Waste biomass-based 3D graphene aerogels for high performance zinc-ion hybrid supercapacitors.

Biomass-based 3D graphene aerogels were explored as cathode materials for the fabrication of high-performance zinc-ion hybrid supercapacitors. These hybrid supercapacitors delivered a high specific capacitance of ∼353.1 F g-1 at a current density of 0.1 A g-1 and maximum specific energy and power of 158.9 W h kg-1 (at 84 W kg-1 of specific power) and 14.8 kW kg-1 (at 77.2 W h kg-1 of specific energy), respectively. These devices exhibited a remarkable rate capability at high current densities and excellent capacity retention, retaining ∼84.2% of their capacity with ∼100% coulombic efficiency up to 10 000 cycles at 10 A g-1.

Facile preparation, characterization and application of novel sugarcane bagasse-derived nanoceria-biochar for defluoridation of drinking water: kinetics, thermodynamics, reusability and mechanism.

Although expensive, rare-earth oxides are well known for being powerful defluoridation agents. Being costlier, cerium is used as a hybrid adsorbent in conjunction with a prudent and environmentally benign substance like biochar. The novel CeO2/BC (surface area 260.05 m2/g) composite was shaped using the facile chemical precipitation technique without any cross-linkers. Surface properties of synthesised CeO2/BC were investigated using powder XRD, FTIR, BET, pH point of zero charge and SEM. According to XRD analysis, immobilized Ce is primarily in form of CeO2, while pristine biochar is in an amorphous state. Batch mode adsorption tests were carried out with different solution pH, F- initial concentration, adsorbent dosage and contact time and counter anions. CeO2/BC can be used in a varied pH range (2-10) but shows maximum removal at pH 4. The Langmuir adsorption isotherm and a pseudo-second-order kinetic model are best fitted to support the adsorption process with a maximum Langmuir adsorption capacity of 16.14 mg/g (F- concentration 5 to 40 mg/L). The removal phenomenon is non-spontaneous in nature. The plausible mechanism of fluoride uptake was explained using XPS and pHPZC, and it was demonstrated that the fluoride was mainly removed by ion exchange and electrostatic attraction. The adsorbent could be successfully used up to fourth cycle after regenerating.

Spatial distribution of heavy metals in the sediments of River Ganges, India: Occurrence, contamination, source identification, seasonal variations, mapping, and ecological risk evaluation.

Present study analyzed the seasonal and spatial distribution patterns, sources, and ecological risks of seven heavy metals (Cr, Fe, Ni, Cu, Zn, Cd and Pb) in the sediments of River Ganges, finding that the majority of concentrations were lithologic, except for Cd, which was significantly higher than background standards. Elevated values of geochemical indices viz. Igeo, CF, RI, Cd, mCd, HQ, mHQ, and PN suggest moderate to high ecological risk in the benthic environment and its organisms due to the synergistic effect of heavy metals. The PEC-Qmetals revealed 8-10 % toxicity in the upstream and downstream sites, due to the influence of agricultural activities. Multivariate statistical techniques (PCM and PCA) indicated that Cd and Pb predominantly originated from anthropogenic sources, while other metals primarily derived from geological background. These geochemical findings may help to understand the potential risks and recommend strategies to mitigate the effects of metallic contamination in river sediments.

Ni modified distillation waste derived heterogeneous catalyst utilized for the production of glycerol carbonate from a biodiesel by-product glycerol: Optimization and green metric studies.

Biodiesel prices could be made competitive with petrol-diesel prices by valorizing its by-product glycerol. Glycerol carbonate can be derived from glycerol and is one of the widely needed chemical having high price and its extensive application in different industrial purposes. Glycerol carbonate can be synthesized via many routes; among them catalytic route gives promising activity and selectivity towards glycerol carbonate. For the first time, Ni modified distillation waste (CaO) derived heterogeneous catalyst Ni/CaO (NDW) was synthesized and utilized for the conversion of glycerol (Gl) to glycerol carbonate (GC). The catalyst's physicochemical properties were studied by performing TGA-DSC, XRD, FT-IR, SEM- EDAX, HRTEM, and basicity through Hammet indicator. Through NDW, solvent-free synthesis of glycerol carbonate was achieved using glycerol and dimethyl carbonate (DMC) as reactants upon conventional heating (90 °C). The validation of the synthesized product was performed through proton and carbon NMR analysis. In addition to this, HR-MS was performed to check the composition of the product formed. A plausible mechanism for the transesterification of glycerol (Gl) to glycerol carbonate (GC) was also designed. Higher conversion (99.2%) and selectivity (95%) towards glycerol carbonate (GC) were achieved at mild reaction conditions, viz., 1:3 M ratio of glycerol to DMC, reaction temperature 90 °C, reaction duration of 90 min with catalyst dose of 300 mg. The green metric parameters were also calculated to show that the overall process is sustainable and the environment benign.

A cleaner route of biodiesel production from waste frying oil using novel potassium tin oxide catalyst: A smart liquid-waste management.

The valorization of waste frying oil (WFO) to biodiesel has been carried out via solid base catalyzed transesterification reaction. A novel potassium tin oxide (KSO) catalyst was synthesized via polymer precursor auto combustion method. The catalyst showed the best physicochemical properties when it was calcined at 800 °C. Using KSO 800 catalyst, the highest FAME conversion (99.5%) of WFO found at moderated reaction condition within very short time (35 min); moreover, no leaching of K-species was observed in reusability test upto 5th cycle. Kinetics proved that the above catalytic reaction followed pseudo-first-order kinetics and the rate of the reaction was doubled with increasing 10 °C reaction temperature. The reaction activation energy, enthalpy of activation, entropy of activation, and Gibb's free energy of activation of the reaction were found to be 66.52 kJ/mol, 62.95 kJ/mol, -74.07 J/mol/K and 88 kJ/mol respectively. Evaluation of the green parameters revealed that KSO 800 catalyzed transesterification process approached a cleaner route with excellent efficacy in terms of turnover frequency and yield. KSO 800 helped to produce high quality biodiesel from WFO adopting faster and greener reaction pathway. Thus, KSO 800 was considered as a potential and green catalyst for transforming waste oil into biofuel.

Development of adsorbent from Mentha plant ash and its application in fluoride adsorption from aqueous solution: a mechanism, isotherm, thermodynamic, and kinetics studies.

In the present study, Mentha plant ash was modified by Na and Al for the synthesis of adsorbent and applied for the removal of Fluoride from an aqueous solution. Mixture of acid washed Mentha plant ash (MPA) and NaOH (in the ratio 1:1.3) thermally treated at 600°C in a muffle furnace then treated with aqueous solution of sodium aluminate. The characterization of sodium aluminum modified ash (Na-Al-MA) powder was done such as SEM (Scanning Electron Microscopy), Particle Size Analysis (PSA), Fourier transformed spectroscopy (FTIR), Zeta Potential, XRD (X-ray Diffraction) analysis, and Brunauer-Emmett-Teller (BET) analysis. The removal of fluoride from an aqueous solution carried out with Na-Al-MA by batch adsorption process. The Na-Al-MA was found to be very effective as adsorbent. The maximum removal of fluoride was achieved Ì´ 86% at neutral pH and at room temperature. It was investigated that Langmuir adsorption isotherm and pseudo-second-order kinetic was best fitted for fluoride adsorption. The fluoride adsorption on Na-Al-MA was an exothermic process. A possible mechanism including electrostatic attraction, hydrogen bonding, and metal-fluoride interaction for fluoride adsorption on Na-Al-MA have described in this study. Novelty statement: Utilization of Mentha plant ash for the development of adsorbent and its application in adsorptive removal of fluoride from aqueous solution is the novelty of this work. Adsorbent preparation may be the better way of waste biomass management.

Advancements in applications of nanotechnology in global food industry.

Nanotechnology has several applications in food industry and it significantly helps in characterization, fabrication, and manipulation of nanostructures. The nanostructures improve the solubility of food ingredients in vivo, along with enhancement in their bioavailability and controlled release at the target site. These nanostructures also serve as anticaking agents, nano-additives, delivery systems for nutraceuticals, etc. Present study highlights different forms of nanoengineered structures applied in food nanotechnology to tune the characteristics of conventional food ingredients and their applications. Literature survey highlighted the application of various types of nanostructures in the food industry. The study focusses on recent advancements in preparation methods of nanostructures as food additives and packaging stuffs along with pros and cons of their application in food industry. The shortcomings associated to nanotechnology in food science have illustrated along with its tentative future perespective. The impact of eco-toxicity due to application of nanostructures has also been discussed based on recent observations. This can suppressed by the application of bioedible polymers instead of synthetic polymers.

Smart waste management of waste cooking oil for large scale high quality biodiesel production using Sr-Ti mixed metal oxide as solid catalyst: Optimization and E-metrics studies.

Biodiesel was prepared at laboratory scale via transesterification reaction from waste cooking oil using Sr-Ti mixed metal oxide as a heterogeneous base catalyst. The solid base catalyst was synthesized by polymer precursor method. The most efficient active phase of catalyst was explored by varying the Sr/Ti atomic ratio in mixed metals oxides. The synthesized catalyst underwent for TGA, Powder XRD, SEM, EDX, FT-IR, XPS, and BET surface area analysis to assess its physicochemical characteristics. Additionally, basicity which has been observed as the most process governing factor was also evaluated through Hammett indicator-benzoic acid titration method. The Sr-Ti mixed metals oxide with 4:1 was observed with highest catalytic activity for methanolysis reaction. Its potency was facilitated by fairly acquired BET surface area (43.6 m2/g) and basic strength (2.89 mmol/g). The appreciable values of both the parameters imparted the high catalytic activity in Sr-Ti mixed metals oxide with atomic ratio 4:1. Onward, transesterification reaction was optimized for the maximum FAME conversion through RSM using CCD. The confirmatory tests showed the consistency with the conclusions drawn from RSM study regarding optimized values of concerned process variables. Transesterification reaction turned out 98% FAME conversion exerting catalyst dose (1.0 wt%), methanol to oil molar ratio (11:1), and reaction time (80 min) at reaction temperature (65 °C) and agitation speed (600 rpm) featured by RSM study. The closeness in optimized value of anticipated and confirmatory results perceived the efficiency of CCD and approving its potency as successful tool to estimate the highest FAME conversion. Next, a pseudo-first-order kinetic model of transesterification reaction was established. In addition to this, the thermodynamic functions were also computed through Eyring plot dictating the non-spontaneity and endergonic nature of transesterification reaction. The Environment-factor (E-factor) and Turn Over Frequency (TOF) were enumerated and they approved the prepared Sr-Ti mixed metals oxide as an efficient and sustainable catalyst for biodiesel production through transesterification. Finally, all the important fuel properties of prepared biodiesel from waste cooking oil was discerned within the range laid by ASTM D-6751 standards for biodiesel which coined the compatibility of prepared methyl ester with CI engines as a substitute of diesel fuel.

Biodiesel synthesis from microalgae (Anabaena PCC 7120) by using barium titanium oxide (Ba2TiO4) solid base catalyst.

In this study, Anabaena PCC 7120 microalgae is used as feedstock for biodiesel synthesis. Anabaena 7120 was cultivated in a closed photobioreactor. Oil was extracted by cell disruption process and purified by degumming process. Anabaena oil was characterized by GCMS spectroscopy. Barium titanium oxide (Ba2TiO4) heterogeneous catalyst was prepared by wet impregnation process and characterized through various techniques such as TGA, XRD, FTIR, HR-SEM, EDX and surface area analyzer. Basicity of synthesized catalyst was calculated by Hammett indicator titration method. The synthesized Ba2TiO4 was used in transesterification of Anabaena oil for biodiesel production and it was reused up to six cycles. The highest FAME conversion from anabaena oil was found to be 98.41% under optimized condition of 1:18 M ratio (oil:methanol), 3.5 wt% of catalyst loading and 180 min of reaction time at 65 °C temperature and 400 rpm stirring speed.

Synthesis and application of Zn/Ce bimetallic oxides for the decontamination of arsenite (As-III) ions from aqueous solutions.

Arsenic contamination has threatened water safety due to its high toxicity and carcinogenicity. Therefore, it is urgent and significant to develop simple and effective approach for dearsenification of drinking water. In present study, Zn/Ce bimetallic oxide particles of various atomic ratios were synthesized by sol-gel process and were applied for adsorption of arsenite from aqueous solutions. The Zn/Ce bimetallic oxide of atomic ratio Zn0.2:Ce0.05 shows better adsorption proficiency in comparison to their monometallic counterparts as well as synthesized bimetal oxides of other atomic ratios. Sorption behavior of arsenite on Zn/Ce bimetal oxide was investigated through batch experiments and optimum conditions were found to be pH = 7.5, adsorbent dose = 0.36 g/L, and contact time = 30 min. The arsenite adsorption data was explained by Langmuir isotherm model and maximum adsorption capacity found to reaching 88.49 mg/g at 318 K. Adsorption mechanism was interpreted using FTIR and XPS data, the former suggesting formation of bond between As(III)Zn/Ce oxide nanoparticles while, latter reveals presence of both As(III) and As(V) peak which further infer that some fraction of As(III) may be get oxidized to As(V) by O2 based on Ce3+ as electron mediation agent between As(III) and O2.

Evaluating features of periphytic diatom communities as biomonitoring tools in fresh, brackish and marine waters.

The aims of this study were to assess the biodiversity of periphytic diatom assemblages in fresh, brackish and marine waterbodies of Korea, and to assess the effect of environmental and anthropogenic factors on parameters such as the quantity and biovolume of lipid bodies and deformations of diatoms as early warning measures of anthropogenic impact. Diatom samples were collected from 31 sites (14 freshwater, 10 brackish and 7 marine), which included less impacted (upstream) and impacted (downstream) sites in each water type. Our results showed higher abundance and biodiversity of periphytic diatoms at the less impacted sites in terms of species richness, Shannon index, cell count and biovolume of the communities than at the impacted sites for freshwater and estuarine sites, but not for marine sites. 84 diatom species were noted in freshwater, 80 in brackish water and 40 in marine waters. In comparison to diatoms of the impacted sites, those of less impacted freshwater, brackish and marine sites had less lipid bodies (also less biovolume) and a lower percentage of teratological frustules, and showed more mobile forms in the community. Principal component analysis (PCA) also showed clear segregation of impacted from less impacted sites by the extent of the presence of lipid bodies (higher both in number and biovolume) and deformities in diatom frustules. Pearson correlation analysis revealed that lipid body induction and deformities were positively correlated with metals (Cd, Co, Cr, Cu, Fe, Pb and Zn) and nutrients (total phosphorus and total nitrogen), whereas they showed negative correlation with salinity, dissolved oxygen, suspended solutes and pH. Life-forms, lipid bodies and deformities in diatoms may be an effective biomonitoring tool for assessing biological effects of pollutants in non-marine aquatic ecosystems in Korea.

Synthesis of High-Quality Biodiesel Using Feedstock and Catalyst Derived from Fish Wastes.

A low-cost and high-purity calcium oxide (CaO) was prepared from waste crab shells, which were extracted from the dead crabs, was used as an efficient solid base catalyst in the synthesis of biodiesel. Raw fish oil was extracted from waste parts of fish through mechanical expeller followed by solvent extraction. Physical as well as chemical properties of raw fish oil were studied, and its free fatty acid composition was analyzed with GC-MS. Stable and high-purity CaO was obtained when the material was calcined at 800 °C for 4 h. Prepared catalyst was characterized by XRD, FT-IR, and TGA/DTA. The surface structure of the catalyst was analyzed with SEM, and elemental composition was determined by EDX spectra. Esterification followed by transesterification reactions were conducted for the synthesis of biodiesel. The effect of cosolvent on biodiesel yield was studied in each experiment using different solvents such as toluene, diethyl ether, hexane, tetrahydrofuran, and acetone. High-quality and pure biodiesel was synthesized and characterized by 1H NMR and FT-IR. Biodiesel yield was affected by parameters such as reaction temperature, reaction time, molar ratio (methanol:oil), and catalyst loading. Properties of synthesized biodiesel such as density, kinematic viscosity, and cloud point were determined according to ASTM standards. Reusability of prepared CaO catalyst was checked, and the catalyst was found to be stable up to five runs without significant loss of catalytic activity.