Efficient Cr(VI) remediation by electrospun composite porous nanofibers incorporating biomass with metal oxides and metal-organic framework.

To develop a highly efficient adsorbent to remediate and remove hexavalent chromium ions (Cr(VI)) from polluted water, cellulose acetate (CA) and chitosan (CS), along with metal oxides (titanium dioxide (TiO2) and ferroferric oxide (Fe3O4)), and a zirconium-based metal-organic framework (UiO-66) were used to fabricate the composite porous nanofiber membranes through electrospinning. The adsorption performance, influencing factors, adsorption kinetics and isotherms of composite nanofiber membranes were comprehensively investigated. The multi-layer membrane with interpenetrating nanofibers and surface functional groups enhanced the natural physical adsorption and provided potential chemical sites. The thermal stability was improved by introducing TiO2 and UiO-66. CA/CS/UiO-66 exhibited the highest adsorption capacity (118.81 mg g-1) and removal rate (60.76%), which were twice higher than those of the control. The correlation coefficients (R2) of all the composite nanofibers regressed by the Langmuir model were significantly higher than those by the Freundlich model. The pseudo-first-order kinetic curve of CA/CS composite nanofibers showed the highest R2 (0.973), demonstrating that the whole adsorption process involved a combination of strong physical adsorption and weak chemical adsorption by the amino groups of CS. However, the R2 values of the pseudo-second-order kinetic model increased after incorporating TiO2, Fe3O4, and UiO-66 into the CA/CS composite nanofiber membranes since an enhanced chemical reaction with Cr (VI) occured during the adsorption.

Synthesis of sustainable mesoporous sulfur-doped biobased carbon with superior performance sodium diclofenac removal: Kinetic, equilibrium, thermodynamic and mechanism.

Over the last years, the strategy of employing inevitable organic waste and residue streams to produce valuable and greener materials for a wide range of applications has been proven an efficient and suitable approach. In this research, sulfur-doped porous biochar was produced through a single-step pyrolysis of birch waste tree in the presence of zinc chloride as chemical activator. The sulfur doping process led to a remarkable impact on the biochar structure. Moreover, it was shown that sulfur doping also had an important impact on sodium diclofenac (S-DCF) removal from aqueous solutions due to the introduction of S-functionalities on biochar surface. The adsorption experiments suggested that General and Liu models offered the best fit for the kinetic and equilibrium studies, respectively. The results showed that the kinetic was faster for the S-doped biochar while the maximum adsorption capacity values at 318 K were 564 mg g-1 (non-doped) and 693 mg g-1 (S-doped); highlighting the better affinity of S-doped biochar for the S-DCF molecule compared to non-doped biochar. The thermodynamic parameters (ΔH0, ΔS0, ΔG0) suggested that the S-DCF removal on both adsorbents was spontaneous, favourable, and endothermic.

Upcycling crab shell waste into biochar for treatment of palm oil mill effluent via microwave pyrolysis and activation.

The escalating consumer demand for crabs results in a growing amount of waste, including shells, claws, and other non-edible parts. The resulting crab shell waste (CSW) is disposed of via incineration or landfills which causes environmental pollution. CSW represents a potential biological resource that can be transformed into valuable resources via pyrolysis technique. In this study, microwave pyrolysis of CSW using self-purging, vacuum, and steam activation techniques was examined to determine the biochar production yield and its performance in treating palm oil mill effluent (POME). The biochar produced through microwave pyrolysis exhibits yields ranging from 50 to 61 wt%, showing a hard texture, low volatile matter content (≤34.1 wt%), and high fixed carbon content (≥58.3 wt%). The KOH-activated biochar demonstrated a surface area of up to 177 m2/g that is predominantly composed of mesopores, providing a good amount of adsorption sites for use as adsorbent. The biochar activated with steam removed 8.3 mg/g of BOD and 42 mg/g of COD from POME. The results demonstrate that microwave pyrolysis of CSW is a promising technology to produce high-quality biochar as an adsorbent for POME treatment.

Degradation of levofloxacin from antibiotic wastewater by pulse electrochemical oxidation with BDD electrode.

Antibiotic-containing wastewater is a typical biochemical refractory organic wastewater and general treatment methods cannot effectively and quickly degrade the antibiotic molecules. In this study, a novel boron-doped diamond (BDD) pulse electrochemical oxidation (PEO) technology was proposed for the efficient removal of levofloxacin (LFXN) from wastewater. The effects of current density (j), initial pH (pH0), frequency (f), electrolyte types and initial concentration (c0(LFXN)) on the degradation of LFXN were systematically investigated. The degradation kinetics under four different processes have also been studied. The possible degradation mechanism of LFXN was proposed by Density functional theory calculation and analysis of degradation intermediates. The results showed that under the optimal parameters, the COD removal efficiency (η(COD)) was 94.4% and the energy consumption (EEC) was 81.43 kWh·m-3 at t = 120 min. The degradation of LFXN at pH = 2.8/c(H2O2) followed pseudo-first-order kinetics. The apparent rate constant was 1.33 × 10-2 min-1, which was much higher than other processes. The degradation rate of LFXN was as follows: pH = 2.8/c(H2O2) > pH = 2.8 > pH = 7/c(H2O2) > pH = 7. Ten aromatic intermediates were formed during the degradation of LFXN, which were further degraded to F-, NH4+, NO3-, CO2 and H2O. This study provides a promising approach for efficiently treating LFXN antibiotic wastewater by pulsed electrochemical oxidation with a BDD electrode without adding H2O2.

Employ a Clay@TMSPDETA hybrid material as an adsorbent to remove textile dyes from wastewater effluents.

A grafting of N1-(3-trimethoxysilylpropyl)diethylenetriamine (TMSPDETA) on natural clay was carried out to obtain an organic-inorganic hybrid clay material that was applied as an adsorbent to the uptake of Reactive Blue 19 (RB-19) and Reactive Green 19 (RG-19) dyes from aqueous wastewaters. This research demonstrates the effect of TMSPDETA contents on amino-functionalized clay materials' hydrophobic/hydrophilic behavior. The resultant material was utilized to uptake reactive dyes in aqueous solutions. The clay@TMSPDETA hybrid material was characterized by isotherm of adsorption and desorption of nitrogen, FTIR, elemental analysis, TGA, pHpzc, total acidity, total basicity groups, and hydrophilic balance. The hybrid samples were more hydrophilic than the pristine clay for ratios from 0.1 up to 0.5 due to adding amino groups to the pristine clay. FTIR spectra suggest that TMSPDETA was grafted onto the clay. The hybrid material presents a surface area 2.17-fold (42.7 m2/g) lower than pristine clay (92.7 m2/g). The total volume of pores of hybrid material was 0.0822 cm3/g, and the pristine clay material was 0.127 cm3/g, corresponding to a diminution of the total pore volume (Vtot) of 1.54 times. The kinetic data followed the pseudo-second-order (PSO) model for RB-19 and RG-19 reactive dyes. The equilibrium data were better fitted to the Liu isotherm model, displaying a Qmax as 178.8 and 361.1 mg g-1 for RB-19 and RG-19, respectively, at 20.0 °C. The main mechanism of interactions of the reactive dyes with the hybrid clay is electrostatic interaction. The clay@TMSPDETA has a very good effect on treating synthetic dye-textile wastewater. The removal percentage of simulated wastewater was up to 97.67% and 88.34% using distilled water and plastic industry wastewater as the solvents, respectively. The clay@TMSPDETA-0.1 could be recycled up to 5 cycles of adsorption and desorption of both dyes, attaining recoveries of 98.42% (RB-19) and 98.32% (RG-19) using 0.1 M HCl + 10% ethanol.

Petroleum Coke Embedded in Cigarette Butts: All Waste-Derived Solar Evaporator for Effective Water Evaporation.

Solar-driven interfacial evaporation is an eco-friendly solution for tackling the impending water scarcity the world is facing in our century. In this work, a solar-driven interfacial evaporator was prepared from cigarette butts loaded with petroleum coke powder (Filter-PetCoke), a by-product of the oil refinery processes, for the improvement of the absorption of the incident solar light. A comparison between a flat 2D and a 3D evaporator with a surface composed of orderly patterned protrusions of 2.1 cm was carried out to assess the influence of the evaporator configuration on the evaporation performance. The 3D evaporator (3D Filter-PetCoke) achieved by far the best performance (evaporation rate: 1.97 ± 0.08 kg m-2 h-1 and solar conversion efficiency: 93.2 ± 5.4%) among the prepared samples (3D Filter-PetCoke, 3D Filter, 2D Filter-PetCoke, and 2D Filter). In addition, this configuration seems to be adaptable for real and more massive operation because of the geometry of the evaporator. The high efficiency was ascribed to the good heat generation of the petroleum coke and the excellent heat management of the 3D structure of the evaporator. Moreover, this evaporator was resistant to multiple repeated usages without significant efficiency loss and capable of producing drinking water from seawater and Escherichia coli (E. coli)-contaminated water. The findings in this work indicate that this evaporator is pertinent to real situations to supply safe freshwater very efficiently from chemically/biologically contaminated water.

Synthesis, Characterization, and Adsorption Properties of Nitrogen-Doped Nanoporous Biochar: Efficient Removal of Reactive Orange 16 Dye and Colorful Effluents.

In this work, nitrogen-doped porous biochars were synthesized from spruce bark waste using a facile single-step synthesis process, with H3PO4 as the chemical activator. The effect of nitrogen doping on the carbon material's physicochemical properties and adsorption ability to adsorb the Reactive Orange 16 dye and treat synthetic effluents containing dyes were evaluated. N doping did not cause an important impact on the specific surface area values, but it did cause an increase in the microporosity (from 19% to 54% of micropores). The effect of the pH showed that the RO-16 reached its highest removal level in acidic conditions. The kinetic and equilibrium data were best fitted by the Elovich and Redlich-Peterson models, respectively. The adsorption capacities of the non-doped and doped carbon materials were 100.6 and 173.9 mg g-1, respectively. Since the biochars are highly porous, pore filling was the main adsorption mechanism, but other mechanisms such as electrostatic, hydrogen bond, Lewis acid-base, and π-π between mechanisms were also involved in the removal of RO-16 using SB-N-Biochar. The adsorbent biochar materials were used to treat synthetic wastewater containing dyes and other compounds and removal efficiencies of up to 66% were obtained. The regeneration tests have demonstrated that the nitrogen-doped biochar could be recycled and reused easily, maintaining very good adsorption performance even after five cycles. This work has demonstrated that N-doped biochar is easy to prepare and can be employed as an efficient adsorbent for dye removal, helping to open up new solutions for developing sustainable and effective adsorption processes to tackle water contamination.

Pharmaceutical residues in the ecosystem: Antibiotic resistance, health impacts, and removal techniques.

Hospital wastewater has emerged as a major category of environmental pollutants over the past two decades, but its prevalence in freshwater is less well documented than other types of contaminants. Due to compound complexity and improper operations, conventional treatment is unable to remove pharmaceuticals from hospital wastewater. Advanced treatment technologies may eliminate pharmaceuticals, but there are still concerns about cost and energy use. There should be a legal and regulatory framework in place to control the flow of hospital wastewater. Here, we review the latest scientific knowledge regarding effective pharmaceutical cleanup strategies and treatment procedures to achieve that goal. Successful treatment techniques are also highlighted, such as pre-treatment or on-site facilities that control hospital wastewater where it is used in hospitals. Due to the prioritization, the regulatory agencies will be able to assess and monitor the concentration of pharmaceutical residues in groundwater, surface water, and drinking water. Based on the data obtained, the conventional WWTPs remove 10-60% of pharmaceutical residues. However, most PhACs are eliminated during the secondary or advanced therapy stages, and an overall elimination rate higher than 90% can be achieved. This review also highlights and compares the suitability of currently used treatment technologies and identifies the merits and demerits of each technology to upgrade the system to tackle future challenges. For this reason, pharmaceutical compound rankings in regulatory agencies should be the subject of prospective studies.

A colorimetric chemosensor for distinct color change with (E)-2-(1-(3-aminophenyl)ethylideneamino)benzenethiol to detect Cu2+ in real water samples.

The study reports the synthesis of chemosensor (E)-2-(1-(3-aminophenyl)ethylideneamino)benzenethiol (C1), a highly sensitive, colorimetric metal probe that shows distinct selectivity for the detection of Cu2+ ion in various real water samples. Upon complexation with Cu2+ in CH3OH/H2O (60:40 v/v) (aqueous methanol), the C1 demonstrate significant enhancement in the absorption at 250 nm and 300 nm with a color change from light yellow to brown which was visualized using naked-eye. Therefore, these properties make C1 as an effective candidate for on-site Cu2+ ions detection. The emission spectrum of C1 illustrated "TURN-ON" recognition of Cu2+ with a limit of detection (LOD) of 46 nM. Furthermore, Density Functional Theory (DFT) calculations were performed to better understand the interactions between C1 and Cu2+. The obtained results suggested that the electron clouds present around the -NH2 in nitrogen and sulfur in -SH play a pivotal role in the formation of a stable complex. The computational results were in good agreement with the experimental UV-visible spectrometry results.

One-step calcination synthesis of 2D/2D g-C3N4/WS2 van der Waals heterojunction for visible light-induced photocatalytic degradation of pharmaceutical pollutants.

It is well-documented that accumulation of pharmaceutically active compounds (PhACs), such as antibiotics, in aquatic ecosystems is a prominent environmental hazard. Herein, a series of 2D materials-based heterojunctions, conceptualized based on the integration of graphitic carbon nitride (g-C3N4) with tungsten disulfide (WS2), was fabricated through a facile one-step calcination process, and systematically evaluated for eliminating tetracycline (TC) and sulfamethoxazole (SMX) from aqueous matrices. The microstructure, optical properties, and surface chemistry of the as-prepared composites were examined with a range of microscopy and spectroscopy techniques. In comparison with pristine g-C3N4 or bare WS2, the g-C3N4/WS2 material, with optimal WS2 loading, showed significantly improved photocatalytic activity, towards degradation of TC (84%) and SMX (96%), under visible light. Free radical scavenging experiments revealed that superoxide anions and hydroxyl radicals were predominantly responsible for the rapid breakdown of the PhACs. In addition, the dissociation intermediates and residues were identified and the plausible photocatalytic degradation pathways of TC and SMX over the as-constructed 2D/2D heterojunction were discussed. Further, the photocatalysis end products were non-toxic, as inferred via the resazurin cell viability assay, employing Escherichia coli as a model organism. Most importantly, the 2D/2D g-C3N4/WS2 architecture was structurally resilient and exhibited a fairly stable cycling performance for persistent usage in wastewater treatment. The outcomes of this study testify that 2D/2D heterojunction of g-C3N4 fragments and WS2 nanosheets holds great promise for destroying antibiotics or their metabolites, usually present in wastewaters.

Adsorption of Omeprazole on Biobased Adsorbents Doped with Si/Mg: Kinetic, Equilibrium, and Thermodynamic Studies.

This paper proposes an easy and sustainable method to prepare high-sorption capacity biobased adsorbents from wood waste. A biomass wood waste (spruce bark) was employed to fabricate a composite doped with Si and Mg and applied to adsorb an emerging contaminant (Omeprezole) from aqueous solutions, as well as synthetic effluents loaded with several emerging contaminants. The effects of Si and Mg doping on the biobased material's physicochemical properties and adsorptive performance were evaluated. Si and Mg did not influence the specific surface area values but impacted the presence of the higher number of mesopores. The kinetic and equilibrium data presented the best fitness by the Avrami Fractional order (AFO) and Liu isotherm models, respectively. The values of Qmax ranged from 72.70 to 110.2 mg g-1 (BP) and from 107.6 to 249.0 mg g-1 (BTM). The kinetic was faster for Si/Mg-doped carbon adsorbent, possibly due to different chemical features provoked by the doping process. The thermodynamic data showed that the adsorption of OME on biobased adsorbents was spontaneous and favorable at four studied temperatures (283, 293, 298, 303, 308, 313, and 318 K), with the magnitude of the adsorption correspondent to a physical adsorption process (ΔH° < 2 kJ mol-1). The adsorbents were applied to treat synthetic hospital effluents and exhibited a high percentage of removal (up to 62%). The results of this work show that the composite between spruce bark biomass and Si/Mg was an efficient adsorbent for OME removal. Therefore, this study can help open new strategies for developing sustainable and effective adsorbents to tackle water pollution.

Delamination of multilayer Ti3C2Tx MXene alters its adsorpiton and reduction of heavy metals in water.

MXenes are considered as an emerging class of two-dimensional (2D) adsorbent for various environmental applications. In this work, two different morphologies of Ti3C2Tx MXene (multilayer (ML-Ti3C2Tx) and delaminated titanium carbide (DL-Ti3C2Tx)) were prepared through mild in situ HF etching and further delamination. The structural differences between the two were explored with a focus on their effects on the performance and mechanism of removing heavy metals from water. In comparison to ML-Ti3C2Tx, DL-Ti3C2Tx had more oxygen-containing functional groups, higher specific surface area (19.713 vs. 8.243 m2/g), larger pore volume (0.135 vs. 0.040 cm3/g), higher maximum Pb(II) adsorption capacity (77.0 vs. 56.68 mg/g), but lower maximum Cu(II) adsorption capacity (23.08 vs. 55.46 mg/g). Further investigation revealed that the removal of Pb(II) by the MXenes was mainly controlled through electrostatic attraction and surface complexation mechanisms, while Cu(II) was removed mainly through surface reduction by Ti-related groups. Because delamination of ML-Ti3C2Tx increased the surface area and surface functional groups, DL-Ti3C2Tx became a better sorbent for Pb(II) in water. During sonication, however, delamination inevitably led to partial oxidation of Ti3C2Tx nanosheets and thus weakened the reducing ability of DL-Ti3C2Tx for Cu(II) in water. Nevertheless, both ML- and DL-Ti3C2Tx not only exhibited excellent heavy metal adsorption capacity under different solution conditions, but also showed good reusability. Findings of this study indicate that Ti3C2Tx MXenes are promising adsorbents for treating heavy metal pollutants in water.

Proteomic analysis reveals mechanisms of mixed wastewater with different N/P ratios affecting the growth and biochemical characteristics of Chlorella pyrenoidosa.

Effects of different nutrient ratios on the biochemical compositions of microalgae and the changes were rarely studied at the molecular level. In this study, the impacts of various nitrogen to phosphorus (N/P) ratios on growing of C. pyrenoidosa, as well as biochemical compositions and the metabolic regulation mechanism in mixed sewage, were investigated. The results suggested that 18 was optimal N/P ratio, while the dry weight (1.0 g/L), chlorophyll-a (Chla) (3.63 mg/L), and lipid production (0.28 g/L) were all the highest comparing with other groups. In contrast, the protein production (0.37 g/L) was the least. The nature of the regulatory mechanisms inthe metabolic pathways of these biochemical compositions was revealed by proteomic results, and there were 62 different expression proteins (DEPs) taken part in fatty acid and lipid biosynthesis metabolism (FA), amino acid biosynthesis metabolism (AA), photosynthesis (PHO), carbon fixation in photosynthetic organisms (CFP), and central carbon metabolism (CCM).

Enhanced photocatalytic activity of cubic ZnSn(OH)6 by in-situ partial phase transformation via rapid thermal annealing.

In this study, a mixed phase ZnSn(OH)6/ZnSnO3 photocatalyst was synthesized by calcining ZHS nanostructures via rapid thermal annealing (RTA) process. The composition ratio of ZnSn(OH)6/ZnSnO3 was controlled by changing the duration of the RTA process. The obtained mixed-phase photocatalyst was characterized by X-ray diffraction, field emission scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy, ultraviolet photoelectron spectroscopy, photoluminescence, and physisorption analysis. Results showed that ZnSn(OH)6/ZnSnO3 photocatalyst obtained by calcining ZHS at 300 °C for 20 sec displayed the best photocatalytic performance under UVC light illumination. Under optimized reaction conditions, ZHS-20 (0.125 g) demonstrated nearly complete removal (>99%) of MO dye in 150 min. Scavenger study revealed the predominant role of OH• in photocatalysis. The enhanced photocatalytic activity of the ZnSn(OH)6/ZnSnO3 composites was mainly ascribed to the photosensitization of ZHS by ZTO and effective electron-hole separation at the ZnSn(OH)6/ZnSnO3 heterojunction interface. It is expected that this study will provide new research input for the development of photocatalyst through thermal annealing-induced partial phase transformation.

Trends in Bioactive Multilayer Films: Perspectives in the Use of Polysaccharides, Proteins, and Carbohydrates with Natural Additives for Application in Food Packaging.

The harmful effects on the environment caused by the indiscriminate use of synthetic plastics and the inadequate management of post-consumer waste have given rise to efforts to redirect this consumption to bio-based economic models. In this sense, using biopolymers to produce materials is a reality for food packaging companies searching for technologies that allow these materials to compete with those from synthetic sources. This review paper focused on the recent trends in multilayer films with the perspective of using biopolymers and natural additives for application in food packaging. Firstly, the recent developments in the area were presented concisely. Then, the main biopolymers used (gelatin, chitosan, zein, polylactic acid) and main methods for multilayer film preparation were discussed, including the layer-by-layer, casting, compression, extrusion, and electrospinning methods. Furthermore, we highlighted the bioactive compounds and how they are inserted in the multilayer systems to form active biopolymeric food packaging. Furthermore, the advantages and drawbacks of multilayer packaging development are also discussed. Finally, the main trends and challenges in using multilayer systems are presented. Therefore, this review aims to bring updated information in an innovative approach to current research on food packaging materials, focusing on sustainable resources such as biopolymers and natural additives. In addition, it proposes viable production routes for improving the market competitiveness of biopolymer materials against synthetic materials.

Remediation and recovery of Kariba weed as emerging contaminant in freshwater and shellfish aquaculture system via solvothermal liquefaction.

Fast growing Kariba weed causes major problems and pollution on freshwater and shellfish aquaculture systems by interfering with nutrient uptake of crops, restricting sunlight penetration, and decreasing water quality due to massive biomass of Kariba weed remnants. Solvothermal liquefaction is considered an emerging thermochemical technique to convert waste into high yield of value-added products. Solvothermal liquefaction (STL) of Kariba weed as an emerging contaminant was performed to investigate the effects of different types of solvents (ethanol and methanol) and Kariba weed mass loadings (2.5-10 % w/v) on treating and reducing the weed via conversion into potentially useful crude oil product and char. Up to 92.53 % of Kariba weed has been reduced via this technique. The optimal conditions for crude oil production were found to be at 5 % w/v of mass loading in methanol medium, resulting in a high heating value (HHV) of 34.66 MJ/kg and yield of 20.86 wt%, whereas the biochar production was found to be optimum at 7.5 % w/v of mass loading in methanol medium, resulting in 29.92 MJ/kg of HHV and 25.38 wt% of yield. The crude oil consisted of beneficial chemical compounds for biofuel production such as hexadecanoic acid, methyl ester (65.02 peak area %) and the biochar showed high carbon content (72.83 %). In conclusion, STL as a remediation for emerging Kariba weed is a feasible process for shellfish aquaculture waste treatment and biofuels production.

Statistical physics double-layer models for the experimental study and theoretical modeling of methyl orange dye adsorption on AlMnTiO nanocomposite.

A Al2O3/MnO2/TiO2 (AlMnTiO) nanocomposite was synthesized using the thermal coprecipitation method and the adsorption performance of methyl orange (MO) dye from aqueous solution was carried out. Single-parameter optimization was used to explore the properties of AlMnTiO nanocomposite parameters on dye adsorption, including dose of adsorbent, solution pH, contact duration, and starting MO concentration. The model is the appropriate adsorption isotherm for the equilibrium process using a pseudo-second-order kinetic model property. Langmuir plot had a Qmax (mg/g) of 198.4 and best fitted (R2=0.990) among different isotherm models. The relevant parameters were computed using the dual-energy binary-layer statistical physics model. The statistical physics binary-layer model yield n (stoichiometric coefficient) values of 0.410, 0.440, and 0.453, all values are below 1, demonstrating the multi-docking process. AlMnTiO nanocomposite was regenerated up to six times, making the material extremely cost-effective. Using AlMnTiO nanocomposite, MO dye was removed from wastewater both in the laboratory and on the industrial scale.

Cobalt ferrite as an electromagnetically boosted metal oxide hetero-Fenton catalyst for water treatment.

The cobalt ferrite Fenton catalysts were obtained by the flow co-precipitation method. FTIR, XRD, and Mössbauer spectroscopy confirmed the spinel structure. The crystallite size of the as-synthesized sample is 12 nm, while the samples annealed at 400 and 600 °C have crystallite sizes of 16 and 18 nm, respectively. The as-synthesized sample has a grain size of 0.1-5.0 µm in size, while the annealed samples have grain sizes of 0.5 µm-15 µm. The degree of structure inversion ranges from 0.87 to 0.97. The catalytic activity of cobalt ferrites has been tested in the decomposition of hydrogen peroxide and the oxidation of caffeine. The annealing of the CoFe2O4 increases its catalytic activity in both model reactions, with the optimal annealing temperature being 400 °C. The reaction order has been found to increase with increasing H2O2 concentration. Electromagnetic heating accelerates the catalytic reaction more than 2 times. As a result, the degree of caffeine decomposition increases from 40% to 85%. The used catalysts have insignificant changes in crystallite size and distribution of cations. Thus, the electromagnetically heated cobalt ferrite can be a controlled catalyst in water purification technology.

Design of hydrotalcite and biopolymers entrapped tunable cerium organic cubic hybrid material for superior fluoride adsorption.

The excess fluoride in drinking water is serious risk which leads to fluorosis. The adsorption method is facile route for defluoridation studies. Hybrid adsorbent possesses unique advantages like high surface area and high stability has been employed for water treatment. In the present work, hydrotalcite (HT) fabricated Ce-metal organic frameworks (MOFs) bridged with biopolymers (alginate and chitosan) namely HT-CeMOFs@Alg-CS cubic hybrid beads was developed and employed towards fluoride removal in batch mode. The fabricated HT-CeMOFs@Alg-CS beads were analyzed by DTA, FTIR, SEM, EDAX, TGA and XRD studies. Besides, FTIR and EDAX proved the affinity of HT-CeMOFs@Alg-CS cubic hybrid beads on fluoride was majorly attributed by electrostatic interaction, ion-exchange and complexation mechanism. To include detail insight into adsorption route; the kinetics, thermodynamic and isotherm studies were investigated for fluoride adsorption. The equilibrium data of HT-CeMOFs@Alg-CS cubic hybrid beads for fluoride adsorption was fitted with Langmuir isotherm model. Thermodynamic investigation results demonstrated that the fluoride adsorption was spontaneous with endothermic nature. The regeneration and field investigation results revealed that the developed HT-CeMOFs@Alg-CS cubic hybrid beads are reusable and more apt at field environment.

The production of activated biochar using Calophyllum inophyllum waste biomass and use as an adsorbent for removal of diuron from the water in batch and fixed bed column.

The Calophyllum inophyllum species annually produces a large volume of cylindrical fruits, which accumulate on the soil because they do not have nutritional value. This study sought to enable the use of this biomass by producing activated biochar with zinc chloride as an activating agent for further application as an adsorbent in batch and fixed bed columns. Different methodologies were used to characterize the precursor and the pyrolyzed material. Morphological changes were observed with the emergence of new spaces. The carbonaceous material had a surface area of 468 m2 g-1, Dp = 2.7 nm, and VT = 3.155 × 10-1 cm3 g-1. Scientific and isothermal studies of the adsorption of the diuron were conducted at the natural pH of the solution and adsorbent dosage of 0.75 g L-1. The kinetic curves showed a good fit to the Avrami fractional order model, with equilibrium reached after 150 min, regardless of the diuron concentration. The Liu heterogeneous surface model well represented the isothermal curves. By raising the temperature, adsorption was encouraged, and at 318 K, the Liu Qmax was reached at 250.1 mg g-1. Based on the Liu equilibrium constant, the nonlinear van't Hoff equation was employed, and the ΔG° were < 0 from 298 to 328 K; the process was exothermic nature (ΔH0 = -46.40 kJ mol-1). Finally, the carbonaceous adsorbent showed good removal performance (63.45%) compared to a mixture containing different herbicides used to control weeds. The stoichiometric column capacity (qeq) was 13.30 and 16.61 mg g-1 for concentrations of 100 and 200 mg L-1, respectively. The length of the mass transfer zone was 5.326 cm (100 mg L-1) and 4.946 cm (200 mg L-1). This makes employing the leftover fruits of the Calophyllum inophyllum species as biomass for creating highly porous adsorbents a very effective and promising option.