Sips Model Research Articles

Elucidation of ammonium and nitrate adsorption mechanisms by water hyacinth biochar: effects of pyrolysis temperature.

Numerous studies indicate biochar's nitrogen (N) adsorption capacity plays a crucial role in soil N retention. However, there is limited understanding on inorganic N adsorption mechanisms in biochar derived from aquatic weeds such as water hyacinth (WH). This study investigated ammonium-N (NH4+-N) and nitrate-N (NO3--N) adsorption capacities and mechanisms of WH biochar pyrolyzed at different pyrolysis temperatures of 400°C, 600°C, and 800°C (BC400, BC600, and BC800, respectively). Results showed NH4+-N adsorption was maximized (1.07-1.09mgg-1) with BC400 at initial solution pH 7.0-9.0, while NO3--N adsorption peaked (0.80mgg-1) with BC800 at initial solution pH 5.0. Both NH4+-N and NO3--N followed well the Pseudo-second-order model in adsorption kinetics (R2 = 0.990-0.997 and 0.962-0.992, respectively). The Sips model accurately described the adsorption isotherms for NH4+-N (R2 = 0.994-0.999) and NO3--N (R2 = 0.992-0.999). The calculated maximum adsorption capacity for NH4+-N and NO3--N using Sips model was 11.2-16.8mgg-1 and 0.693-4.99mgg-1, respectively. Co-existing cations and anions reduced NH4+-N and NO3--N adsorption capacity, respectively, with other ions with higher valence exhibiting higher inhibition effects (43%-97% and 44%-73%, respectively). Primary adsorption mechanism for NH4+-N included cation exchange via oxygen-containing surface functional groups in BC400 and pore filling and surface struvite precipitation in BC800. Major adsorption mechanisms for NO3--N included electrostatic interactions in BC400 and pore filling in BC800. These findings suggested that biochar derived from aquatic weeds possessed the same potential usefulness for soil N retention as biochar from other feedstocks, and that it might assist for further detailed considerations in other studies for biochar soil application.

Facile sponge-like chitosan capsules as efficient adsorbent for anionic Congo red, Reactive brilliant blue KNR, and Methyl blue dyes: Performance and mechanism

In this study, sponge-like chitosan capsules (CTS-S) were successfully prepared as efficient adsorbent through a facile and green method. The cross-linked porous structure and abundant adsorption sites of CTS-S led to stable and remarkable adsorption efficacy for the purification of wastewater containing anionic dyes in a wide pH range. The highest maximum adsorption capacity for Congo red (CR), Reactive brilliant blue KN-R (KNR), and Methyl blue (MB) were 1372.49, 881.75, and 169.04mg/g, respectively. Kinetics study suggested that KN-R and CR adsorption processes were best depicted by the PSO model, while PFO model was applicable for MB. Adsorption isotherms of CR, KNR, MB conformed to the Sips model, demonstrating that the adsorption of CR, KNR, MB onto CTS-S was monolayer and heterogeneous. Adsorption mechanism insights further verified that electrostatic forces, hydrogen bonds, and n-π stacking worked for efficient removal of CR, KNR, MB by CTS-S, which was supported by characterization results and DFT calculation. Overall, CTS-S provided a useful and promising option as low-cost and eco-friendly absorbents for the adsorption of synthetic dyes.

Modeling of the Adsorption of Tigecycline from Water on CoFe2O4-Graphene Nanocomposites.

A CoFe2O4(11.04%)-graphene (5.45%) nanocomposite was synthesized and characterized by spectroscopic techniques. This nanocomposite was used to eliminate tigecycline antibiotics from the water. The adsorbent showed 160.0 mg/g adsorption capacity of tigecycline antibiotic at 175 mg/L tigecycline, 0.75 g/L dose, 100 min of contact time, and a temperature of 25 °C. One-, two-, and three-parameter models were applied, i.e., Henry, Langmuir, Freundlich, D-R, Temkin, Flory-Huggins, Halsey, Jovanovich, Redlich-Peterson, and Sips models. According to statistical data, Langmuir and Sips models were the best fitted. The adsorption was spontaneous thermodynamically following pseudo-second-order kinetics. The adsorption occurred via a combination of intraparticle diffusion and external mass transfer mechanisms. The supramolecular mechanism showed the adsorption of the tigecycline antibiotic via coordination and π-π stacking bonds. The characterization results showed that the average nanoparticle size obtained was 91.45 nm. The removal efficiency of the adsorbent reduced up to the fifth cycle and later became constant at 50%. Hence, CoFe2O4-graphene nanocomposites propose a highly effective and recyclable solution for water treatment through adsorption, and hence, this method may be used to remove tigecycline antibiotics from water bodies.

Comparative adsorption of tetracycline by acid-modified silicomanganese fumes: kinetic and process modelling

ABSTRACT In this novel study, we treated silicomanganese fumes with HNO3 and HCl to produce high-performance adsorptive materials, namely SMF-HN and SMF-HC. These acid-modified materials were then subjected to morphology, crystallinity, thermal, and spectroscopic analysis. The prepared materials were then tested for their efficacy in removing tetracycline antibiotics from wastewater. Surface analysis, a key property in the adsorption process, revealed BET surface areas of 178.14, 154.1, and 7.73 m2/g for SMF-HC, SMF-HN, and SMF, respectively. The adsorption performance was further analysed with respect to various parameters such as pH, dosage, pollutant concentration, and contact time. The adsorption isotherms models in agreement with the Langmuir, Redlich-Peterson, and Sips models, with high R2 values for all the samples. The SMF-HN and SMF-HC show a comparable adsorption capacity at 111.17 and 93.32 mg/g, respectively. The kinetics models indicated that the reaction follows pseudo-second-order kinetics. This study suggests that the adsorption mechanism occurs via chemisorption methods. The regeneration studies demonstrated that SMF-HN and SMF-HC adsorbents maintained a high removal percentage of TC after undergoing five cycles of adsorption-desorption experiments. Specifically, both adsorbents maintained 100% removal of TC in the first three cycles and a slight drop in the fourth (~96%) and fifth cycles (~90%).

Sorption of the emerging pollutant oxytetracycline on eggshell. Experimental and theoretical approaches

The constant use of drugs for health treatments increases the presence of antibiotics, analgesics, antipyretics and hormones in wastewater and water bodies, negatively affecting the biosphere. Among the emerging pollutant sources, the main are wastewater, hospital effluents, agriculture, animal breeding and improper management of industrial effluents. Therefore, it is essential to develop or adapt methods to remove these pollutants from environmental matrices. This work studies experimental and theoretically the removal of the widely used antibiotic oxytetracycline (OTC) from water through its sorption by a globally abundant solid waste: eggshell (ES). Experimentally, the OTC sorption by ES powders has been performed at different OTC concentrations. The obtained isotherm has been fitted by the Langmuir, Freundlich and Sips models. Theoretically, first principles calculations to model the OTC molecule on different CaCO3 surfaces were done. Experimentally the maximum sorption capacity was 15 ± 3 mg/g at RT, disclosed by the best model representing the data, the Langmuir one at a single site. Theoretically OTC sorption involves the interaction between Ca2+ of ES and O atoms of OTC. Therefore, ES waste is a promising material for low-cost remediation technologies based on the sorption process for the treatment of waters containing OTC.

Sodium titanate (Na2Ti4O9) nanoribbons for effective removal of organic dyes from water: Experimental and computational studies

In this work, Na2Ti4O9 nanoribbons (NTRs) were synthesized using the hydrothermal method for its potential application in water treatment. The NTRs were characterized by X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, zeta potential, Fourier Transform infrared spectroscopy, and surface area analyzer. The adsorption of organic dyes, including cationic methyl green (MeG) and methylene blue (MB) model pollutants, onto the NTRs was explored for the first time. Various parameters such as pH, adsorbent dose, initial dye concentration, regeneration, contact time, the effect of temperature, and thermodynamics were studied to determine the efficiency of NTRs for removing both dyes from water. A variety of isotherm and kinetic models were applied to fit the dye adsorption data at pH 7.0, providing insights into the adsorption mechanism and process kinetics. Kinetic data for both dyes fit well with pseudo-second-order and mixed 1,2-order models. The isotherm data agreed well with Langmuir-Freundlich and Sips models. At the studied temperatures of 298.2, 318.2, and 328.2 K, the maximum adsorption capacities for MeG (353.2, 367.7, and 443.2 mg·g−1) are significantly higher than for MB (29.3, 52.6, and 67.2 mg·g−1), indicating a stronger affinity for MeG, with adsorption efficiency improving as temperature increases. The MeG samples at 328.2 K exhibited interesting behavior. After adsorption, the samples became colorless, with a final pH near 7.0, indicating effective dye removal. However, the color faintly reappeared at pH 4.0, suggesting pH-dependent behavior and incomplete dye removal. The adsorption mechanism on the NTRs surface was investigated using Monte Carlo and molecular dynamics simulations.

Treating waste with waste: New insight into phosphorus removal by graphitic carbon nitride modified water treatment sludge-based ceramsite

This study developed a novel ceramsite adsorbent, combining water treatment sludge (WTS) and graphite carbon nitride, which aimed at removing phosphate from wastewater to realize the sustainable development strategy of ‘treating waste with waste’. The optimal conditions for the preparation of N-modified WTS (NWTS)-based ceramsite were determined as follows: NWTS: bentonite: CaCO3=1:0.4:0.5, preheating at 450 °C for 15 min, and calcinating at 1100 °C for 15 min. The study examined the effects of pH, ceramsite dosage, initial phosphorus concentration, and temperature on phosphate removal, and it assessed the potential risk of heavy metal release from the ceramsite during application. The result indicated that phosphorus adsorption of the ceramsite reached 0.5 mg/g at pH=6, T=303 K, Pinitial=1 mg/L and dosage of 2 g/L, achieving 100% removal efficiency. The adsorption process of phosphate by ceramsite followed pseudo-second order kinetic and the Sips model, suggesting that the adsorption mechanism involved multilayer chemisorption. Ligand exchange reaction was the primary driver of adsorption, with hydrogen bonding further augmenting the adsorption efficiency. Additionally, the heavy metal content released by the ceramsite was significantly below the relevant standard limits, confirming its excellent feasibility and safety. These characteristics suggested that the ceramsite adsorbent had broad application potential in actual wastewater treatment process.

Synthesis of novel Fe3O4@gly@Indole@CuNO3 magnetic nanoparticle as high-performance antibiotic absorbent, antimicrobial agent, and reusable magnetic Nano catalyst

The synthesis of nanoparticles has gained attention for their broad applications. Our research focused on developing a novel material, Fe3O4@gly@Indole (FGI), and exploring its diverse uses. FGI was synthesized in two steps using FeCl2.4H2O, FeCl3.6H2O, glycine, and indole-3-carboxaldehyde. Its structure was confirmed via FT-IR, XRD, VSM, SEM, TGA, and EDAX. Antimicrobial tests revealed FGI exhibited higher activity than some antibiotics, with a Minimum Inhibitory Concentration (MIC) of 1µg/mL against Staphylococcus aureus. To enhance its properties, a magnetic nanocatalyst (FGICu) was synthesized by combining FGI with Cu(NO3)2. FGICu proved effective in synthesizing chromeno[4,3-b]chromen-6-one derivatives, achieving 95% yield in 20minutes at 50°C. Additionally, FGICu outperformed FGI in antibacterial tests, showing a lower MIC of 0.5µg/mL and stronger bactericidal activity (MBC of 2-8µg/mL). FGICu also demonstrated significant potential as an adsorbent, with a maximum adsorption capacity of 500.8mg/g for tetracycline (TC). The adsorption mechanism involved electrostatic interactions, hydrogen bonding, and π-π stacking, with the SIPS model best fitting the isotherm and pseudo-second-order model describing the kinetics. FGICu maintained over 70% efficiency after five adsorption cycles, showing excellent stability and reusability. These findings suggest FGICu is a promising material for antimicrobial applications and pollutant removal from wastewater.

Eco-friendly property modulation of biobased gels of carboxymethyl cellulose-integrated poly(tertiary amine)s for the removal of azo-food dyes

Anionic polysaccharide-based gels enable the design of biobased materials with biochemical properties, non-toxic and natural origin. A new set of cationic gels was prepared from carboxymethylcellulose (CMC)-doped tertiary amino functional cationic monomers 2-(dimethylamino)ethyl methacrylate and N-(3-(dimethylamino)propyl) methacrylamide via the formation of semi-interpenetrated network (semi-IPN) at different polymerization temperatures, Tprep. A detailed understanding of the temperature-dependent synthesis and physicochemical response is required for the design of interpenetrating networks with CMC as an adsorbent that provides effective sources for the removal of azo-food dyes such as tartrazine and carmoisine from aqueous solutions. The variation of elasticity and swelling properties with respect to polymerization temperature was investigated. CMC-integration and polymerization temperature played a decisive role in the compressive elasticity. Incorporation of CMC into copolymer matrix led to a significant increase in elasticity of semi-IPNs, while mechanically weaker gels were obtained with increasing Tprep. Addition of CMC increased the swelling modulus of semi-IPNs formed at −18 °C by 2.6-fold. While the transparency changed depending on Tprep and microstructure, addition of CMC decreased the swelling rate of gels at all polymerization temperatures. The compressive modulus decreased with the swelling process in accordance with the Rubber elasticity theory. Semi-IPN gels showed stable swelling against pH-change in aqueous solutions and exhibited excellent pH-sensitivity significantly in low pH. A 4 to 12 fold decrease in maximum volume was observed by varying the pH between 2.1 and 9.8. The correlation between polymerization temperature and removal of azo-food dyes; tartrazine and carmoisine from contaminated wastewater with CMC-based gels was studied. Dynamic adsorption equilibrium was reached in 30 min, and tartrazine and carmoisine removal performances varied between 92.8 % and 98.4 %. respectively. The adsorption data for azo-dyes were evaluated by Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Redlich-Patterson, Sips, and Tooth isotherm models, but were best described by Langmuir and Redlich-Patterson models as they gave the highest correlation. Pseudo-first order, pseudo-second order, Elovich, Avrami kinetic and intra-particle diffusion models were investigated and dye adsorption was represented by pseudo-second-order model. After the adsorption process, semi-IPNs can easily be regenerated and effectively reused over five cycles. The study provided new insights towards the facile and sustainable synthesis of eco-friendly multifunctional CMC-based gels carrying tertiary amino groups for effective removal of azo-based food colorants.

Construction and demolition waste as a low-cost adsorbent for water treatment: kinetics, isotherm, thermodynamics, and Fenton regeneration.

The present study proposes to investigate the feasibility of using construction and demolition waste (CDW) as an aqueous remediation agent through adsorption. The CDW, with and without chemical and thermal pre-activation, was evaluated to remove the methylene blue (MB) dye from the water solution. Variables interfering with adsorption processes, such as adsorbent dosage, solution pH, and particle size, were evaluated. The material was characterized by pHZPC, FTIR, XRD, SEM, EDS, and TG. The kinetic and equilibrium data better fitted the Elovich and Sips models, respectively. A maximum adsorption capacity of 18.62mgg-1 at 60°C was observed. Thermodynamic data indicated that adsorption occurred through a spontaneous and favorable process governed mainly by physical processes. The regeneration studies were carried out using processes based on the Fenton reaction, where the catalytic action of the iron naturally present in the CDW was evaluated. The results showed that the desorption balance was the main limiting factor for the effective regeneration of the saturated material. Adding Fe2+ to the system made this process suitable for the regeneration of the CDW and degradation of the pollutant in the aqueous phase. A regeneration efficiency of 65%, maintained practically constant during five adsorption-regeneration cycles, was observed. These results highlight the high potential of using CDWs as an adsorbent material.

Sonochemical synthesis of guar gum - Zirconium phosphate composite for efficient capture of uranium from water

The increasing presence of uranium as a radionuclide contaminant in water is a threat to human health and the environment. Sonication-assisted crosslinking of guar gum, a biopolymer, is carried out with zirconium phosphate to form an adsorbent (GG@ZrP) for the removal of uranium from water. The surface characteristics, functionalities, and thermal stability of the composite were established using various analytical and spectral tools. Langmuir, Freundlich, and Sips models were used to evaluate the batch adsorption parameters. The adsorbent exhibited an excellent Langmuir adsorption capacity of 500 mg g−1 towards adsorption of uranium at pH 6. The adsorption was endothermic (ΔH, 22.63 kJ mol−1) and followed pseudo-second order kinetics. The synergistic influence of hydroxyl-rich guar gum and phosphate moieties resulted in efficient binding of uranium. With a high selectivity towards interfering cations and anions and applicability over a good range of pH, this adsorbent is a promising candidate for uranium remediation from water.

CARBON-SILICA COMPOSITE AS ADSORBENT FOR REMOVAL OF CATIONIC DYE (METHYLENE BLUE)

The aim of this research was to synthesize carbon-silica composite (CSC) as an adsorbent for cationic dye removal from wastewater. Molasses, a by-product of the sugar industry, was successfully utilized to prepare CSC by sol-gel method with tetraethoxylsilane (TEOS) as silica source. The physicochemical properties of the composites were studied by N2 adsorption, FTIR and TGA. The highest specific surface areas of CSC was 144 m2/g at a molasses/TEOS ratio of 0.8, with a mesopore volume of 83% and average pore width of 9.71 nm. This optimal CSC was evaluated for methylene blue (MB) adsorption using batch experiments under varying adsorption times and initial MB concentrations. Adsorption equilibrium was reached within 14 h and the pseudo-second order equation provided the adequate fit for the kinetic studies, suggesting that dye adsorption was limited by chemisorption. The equilibrium data were best described by the Sips model with a maximum adsorption capacity of 180.22 mg/g. The CSC derived from molasses is considered a potentially promising adsorbent for cationic dye removal in wastewater.

Sugarcane bagasse-derived biochar modified by alkali for enriching surface functional groups to effectively treat ammonium-contaminated water.

In this study, sugarcane bagasse (SB), which was preliminarily treated with H3PO4, was utilized to produce biochar (SB-BC). The SB-BC was subsequently modified with KOH to enrich oxygen-containing functional groups (OCFGs) for the enhanced adsorption of NH4+ from wastewater. Batch tests revealed that KOH-modified SB-BC (SB-MBC) increased the maximum Langmuir adsorption capacity of NH4+ by approximately twofold, from 27.1mg/g for SB-BC to 53.1mg/g for SB-MBC. The optimal operational conditions for NH4+ adsorption onto SB-MBC were pH of 7.0 and a biochar dose of 3.0g/L for the removal of 50mg/L NH4+ at room temperature (25 ± 2°C) over 180min of contact. The enhanced adsorption capacity of NH4+ onto SB-MBC was due to the important contribution of the OCFGs enriched on the surface of biochar, which was increased by about fourfold, after being modified by KOH. The NH4+ adsorption dynamics were better fitted by the Elovich and the NH4+ adsorption isotherms were better described by Langmuir and Sips models, showing that the adsorption process was dominated by monolayer chemisorption. The properties of the adsorption materials before and after adsorption of NH4+ confirmed that cation exchange, electrostatic attraction and surface complexation were the main mechanisms controlling the adsorption process. The desorption and reusability tests of NH4+-saturated SB-MBC revealed that NH4+ adsorption slightly decreased after three successive sorption‒desorption cycles. The findings suggested that SB-MBC is a promising and feasible adsorbent for the effective treatment of NH4+-contaminated water sources. Future work should conduct tests for treatment of NH4+-rich real wastewater and utilize NH4+-saturated SB-MBC as slow releasing fertilizer for plants growth.

The role of the activation heating source on the carbon capture performance of two new adsorbents produced from household-mixed-plastic waste

This study reveals the impact of the activation with microwave and conventional heating sources on textural properties and CO2 uptake of a mixed plastic-based char. Two mixed plastic-based adsorbents, one activated using microwaves and the other using conventional heating, were produced at optimum activation conditions, and subsequently compared. The findings show that both heating sources produced microporous adsorbents, but activation heating sources influenced their physicochemical properties and CO2 uptake. The microwave-produced activated carbon (AC) displayed superior BET surface area, total, micro- and ultra-micropore volumes compared to the conventionally produced AC. The microwave-produced AC possessed CO2 adsorption capacities of 1.66 and 2.37 mmol/g under dynamic and equilibrium conditions, respectively, at 25 °C and 1 bar. These capacities represent an 8 and 30 % higher uptake, respectively, compared to the 1.53 and 1.66 mmol/g displayed by the conventionally prepared AC under the same adsorption conditions. Both samples displayed stable and excellent CO2 recyclability over 10 adsorption-desorption cycles, with desorption efficiencies ranging from 93.46 % to 96.72 % (microwave- and conventionally- produced ACs respectively). The Avrami model most accurately described the experimental CO2 adsorption data under dynamic conditions, while the Sip model gave the best fit for equilibrium conditions. These findings apply to both types of ACs at various temperatures, irrespective of the heating source. Overall microwave heating is more efficient than conventional heating, requiring 300°C lower temperature, 115 minutes shorter time, 0.79 kWh less energy, and less KOH. It improves CO2 uptake and reduces production costs by 80 %, offering a sustainable alternative for CO2 adsorbent production.

Empowering Rural Left-behind Children in Meizhou, Guangdong: SIPS Model-Based Approach to Promoting Reading and Fostering Holistic Development

Objective: Under the dual influence of globalization and urbanization, the issue of left-behind children in rural areas has become increasingly prominent. Taking Meizhou, Guangdong Province, as a case study, this paper underscores the urgency of promoting reading activities for these children in this major agricultural hub in southern China. Methods: Leveraging a comprehensive approach that integrates online searches, official data, and other information-gathering techniques, the paper delves into the specifics of the challenge.The SIPS model, consisting of Resonance, Confirmation, Participation, and Sharing, offers a fresh perspective on tackling the challenge of promoting reading among these children. It explores how the collaboration of multiple stakeholders, including university student volunteers, government agencies, and private enterprises, can harness tools such as simulated data and data integration methods to gain a nuanced understanding of the reading needs, obstacles, and untapped resources of left-behind children. Results: The paper outlines a series of actionable strategies under the SIPS model to advance reading promotion activities for left-behind children in rural Meizhou, thereby fostering their holistic development and contributing to local rural progress. Conclusion: By engaging stakeholders and utilizing methods like simulation data and data integration, the paper proposes practical strategies to create a richer and healthier reading environment for left-behind children, ultimately contributing to their development and the overall progress of rural communities.

Stationary and Dynamic Sorption of 141Ce(III) and 152+154Eu(III) Using Alginate–Gypsum Bio-composite Beads

AbstractThis study introduces a novel Alginate–Gypsum bio-composite, synthesized at a 2:1 weight ratio, as an effective sorbent for Eu(III) and Ce(III) ions in aqueous solutions. Optimal conditions (pH 3, 5-h contact time) yielded 98% sorption efficiency for both ions in single batch systems (50 mg L−1, 20 °C). In binary systems, the composite adsorbed 33.04% of Ce(III) and 47.26% of Eu(III) (mg L−1, 20 °C). Dynamic column system showed 80.297% Ce(III) and 77.5% Eu(III) sorption. The process was endothermic, spontaneous, and best described by a quasi-nth order kinetic model. The sorption process was best described by the quasi-nth order kinetic model, with Eu(III) sorption aligning with the Langmuir and Sips models, and Ce(III) sorption following the Redlich–Peterson and Sips models. Desorption was highly efficient, with up to 99% for Eu(III) and 97% for Ce(III) using 0.1 M EDTA.

Sctudies on adsorption of Brilliant Green from aqueous solution onto nutraceutical industrial pepper seed spent

The study proposed the removal of Brilliant Green, a cationic dye, by adsorption process from wastewater solution utilizing a low-cost adsorbent such as Nutraceutical Industrial Pepper Seed Spent (NIPSS). The study comprises an investigation of the parametric influence on the adsorption process. The parameters identified are pH, dye concentration, process temperature, quantity of the adsorbent, and particle size. The study of statistics found from experiments was carried out by incorporating Freundlich, Brouers-Sotolongo, Langmuir, Toth, Sips, Jovanovic, and Redlich-Peterson isotherm models. The adsorption kinetics were determined by implementing pseudo-first-order and second-order models, diffusion film models, and Dumwald-Wagner and Weber-Morris models. The experimental adsorption capacity qe was found to be about 130 mg/g. This value was closest to the maximum adsorption of 144.6mg/g predicted by the Brouers-Sotolongo isotherm which had a correlation coefficient (R2) of 0.998. The adsorption kinetics data was confirmed to be a pseudo-second-order model. The change in free energy, enthalpy change, and entropy change were vital thermodynamic factors in concluding that adsorption is almost spontaneous and endothermic process. Change in enthalpy (ΔH°) reduced value indicates the physical nature of the process. The adsorption of BG dye on the adsorbent surface was authenticated by FTIR spectroscopy and SEM imaging. A Central Composite Design (CCD) Quadratic model under Response Surface Methodology (RSM) was implemented for statistical optimization of adsorption capacity for the five parameters studied, namely, time, temperature, concentration of the dye, weight of the adsorbent, and pH. Software Design Expert 7.0 was used to evaluate 3D contour plots. The process of optimization yielded a value of 350 mg/g. Thus, incrementing the adsorption process by 84.2 %. The study provides insights on various dye and adsorbent interaction possibilities and derives that NIPSS is an efficient adsorbent to extract BG dye from wastewater solutions.

Comparison of adsorption potential of methylene blue and 17β-stradiol on biochar, activated biochar and catalytic biochar from lignocellulosic waste

This work compares the adsorption capacity of methylene blue (MB) and 17β-stradiol (17β-S) onto biochar (B), activated biochar (AB) and catalytic biochar (CB), obtained through pyrolysis of residual lignin of the second-generation (2G) ethanol production process from a sugarcane industry. K2CO3 was used as activating agent and catalyst. Biochars were characterized by the techniques of point of zero charge, nitrogen adsorption and desorption, SEM and FTIR. Kinetic, isothermal and thermodynamic adsorption studies were carried out. Biochars behaved according to the pseudo-second order (PSO) kinetic model, with similar removal percentages of MB using AB and CB. In contrast, AB showed significantly higher removal percentages of 17β-S than CB. The Sips model agreed to isothermal adsorption data of 17β-S onto all biochars. For MB adsorption, Freundlich model agreed to data using B and AB, and Langmuir model was more suitable for CB. The process was viable, spontaneous, endothermic and showed increase in entropy, except for 17β-S adsorption onto CB. Consequently, the activated and catalytic pyrolysis processes increased the adsorptive potential of biochar derived from 2G lignocellulosic residue. Finally, CB and AB obtained significant removal percentage values of MB (85.8–99.3 %) and 17β-S (37.6–76.7 %), where CB is favorable due to its simpler preparation steps.

A novel potato peels waste β-cyclodextrin biocomposite for the efficient uptake of diuron and glyphosate herbicides.

A novel biocomposite (FPPW-β-CD) was prepared by a simple and sustainable method involving fine potato peel waste, β-cyclodextrin (β-CD), and green citric acid through the crosslinking reaction. The polymer was characterized using SEM, FTIR, XRD, TGA, and DSC analyses. The adsorbent performance was evaluated about the glyphosate and diuron adsorption from the aqueous solution. Pesticide removal was investigated regarding the influence of solution pH, temperature, and initial concentration of contaminants. Also, it highlights the main interactions involved in the adsorption phenomenon based on the pH effect and characteristics of adsorbent and adsorbate molecules. The maximum adsorption capacity values according to the Sips model were higher than 2000µgg-1. The pseudo-second-order and general-order models described the kinetic data well. Thermodynamic parameters indicated that pesticide removal was spontaneous and favorable. The magnitude of enthalpy variation values (27.37kJmol-1 and - 100.79kJmol-1) revealed that the glyphosate and diuron adsorption occurred through the physisorption and chemisorption, respectively. The novel biocomposite is a promising green adsorbent for the uptake of micropollutant pesticides in aqueous solutions at concentrations of µg L-1.

Adsorption characteristics and separation behavior of binder and binderless zeolite LiX Pellets: O2, N2, and CO2

In adsorptive gas separation process design, optimal adsorbent selection acts as a critical factor in process efficiency. This study investigated the adsorption equilibria and kinetics of O2, N2, and CO2 (weak, medium and strong affinity, respectively) and the breakthrough performance of four commercial zeolite LiX pellets (one binderless and three binder zeolite LiX pellets) because the performance of pelletized zeolites becomes different by adding binders and pelletizing methods. The adsorption isotherms at 293–323 K and up to 100 kPa were correlated with the dual-site Langmuir and Sips models. For all adsorbents, the order of adsorption amount and isosteric heat of adsorption was CO2 ≫ N2 > O2. However, differences among the four zeolite pellets were also observed, showing the highest values of the binderless zeolite LiX pellet. Furthermore, the adsorption capacity was 20–25 % smaller for CO2 and 40–50 % smaller of N2 and O2 at 100 kPa compared to pure zeolite LiX powder. According to kinetic analysis using a non-isothermal diffusion model, the adsorption rate of N2 was faster than that of CO2 for all adsorbents, showing the order difference in the low-pressure range. The kinetic difference among the zeolite pellets resulted from the effects of heat of adsorption, heat dissipation, and thermal resistance. The breakthrough performance using N2 and O2 was mainly controlled by the adsorption capacity, showing almost constant breakthrough pattern regardless of the samples. This study suggests that detailed evaluation of pelletized adsorbent is essential before designing adsorptive processes because performance of adsorbent powder would lead to under-design of the process. (255 words)