Second-order Kinetics Research Articles

Degradation and Transformation Mechanisms of Zanthoxylum Alkylamides Exposed to UVB Light.

Zanthoxylum oleoresin, a concentrated extract derived from Zanthoxylum bungeanum, is rich in non-volatile, intensely flavorful substances and amide compounds, such as hydroxy-α-sanshool, hydroxy-β-sanshool, and hydroxy-ε-sanshool. The production process of Zanthoxylum oleoresin remains unstandardized, and there is still a lack of research on the precise classification and quantification of its key chemical constituents, as well as the stability of these compounds when produced using different extraction methods. This study utilized preparative liquid chromatography to extract and purify amide compounds from Zanthoxylum oleoresin, successfully isolating three sanshools: hydroxy-α-sanshool, hydroxy-β-sanshool, and hydroxy-ε-sanshool. The stability of three these sanshools under UVB irradiation in different solvents was explored in UVB-simulated sunlight conditions to investigate the degradation or transformation mechanism of Zanthoxylum alkylamides under UVB irradiation. The findings indicate a rapid decrease in the hydroxy-α-sanshool content under UVB ultraviolet light, aligning with the second-order kinetics. This study revealed alterations in the contents of hydroxy-α-sanshool, hydroxy-β-sanshool, and hydroxy-ε-sanshool and the formation of a new compound following exposure to UVB light. This new compound, along with the three sanshools, possesses a uniform m/z 264 and shares similar chemical structures. Further analysis also uncovered that these compounds are capable of undergoing isomerization reactions under UVB irradiation. This demonstrates that UVB irradiation of certain intensities can modify the concentrations and chemical structures of these Zanthoxylum alkylamides. These insights offer crucial guidance for future studies on the processing and preservation of Zanthoxylum alkylamides and their derivatives.

Taguchi optimisation studies for removal of hexavalent chromium using magnetic chitosan crosslinked tripolyphosphate/TiO2 hybrid nanocomposite

ABSTRACTChromium contamination has been a concern over decades owing to its carcinogenic and determinantal impact on human health. The study aims to develop an easy to synthesise environment-friendly material capable of removing Cr(VI) from phenolic wastewater. To this end, a novel hybrid composite in the form of magnetic chitosan crosslinked tripolyphosphate functionalised with titanium dioxide (CFTPP/TiO2) was prepared using a simple reduction-precipitation technique. Taguchi optimisation study showed that maximum Cr(VI) adsorption could be achieved at optimum synthesis conditions of 90% CFTPP concentration, duration 60 min at room temperature. Similarly, the taguchi optimised adsorption process yielded maximum Cr(VI) removal of 94.36% at pH (2), composite dose (0.8 g), and initial chromium (20 mg L−1) in an equilibrium time of 270 min. Successful formation of composite having a rough surface with broad pore size distribution was further verified using characterisation techniques like FTIR, FESEM-EDX, BET and XRD. Adsorption studies showed that process is mostly chemisorption aligning best with Freundlich isotherm and pseudo second-order kinetics having the maximum adsorption capacity of 82.89 mg g−1. The composite showed good reuse potential and maintained removal efficiencies around 80% even after five cycles. It was observed that %CFTPP concentration in the composite played a significant role in the behaviour of the composite as a photocatalyst in which 35% CFTPP demonstrated higher photocatalytic performance. Higher Cr(VI) removal efficiencies of 70.88% and 98.74% were attained under both visible and UV light respectively on treating 50 mg L−1 Cr(VI) in an irradiation time of 420 min. The research findings demonstrate that CsFe@TPP/TiO2 composite as an environment-friendly material is capable of providing synergistic effect in adsorption and oxidation of chromium contaminated wastewaters.

Cooperation of ferrous ions and hydrated ferric oxide for advanced phosphate removal over a wide pH range: Mechanism and kinetics

Excessive phosphate loading leads to eutrophication problems in rivers or lakes and causes serious environmental and economic damages, urging new technologies to reduce effluent phosphate at ultra-low levels. As a promising candidate, adsorption over metal oxides is restricted by the released hydroxide anions (OH−) through ligand exchange, which elevates pH and suppresses further adsorption. In this contribution, we found ferrous ions (Fe2+) significantly enhance phosphate removal over hydrated ferric oxide (HFO) in a wide pH range via a cooperation of adsorption and precipitation, and clarified the synergistic mechanism by a series of characterizations and the modified models of adsorption isotherms and pseudo second-order kinetics. The combination of Fe2+and HFO removed up to 51.7 mg/g of phosphate at pH 4.0, with 43.6 and 8.1 mg/g attributing to adsorption and precipitation, respectively. In comparison to HFO alone, HFO/Fe2+ system achieved 2.2-fold increase in phosphate removal, 1.9-fold increase in phosphate adsorption capacity, and 3.4-fold increase in phosphate removal rate. The enhancement is understood by that hydroxide anions released from ligand exchange over HFO are neutralized by protons produced from the oxidative precipitation of ferrous ions. The HFO/Fe2+ combining system is promising to realize advanced removal of low concentration phosphate containing wastewater, and these findings bring new insights for the development of novel phosphate removal technologies through a rational design of a combination process.

Kinetic Study of the Acylation Reaction of Dibutylcarbamyl Chloride and Dibutylamine

AbstractTetrabutylurea (TBU) is mainly used as a working liquid in the preparation of hydrogen peroxide via the anthraquinone process. It is reported that dibutylamine (A) reacts with dibutylcarbamyl chloride (B) to produce TBU in the presence of triphosgene, which is the decisive step of the reaction. In this study, we aimed to investigate the reaction kinetics of the decisive step to gain more insight into the reaction. The reaction order as well as the pre-exponential factors (A) and the activation energies (E a) were determined. The kinetic study suggested that the total order of the reaction is second. E a = 5.4 × 104 J/mol, A = 1.5257 × 107 L/(mol × min), calculated through a second-order kinetics model. The accuracy and applicability of the kinetic model were verified by serval experiments, showing that enhancing reaction temperature could shorten the reaction time and increase the conversion rate.

Study on Influencing Parameters of Total Phosphorus Degradation in Cattle Farm Wastewater by Electrocoagulation Using Magnesium, Aluminum, and Iron Electrodes

Magnesium, aluminum, and iron electrode were common anodes in electrocoagulation (EC), but there were few studies comparing the influence of operating parameters on the reaction and the effects of these three different anodes in removing total phosphorus (TP) in cattle farm wastewater (CFW). This study used these three different electrodes as the anode of the electrocoagulation method. The operating parameters such as electrode distance (ED), initial pH, and voltage were examined by the Taguchi method and single-factor method. The result of Taguchi analysis shows that voltage has a significant impact on TP removal of magnesium (Mg) and aluminum anode (Al), and ED has a significant impact on TP removal of magnesium and iron anode (Fe). Among the three operating parameters, the first in the order of the impact on the reaction was ED because ED has the greatest influence on the dissolution of the anode. The result of single-factor analysis shows that the optimum conditions of Mg were ED = 3 cm, voltage = 5 V, pH = 7, Al were ED = 3 cm, voltage = 5 V, pH = 5, and Fe were ED = 3 cm, voltage = 5 V, and pH = 7. For Mg and Fe, the voltage and reaction results follow the second-order reaction kinetics, and Al is the first-order reaction kinetics. Through comparison of the three anodes, it was found that Al worked best in actual CFW. It was noted that the conditions obtained by the single-factor method were more economical in the treatment of actual CFW. This work could provide reference for determining the extent of the influence of operating parameters when other contaminants are removed, and provide reference for comparing the other anodes in EC.

Dual functional porous organic polymer: Reversible iodine capture and selective sensing of picric acid

The development of porous organic materials for removing radiotoxic iodine from nuclear plant waste is significantly relevant to environmental remediation as well as the detection of trace amounts of nitroexplosive picric acid for environmental safety is challenging. To achieve reversible iodine adsorption by the porous material, we have synthesized a highly stable porous organic polymer POF-1 by Schiff base condensation of tris(4-aminophenyl)methane and 2,2′-bithiophene-5,5′-dicarbaxaldehyde under microwave irradiation. POF-1 showed high affinity towards iodine adsorption due to electron-rich sulfur and nitrogen atoms in the porous structure which interact with iodine and form polyiodide ions by electrostatic interactions. POF-1 showed a remarkable iodine uptake capacity of 4.25 g g−1 in the vapor phase and could efficiently remove iodine from an iodine-cyclohexane solution with an adsorption efficiency of 141.0 mg/L. The iodine adsorption follows Langmuir's isothermal model i.e. monolayer adsorption and Pseudo second-order kinetics. POF-1 exhibited good recyclability towards reversible iodine capture even after five cycles. Furthermore, the luminescence characteristic of POF-1 has been employed for the selective detection of picric acid with high sensitivity with a detection limit of 8 μM among a range of nitroaromatic. The Fluorescence quenching mechanism is mainly attributed to photo-induced electron transfer and the inner filter effect.

Efficient multi-ion adsorption using chitosan-malonic acid film: Enhancement using response surface methodology

The objective of this research is to conduct a comprehensive characterization of chitosan while also improving its attributes by crosslinking with malonic acid, with a focus on its efficacy in removing hexavalent chromium, arsenite and fluoride ions. Crosslinking chitosan in 1:0.5 mass ratio forming a film led to substantial enhancement in confiscation of these target pollutants. The characterization of the adsorbent involved several techniques, including FT-IR, TGA-DSC, SEM-EDX, XRD, and BET surface area analysis. In batch adsorption experiments, Chitosan-malonic acid (CMA) was employed to remove CrVI, AsIII and F− from aqueous solutions. These experiments were conducted while varying conditions such as pH, dosage, concentration, temperature, and time. Through the implementation of response surface methodology (RSM), parameters were optimized, resulting in over 95% removal of CrVI, AsIII and F− ions. The isotherm and kinetics data demonstrated a good fit with the Langmuir isotherm model and pseudo second-order kinetics, respectively. According to the Langmuir isotherm, the maximum adsorption capacities on CMA for CrVI, AsIII and F− were determined to be 687.05 mg g−1, 26.72 mg g−1 and 51.38 mg g−1 respectively under optimum pH of 4.0, 7.0 and 5.0 respectively under ambient temperature of 303 K. Thermodynamic analysis indicated that the adsorption process was spontaneous and driven by enthalpy. The regenerability of the adsorbent was validated through five adsorption-desorption cycles, signifying its reusability. An assessment of the adsorbent's sustainability indicated an eco-friendly synthesis, as reflected by the low E-factor value of 0.0028.

CQTDs/SiO2NPs nanocomposite for Pb2+ and Cd2+ remediation and reuse applications in LFP detection and photocatalysis

Due to their propensity to bioaccumulate, lead and cadmium, two hazardous heavy metals, can seriously disrupt the ecosystem. These metals have the potential to cause major environmental and human health problems. Herein, carbon quantum dots were used to coat silica nanoparticles to create a brand-new nanocomposite called CQTDs/SiO2NPs. Cd2+ and Pb2+ ions were effectively removed from water and preconcentrated using the produced nanocomposite. The novel nanocomposite was characterized using SEM, TEM, FT-IR, XRD, and XRF. The bending vibration of Si–O–Si/Si–O–C and Si–OH are responsible for the FT-IR bands that were detected in the nanocomposite at 1041 and 954 cm−1, respectively. XRD demonstrated that the silica nanoparticles were amorphous. Additionally, SEM and TEM analysis revealed the nanocomposite's shape, which was determined to be spherical with minimal agglomeration.While XPS demonstrated the binding energy of the functional group present in the composite and further confirmed the metal loaded onto the adsorbent. On CQTDs/SiO2NPs nanocomposite, the optimum pH and dosage were 8 and 0.2 g respectively. The highest Cd2+ and Pb2+ ion adsorption capabilities are 14.87 and 38.49 mg g −1, respectively. The use of the nanocomposite resulted in an exothermic, physical and non-spontaneous adsorption that closely resembled the Langmuir equilibrium isotherm and the second-order kinetics. The metal loaded adsorbent used as a fingerprint labelling agent displayed clear fingerprint ridges and degraded the sulfamethoxazole (SMX) for up to 90 %. The prepared composite has proven to be coherent in heavy metal removal and can thus be reused in Latent fingerprint and photocatalysis applications. The reuse of the nanocomposite in the above-mentioned applications is an alternative solution to avoid secondary pollution.

Detection and sorption of heavy metal ions in aqueous media using Zn-based luminescent metal-organic framework

In this study, we present the synthesis and comprehensive characterisation of a novel, luminescent Metal-Organic Framework (MOF) denoted as PUC7, derived from Zn(NO3)2·6H2O, 1,2-di(4-pyridyl)ethylene, and 2-amino-terephthalic acid through solvothermal method. The PUC7 was successfully characterised using many techniques, including single crystal X-ray diffraction, powder X-ray diffraction, FTIR spectroscopy, BET surface area analysis, FESEM imaging, XPS, UV–visible spectroscopy, and zeta potential measurements. Remarkably, PUC7 exhibited high luminescence properties and water stability. The luminescence properties were utilised for the detection of heavy metal ions. Consequently, PUC7 displayed exceptional selectivity and sensitivity towards W6+ and V5+, with impressively low detection limits of 0.17 μM and 0.22 μM, along with high quenching constant values of 2.5 × 105 M−1 and 1.1 × 105 M−1, respectively. Additionally, we explored PUC7′s proficiency in removing W6+ and V5+ ions from aqueous solution, revealing maximum adsorption efficiencies of 476.2 mg/g and 460.8 mg/g, respectively, fitting well with the Langmuir adsorption model and exhibiting second-order kinetics. Encouragingly, PUC7 demonstrated reusability for up to five cycles in removing W6+ and V5+ ions. Altogether, this research underscores the potential of PUC7 as a versatile and promising tool for efficiently detecting and removing W6+ and V5+ ions from water, with implications for environmental remediation and water purification applications.

Ragone plots of material-based hydrogen storage systems

This paper presents an analytical assessment of the energy–power relationship for different material-based hydrogen storage systems, namely Metal Hydrides (MHs) and Liquid Organic Hydrogen Carriers (LOHCs). Storage systems are subjected to continuous flow discharge processes through suitable control systems to meet constant specific power demands of end users. By means of reasonable assumptions, analytical expressions of the time-dependent degree of hydrogenation (representing the state of charge) are obtained to find the amount of hydrogen discharged (delivered energy) as a function of flow rate (required power). The results are first presented in the form of dimensionless Ragone plots to highlight the dependence of the amount of discharged hydrogen on the required mass flow rate. Numerical examples are presented for a couple of illustrative systems. Moreover, these analytical expressions are shown to produce very similar results to those obtained with the solution of a dynamic model, including, beyond the kinetic equation, mass and energy conservation applied to the reactor. The results show a significant impact of power demand on the released hydrogen for most systems, similar to that of capacitors, due to the dependence of the rate of reaction on the degree of hydrogenation: as a consequence, the amount of energy that can be delivered to an end user decreases substantially with an increase in the required power, resulting in a poor utilisation factor. Based on these results, MHs exhibit almost first-order kinetics and can sustain efficient discharge with theoretical specific power up to 2kW/kg (rate of chemical energy delivered per unit mass of active substance), corresponding to a discharge duration of the order of 0.25h; some LOHCs are limited by second-order kinetics and the specific power should be lower than 1kW/kg, with discharge durations that must be above 2hour, to ensure effective utilisation of stored hydrogen.

Adsorption behavior of trace elements of 90Sr on MnO2–ZrO2 loaded with polyacrylonitrile polymer from aqueous solutions

A MnO2–ZrO2-polyacrylonitrile (MnO2–ZrO2-PAN) composite ion exchanger was produced and its properties were examined by Fourier-transformed infrared spectroscopy, scanning electron microscopy, The BET (Brunauer, Emmett and Teller) surface area, X-Ray diffraction analysis and thermogravimetric analysis. The adsorption of Strontium (Sr) from solutions by MnO2–ZrO2-PAN composite was studied thru batch experiments. The distribution Coefficient of Sr (II) on the composite sorbent was investigated against pH, interaction time, and primary concentration ion. To study the kinetics of adsorption, Pseudo-first-order and Pseudo second-order adsorption kinetics were studied and the results revealed that adsorption kinetics better fit to the pseudo-second-order model. Three iso-temperature models, Langmuir, Freundlich, and Temkin were applied to fit the experimental results. Among those models, Langmuir revealed the most suitable one with minimum deviation. The created composite exhibited strong compatibility to the elimination of Y (III), Ni (II), Pb (II), and Co (II) from radioactive waste streams. On the other, it is evident from the data that the quantifiable extraction of Sr (II) ions from Zr (IV), Mo (VI), and La (III) is feasible. MnO2–ZrO2 Loaded with (PAN) Polymer was figured out to have high ion exchange capacity and thermal stability and selectivity for strontium.

Adsorption of trace heavy metals through organic compounds enriched biochar using isotherm adsorption and kinetic models

Trace heavy metals such as copper and nickel, when exceeds a certain level, cause detrimental effects on the ecosystem. The current study examined the potential of organic compounds enriched rice husk biochar (OCEB's) to remove the trace heavy metals from an aqueous solution in four steps. In 1st step, biochar’ physical and chemical properties were analyzed through scanning electron microscope (SEM) and Fourier transforms infrared spectroscopy (FTIR). In the 2nd step, two biochar vis-a-vis glycine, alanine enriched biochar (GBC, ABC) was selected based on their adsorption capacity of four different metals Cr, Cu, Ni and Pb (chromium, copper, nickel, and lead). These two adsorbents (GBC, ABC) were further used to evaluate the best interaction of biochar for metal immobilization based on varying concentrations and times. Langmuir isotherm model suggested that the adsorption of Ni and Cu on the adsorbent surface supported the monolayer sorption. The qmax value of GBC for Cu removal increased by 90% compared to SBC (Simple rice husk biochar). The interaction of Cu and Ni with GBC and ABC was chemical, and 10 different time intervals were studied using pseud first and second-order kinetics models. The current study has supported the pseudo second-order kinetic model, which exhibited that the sorption of Ni and Cu occurred due to the chemical processes. The % removal efficiency with GBC was enhanced by 21% and 30% for Cu and Ni, respectively compared to the SBC. It was also noticed that GBC was 21% more efficient for % removal efficiency than the CBC. The study's findings supported that organic compound enriched rice husk biochar (GBC and ABC) is better than SBC for immobilizing the trace heavy metals from an aqueous solution.

Formation of tannic acid-calcium polymeric network in pore solution: Characterization and kinetics

This study investigates the changes of tannic acid (TA) at varying concentrations in cement pore solution. Interestingly, TA spontaneously forms nanosheet tannic acid-calcium polymeric networks (TA-Ca) by interacting with Ca2+. Spectral, thermal, ionic and organic carbon analyses determine the composition and structural characteristics of these networks and detail the formation mechanism. The networks are connected via hydrogen bonding, C–C coupling and complexation. Moreover, network composition, structure and formation are closely dependent on TA concentration. At low concentrations, crystalline coordination polymer networks form, following second-order kinetics (key factor: Ca2+ concentration). At high concentrations, amorphous C–C coupled polymer networks form, following first-order kinetics (key factor: catalytic oxidation of Ca2+). This study aims to elucidate the reaction and mechanism of TA in cement paste, providing a novel theoretical basis for applying renewable bio-admixtures in sustainable construction.

Removal of aflatoxin B1 from contaminated milk and water by nitrogen/carbon-enriched cobalt ferrite -chitosan nanosphere: RSM optimization, kinetic, and thermodynamic perspectives

In view of the feed/foods inevitably contaminated by toxic and carcinogenic aflatoxin B1 (AFB1), efficient mesoporous metformin-chitosan/silica‑cobalt ferrite nanospheres (Mt-CS/CFS NSs) was prepared to remove AFB1 from aqueous/non-aqueous media. The morphological, functional, and structural characteristics and adsorption properties of C/N-enriched CS/CFS were investigated systematically. The interactive operating variables (temperature (5.0–35 °C); time (10–100 min); AFB1 dose (50–100 μg/mL); and Mt-CS/CFS dosage (0.5–3.5 mg) were optimized via the Box-Behnken design (BBD), which demonstrated good agreement between the experimental data and proposed model. The adsorption efficiency in artificially contaminated cow's milk as well as aqueous environment reached over 91.0 % in a wide pH range (3.0–9.0), without significant change in the nutritional value of milk. Freundlich isotherm and second-order adsorption kinetics were regarded as the most suitable models to fit the adsorption results, and the adsorption rate is dominated by the intra-particle diffusion and boundary layer diffusion. Thermodynamic analyses proved that the process was spontaneous and exothermic. The adsorption mechanism could be explained as physisorption via hydrogen bonding, n-π interaction, and hydrophobic/hydrophilic interactions. The porous Mt-CS/CFS NS derived from chitosan nanoparticles is therefore outstanding adsorbent, offering great adsorptive performance and recycabilities, which impedes economic losses in the food industry.

Reactivity and reaction pathways of peroxymonosulfate and peroxydisulfate with neonicotinoid insecticides

Neonicotinoid insecticides (NNIs), which have been detected across diverse aquatic environments, have sparked substantial concerns regarding their potential adverse ecological and health risks. In this study, the removal of NNIs by unactivated peroxymonosulfate (PMS) and peroxydisulfate (PDS) was systematically investigated. Results showed that PMS/PDS direct oxidation is mainly responsible for the degradation of imidacloprid (IMD), and the degradation kinetics can be well described by a second-order kinetics model, first-order in both IMD and PMS/PDS concentration. The species-specific reaction rate constants of HSO5− and SO52− with IMD were calculated to be 429.36 ± 15.41 M−1h−1 and 9.72 ± 35.48 M−1h−1, while the corresponding rate constant between S2O82- and IMD is 25.04 ± 3.04 M−1h−1. Over 100 transformation products in the degradation of IMD by PMS/PDS were identified by HPLC/Q-Orbitrap HRMS, and five major reaction pathways were proposed thereafter: hydroxylation on imidazolidine ring, olefin reaction on imidazolidine ring, desnitro reaction on nitroguanidine moiety, and two chain-breaking reactions between imidazolidine ring and chloro-pyridyl moiety. Toxicity evaluation on the transformation products found that their ecotoxicity is various at a wide range with an overall indeterminacy, while their bioconcentration factors show a definite decrease. The reactivity of six NNIs with PMS/PDS was found varied by structures but generally low, indicating that in-situ oxidation with unactivated PMS/PDS is safe but inefficiency for the mitigation of NNIs. It is thus suggested that further investigations into activated PMS/PDS systems involving radicals promise enhanced remediation of NNIs, and fundamental data in this study has laid the groundwork.

Ultra-fine potassium hexacyanoferrate(II) nanoparticles modified ZIF-67 for adsorptive removal of radioactive strontium from nuclear wastewater

Development of a material with high adsorption capacity and selectivity for removal of strontium ion (Sr2+) from nuclear wastewater is a challenge. Herein, dodecahedral zeolitic imidazolate frameworks-67 (ZIF-67) was successfully modified by potassium hexacyanoferrate(Ⅱ) (K4Fe(CN)6) nanoparticles, and used as an effective adsorbent for Sr2+ removal from model wastewater. In construction of adsorbent, methanol was used as the medium for assembly of ultra-fine and uniform 25 nm of K4Fe(CN)6 nanoparticles on ZIF-67, well maintaining the original dodecahedral morphology and mesoporous structure of ZIF-67 crystal. N in 2-methylimidazole (2-MI) bonded with Co to generate ZIF-67, while the unsaturated Co in ZIF-67 bonded with N in K4Fe(CN)6 to form spherical nanoparticles. Specific surface area of ZIF-67 were regulated by K4Fe(CN)6 to an appropriate value of 607.464 m2·g−1 for Sr2+ adsorption. Adsorption efficiency of K4Fe(CN)6 modified ZIF-67 for Sr2+ was significantly enhanced to 90 % within 2 h at ambient conditions, due to the improvement in morphology, structure and chemical property of adsorbent. K4Fe(CN)6 modified ZIF-67 exhibited high adsorption selectivity 45 mg·g−1 for Sr2+ in the presence of competing metal ions such as K+, Na+, Mg2+ and Ca2+, and thus achieved 40 mg·g−1 of adsorption capacity for Sr2+ in actual tap water. Adsorption kinetics and isotherms were well fitted with the second-order kinetics and the Langmuir model, respectively, suggesting a chemisorption process. Mechanism studies showed that the surface of ZIF-67 was uniformly covered by ultra-fine nanoparticles, on the outer layer of which K+ ions were distributed as the adsorption sites for ion exchange with Sr2+.

Myrica esculenta Leaf Extract-Assisted Green Synthesis of Porous Magnetic Chitosan Composites for Fast Removal of Cd (II) from Water: Kinetics and Thermodynamics of Adsorption.

Heavy metal contamination in water resources is a major issue worldwide. Metals released into the environment endanger human health, owing to their persistence and absorption into the food chain. Cadmium is a highly toxic heavy metal, which causes severe health hazards in human beings as well as in animals. To overcome the issue, current research focused on cadmium ion removal from the polluted water by using porous magnetic chitosan composite produced from Kaphal (Myrica esculenta) leaves. The synthesized composite was characterized by BET, XRD, FT-IR, FE-SEM with EDX, and VSM to understand the structural, textural, surface functional, morphological-compositional, and magnetic properties, respectively, that contributed to the adsorption of Cd. The maximum Cd adsorption capacities observed for the Fe3O4 nanoparticles (MNPs) and porous magnetic chitosan (MCS) composite were 290 mg/g and 426 mg/g, respectively. Both the adsorption processes followed second-order kinetics. Batch adsorption studies were carried out to understand the optimum conditions for the fast adsorption process. Both the adsorbents could be regenerated for up to seven cycles without appreciable loss in adsorption capacity. The porous magnetic chitosan composite showed improved adsorption compared to MNPs. The mechanism for cadmium ion adsorption by MNPs and MCS has been postulated. Magnetic-modified chitosan-based composites that exhibit high adsorption efficiency, regeneration, and easy separation from a solution have broad development prospects in various industrial sewage and wastewater treatment fields.

PSXIV-23 In Vitro Evaluation of Protein Kinetics of Soy-Based Ingredients

Abstract Protein kinetics is the evaluation of how quickly a protein can be digested, absorbed, and entered into the portal system. It is more indicative of growth, feed efficiency, and protein deposition than the extent of digestibility per se. Feed ingredients may have the same digestibility (SID), but will differ in the speed of protein digestion. It was therefore decided to evaluate differences in speed of in vitro protein hydrolysis between 9 different soy-based protein ingredients: soybean meal (SBM), enzyme-treated soy protein (ESP), 3 types of soy protein concentrate (SPC), 2 types of extruded soy (ExS), and 2 types of fermented soybean meal (FSBM). Protein hydrolyzation rate was determined in vitro for the soy-based samples (SBM, ESP, SPC1, SPC2, SPC3, ExS1, ExS2, FSBM1, and FSBM2) using a pH-stat method that quantifies progress of protein hydrolysis by indirect measurement of released acid during hydrolysis. For each sample a 10 mL aqueous suspension containing 1 mg N/mL was prepared and adjusted to pH 8.0 at 39 oC using 0.1 M NaOH. One mL of a proteolytic enzyme-solution (trypsin, chymotrypsin and intestinal peptidase) was added to each sample to start protein hydrolysis followed by auto-titration (Mettler Toledo Titrator T9) with 0.1 M NaOH for 120 minutes. The volume of 0.1 M NaOH added to maintain pH at 8 throughout the incubation was recorded and used to calculate degree of hydrolysis (DH). The curve representing DH followed a second-order reaction kinetics and regression was used to estimate the rate constant (k) for each sample. The control sample (SBM) and ESP were analyzed in quadruplicates, the rest of the samples were in duplicates. A pairwise t-test was conducted in the statistical software R (version 4.0.0) to separate means. Significant difference was declared at P < 0.05. Degree of protein hydrolysis increased exponentially for all tested protein ingredients. The speed of protein hydrolysis (k-value) varied with soy-based protein ingredient (Table 1). The greater the k-value is representative of faster protein hydrolysis. There was a numerical 40% increase (P > 0.05) of ESP k-value when compared with the control, which was SBM. The SPC and FSBM samples were significantly less (P < 0.05) when compared with ESP, SBM and ExS2, with ExS1 sample being intermediate. In conclusion, soy processing technique (enzymatic, fermented, extrusion, or alcohol extraction) affects speed of in vitro protein hydrolysis. Therefore, more research is needed to see if these results coincide with protein utilization in vivo.

Competitive adsorption and bioaccumulation of sulfamethoxazole and roxithromycin by sediment and zebrafish (Danio rerio) during individual and combined exposure in water

Antibiotics are extensively used for health protection and food production, causing antibiotic pollution in the aquatic environment. This study aims to determine the bioavailability and bioaccumulation of typical antibiotics sulfamethoxazole (SMX) and roxithromycin (RTM) in zebrafish under environmentally realistic conditions. Four different microcosms, i.e. water, water-sediment, water-zebrafish, and water-sediment-zebrafish were constructed, with three replicates in parallel. The concentrations of SMX and RTM in water, sediment and zebrafish were extracted and analyzed by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) to assess their kinetic behavior and bioavailability. In the water-sediment system, the dissolved concentration of both SMX and RTM decreased with time following the first-order kinetic while their adsorption by sediment increased with time. In the water-zebrafish system, SMX and RTM bioaccumulation was increasing with time following the pseudo second-order kinetics. RTM bioaccumulation in zebrafish (up to 16.4 ng/g) was an order of magnitude higher than SMX (up to 5.2 ng/g), likely due to RTM being more hydrophobic than SMX. In addition, the bioaccumulation factor (BAF) value of SMX in zebrafish was greater than its sediment partition coefficient, while the opposite trend was observed for RTM, demonstrating the importance of antibiotics properties in affecting their bioavailability. Furthermore, increasing dissolved organic carbon concentration in water reduced SMX bioaccumulation, but increased RTM bioaccumulation at the same time. The findings are important in future studies of environmental fate and bioavailability of toxic chemicals with different pollution sources and physicochemical properties.

Adsorptive abatement of Pb2+ and crystal violet using chitosan-modified coal nanocomposites: A down flow column study

Every moment huge amounts of industrial wastewater are contaminating our surface/groundwater sources by discharging into the environment directly. This crude wastewater is the most problematic subject because it is the matrix of hazardous toxicants, which can drastically damage public health-safety. So, it is urgent to purify before discharging/reusing. This study focused on the recent improvement and latent implication of Activated Chitosan-Modified Coal(ACMC) bionanocomposite filter. Here, we briefly described how ACMC was produced and its potential application in the removal of Pb2+ and Crystal Violet (CV) effectively from wastewater. However, the influence of different parameters like initial concentration (20–40 ppm), volumetric flow rate (4–6 mL/min) and bed height (0.4–1.0 cm) were investigated appropriately meanwhile the adsorbent amount was (1.0–2.0 g). The adsorption efficiency and removal percent were strongly correlated with inlet concentration, flow rate, and bed height. The highest removal capacity and percentage were found nearly (243.08 and 238.51)mg/g additionally (78.48 and 82.50)% for Pb2+ and CV. Finally, three well-known column adsorption models namely Thomas, Yoon-Nelson and Adam-Bohart model were applied for the fitting of experimental data which exhibited a decent agreement with all three models that are also suitable for the description of breakthrough curve (BTC) and supports the Langmuir isotherm by following second-order reversible reaction kinetics. Thus this new class of ACMC nanoadsorbents could be beneficially used for the real-time bulk scale industrial wastewater treatment as a suitable replacement of hazardous fossil-based synthetic ones for sustainable environmental protection.