Search

[Display omitted] • PUF modified with Fe 3 O 4 and combined with PVA, SA, and bacterial consortium. • Maximum removal efficiency of 2, 4-DCP was found 92.51 ± 0.83 %. • Edward's empirical model predicted the growth inhibition kinetic model. • Modified polyurethane foam shows great stability and reusability up to four cycles. In this work, an effort has been made to enhance the efficacy of biological process for the effective degradation of 2, 4-dichlorophenol (2, 4-DCP) from wastewater. The polyurethane foam was modified with Fe 3 O 4 nanoparticles and combined with polyvinyl alcohol, sodium alginate, and bacterial consortium for biodegradation of 2, 4-DCP in a packed bed biofilm reactor. The maximum removal efficiency of 2, 4-DCP chemical oxygen demand, and total organic carbon were found to be 92.51 ± 0.83 %, 86.85 ± 1.32, and 91.78 ± 1.24 %, respectively, in 4 days and 100 mg L−1 of 2, 4-DCP concentration at an influent loading rate of 2 mg L−1h−1 and hydraulic retention time of 50 h. Packed bed biofilm reactor was effective for up to four cycles to remove 2, 4-DCP. Growth inhibition kinetics were evaluated using the Edward model, yielding maximum growth rate of 0.45 day−1, inhibition constant of 110.6 mg L−1, and saturation constant of 62.3 mg L−1. [ABSTRACT FROM AUTHOR]

We report the complex evaporation kinetics of saline sessile droplets on surfaces with elevated temperatures. Our previous studies show that on non-heated substrates, saline sessile droplets evaporate faster compared to the water counterparts. In the present study, we discover that on heated surfaces, the saline droplets evaporate slower than the water counterpart, thereby posing a counter-intuitive phenomenon. The reduction in the evaporation rates is directly dependent on the salt concentration and the surface wettability. Natural convection around the droplet and thermal modulation of surface tension is found to be inadequate to explain the mechanisms. Flow visualizations using particle image velocimetry (PIV) reveal that the morphed advection within the saline droplets is a probable reason behind the arrested evaporation. Infrared thermography is employed to map the thermal state of the droplets. A thermo-solutal Marangoni based scaling analysis is put forward and the major governing non-dimensional numbers have been accounted for in the analysis. It is observed that the Marangoni flow and internal advection borne of thermal and solutal gradients are competitive, thereby leading to the overall decay of internal circulation velocity compared to the equivalent pure water case, which reduces the evaporation rates. The theoretically proposed advection velocities conform to the experimental results. This study sheds rich insight on a novel species transport behaviour in saline droplets. [ABSTRACT FROM AUTHOR]

The present article experimentally and theoretically probes the evaporation kinetics of sessile saline droplets. Observations reveal that presence of solvated ions leads to modulated evaporation kinetics, which is further a function of surface wettability. On hydrophilic surfaces, increasing salt concentration leads to enhanced evaporation rates, whereas on superhydrophobic surfaces, it first enhances and reduces with concentration. Also, the nature and extents of the evaporation regimes (constant contact angle or constant contact radius) are dependent on the salt concentration. The reduced evaporation on superhydrophobic surfaces has been explained based on observed (via microscopy) crystal nucleation behaviour within the droplet. Purely diffusion driven evaporation models are noted to be unable to predict the modulated evaporation rates. Further, the changes in the surface tension and static contact angles due to solvated salts also cannot explain the improved evaporation behaviour. Internal advection is observed (using PIV) to be generated within the droplet and is dependent on the salt concentration. The advection dynamics has been used to explain and quantify the improved evaporation behaviour by appealing to the concept of interfacial shear modified Stefan flows around the evaporating droplet. The analysis leads to accurate predictions of the evaporation rates. Further, another scaling analysis has been proposed to show that the thermal and solutal Marangoni advection within the system leads to the advection behaviour. The analysis also shows that the dominant mode is the solutal advection and the theory predicts the internal circulation velocities with good accuracy. The findings may be of importance to microfluidic thermal and species transport systems. • Saline sessile droplets are observed to vaporize faster than sessile water droplets. • The evaporation rate increases with concentration, but decreases on superhydrophobic surfaces. • Internal hydrodynamics is noted to lead to the improved evaporation. • The thermal and the solutal Marangoni effects are found to be the driving mechanism of the advection. • The advection modifies the external Stefan flow, which morphs the vaporization rates. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lab-scaled photocatalyst (TiO 2) was prepared by the solution combustion method. • Synthesize photocatalyst characterized by FESEM, XRD and XPS. • BOD 5 /COD (0.59±0.089) and BOD 5 /TOC (1.74±0.03) were improved by photocatalytic degradation. • Maximum removal efficiency obtained was 98.43±1.31% through integrated system. • The performance of PBBR was analyzed in terms of % RE P , PLR and % EC PR. Integrating photocatalysis and biodegradation has shown great potential in wastewater treatment technology. In this study, the degradation of p-cresol in water has been investigated through an integrated system comprising of photocatalytic and packed bed biofilm reactor (PBBR). In the photocatalytic reactor, the biodegradability index (BOD 5 /COD, BOD 5 /TOC) of the p-cresol solution was first shown to increase (from 0.098±0.023 to 0.59±0.089 for BOD 5 /COD and from 0.27±0.030 to 1.74±0.03 for BOD 5 /TOC). The pseudo-first-order rate constant (k ap) was found to be 0.011 min−1. The % removal of the integrated system was found to be 98.43±1.31% at an initial concentration of 700 mg L-1 and residence time of 120 h, which was significantly higher than the PBBR operated alone (34.82±2.62%) under optimized conditions (pH 7.0 and T = 32±2 °C). Using an integrated approach, the efficient removal of p-cresol opens novel future perspectives for catalytic degradation using chemical oxidation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Serratia marcescens and Ochrobactrum intermedium were used p-cresol degradation. • Optimum inoculum of 14 ml, pH of 7.0, and NaCl of 1% were obtained. • Optimum microbial growth was obtained at inoculum of 14 ml, pH of 7.0, and NaCl of 1%. • Removal efficiency of 99.36±0.2% was achieved at 100 mg L−1p-cresol. • Continuous mode operation of RPBBR was better than batch mode operation. Wastewater containing excess phenolic compounds is considered a major environmental concern due to its adverse impacts on the ecosystem. In this work, an effort has been given to treat the p-cresol from wastewater using Recirculating Packed Bed Biofilm Reactor (RPBBR). The process parameters, namely inoculum dose, pH, and NaCl (w/v) concentration were optimized to enhance the specific growth and obtained to be 14 ml, 7.0, and 1% NaCl (w/100 ml), respectively. Maximum p-cresol removal efficiency of 99.36±0.2% was achieved at 100 mg L−1 of p-cresol. First-order rate constants were found to be 0.70 day−1 and 0.96 day−1 for batch and continuous mode, respectively. The intermediates were analysed using FT-IR and GC–MS analysis. Pseudomonas fluorescens was used to assess bacterial toxicity and observed that the toxicity was reduced in case of treated wastewater. Finally, the performance of continuous RPBBR was better than the batch mode. [ABSTRACT FROM AUTHOR]

• Cellulose was modified using octenyl succinic anhydride and sodium hypochlorite. • Intrinsic viscosity varied with degree of substitution according to power law. • Adsorption capacity of cellulose for Cu(II) ions was increased on modification. • Adsorption was spontaneous at room temperature. Cellulose powder was modified with Sodium Hypochlorite (NaOCl) and Octenyl Succinic Anhydride (OSA) in different proportions. The adsorbents were characterised by BET, FTIR, XRD, TGA and SEM. Intrinsic viscosity increased with degree of substitution (DS). FTIR peaks confirmed the presence of carbonyl groups. Batch adsorption parameters studied were contact time, adsorbent dosage, pH and temperature. Adsorption process was influenced significantly by pH. Freundlich isotherm showed a better correlation coefficient (R2 and χ2) than Langmuir and Temkin isotherms. The adsorption process was inferred as physico-chemical adsorption process (based on isotherm and kinetic modelling). Pseudo second order kinetics model was found to fit well on the empirical data obtained. Adsorption of Cu(II) ions over the modified cellulose was found to be exothermic in nature (ΔH<0). HCl was found to be more effective desorbing agent than NaOH. [ABSTRACT FROM AUTHOR]