behavior of ciprofloxacin hydrochloride (CIP) onto the cationic resin Amberlite IR120. Equilibrium and kinetic experiments were conducted to assess the influence of resin mass (0.02 to 0.19 g), agitation rate (200 to 500 rpm), pH (2 to 11), and temperature (15 to 45 °C) on the efficiency of CIP removal. Non-linear models, coupled with error functions such as coefficient of determination (r2) and the sum of squared residuals (SQR), were employed to assess the compatibility between kinetic models (pseudo-first order, pseudo-second order, Elovich) and isotherm adsorption equations (Langmuir and Freundlich). The IR120 resin underwent characterization through scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), laser granulometry, nitrogen adsorption–desorption isotherms (BET), and attenuated total reflection infrared spectroscopy (ATR-FTIR). Utilizing the Langmuir model, the maximum adsorption capacity of CIP was determined to be 37 mg g−1. Based on the r2 values obtained from the kinetic models, the pseudo-first order and pseudo-second order models exhibited the best fit for all experimental data. Optimal conditions for the adsorption occurred at pH 7, temperature of 15 °C, resin mass of 0.08 g, and agitation rate at 300 rpm. Remarkably, complete elimination of toxicity towards Escherichia coli organisms was achieved, evidenced by the absence of antibacterial effects after 60 min of operation. Consequently, the results suggest that IR120 holds promising potential as an adsorbent for CIP removal.

Effects of Different Cations on the Flocculation and Sedimentation of Static Fine-Grained Sediments

Natural water bodies mostly contain cations, and the type and content of these cations are the main factors affecting the flocculation of fine-grained cohesive sediments and the floc sedimentation rate at the interface between clear and turbid water. From the microscopic aspect, this study examined the changing patterns of porosity and the fractal dimension of the flocs of fine-grained cohesive sediments. Sedimentation experiments under different sediment contents and electrolyte conditions were conducted, and microscopic images of the flocs were analysed using Image-Pro Plus (IPP) and MATLAB based on the fractal theory. From the macroscopic aspect, this study experimentally investigated the flocculation and sedimentation of fine-grained cohesive sediments and proposed a sedimentation rate equation by introducing an ion concentration-related parameter into an existing sedimentation rate equation (stagnation zone) based on the adsorption isotherm equation. The equation proposed in this study was validated with measured data. The calculated values were in good agreement with the measured values, with a relative error of 16%. The findings of this study provide a reference for further research on the flocculation and sedimentation of fine-grained cohesive sediments in different water bodies.

Adsorption of Heavy Metal Cu(II) in Wastewater Using Adsorbents from Empty Oil Palm Bunches

Heavy metal pollution has increased with increasing industrialization. To overcome this contamination, carried out by using the adsorption method. The adsorbents used are activated carbon and porous polymer composite carbon Cu(TAC). in liquid waste, one of which is Cu metal. This is evidenced by the existence of data showing the efficiency of activated carbon and porous polymer composite carbon Cu(TAC) above 90%. In addition, activated carbon and porous polymer composite carbon Cu(TAC) have an adsorption isotherm equation that is suitable for Cu(II) adsorption is the Langmuir isotherm with linear regression values of 0.9045 and 0.8912

Efficient removal of organic pollution via photocatalytic degradation over a TiO2@HKUST-1 yolk-shell nanoreactor

Currently, the design and development of yolk-shell nanoreactors for photocatalytic organic pollution removal have received increasing attention because of their unique architecture. In this work, we developed a novel TiO2@HKUST-1 yolk-shell nanoreactor for the removal of tetracycline (TC) and rhodamine B (RhB) under visible light radiation with clearly increased photocatalytic activity and stability. The degradation efficiency of RhB and TC over the TiO2@HKUST-1 composite was significantly higher than that of pure TiO2 and HKUST-1. Within 60 min, the RhB and TC elimination rates reached 95.2% and 92.40%, respectively when exposed to visible light radiation. After the fifth cycle, the photocatalytic TC degradation efficiency by TiO2@HKUST-1 remained at 89.02%. In TiO2@HKUST-1, a yolk-shell nanoreactor structure with intimate interfacial contact significantly increased the carrier density, specified surface area, and separation effect of photogenerated electron-hole pairs, all of which were highly helpful for enhancing the photocatalytic performance. Additionally, by using electron spin resonance (ESR) spin-trap technology, density function theory (DFT) calculations, positive species trapping studies, and other methods, a potential photocatalytic degradation mechanism was proposed. It was discovered that h+ and •OH were the main active species. In view of its excellent gas properties, TiO2@HKUST-1 was used as an adsorbent for Rh B solution. The effect of mixing time and different initial mass concentration on the adsorption effect was investigated, and the adsorption isotherm and kinetic equation were fitted to the experimental results. This work's successful augmentation can effectively remove organic contaminants and has a wide range of potential environmental applications.

Investigation of the removal kinetics, thermodynamics and adsorption mechanism of anionic textile dye, Remazol Red RB, with powder pumice, a sustainable adsorbent from waste water.

Excessive growth and abnormal use of dyes and water in the textile industry cause serious environmental problems, especially with excessive pollution of water bodies. Adsorption is an attractive, feasible, low-cost, highly efficient and sustainable technique in terms of green chemistry for the removal of pollutants from water. This study aims to investigate the removal kinetics, thermodynamics and adsorption mechanism of Remazol Red RB, which was chosen as a representative anionic reactive dye, from synthetic wastewater using powdered pumice, taking into account various experimental parameters such as initial dye concentration, adsorption time, temperature and pH. Moreover, to support the proposed adsorption mechanism, before and after adsorption of the samples, the Fourier transform infrared spectrophotometer (FTIR) spectra, X-ray powder diffraction (XRD) diffractograms and High resolution transmission electron microscopy (HRTEM) images were also taken and used. The results show that powder pumice can be an efficient adsorbent for anionic dye removal with a relatively high adsorption capacity of 38.90mg/g, and it is very effective in 30-60min in mild conditions. The experimental data showed a high agreement with the pseudo-second-order kinetic model and the Freundlich adsorption isotherm equation. In addition, thermodynamically, the process exhibited exothermic nature and standard isosteric enthalpy and entropy changes of -4.93kJ/mol and 16.11J/mol. K were calculated. It was determined that the adsorption mechanism was predominantly based on T-shaped pi-pi interactions and had physical characteristics.