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Sugar beet pulp (SBP) is a major byproduct from the sugar industries and consists of >20% w/w arabinose. The current work evaluated the potential of Enterobacter ludwigii assimilating pure arabinose and arabinose rich hydrolysate from SBP pellets for 2,3-butanediol (BDO) production. The hydrolysate was obtained through dilute acid pretreatment (DAP) with sulphuric acid. The process was optimized for acid and solid loading to obtain a hydrolysate free from furan derivatives. The effect of different levels of substrate (10–60 g/L) using pure arabinose was conducted in shake flask experiments, followed by co-fermentation with small amounts of glucose and SBP hydrolysate. After flask cultivations, BDO fermentations were carried-out in a bench-top bioreactor in batch and fed-batch modes using pure arabinose as well as SBP hydrolysate. The fed-batch culture led to BDO production of 42.9 and 35.5 g/L from pure arabinose and SBP hydrolysate with conversion yields of 0.31 and 0.29 g/g, respectively. Finally, BDO accumulated on pure arabinose and SBP hydrolysate were recovered using an aqueous two-phase extraction system. The recovery yield of BDO accumulated on arabinose and hydrolysate was ∼97%. The work demonstrated the feasibility of using SBP as a suitable feedstock for manufacturing BDO.

Lignin is one of the most abundant naturally occurring polymers and can produce value-added products such as vanillin and p-coumaric acid. In the current work, in-situ depolymerization of lignin for its valorization in a microbial peroxide-producing cell (MPPC) system was performed. It is an electrochemical cell that requires no external energy to produce H

Nitrogen-functionalized graphene oxide (GO) nanocatalysts were prepared using ammonia, methylamine, ethylamine, and hydrazine hydrate as a nitrogen source. Nanocatalysts samples were thoroughly characterized using XRD, Raman, FTIR, XPS, FESEM, TEM, and TGA techniques. Quantitative and qualitative analyses of surface acidic and basic sites were done by NH3- and CO2-TPD techniques. Nanocatalysts were further examined for DMC production via transesterification reaction of propylene carbonate (PC) with CH3OH. Quantitative analysis of nitrogen-containing functional groups in the prepared sample with respect to other functional moieties was performed. Among various nanocatalysts, ammonia functionalized GO (AGO) was found to be the best for DMC production. At optimized reaction conditions of temperature (180 °C), time (6 h), and catalyst dose (1 wt% with respect PC), the highest DMC yield of ∼50% was observed. Reusability studies using AGO nanocatalyst were conducted up to four consecutive test cycles to evaluate catalysts' potentiality towards DMC synthesis. Thus, N-functionalized GO is a useful metal-free nanocatalyst that could also be explored for other chemical processes.

In the present study, electro-coagulation (EC) with stainless steel (SS) electrodes has been used as a pretreatment process before the reverse osmosis (RO) for the biologically treated distillery spent wash. The optimized operating parameters (pH, time, current, and electrode distance) for the EC process were obtained from the previous study. EC treated wastewater was further used as a feed for the RO system. RO membrane system operating parameters (pH, temperature, and trans-membrane pressure) were optimized by employing response surface methodology. Optimized conditions for the RO process were found to be: pH (pHo): 6.12; temperature (T): 20°C and trans-membrane pressure (TMP): 45.7 bar. The combined (EC-RO) process showed 98%, 99.2%, and 98.5% of COD, color, and TDS removal, respectively, with permeate flux of 40.5 L/m2/h (EC-RO). Experimental results indicated that EC followed by RO could be used as an additional step for biologically treated spent wash treatment to improve the treated effluent quality and membrane life. Results also revealed that the techno-economic performance of combined (EC-RO) treatment in terms of total annual water production is more efficient and economical than RO alone.

The electrochemical reduction of nitrate and ammonium ion oxidation has been performed with the cathode (Al) and anode (Ti/RuO₂) in the explosive industry wastewater polluted with a significant quantity of NO₃– and NH₄⁺. For this, the influences of various other cathode materials (Fe, Cu, and C), the current density (j = 35.71 to 142.86 A m–²), wastewater pH (pH = 3–12), and treatment time (t = 180 min) were analyzed for nitrate ion reduction, ammonium ion oxidation, nitrite ion generation, and total nitrogen (TN) degradation. The maximum nitrate removal and TN removal efficiencies were found to be ≈51 and ≈63% at j = 142.86 A m–² and wastewater natural pH after 180 min treatment time, respectively. In this condition, SEC was calculated to be 74.4 kWh (kg NO₃– reduced)⁻¹. The mechanistic analysis suggested that the atomic hydrogen molecules, H⁺, and e– help in the nitrate ion reduction and the available Cl– ion in the wastewater helps in the oxidation of the ammonium ion into gaseous nitrogen through the electrochemical process. The new and used electrodes were characterized by FE-SEM, AFM, and XRD techniques. Electrodes were also characterized within untreated and treated wastewater through CV and EIS analysis. The in situ generated oxidizing species were identified by the p-nitrosodimethylaniline (RNO) bleaching test. Pseudo-first-order and nᵗʰ-order kinetic models were applied, and the reaction rate was calculated to understand the reaction rate of the nitrate reduction. The approximate operational cost estimation has been performed for the lab-scale batch reactor treatment of the explosive industry wastewater. No scum or sludge was produced throughout the treatment process. This study helps to understand the parametric, mechanistic, and kinetic aspects of electrochemical nitrate reduction and oxidation of the previously present and produced ammonium ion in the explosive industry wastewater.

This study reports an electrochemical reduction of the NO3− along with oxidation of the in-situ generated NH4+ with maximum selectivity of the N2 gas as the final-product. The use of aluminum as a cathode and Ti/RuO2 as an anode showed enhanced electrochemical nitrate reduction at the cathode and oxidation of the ammonium ion at the anode. Effects of various parameters like initial NO3− concentration (Co = 100−400 mg L−1), a dose of the Cl− as NaCl (NaCl = 100−400 mg L−1), current density applied (j = 83.3-333.3 A m−2), solution pH (pH = 4–10) and electrolysis time (t = 0−120 min) were studied in terms of NO3− reduction and total nitrogen (TN) removal efficiencies. Current efficiency (CE) was elaborated with respect to end products like N2, NO2− and NH4+. Specific electrical energy consumption (SEC) was calculated in kWh kg−1 NO3− removed for the electrochemical process. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were utilized for understanding the oxidation/reduction mechanism over electrodes and the characteristics of the electrodes in a different solution. The studied mechanism suggested a circular conversion of NO3− through complex processes into the N2 gas as the final product. The ultimate nitrate and TN degradation efficiency of ≈95 % with N2 selectivity of ≈100 % were achieved at the optimum condition of Co = 100 mg L−1, NaCl = 300 mg L−1, j = 333.3 A m−2, pH = 6 and time = 120 min with SEC = 927.4 kW h kg−1 NO3− removed. The 1st, 2nd, and nth-order kinetic models were used for the reaction kinetics. FE-SEM, XRD, and AFM techniques were used for the characterization of the electrodes before and after all the electrochemical runs. The operating cost was calculated for lab-scale treatment along with a comparison with previous studies. No sludge or scum got produced for each electrochemical run. Finally, this study delivers a superior perceptive for electrochemical characteristics of Al at the cathode side and Ti/RuO2 at anode side as well as electrochemical NO3− reduction and oxidation of the generated NH4+, simultaneously.

Present study proposed a sorption and desorption approach of aqueous mercury ion (Hg2+) on sulfur impregnated attapulgite (ATPS) adsorbent. Morphological characterization of natural and impregnated ATP confirmed the mesoporous nature of ATPS-adsorbents. The presence of various types of functional groups on the surface of ATPS was confirmed by using the zeta-potential measurement, X-ray fluorescence (XRF), and FT-IR analysis. Batch adsorption tests were carried out to detect the optimum condition of temperature for sulfur impregnation, and the results illustrated that the best adsorbent (ATPS-500) produced via the impregnation at 500 °C, with the highest equilibrium uptake of Hg2+ at initial pH 7. Different parameters like solution pHo, initial concentration of mercury (Co), temperature (T), contact time (t) and the effect of co-existing ions were optimized. Optimum pH and equilibrium contact time at the optimum dose of adsorbent (m) = 0.02 g in 50 mL and Co = 2.0 mg L − 1 were found to be pH~5 and 24 h at T = 313 K for ATPS-500.The best representation of adsorption kinetic was followed by the pseudo-first order kinetic model. The adsorption of Hg2+ions onto ATPS-500 was found to be endothermic. The heat of adsorption and changes in the entropy of Hg2+ions sorption on ATPS-500 were determined as 10.35 kJ mol−1 and 0.16 kJ mol−1 K − 1, respectively. Thermal regeneration represented that ATPS-500 was used for five desorption–sorption cycles with excellent efficiency of Hg2+ in each cycle.

Perfluorooctanoic acid (PFOA) is a chemical used for both commercial and industrial applications. It has turned out to be worldwide anxiety owing to its extensive existence in the water bodies and subsequent harmful ecological effects. This study illustrates the significance of hybrid aerated electrocoagulation (EC) and modified peroxi-coagulation (PC) for the PFOA degradation in an aqueous solution. Consumable iron plate electrodes were employed as an electrode pair in both EC and modified PC processes. The laboratory tests were conducted in a batch reactor with a functioning capacity of 1 L. Aeration improved the EC process performance considerably. Higher than 56% PFOA and 38% defluorination occurred after 60 min of electrolysis with EC being operated at a pH of 3.6 and applied a current density of 78.34 Am−2. The performance of the modified PC process was considerably higher than that of the aerated EC process. More than 90% PFOA, 87%total organic carbon (TOC), and 71% deflorination were attained with modified PC process after 60 min of electrolysis operated at 78.34 Am−2 and initial pH of 3.6 when 50 mM hydrogen peroxide (H2O2) was added. The superior performance of the modified PC than aerated EC is mostly owing to the attack of in-site produced OH• radicals. PFOA decayed stepwise into small‒chain perfluoro carboxylic acids (PFCAs) and fluoride ions during modified PC oxidation.

Inexpensive and nontoxic metal-free heteroatom (P, N, and O) enriched high surface area nanoporous materials (CHNM and HNM) as efficient heterogeneous catalysts for the conversion of epoxides to cyclic carbonates by utilizing CO2 is reported. The catalysts were made by condensing the heteroatom enriched precursor with melamine and pyrrole to produce HNM and CHNM, respectively. The catalysis was carried out under mild experimental conditions, i.e. 100 °C reaction temperature and 4 bar CO2 pressure under solvent-free conditions. Almost 100% conversion can be realized using HNM as a catalyst and this superior performance was attributed to the presence of larger heteroatoms as compared to CHNM, although the latter has 159% specific surface area and 115% pore volume as compared to the former. The obtained results are discussed in terms of the Lewis acid–Lewis base interaction, textural properties and the frameworks of the catalysts and the reactants.

The development of green and sustainable processes to synthesize active pharmaceutical ingredients and key starting materials is a priority for the pharmaceutical industry. A green and sustainable protocol for the oxidative cleavage of olefins to produce pharmaceutically and biologically valuable carboxylic acids is achieved. The developed protocol involves 70% aq. TBHP as an oxidant over a heterogeneous vanadium catalyst system. Notably, the synthesis of industrially important azelaic acid from various renewable vegetable oils is accomplished. The catalyst could be recycled for up to 5 cycles without significant loss in yield and the protocol was successfully demonstrated at the gram-scale.

Co(II) porphyrins have been utilized as efficient and selective catalysts for the extractive oxidative desulfurization reaction on the refractory dibenzothiophene (DBT) in [Formula: see text]-dodecane (model middle distillate fuel oil). The acetonitrile was taken as extracting polar solvent and H2O2 was used as oxidant. The reaction optimization was done with respect to DBT:catalyst molar ratio; DBT:H2O2 molar ratio; extracting solvent: CH3CN/[Formula: see text]-dodecane volume ratio; reaction temperature and time. Under the optimized conditions, a maximum of [Formula: see text]98% DBT removal was achieved by using the meso-tetrakis(4[Formula: see text] methoxyphenyl)porphyrinatocobalt(II) as catalyst under mild conditions at 50[Formula: see text]C.

The main objective of the present work was to understand the interactive behaviour of various operating parameters including concentration of pollutants during binary electrochemical mineralization of the two nitrogenous heterocyclic pollutants in the aqueous solution. Indole and pyrrole were selected as pollutants, whereas Pt/Ti was selected as anode and cathode. The effects of different operating parameters like current density, solution conductivity, initial concentration of the pollutants and time were studied. Taguchi method was used to optimize these operating parameters for obtaining the ultimate rate of degradation for the nitrogenous compounds. There were basically two responses, i.e. chemical oxygen demand (COD) degradation and specific energy consumption. These responses were maximized and minimized, respectively. At the optimum condition, removal efficiencies of pyrrole, indole and COD were found to be 46.1%, 62.4% and 61.4%, respectively. The optimum value of specific energy consumption was found to be 159.5 kWh per kg COD removed. Possible mineralization pathways are also proposed on the basis of the identified intermediates by gas chromatography coupled with mass spectroscopy. The operating cost was also calculated for the binary lab-scale treatment of the indole and pyrrole and compared with reported cost analysis for the electrochemical treatment.

In the present study, reduced graphene oxide-supported zinc oxide nanocatalysts (rGO/ZnO) with varying graphene contents (1, 2, 5, and 10%) were synthesized and employed for the production of dimet...

In this study, zinc ferrocyanide nano-composite materials were synthesized and developed by reaction of aqueous K4Fe(CN)6·3H2O and ZnCl2 in the presence of tri-block copolymer and tert-butanol. The synthesized catalysts were characterized by CO2- and NH3-temperature-programmed desorption (TPD), N2-sorption, SEM, TEM, XRD and used for transesterification reactions. The zinc ferrocyanide catalyst showed a sharp cube shaped structure with a high amount of basic sites. The zinc ferrocyanide catalyst showed type IV isotherm with H3 hysteresis loop. BET surface area and pore volume were found to be 125 m2/g and 0.1395 cm3/g, respectively. The transesterification of Jatropha oil using Fe-Zn-1 showed the maximum 94.5% jatropha oil conversion. The prepared catalyst can be easily recovered and successfully reused after five times. The slight loss of activity of Fe-Zn-1 catalyst can be attributed to the deposition of the reaction products on the active sites and the blockage of the pores. Overall, the zinc ferrocyanide catalyst activity was found to be directly dependent upon both the textural and surface basic/acidic properties.

Distilleries are among the most pollution-generating industries as their ≈80% raw material converted into waste. In the present study, sustainable biochar was prepared from distillery sludge (DS) by chemical activation with KOH, ZnCl2, and H3PO4 (coded as DS-K, DS-Z, DS-H) and used for the removal of tetracycline, an emerging pollutant. Additionally, biochar was also prepared by adding the distillery sludge and oily sludge from sugar mill in the ratio of 2:1 (coded as DS-O). The raw sludge and prepared biochar were characterized by various sophisticated techniques like XRF, XRD, TGA-FTIR, BET, FE-SEM, and zeta potential analyzer. FTIR, coupled with the TGA system, gave traces of CO2 and H2O (steam) as the temperature of the sample increased. Batch adsorption study showed TC removal efficiencies of 57%, 64%, 43%, and 70% by DS-K, DS-Z, DS-H, and DS-O, respectively, at optimum conditions: Co = 20 mg L−1, time = 300 min, rpm = 160 ± 5, dose = 1 g L−1, T = 25 ±1 °C, and pH = 6. Experimental data was well-fitted in both pseudo-first-order and pseudo-second-order kinetic models. Langmuir isotherm nicely described the adsorption of TC onto biochar. pH played a significant role in the adsorption due to the amphoteric behavior of TC. Reusability studies showed a marginal decrease in removal efficiencies of ≈ 9%, ≈ 7%, ≈ 4%, and ≈ 8% after three consecutive runs with DS-O, DS-Z, DS-K, and DS-H, respectively.

Advanced oxidation processes triggered by nanoscale materials are promising owing to the in-situ generation of reactive radicals that can degrade toxic organic pollutants. In the present study, zinc sulfide (ZnS) nanoparticles with polyethylene glycol-4000 (PEG-4000) and polyvinylpyrrolidone (PVP) cappings were prepared using the chemical precipitation method and characterized thoroughly. Optical and structural characteristics of the capped ZnS nanoparticles were investigated and compared with those of uncapped ZnS nanoparticles. Results showed that PVP and PEG capped ZnS nanoparticles exhibited smaller crystallite size of 1.42 and 1.5 nm, respectively, as compared to uncapped ZnS (1.93 nm). Consequently, band gap energies of capped ZnS nanoparticles were higher which enable them to work as solar photocatalyst. The photocatalytic performance of the PEG, PVP-capped, and uncapped ZnS nanoparticles were evaluated against methyl orange (MO) dye and showed 85%, 87%, and 80% dye removal efficiencies, respectively. Degradation rate constant derived using Langmuir-Hinshelwood model revealed faster degradation kinetics bycapped ZnS photocatalysts owing to broader light absorption range. A possible dye degradation mechanism based on the energy levels positions was proposed to explain the route of photocatalytic degradation of MO by ZnS materials. It was inferred that the generation of reactive oxygen species by photogenerated electron-hole pairs facilitate degradation of MO dye molecules under sunlight illumination. It is expected that this work will provide insights into the development of strategies employed to achieve enhanced photocatalysis by nanoscale materials through organic capping.

A series of calcium oxide–magnesium oxide (CaO–MgO) catalysts were prepared under the effects of different precipitating agents and using varied Mg/Ca ratios. The physiochemical characteristics of the prepared catalysts were analyzed using XRD, FE-SEM, BET, FTIR, and TG/DTA techniques. Quantification of basic active sites present on the surface of the CaO–MgO catalysts was carried out using the Hammett indicator method. The as-prepared mixed oxide samples were tested for propylene carbonate (PC) synthesis through the alcoholysis of urea with propylene glycol (PG). The effects of the catalyst composition, catalyst dose, reaction temperature, and contact time on the PC yield and selectivity were investigated. The maximum PC yield of 96%, with high PC selectivity of 99% and a urea conversion rate of 96%, was attained at 160 °C using CaO–MgO catalysts prepared using a Mg/Ca ratio of 1 and Na2CO3 as a precipitating agent. The best-performing catalysts also exhibited good reusability without any significant loss in PC selectivity. It is expected that the present study will provide useful information on the suitability of different precipitating agents with respect to the catalytic properties of the oxides of Ca and Mg and their application in the synthesis of organic carbonates.

The present study investigated the roles of peroxydisulfate (PDS) radicals and sulfate radicals (SO

The present review compiles and critically evaluates studies on the synthesis of dimethyl carbonate (DMC) using different techniques and catalysts with reaction conditions, a wide range of applicat...

The disposal and management of sulfur-rich sludges (SRS) are challenging issues for the industries due to their adverse environmental impact. The present study reports the detailed characterizations and assessment of the thermo-kinetics of sludge generated from the sulfuric acid plant. In addition, the sulfur was retrieved with the help of the evaporation–condensation method. In the active devitalization zone (200–400 °C), a substantial mass loss (91 ± 3%) was observed, primarily due to the vaporization of sulfur. The isoconversional model-free methods were used to appraise kinetic parameters for the pyrolytic process. The average activation energy (64.5 kJ mol−1) estimated by the Starink method admired the less energy-intensive process and validated the occurrence of thermochemical reactions at low temperatures. The thermodynamic parameters and frequency factor calculated at 10 °C min−1 were ΔG* = 149.1 kJ mol−1, ΔH* = 59.8 kJ mol−1, ΔS* = −0.157 kJ mol−1K−1, and A = 2.1 × 105 s−1. Criado's Z-master plot revealed the dominance of the diffusion mechanism on the process. The efficient recovery of sulfur (≈96% with purity 99 ± 0.5%) was achieved at 440 °C by evaporation–condensation technique, and the findings closely complemented the kinetic and thermodynamic parameters. This study provides a background for a better understanding SRS and efficient sulfur recovery.

This paper deals with the hazards associated with a liquefied petroleum gas (LPG) bottling plant. Due to the release of LPG, different possible hazards, such as fireball, jet fire and vapour cloud explosion (VCE), may take place in the bottling plant. Each critical stages of bottling plants are briefly discussed and modelled in ALOHA and PHAST, and their simulated consequences of results are compared. In this article, the complete bottling plant has been divided into various risk zones which are expected accidental areas (like tank storage area, small domestic cylinder storage area, and LPG pump and compressor area). The risks during handling and the use of LPG have been analysed and modelled and their results are compared. Among all the accident scenarios, fireball was found to be the most dangerous condition in the bullet and small cylinder storage units. Overall, bullet storage unit was found to be the most hazardous section having the most destructive damage (with an overpressure of 0.41 bar), which causes complete destruction, large number of injuries and fatalities (within a distance of 215 m) in case of VCE and having a thermal intensity of 37.5 kW/m2 which causes deaths due to burn up to the largest distance (324 m) in the case of fireball.

The FeCl2/K2CO3 catalyst system was used successfully for the synthesis of oil soluble N-benzylated cobalt phthalocyaninetetrasulfonamide by the reaction of benzyl alcohol on water-soluble ...

Present paper evaluates the catalytic activity of Ce/Al2O3 (CeAl) catalyst for the oxidative removal of sulfur from model oil (dibenzothiophene, DBT, dissolved in iso-octane). CeAl catalyst synthes...

Present study deals with the binary batch adsorption of aniline (AN) and nitrobenzene (NB) onto granular-activated carbon (GAC). For single component, the adsorptive uptake of AN and NB increased a...

The aim of this work was to study the thermogravimetric analysis through the pyrolysis of almond (Prunus amygdalus) shells for evaluating its potential for bioenergy at different heating rates (10, 25, and 50 K min−1). The activation energy values for the process were of the range of 153.0, 152.02, and 152.73 kJ mol−1 as calculated by Kissenger-Akahira-Sunrose (KAS), Ozawa-Flynn-Wall (OFW) and Starink models respectively. The change in the Gibbs free energy was ~181 kJ mol−1. Diffusion-based reaction, followed by the chemical reaction mechanism,was dominant thermal degradation as envisaged by the Coats-Redfern method. The validation of the experiments was accomplished through the artificial neural network, reiterating its further usage in any conversional studies of biomass. A difference of