Film Diffusion Research Articles

Biosorption of cypermethrin from aqueous solutions by Pediococcus acidilactici: kinetics, isotherms, and mechanisms.

Pediococcus acidilactici is an effective adsorbent for removing of pyrethroid insecticides. This study investigated the biosorption characteristics and mechanisms of P. acidilactici D15 using adsorption measurement, scanning electron microscopy, and Fourier-transform infrared spectroscopy. Isotherm and kinetic models were used to analyze the biosorption process. The Langmuir isotherm model best described the cypermethrin biosorption process, with the maximum adsorption capacity of P. acidilactici D15 being 21.404 mg/g. The biosorption appeared to involve monolayer coverage with uniform forces. The pseudo-second-order model also fits well. The rate-controlling steps involved intraparticle diffusion, film diffusion and chemosorption. The main cellular components involved in cypermethrin biosorption were exopolysaccharides, spheroplast, and cell wall, especially peptidoglycan. The functional groups (-OH, -NH, -CH3, -CH2, -CH, -CONH-, -CO, and -C-O-C-) from proteins, polysaccharides, and peptidoglycan on the cell surface likely played a role in binding cypermethrin. Additionally, P. acidilactici D15 effectively reduced cypermethrin in pickle wastewater. These findings suggest that P. acidilactici D15 could be a potential agent for reducing pesticide residues, laying the groundwork for treating pickle wastewater containing such pesticide residues. © 2024 Society of Chemical Industry.

Advancing Parameter Estimation in Differential Equations: A Hybrid Approach Integrating Levenberg–Marquardt and Luus–Jaakola Algorithms

This study presents an integrated approach that combines the Levenberg–Marquardt (LM) and Luus–Jaakola (LJ) algorithms to enhance parameter estimation for various applications. The LM algorithm, known for its precision in solving non-linear least squares problems, is effectively paired with the LJ algorithm, a robust stochastic optimization method, to improve accuracy and computational efficiency. This hybrid LM-LJ methodology is demonstrated through several case studies, including the optimization of MESH equations in distillation processes, modeling controlled diffusion in biopolymer films, and analyzing heat and mass transfer during the drying of cylindrical quince slices. By overcoming the convergence issues typical of gradient-based methods and performing global searches without initial parameter bounds, this approach effectively handles complex models and closely aligns simulation results with experimental data. These capabilities highlight the versatility of this approach in engineering and environmental modeling, significantly enhancing parameter estimation in systems governed by differential equations.

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

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

Eco-friendly micro-mesoporous carbon from sucrose and sodium metasilicate template for ciprofloxacin adsorption: Effect of molecules self-association over diffusion mechanisms

A green synthesis route of ordered mesoporous carbon by nanocasting of sucrose/sodium metasilicate with template removal only by hot water (70 °C) is proposed. The metasilicate-sucrose mesoporous carbon (MSMC) was characterized by structural, textural, surface chemistry properties and their effect on ciprofloxacin (CIP) adsorption. Phenomenological modeling was applied, including two surface-reaction models: adsorption on adsorbent sites (AAS) and on heterogeneous surface (AHS), and two mass transfer models: external film (EFD) and intraparticle homogeneous (IHD) diffusion. A controlled porous structure containing mesopores (3.8 nm) with micropores (1.8 and 0.87 nm) allowed the “pore filling effect” mechanism and strongly favorable kinetics. A highly oxygenated carbon material (C: 81.84 % O: 15.04 % Si: 1.72 % Na: 1.29 %) with efficient template removal was obtained. Unusual behavior of the rate-limiting step (AAS or IHD) as a function of CIP concentrations was observed, with mechanism changes due to self-aggregation of CIP molecules (dimers, trimers and tetramers).

Cover crops and P‐fertilizer management affect microbial activity in a US Midwest corn and soybean rotation

AbstractMicroorganisms can have a substantial effect on labile phosphorus (P), which may be lost from the soil surface and impact water quality. Changes in nutrient availability and soil health from agricultural management can affect microbial biomass carbon (MB‐C), microbial biomass phosphorus (MB‐P), and the expression of P cycling enzymes. The objective of this research was to investigate biological mechanisms affecting P availability and potential loss to runoff in a no‐till, corn (Zea mays)–soybean (Glycine max) cropping system with two cover crops (cover crop [CC] and no cover crop [NC]) and three P management treatments (fall broadcast [FB], spring injected ammonium polyphosphate [SI], and no phosphorus application [NP]). Treatments were applied to a randomized block design with three replicates. Soil samples were analyzed for MB‐P, MB‐C, phosphatase activity, and Mehlich‐III P (PM). The P supply to the soil solution was measured using diffusive gradient thin film P (PDGT). In Spring 2018, Fall 2018, and Spring 2019, all phosphatase activity was greater in CC versus NC (p < 0.01). Microbial biomass C was greater in CC compared with NC in spring but not fall samplings. On average, MB‐P was fivefold greater in the P fertilized than unfertilized treatments (p < 0.001). CCs did not change MB‐P, PM, or PDGT within FB or NP, but did affect SI fertilizer treatments. Our results suggest CC can increase potential for organic P mineralization, application of P fertilizer increases MB‐P, and an interaction between SI P fertilizer management and CC may increase P supply to the soil solution.

Hierarchically-porous resin for the adsorption of organic matter in raffinate produced by solvent extraction from the vanadium industry

Solvent extraction wastewater contains high concentrations of organic pollutants and metal ions, making it difficult to treat. This paper presents a method of using hierarchically-porous adsorption resin to recover organics from raffinate and regenerate the resin, addressing secondary pollution in extraction processes. The chosen resin, WS6108, removes over 95 % of organics from raffinate, with high metal ion concentrations enhancing its adsorption efficiency. The article conducted an optimization experiment and mechanism study on WS6108 resin for adsorbing organic matter in vanadium raffinate (OIVR), followed by desorption and recycling tests. Results showed WS6108 resin achieved a 96.7 % adsorption efficiency at a solid–liquid ratio of 24 g/L after optimization. The chosen methanol desorbent achieves over 99 % desorption efficiency for the WS6108 cycle under specific conditions. The resin’s performance remains stable for up to 45 cycles. Adsorption isotherms and kinetic experiments indicate that OIVR adsorption by WS6108 resin is endothermic, non-spontaneous and entropy increasing. Moreover, the adsorption kinetics of OIVR by WS6108 resin followed a pseudo-second-order model, based on the activation energy, liquid film diffusion was considered the main rate-controlling step. A column experiment was conducted to verify that WS6108 resin can be used in real vanadium raffinate to remove organics. Density functional theory (DFT) revealed that strong hydrogen bonding, π-π stacking and excellent adsorption diffusion behavior drive OIVR adsorption. This study aims to increase the use of adsorption to treat oily wastewater generated by solvent extraction.

Sample-to-answer point-of-care testing platform for quantitative detection of small molecules in blood using a smartphone-and microfluidic-based nanoplasmonic biosensor

Rapid and ultrasensitive detection of small molecules is of great significance in point-of-care testing (POCT) for health management and biomarker detection for many diseases. In this study, a novel POCT device integrated with a metasurface plasmon resonance (MetaSPR) chip with diffusion film enhancement was designed and controlled by a smartphone app for small molecule ultrasensitive detection based on competitive immunoassays. In this method, the sample competes with the antigen immobilized on the chip, and labeled antibodies are pumped from the sample pad to the chip for multiplexed and sample-to-answer analysis of blood. The entire process of detection is 14.3-fold less time (210 s in total) compared to an enzyme-linked immunosorbent assay (ELISA). For this assay, the limit of detection was 0.36 ppt and 1.05 ppt for testosterone and 25-hydroxyvitamin D3, respectively, and showed 100- to 1000-fold greater sensitivity than that of ELISA. Collectively, the data suggest that this novel POCT platform, based on a MetaSPR biosensor, provides ultrasensitive, rapid, regenerable, versatile, and real-time quantitative analysis for applications in health management and early diagnosis.

Ultrafast Charge and Exciton Diffusion in Monolayer Films of 9-Armchair Graphene Nanoribbons.

Determining the electronic transport properties of graphene nanoribbons is crucial for assessing their suitability for applications. So far, this has been highly challenging both through experimental and theoretical approaches. This is particularly the case for graphene nanoribbons that are prepared by chemical vapor deposition, which is a scalable and industry-compatible bottom-up growth method that results in closely packed arrays of ribbons with relatively short lengths of a few tens of nanometers. In this study, the experimental technique of spatiotemporal microscopy is applied to study monolayer films of 9-armchair graphene nanoribbons prepared using this growth method, and combined with linear-scaling quantum transport calculations of arrays of thousands of nanoribbons. Both approaches directly resolve electronic spreading in space and time through diffusion and give an initial diffusivity approaching 200 cm2 s-1 during the first picosecond after photoexcitation. This corresponds to a mobility up to 550 cm2 V-1 s-1. The quasi-free carriers then form excitons, which spread with a diffusivity of tens of cm2 s-1. The results indicate that this relatively large charge carrier mobility is the result of electronic transport not being hindered by defects nor inter-ribbon hopping. This confirms their suitability for applications that require efficient electronictransport.

Revolutionizing superhighway traffic board lighting with remote LED spotlights

In this paper, we present a groundbreaking approach to enhance the illumination of traffic boards along superhighways, addressing significant challenges associated with conventional lighting systems. Our innovative method revolves around the strategic placement of remote spotlights at the side of the roadway to illuminate traffic signs equipped with retroreflector film (RTRF). The essence of our approach lies in remote illumination, which requires meticulous adjustment of the divergence angle of the spotlights to match the size of the signs and their distance from the projection source. To achieve the desired spotlight configuration, we have developed a hybrid optical system that incorporates a paraboloid reflector and a lens mounted on a bridge holder situated on top of the mirror. Through spot light illumination, we discovered that the initial divergence angle of the RTRF was too narrow. To improve projection angle tolerance, we recommend attaching a light diffuser film onto the surface of the RTRF. The coverage area ratio of the diffuser film can be adjusted to select the desired divergence angle for the reflected light. Our experimental measurements have yielded significant results, showcasing the half-divergent angle of the RTRF ranging from 3° to 7° for different coverage area ratios of the diffuser. In practical terms, with a target luminance of 300 nits at the white word on the traffic board, the power consumption of the spotlight fixture of the roadway was only 40 W, representing over 75% power savings when compared to traditional lighting methods. Consequently, our approach opts to utilize spotlights for illuminating specific traffic boards on superhighways, offering a more efficient and manageable lighting solution that greatly benefits both motorists and road maintenance personnel.

Kinetics and Mechanism Study of Different Types of Surface‐Imprinted Polymers for CO2 Adsorption

ABSTRACTThe increased level of CO2 in the atmosphere has led to global warming and climate change. To mitigate these problems, solid adsorbents have become attractive materials for capturing excess CO2 in the post‐combustion method. Molecularly imprinted polymer (MIP) can be applied to prepare highly selective adsorbents that could capture CO2 molecules. The MIP was prepared using the surface imprinted polymer technique in this preliminary work. Only two types of support materials were used (graphite and silica gel) to screen the best support material that could enhance the CO2 adsorption capacity of the resulting adsorbent, which was analyzed using a fixed‐bed column reactor. Graphite‐imprinted polymer (GMIP) was found to be a good potential for CO2 adsorption. The Avrami model best described the adsorption system, while the fixed‐bed curve data fit the Yoon–Nelson model well. The semi‐empirical method was used to assess the interaction mechanism of the molecularly imprinted polymer with CO2 during adsorption. This investigation involved testing four different ratios of the template complex to functional monomers. The ratio of 1:4 (CO2:Allylthiourea) demonstrated the highest binding energy, with a higher formation of hydrogen bonds. Film diffusion and intraparticle diffusion were the main rate‐limiting steps that played vital roles at different stages of CO2 adsorption. This preliminary work has enhanced the development of MIP for CO2 adsorption and showcased the integration of computational approaches in tailoring specific MIPs.

Hierarchical exsolution in vertically aligned heterostructures

Metal nanoparticle exsolution from metal oxide hosts has recently garnered great attention to improve the performance of energy conversion and storage devices. In this study, the nickel exsolution mechanisms in a vertically aligned nanostructure (VAN) thin film of heteroepitaxial (Sr0.9Pr0.1)0.9Ti0.9Ni0.1O3−δ-Ce0.9Gd0.1O1.95 with a columnar architecture was investigated for the first time. Experimental results and Density Functional Theory (DFT) calculations reveal that the multiple vertical interphases in a VAN with a hierarchical arrangement provide faster and more selective Ni diffusion pathways to the surface than traditional bulk diffusion in epitaxial films. Kinetic studies conducted at different temperatures and times indicate that the nucleation process of the exsolved metal nanoparticles primarily takes place at the surface through the phase boundaries of the columns. The vertical strain is crucial in preserving the film’s microstructure, yielding a robust heteroepitaxial architecture after reduction. This innovative heteromaterial opens up new possibilities for designing efficient devices through advanced structural engineering to achieve controlled nanoparticle formation.

Dissolved organic matter-mediated adsorption behavior of benzophenones on functionalized covalent triazine frameworks

Adsorption is a highly efficacious technique for the remediation of organic micropollutants (OMPs). However, the presence of dissolved organic matter (DOM) frequently impedes adsorbent process, with insufficient attention given to this influence. This study systematically evaluates the adsorption performance of covalent triazine frameworks (CTFs) functionalized with electron-donating or electron-withdrawing groups for benzophenones (BPs). The adsorption capacities of SO3H-CTF, OH-CTF, and NH2-CTF for BPs were 512.11 μmol/g, 1356.27 μmol/g, and 1421.85 μmol/g, respectively. The adsorption mechanism is predominantly governed by π-π electron donor–acceptor (EDA) interactions, supplemented by hydrogen bonding, particularly in hydroxyl-containing BPs, with electrostatic interactions being relatively negligible. Functionalization with − OH and − NH2 groups increased the electron density in π-conjugated regions, enhancing BPs adsorption capacity, whereas − SO3H modification, due to its electron-withdrawing nature, acted as a π electron acceptor. Importantly, the mediating role of humic acid (HA) in the adsorption process was investigated. The CTF-BPs-HA ternary system can either inhibit/enhance π-π EDA interactions between π-electron donor/acceptor and BPs by adsorbing onto the CTF materials. The HA-mediated system primarily affects the film diffusion stage, with minimal impact on pore diffusion and inner surface adsorption. The oxygenated functional groups in HA slightly enhanced hydrogen bonding within the adsorption system, with negligible influence on electrostatic interactions. In the presence of HA, the overall adsorption capacity of SO3H-CTF decreased by 67.0 %, while that of OH-CTF and NH2-CTF increased by 120.9 % and 55.3 %, respectively. This study elucidates the electronic behavior modifications of functionalized CTFs during BPs adsorption and underscores the significant role of HA in interaction mechanisms, providing theoretical guidance for the design of advanced adsorbents to enhance pollutant removal efficiency.

Crude oil sorption performance of native and acetylated Siamese senna seed pods

The recurring problem of oil spillage has directed research to the exploration of various agricultural wastes in order to discover new, inexpensive, and environmentally friendly oil sorbents. This research studied the viability of native and acetylated seed pods of Siamese senna as oil spill mop. SEM, BET, and FTIR analyses were employed to assess the adsorption tendency of the adsorbents for crude oil. Investigation of the oil sorption behaviors of the adsorbents involved batch sorption experiments. The SEM analysis revealed improvements in the surface morphology of the acetylated pods. The BET surface area increased from 265.2 m2/g to 335.0 m2/g after acetylation. The FTIR spectra of the oil-treated pods showed that the acetylated pods adsorbed more oil than the native pods. The Langmuir isotherm best described the sorption equilibrium for the adsorbents. Kinetic analysis showed that the sorption processes conformed to the pseudo-second-order model, and were controlled by film diffusion alone or in conjunction with other mechanisms. The results obtained in this work show that Siamese senna seed pods can be used for crude oil sorption from an aqueous medium. The improved oil sorption capacity of the acetylated pod shows that it has more potential to serve as a low-cost alternative for oil spill remediation than the native seed pod.

Activated carbons prepared from stump wood of various tree species by chemical activation and their application for water purification

AbstractActivated carbons (ACs) were produced from stump wood of different tree species, such as pine, bearded birch, and American black cherry using chemical activation with KOH and NaOH. The activated carbons were characterized and evaluated as adsorbents for eliminating bisphenol A (BPA) from aqueous solutions. The kinetics of adsorption and equilibrium adsorption, as well as the impact of solution pH and ionic strength, were examined. The kinetics were analyzed using the pseudo-first-order, pseudo-second-order, intra-particle diffusion, and Boyd kinetic models. The findings suggest that the adsorption kinetics followed the pseudo-second-order model. Additionally, the film diffusion was found to be the rate-determining step for the adsorption of BPA on all of the activated carbons. The data for adsorption equilibrium were tested using the Langmuir, Freundlich, and Sips equations, with results indicating that the Langmuir model was the most applicable. The capacity of activated carbons to adsorb BPA was dependent on their surface area. Higher BET surface areas resulted in increased adsorption. The birch-derived AC activated by NaOH had a monolayer adsorption capacity of 1.980 mmol/g, while the AC from black cherry activated with KOH had 2.195 mmol/g. The adsorption of BPA was pH-dependent, and no effect of ionic strength was observed. The activated carbons had very high adsorption capacities, indicating that stump wood is an excellent precursor for the production of highly effective adsorbents.

Modeling of adsorptive treatment of lead (II) ions contaminated effluents using cashew nut shell alkali activated carbon: Batch kinetic, isothermal and thermodynamic studies

The numerical study of the decontamination of lead(II) ions-rich effluent employing activated carbon derived from cashew nut shell was the central focus of this work. Chemical activation with zinc chloride (ZnCl2) was used to produce powdered activated carbon at optimized activation conditions of impregnation ratio (0.531), activation temperature (1083 K) and activation time (63min). The physiochemical properties of raw and activated cashew nut shell were determined using Fourier transform infrared spectroscopy, scanning, X-ray diffractor (XRD), scanning electron microscopy (SEM), and Brunauer-Emmet-Teller (BET) analyses. Batch adsorption experiments were performed at varied process conditions of temperature (303–323) K, contact time (5–80min), and initial lead(II) ion concentrations (100–400 mg.L−1). The adsorption behavior of the batch–type operation was mathematically described in the form of non-linear parabolic partial differential equations (PDE’S) incorporating film, pore and surface diffusion mechanisms. The batch mathematical model was solved by implementing a custom MATLAB program-OkiyNwabannebatch and calibrated to predict the desired response (percentage removal) using measured adsorption data. The equilibrium adsorption, kinetics and thermodynamics of lead(II) ions adsorption onto activated cashew nut shell were also assessed using nonlinear isotherm, kinetic and thermodynamic models. Sensitivity analysis unveiled that temperature with sensitivity value of 37.31 % had a predominant effect on the model performance. The simulated equilibrium data was well explicated by the Freundlich model for lead(II) ions adsorption onto activated cashew nut shell. The pseudo-second order kinetic model best reproduced the simulated adsorption data for lead(II) ions uptake by cashew nut shell adsorbent. Likewise, the kinetic data followed Boyd model, indicating that the adsorption process is controlled by external (film) diffusion for the uptake of lead(II) ions by alkali activated cashew nut shell. Thermodynamic analysis using the Gibbs and Van’t Hoff’s models indicated that lead(II) ions adsorption by modified cashew nut shell is spontaneous and exothermic. The physical nature of the adsorption process was elucidated from the low values of the isosteric heats of adsorption (ΔHX) evaluated (<80 kJ mol−1). This study showed that zinc chloride activated cashew nut shell has good potential to be used as a cost-effective and efficient adsorbent for the uptake of lead(II) ions from aqueous solution.

Facile synthesis and characterization of magnetic iron oxide (Fe3O4)-loaded cationic amino-modified passion fruit shell nanocomposite and their application in removal of anionic Alizarin Red S dye from aqueous medium

A newly synthesized magnetic nanocomposite, iron oxide-loaded cationic amino-modified passion fruit shell (Fe3O4@CMPFS), was utilized as a sorbent to eliminate anionic Alizarin Red S (ARS) dye from the wastewater. The Fe3O4@CMPFS was characterized to confirm the properties by physicochemical methods such as VSM, XRD, pHPZC, BET, FTIR, and FE-SEM with EDX. Batch tests were conducted to study the adsorption process, focusing on factors like the solution pH (from 2.0 to 11), amount of Fe3O4@CMPFS (from 10 to 80 mg/30 mL), contact duration (from 0 to 240 min), agitation speed (from 0 to 400 rpm) and temperature (from 298 to 328 K). The optimal conditions for attaining a 92.3 % removal efficiency were found to be a pH of 2.0, 60 mg of Fe3O4@CMPFS, a contact time of 60 min, agitation at 250 rpm, and a temperature of 298 K. The Fe3O4@CMPFS was determined to have a pHPZC value of approximately 6.2. The kinetic data indicated that the adsorption of ARS onto Fe3O4@CMPFS followed the pseudo-second-order model (high R2 = 0.9919; low SSE = 1.5) and was governed by film and intraparticle diffusion mechanisms. Furthermore, the isotherm data fit well with the Langmuir model (high R2 = 0.9983; low χ2 = 12.69), suggesting monolayer adsorption behaviour. The maximal sorption uptake of ARS on the Fe3O4@CMPFS was determined to be 233.4 ± 3.174 mg/g at 298 K through the Langmuir model. The estimated ΔH° (18.3 kJ/mol) and ΔS° (82 J/mol K) indicate the endothermic and enhanced randomness at the adsorbent/solute interface. The negative ΔG° values (−6.2298 to −8.7283 kJ/mol at 298–328 K) confirm spontaneous sorption dominated by physisorption. The Fe3O4@CMPFS composite had good recyclability and was easy to separate from water, which maintained excellent adsorption performance after eight regeneration cycles. The superb adsorption efficiency and recycling performance of Fe3O4@CMPFS provide a prospect way to remove ARS dye from industrial effluents.

Effect of conditioners used for sludge dewatering on the adsorption performance of sludge-derived adsorbent

Converting waste activated sludge into adsorbent is a promising alternative for sludge valorization. While various conditioners are widely employed in sludge conditioning and dewatering processes, the influence of these conditioners on the properties of sludge derived adsorbents remains largely unexplored. Four conditioners, including FeCl3, CaO, polyacrylamide, FeSO4·7 H2O/Na2S2O8, were used for sludge conditioning, and the sludge dewaterability and the adsorption performance of the resultant adsorbents were evaluated. The sludge dewaterability was markedly improved by the conditioners in a descending order as polyacrylamide, FeCl3, FeSO4·7 H2O/Na2S2O8, and CaO. The type of conditioner highly influenced the adsorption ability of the sludge adsorbent: FeSO4·7 H2O/Na2S2O8 enhanced the adsorption ability, while others deteriorated it. Infrared spectra, pore size distribution, and micromorphology analysis of the adsorbents suggest that: FeCl3 reduced mesopores through strong electrostatic interactions; CaO acted as a physical barrier for adsorption; polyacrylamide reduced the adsorbent surface area through hydrogen bond-driven bridging and potentially forming polymeric barrier; FeSO4·7 H2O/Na2S2O8 disrupted the sludge flocs and exposed abundant adsorption sites, promoting the adsorbent performance markedly. FeSO4·7 H2O/Na2S2O8 conditioning was thus beneficial to both sludge dewatering and adsorption. Adsorption of methylene blue by FeSO4·7 H2O/Na2S2O8-conditioned sludge adsorbent was best described by the pseudo-second-order model and Langmuir model, indicating the dominance of monolayer chemisorption. The adsorption mainly occurred in the mesopores of the adsorbent, with hydroxyl group and carbonyl in carboxyl group as the main binding sites. Both film and pore diffusion contributed to the adsorption rate, with pore diffusion serving as the main rate limiting step. Results highlight the beneficial effect of destructive conditioning method on sludge adsorbent performance.

Preparation and characterization of chitosan graphene oxide nanocomposite for the removal of 17-β-estradiol sulfate from water: kinetics, thermodynamics and simulation studies

The presence of 17-β-estradiol sulfate residue in water is of great concern due to its hazardous nature (endocrine disruptor and carcinogen). For this, chitosan was used with graphene oxide to prepare chitosan graphene oxide nanocomposite. This material was characterized and used as an adsorbent for the removal of 17-β-estradiol sulfate residue in water. This adsorbent showed a rapid, efficient, and environmentally friendly method of 17-β-estradiol sulfate removal from water. The optimal conditions for maximum removal were 93.6% (4.68 mg/g) with 2500 µg/L of 17-β-estradiol sulfate, 30 min of agitation, 0.50 g/L of graphene oxide chitosan nanocomposite, a pH of 7.0, and temperature of 25 °C. The thermodynamic parameters confirmed the spontaneity and exothermic nature of the 17-β-estradiol sulfate uptake process. The kinetic study revealed a first-order reaction, with the mechanism of uptake attributed to liquid film diffusion. The supra-molecular interaction between β-estradiol and graphene oxide chitosan nanocomposite was elucidated, highlighting the pivotal role of two hydrogen bonds with binding affinities of −6.80 and −7.03 kcal/mole for the first and second hydrogen bonds. This method is speedy, efficacy, and environmentally friendly; making it applicable for the removal of β-estradiol from water in diverse water systems.

Biosorption of Cr(VI) by Theobroma cacao pericarp.

This paper reports a comprehensive study of Theobroma cacao pericarp (TCP) residues, which has been prepared, characterized, and tested as an inexpensive and efficient biosorbent of Cr(VI) from aqueous solutions. The maximum adsorption capacity of TCP obtained at optimal conditions (pH = 2, dose = 0.5g L-1, C0 = 100mg L-1) was qmax = 48.5mgg-1, which is one of the highest values reported by the literature. Structural and morphological characterization has been performed by FTIR, SEM/EDX, and pHPZC measurements. FTIR analysis revealed the presence of O-H, -NH, -NH2, C = H, C = O, C = C, C-O, and C-C functional groups that would be involved in the Cr(VI) biosorption processes. The experimental equilibrium data of biosorption process were successfully fitted to non-linear Langmuir (R2 = 0.95, χ2 = 11.0), Freundlich (R2 = 0.93, χ2 = 14.8), and Temkin (R2 = 0.93, χ2 = 14.7) isotherm models. Kinetics experimental data were well adjustment to non-linear pseudo-2nd (R2 = 0.99, χ2 = 2.08)- and pseudo-1st-order kinetic models (R2 = 0.98, χ2 = 2.25) and also to intra-particle Weber-Morris (R2 = 0.98) and liquid film diffusion (R2 = 0.99) models. These results indicate that Cr(VI) biosorption on heterogeneous surfaces as well as on monolayers of TCP would be a complex process controlled by chemisorption and physisorption mechanisms. The thermodynamic results indicate that the Cr(VI) biosorption on TCP is a feasible, spontaneous, and endothermic process. TCP can be regenerated with NaOH and reused up to 3 times.

Removal of 4-(2-pyridylazo) resorcinol and Arsenazo-III from liquid waste solutions using Penicillium oxalicum: Gamma irradiation studies

The current investigation involved the isolation of a fungal strain from liquid radioactive wastewater, which was then identified as Penicillium oxalicum and was employed to remove 4-(2-pyridylazo) Resorcinol (PAR) and Arsenazo-III (Ar-III) from liquid waste solutions. The physicochemical properties of the biosorbent fungi were analyzed using SEM and FT-IR. The biosorption effectiveness of PAR and Ar-III was investigated under several experimental settings, including pH values, adsorption times, biosorbent weight, initial dye concentrations, and reaction temperatures. The Langmuir isotherm model describes the adsorption isotherms well, with capacities of 10.88 and 11.96mgg-1 for PAR and Ar-III, respectively. The sorption of PAR and Ar-III exhibited E values of 19.84 and 17.84kJ/mol, respectively, indicating that the process is chemical adsorption. The pseudo-second-order kinetic model was determined as the most accurate representation of the biosorption kinetics. Both film diffusion and intra-particle diffusion describe the diffusion of coloring reagents through the biosorbent material. The thermodynamic analysis showed that chemical adsorption regulated the biosorption of the coloring reagent on the biosorbent material, while exothermic and spontaneous biosorption of PAR and Ar-III was observed. The extensive decolorization and easy operating circumstances demonstrated the promise of Penicillium oxalicum for the biological treatment of textile dyes.