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As a promising green and sustainable coating material, gum was extracted from durian seed to produce eutectogel, which the properties were tunable using natural deep eutectic solvent (NADES). Ten different eutectogels were successfully synthesized using durian seed gum (DSG) and xanthan gum (XG) gelators at different composition (5, 10, 15 %) to gel choline chloride-glucose (1:1), choline chloride-fructose (1:2) and betaine-glucose-water (1:1:1) NADESs. Results revealed that eutectogel was non-Newtonian and weak gel material with excellent thermostability up to 200 °C. When the gum content increased, the resulted eutectogel showed higher viscosity, yield stress, hardness, gumminess, adhesiveness, and weight holding capacity. In overall, choline chloride-fructose (1:2) NADES and 10 % of DSG formed an excellent eutectogel which remained stable and compatible upon 12 weeks of storage. It displayed superior viscoelastic, texture, gases and moisture barrier properties which were beneficial for food coating application. This eutectogel was able to extend the shelf life of fresh-cut apples during storage with lower weight loss and higher total phenolic content (TPC). The potential future of this well-characterized tunable DSG-derived eutectogel includes, but not limited to, food and pharmaceutical industries, smart sensing, flexible wearable electronics, water purification, supercapacitors and batteries.
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Bombacaceae , Conservación de Alimentos , Geles , Gomas de Plantas , Reología , Semillas , Gomas de Plantas/química , Semillas/química , Geles/química , Bombacaceae/química , Conservación de Alimentos/métodos , Viscosidad , Polisacáridos Bacterianos/química , TemperaturaRESUMEN
Three-dimensional heteroatom-doped graphene presents a state-of-the-art approach for effective remediation of pharmaceutical wastewater on account of its distinguished adsorption and physicochemical attributes. Amitriptyline is an emerging tricyclic antidepressant pollutant posing severe risks to living habitats through water supply and food chain. With ultra-large surface area and plentiful chemical functional groups, graphene oxide is a favorable adsorbent for decontaminating polluted water. Herein, a new boron-doped graphene oxide composite reinforced with carboxymethyl cellulose was successfully developed via solution-based synthesis. Characterization study revealed that the adsorbent was formed by graphene sheets intertwined into a porous network and engrafted with 13.37 at% of boron. The adsorbent has a zero charge at pH 6 and contained various chemical functional groups favoring the attachment of amitriptyline. It was also found that a mere 10 mg of adsorbent was able to achieve relatively high amitriptyline removal (89.31%) at 50 ppm solution concentration and 30 °C. The amitriptyline adsorption attained equilibrium within 60 min across solution concentrations ranging from 10 to 300 ppm. The kinetic and equilibrium of amitriptyline adsorption were well correlated to the pseudo-second-order and Langmuir models, respectively, portraying the highest Langmuir adsorption capacity of 737.4 mg/g. Notably, the predominant mechanism was chemisorption assisted by physisorption that contributed to the outstanding removal of amitriptyline. The saturated adsorbent was sufficiently regenerated using ethanol eluent. The results highlighted the impressive performance of the as-synthesized boron-doped adsorbent in treating amitriptyline-containing waste effluent.
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Grafito , Contaminantes Químicos del Agua , Grafito/química , Amitriptilina , Boro , Adsorción , Preparaciones Farmacéuticas , Cinética , Contaminantes Químicos del Agua/química , Concentración de Iones de HidrógenoRESUMEN
ABSTRACTThe current work focused on the intermediate pyrolysis of Bambara Groundnut Shells (BGS-G1), Sweet Sorghum Stalk (SSS), and Shea Nutshells (SNS). These feedstocks are readily available as wastes or by-products from industrial and agricultural activities. The thermo-gravimetric analysis of the biomass samples exhibited decomposition and devolatilization potentials in the temperature range of 110-650°C. The kinetic modelling resulted in the activation energy of BGS G1 being the lowest as 20.43â kJ/mol and SNS as the highest 24.89â kJ/mol among the three biomass samples. Intermediate pyrolysis was conducted in a vertical tube reactor at a temperature of 600°C, with nitrogen flow at 10â ml/min and heating rate ≥ 33.0â/min. The yield of pyrolysis bio-oil was 38.0 ± 6.4, 44.2 ± 6, and 39.7 ± 5.2 wt.% for BGS-G1, SSS, and SNS, respectively. The HHV of bio-oil varied as 23.7 ± 1.8, 23.8 ± 1.8, to 26.5 ± 2.0â MJ/kg for BGS-G1 SSS and SNS respectively. The biochar recorded the lowest HHV for BGS-G1 as 18.8 ± 1.2â MJ/kg and the highest for SNS as 26.4 ± 1.8â MJ/kg. The FTIR of bio-oil revealed significant functional groups, and GC-MS (Gas Chromatography and Mass Spectrometry) analysis categorized the compounds in bio-oils as ketones, furans, phenolics, acids, phenols and benzene derivatives. The physicochemical analysis of the feedstocks and the products (bio-oil and biochar) showed their potential for bioenergy and biochemical (green chemicals) production.
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Water contamination by non-steroidal anti-inflammatory drugs, such as acetaminophen, is an emerging ecological concern. In this study, a new three-dimensional manganese dioxide-engrafted reduced graphene oxide (3D MnO2/rGO) hybrid aerogel was developed for acetaminophen sequestration. The synthesis involved firstly the self-assembly of GO aerogel, followed by thermal reduction and in-situ MnO2 growth by redox-reaction. The aerogel demonstrated interlinked planes with smooth surfaces deposited with MnO2 nanospheres and pores of 138.4 - 235.3 µm width. The influences of adsorbent dosage, initial pH, acetaminophen concentration, temperature and contact time were investigated. It was determined that the adsorption of acetaminophen occurred on uniform sorption sites in the aerogel, as suggested by the best fit of data to the Langmuir isotherm, yielding a maximum adsorption capacity of 252.87 mg/g. This highest adsorption performance of the 3D MnO2/rGO aerogel was attained at a dosage of 0.6 g/L, initial pH of 6.2 and temperature of 40°C. The process kinetics were in-line with the pseudo-first-order and pseudo-second-order kinetics at 10 and 20 - 500 mg/L concentrations, respectively. Thermodynamic assay showed the spontaneity and endothermicity features of the 3D MnO2/rGO-acetaminophen system. The acetaminophen adsorption mechanisms were mainly hydrogen bonding and pore entrapment. Moreover, the as-synthesised aerogel was effectively regenerated using acetone and re-utilised in four adsorption-desorption cycles. Overall, the results highly recommend the implementation of the 3D MnO2/rGO hybrid aerogel for purification of wastewater polluted by acetaminophen residue.
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Residuos de Medicamentos/aislamiento & purificación , Compuestos de Manganeso , Óxidos , Purificación del Agua/métodos , Adsorción , Grafito , Aguas ResidualesRESUMEN
This study investigated the role of humic acid in Fenton reaction for the total petroleum hydrocarbons (TPH) (diesel) in soil. Batch reactions were conducted at varying humic acid dosages and pH. For the lowest molecular weight diesel contaminants, a humic acid dosage of 10 mg/l produced the favourable effect of reducing Fe3+ to Fe2+ which continued for higher humic acid dosages of 50, 100 and 150 mg/l. Conversely, for higher molecular weight diesel contaminants, the negative effect of hydroxyl radicals consumption by the humic acid was more significant than its reduction of Fe3+ to Fe2+. The positive role of humic acid on Fenton reaction increased with increasing humic acid dosage for the overall TPH, with an optimum dosage of 150 mg/l. At higher pH, the removal efficiencies increased or reduced depending on the molecular weight of TPH. The power law and pseudo-first-order kinetic models fitted the experimental kinetic data well.
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Heavy metals released by various industries are among the major pollutants found in water resources. In this research, biosorption technique was employed to remove cadmium (Cd2+) from an aqueous system using a novel biosorbent developed from okara waste (OW), a residue from soya bean-based food and beverage processing. Characterisation results revealed that the OW biosorbent contained functional groups such as hydroxyl-, carboxyl- and sulphur-based functional groups, and the surface of the biosorbent was rough with multiple fissures which might be the binding sites for the pollutant. The effects of dosage, solution pH, initial Cd2+ concentration, temperature and contact time were investigated using batch adsorption mode. The biosorption equilibrium and kinetic were best described by the Langmuir and Elovich models, respectively. The maximum biosorption capacities predicted by the Langmuir model were 10.91-14.80 mg/g at 30-70 °C, and the biosorption process was favourable as evident from 0 < RL < 1. The uptake of Cd2+ by the OW biosorbent was spontaneous and endothermic. The plausible biosorption mechanisms of this study could be ionic exchange, hydrogen bonding and electrostatic interactions. The Cd2+ loaded OW biosorbent could be regenerated using 0.4 M of HCl solution and regeneration was studied for 4 adsorption-desorption cycles. The present investigation supported that OW can be reused as a value-added biosorbent product for the removal of Cd2+ from the contaminated water.
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Metales Pesados , Contaminantes Químicos del Agua , Adsorción , Cadmio/análisis , Concentración de Iones de Hidrógeno , Cinética , Contaminantes Químicos del Agua/análisisRESUMEN
Xanthan integrated graphene oxide functionalized by titanium dioxide was successfully prepared through facile, eco-friendly and cost effective ice-templating technique. The three-dimensional (3D) graphene composite demonstrated relatively high temperature stability, chemical functionalities and porous sponge-like structure. The adsorption of lead was favored by high initial concentration and shaking speed at the operational solution pH. The process equilibrium and kinetic adhered to the Langmuir and pseudo-second-order correlations, respectively. The biomass integrated graphene composite showed maximum adsorption capacities ranging from 132.18 to 199.22 mg/g for 30-70 °C. Moreover, it was highly regenerable under mild conditions (0.1 M hydrochloric acid, 30 °C) and used repeatedly while retaining 84.78% of its initial adsorption capacity at the fifth adsorption-regeneration cycle. With comparatively high lead adsorption capacities, adequate recyclability and environmentally friendliness, the as-prepared 3D graphene composite has high application potential in heavy metal-wastewater separation for protection of the environment and human health.
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Grafito , Contaminantes Químicos del Agua , Adsorción , Biopolímeros , Cinética , Plomo , Polisacáridos Bacterianos , Titanio , Aguas ResidualesRESUMEN
Fast pyrolysis is a potential technology for converting lignocellulosic biomass into bio-oil. Nevertheless, the high amounts of acid, oxygenated compounds, and water content diminish the energy density of the bio-oil and cause it to be unsuitable for direct usage. Catalytic fast pyrolysis (CFP) is able to improve bio-oil properties so that downstream upgrading processes can be economically feasible. Here, calcium oxide (CaO), magnesium oxide (MgO), and zinc oxide (ZnO) were employed due to their potential in enhancing bio-oil properties. The results showed that overall, all three catalysts positively impacted the empty fruit bunch fibre-derived bio-oil properties. Among the catalysts, CaO showed the most favorable effects in terms of reducing the acidity of the bio-oil and anhydrosugar. Thermal stability of bio-oils produced in the presence of CaO was studied as well.
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Frutas , Pirólisis , Biocombustibles , Biomasa , Catálisis , Óxidos , Aceites de Plantas , PolifenolesRESUMEN
The remediation of wastewater requires treatment technologies which are robust, efficient, simple to operate and affordable such as adsorption. Lately, three-dimensional (3D) graphene based materials have attracted significant attention as effective adsorbents for wastewater treatment. The intrinsic properties of 3D graphene structure such as large surface area and interconnected porous structure can facilitate the transport of pollutants into the 3D network and provide abundant active sites for trapping the pollutants. For the synthesis of 3D graphene structure, ice-templating is commonly practiced due to its facile steps, cost effectiveness and high scalability potential. This review covers the ice-templating fabrication technique for 3D graphene based materials and their application as adsorbents in eliminating dyes and heavy metals from aqueous media. The assembly mechanisms of the ice-templating fsynthesis are comprehensively discussed. Further discussion on the fundamental principles, critical process parameters and characteristics of ice-templated 3D graphene structures is also included. A thorough review on the mechanisms for batch adsorption of dyes and heavy metals is presented based on the structures and properties of the 3D graphene materials. The review further evaluates the dynamic adsorption in packed columns and the regeneration of 3D graphene based materials.
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Colorantes/química , Grafito/química , Metales Pesados/química , Contaminantes Químicos del Agua/química , Purificación del Agua/métodos , Adsorción , HieloRESUMEN
Graphene oxide/chitosan aerogel (GOCA) was prepared by a facile ice-templating technique without using any cross-linking reagent for metanil yellow dye sequestration. The adsorption performance of GOCA was investigated by varying the adsorbent mass, shaking speed, initial pH, contact time, concentration and temperature. The combined effects of adsorption parameters and the optimum conditions for dye removal were determined by response surface methodology. GOCA exhibited large removal efficiencies (91.5-96.4%) over a wide pH range (3-8) and a high adsorption capacity of 430.99â¯mg/g at 8â¯mg adsorbent mass, 400â¯mg/L concentration, 35.19â¯min contact time and 175â¯rpm shaking speed. The adsorption equilibrium was best represented by the Langmuir model. GOCA could be easily separated after adsorption and regenerated for re-use in 5 adsorption-desorption cycles thereby maintaining 80% of its adsorption capability. The relatively high adsorption and regeneration capabilities of GOCA render it an attractive adsorbent for treatment of azo dye-polluted water.
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Compuestos Azo/química , Quitosano/química , Grafito/química , Adsorción , Colorantes/química , Geles/química , HieloRESUMEN
The drawbacks associated with chemical skin permeation enhancers such as skin irritation and toxicity necessitated the research to focus on potential permeation enhancers with a perceived lower toxicity. Crude palm oil (CPO) is obtained by direct compression of the mesocarp of the fruit of the oil palm belonging to the genus Elaeis. In this research, CPO and tocotrienol-rich fraction (TRF) of palm oil were evaluated for the first time as skin permeation enhancers using full-thickness human skin. The in vitro permeation experiments were conducted using excised human skin mounted in static upright 'Franz-type' diffusion cells. The drugs selected to evaluate the enhancing effects of these palm oil derivatives were 5-fluorouracil, lidocaine and ibuprofen: compounds covering a wide range of Log p values. It was demonstrated that CPO and TRF were capable of enhancing the percutaneous permeation of drugs across full-thickness human skin in vitro. Both TRF and CPO were shown to significantly enhance the permeation of ibuprofen with flux values of 30.6 µg/cm2 h and 23.0 µg/cm2 h respectively, compared to the control with a flux of 16.2 µg/cm2 h. The outcome of this research opens further scope for investigation on the transdermal penetration enhancement activity of pure compounds derived from palm oil.
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Química Farmacéutica/métodos , Aceite de Palma/análisis , Aceite de Palma/farmacocinética , Absorción Cutánea/efectos de los fármacos , Tocotrienoles/análisis , Tocotrienoles/farmacocinética , Administración Cutánea , Evaluación Preclínica de Medicamentos/métodos , Humanos , Ibuprofeno/análisis , Ibuprofeno/farmacocinética , Técnicas de Cultivo de Órganos , Absorción Cutánea/fisiologíaRESUMEN
Pharmaceutical residues are emerging pollutants in the aquatic environment and their removal by conventional wastewater treatment methods has proven to be ineffective. This research aimed to develop a three-dimensional reduced graphene oxide aerogel (rGOA) for the removal of diclofenac in aqueous solution. The preparation of rGOA involved facile self-assembly of graphene oxide under a reductive environment of L-ascorbic acid. Characterisation of rGOA was performed by Fourier transform infrared, scanning electron microscope, transmission electron microscopy, nitrogen adsorption-desorption, Raman spectroscopy and X-ray diffraction. The developed rGOA had a measured density of 20.39⯱â¯5.28â¯mg/cm3, specific surface area of 132.19â¯m2/g, cumulative pore volume of 0.5388â¯cm3/g and point of zero charge of 6.3. A study on the simultaneous interactions of independent factors by response surface methodology suggested dosage and initial concentration as the dominant parameters influencing the adsorption of diclofenac. The highest diclofenac adsorption capacity (596.71â¯mg/g) was achieved at the optimum conditions of 0.25â¯g/L dosage, 325â¯mg/L initial concentration, 200â¯rpm shaking speed and 30⯰C temperature. The adsorption equilibrium data were best fitted to the Freundlich model with correlation coefficient (R2) varying from 0.9500 to 0.9802. The adsorption kinetic data were best correlated to the pseudo-first-order model with R2 ranging from 0.8467 to 0.9621. Thermodynamic analysis showed that the process was spontaneous (∆G = -â¯7.19 to -â¯0.48â¯kJ/mol) and exothermic (∆H = -â¯12.82 to -â¯2.17â¯kJ/mol). This research concluded that rGOA is a very promising adsorbent for the remediation of water polluted by diclofenac.
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Diclofenaco/química , Grafito/química , Contaminantes Químicos del Agua/química , Adsorción , Descontaminación , Concentración de Iones de Hidrógeno , Cinética , Espectroscopía Infrarroja por Transformada de Fourier , TermodinámicaRESUMEN
In this study, AB113 dye was successfully sequestered using a novel adsorbent made of mixed fish scales (MFS). The influence of adsorbent dosage, initial pH, temperature, initial concentration and contact time on the adsorption performance was investigated. The surface chemistry and morphology of the adsorbent were examined by FTIR, TGA and SEM. Amides, phosphate and carbonate groups were evidently responsible for the high affinity of MFS towards the dye. The adsorption equilibrium and kinetic were well described by Langmuir and pseudo-second-order models, respectively. The maximum adsorption capacities of MFS were 145.3-157.3mg/g at 30-50°C. The adsorption of AB113 dye onto the adsorbent was exothermic and spontaneous as reflected by the negative enthalpy and Gibbs energy changes. The results support MFS asa potential adsorbent for AB113 dye removal.
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Escamas de Animales , Compuestos Azo , Peces , Contaminantes Químicos del Agua , Adsorción , Animales , Concentración de Iones de Hidrógeno , Cinética , Temperatura , TermodinámicaRESUMEN
This research investigated the removal of lead (Pb2+) by a novel biochar derived from palm oil sludge (POS-char) by slow pyrolysis. Multistage optimizations with central composite design were carried out to firstly optimize pyrolysis parameters to produce the best POS-char for Pb2+ removal and secondly to optimize adsorption conditions for the highest removal of Pb2+. The optimum pyrolysis parameters were nitrogen flowrateof30mLmin-1, heating rateof10°Cmin-1, temperatureof500°C and timeof30min. The optimum Pb2+ adsorption conditions were concentrationof200mgL-1, timeof60min, dosageof0.3g and pH of 3.02. The various functional groups within POS-char played a vital role in Pb2+ uptake. Regeneration was demonstrated to be feasible using hydrochloric acid. Adsorption equilibrium was best described by Freundlich model. At low concentration range, adsorption kinetic obeyed pseudo-first-order model, but at high concentration range, it followed pseudo-second-order model. Overall, the results highlighted that POS-char is an effective adsorbent for Pb2+ removal.
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Carbón Orgánico , Aceite de Palma , Adsorción , Cinética , Plomo , Aguas del AlcantarilladoRESUMEN
Due to the health and environmental risks posed by the presence of petroleum-contaminated areas around the world, remediation of petroleum-contaminated soil has drawn much attention from researchers. Combining Fenton reaction with a solvent has been proposed as a novel way to remediate contaminated soils. In this study, a green solvent, ethyl lactate (EL), has been used in conjunction with Fenton's reagents for the remediation of diesel-contaminated soil. The main aim of this research is to determine how the addition of EL affects Fenton reaction for the destruction of total petroleum hydrocarbons (TPHs) within the diesel range. Specifically, the effects of different parameters, including liquid phase volume-to-soil weight (L/S) ratio, hydrogen peroxide (H2O2) concentration and EL% on the removal efficiency, have been studied in batch experiments. The results showed that an increase in H2O2 resulted in an increase in removal efficiency of TPH from 68.41% at H2O2 = 0.1 M to 90.21% at H2O2 = 2 M. The lowest L/S, i.e. L/S = 1, had the highest TPH removal efficiency of 85.77%. An increase in EL% up to 10% increased the removal efficiency to 96.74% for TPH, and with further increase in EL%, the removal efficiency of TPH decreased to 89.6%. EL with an optimum value of 10% was found to be best for TPH removal in EL-based Fenton reaction. The power law and pseudo-first order equations fitted well to the experimental kinetic data of Fenton reactions.
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Hidrocarburos , Lactatos , Petróleo , Contaminantes del Suelo , Peróxido de Hidrógeno , Suelo , SolventesRESUMEN
This research investigated the potential of palm kernel shell (PKS), empty fruit bunch (EFB) and palm oil sludge (POS), abundantly available agricultural wastes, as feedstock for biochar production by slow pyrolysis (50mLmin-1 N2 at 500°C). Various characterization tests were performed to establish the thermochemical properties of the feedstocks and obtained biochars. PKS and EFB had higher lignin, volatiles, carbon and HHV, and lower ash than POS. The thermochemical conversion had enhanced the biofuel quality of PKS-char and EFB-char exhibiting increased HHV (26.18-27.50MJkg-1) and fixed carbon (53.78-59.92%), and decreased moisture (1.03-2.26%). The kinetics of pyrolysis were evaluated by thermogravimetry at different heating rates (10-40°C). The activation energies determined by Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa models were similar, and comparable with literature data. The findings implied that PKS and EFB are very promising sources for biochars synthesis, and the obtained chars possessed significant biofuel potential.
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Carbono/química , Termogravimetría , Frutas/química , Cinética , LigninaRESUMEN
Treatment of oil-contaminated soil is a major environmental concern worldwide. The aim of this study is to examine the applicability of a green solvent, ethyl lactate (EL), in desorption of diesel aliphatic fraction within total petroleum hydrocarbons (TPH) in contaminated soil and to determine the associated desorption kinetics. Batch desorption experiments were carried out on artificially contaminated soil at different EL solvent percentages (%). In analysing the diesel range of TPH, TPH was divided into three fractions and the effect of solvent extraction on each fraction was examined. The experimental results demonstrated that EL has a high and fast desorbing power. Pseudo-second order rate equation described the experimental desorption kinetics data well with correlation coefficient values, R 2, between 0.9219 and 0.9999. The effects of EL percentage, initial contamination level of soil and liquid to solid ratio (L/S (v/w)) on initial desorption rate have also been evaluated. The effective desorption performance of ethyl lactate shows its potential as a removal agent for remediation of TPH-contaminated soil worldwide.
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Hidrocarburos/química , Lactatos/química , Contaminación por Petróleo/prevención & control , Contaminantes del Suelo/química , Contaminación Ambiental , Gasolina , Petróleo , Suelo , Solventes/químicaRESUMEN
Lansium domesticum peel (LDP), a waste material generated from the fruit consumption, was evaluated as a biosorbent for nickel removal from aqueous media. The effects of dosage, contact time, initial pH, initial concentration and temperature on the biosorption process were investigated in batch experiments. Equilibrium data were fitted by the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models using nonlinear regression method with the best-fit model evaluated based on coefficient of determination (R(2)) and Chi-square (χ(2)). The best-fit isotherm was found to be the Langmuir model exhibiting R(2) very close to unity (0.997-0.999), smallest χ(2) (0.0138-0.0562) and largest biosorption capacity (10.1mg/g) at 30°C. Kinetic studies showed that the initial nickel removal was rapid with the equilibrium state established within 30min. Pseudo-second-order model was the best-fit kinetic model indicating the chemisorption nature of the biosorption process. Further data analysis by the intraparticle diffusion model revealed the involvement of several rate-controlling steps such as boundary layer and intraparticle diffusion. Thermodynamically, the process was exothermic, spontaneous and feasible. Regeneration studies indicated that LDP biosorbent could be regenerated using hydrochloric acid solution with up to 85% efficiency. The present investigation proved that LDP having no economic value can be used as an alternative eco-friendly biosorbent for remediation of nickel contaminated water.
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Meliaceae/metabolismo , Níquel/farmacocinética , Contaminantes Químicos del Agua/farmacocinética , Adsorción , Biodegradación Ambiental , Concentración de Iones de Hidrógeno , Industrias , Cinética , Modelos Químicos , Níquel/metabolismo , Temperatura , Termodinámica , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/químicaRESUMEN
This study focuses on the feasibility of treating aged polycyclic aromatic hydrocarbons (PAHs)-contaminated soils using ethyl lactate (EL)-based Fenton treatment via a combination of parametric and kinetic studies. An optimised operating condition was observed at 66.7 M H2O2 with H2O2/Fe(2+) of 40:1 for low soil organic carbon (SOC) content and mildly acidic soil (pH 6.2), and 10:1 for high SOC and very acidic soil (pH 4.4) with no soil pH adjustment. The desorption kinetic was only mildly shifted from single equilibrium to dual equilibrium of the first-order kinetic model upon ageing. Pretreatment with EL fc = 0.60 greatly reduced the mass transfer coefficient especially for the slow desorbed fraction (kslow) of high molecular weight (HMW) PAHs, largely contributed by the concentration gradient created by EL-enhanced solubility. As the major desorption obstacle was almost fully overcome by the pretreatment, the pseudo-first-order kinetic reaction rate constant of PAHs degradation of aged soils was statistically discernible from that of freshly contaminated soils but slightly reduced in high SOC and high acidity soil. Stabilisation of H2O2 by EL addition in combination with reduced Fe(2+) catalyst were able to slow the decomposition rate of H2O2 even at higher soil pH.
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Lactatos/química , Hidrocarburos Policíclicos Aromáticos/química , Contaminantes del Suelo/química , Restauración y Remediación Ambiental , Estudios de Factibilidad , Peróxido de Hidrógeno/química , Cinética , Hidrocarburos Policíclicos Aromáticos/análisis , Suelo/química , Contaminantes del Suelo/análisis , SolubilidadRESUMEN
Polycyclic aromatic hydrocarbons (PAHs) in soil have been recognised as a serious health and environmental issue due to their carcinogenic, mutagenic and teratogenic properties. One of the commonly employed soil remediation techniques to clean up such contamination is soil washing or solvent extraction. The main factor which governs the efficiency of this process is the solubility of PAHs in the extraction agent. Past field-scale soil washing treatments for PAH-contaminated soil have mainly employed organic solvents or water which is either toxic and costly or inefficient in removing higher molecular weight PAHs. Thus, the present article aims to provide a review and discussion of the alternative extraction agents that have been studied, including surfactants, biosurfactants, microemulsions, natural surfactants, cyclodextrins, vegetable oil and solution with solid phase particles. These extraction agents have been found to remove PAHs from soil at percentages ranging from 47 to 100% for various PAHs.