Synthesis and application of alginate-nanocellulose composite beads for defluoridation process in a batch and fluidized bed reactor.

Electronegative Fluorine has great reactivity and it exists as organic or inorganic fluoride compounds. Biosorption feasibility of fluoride onto alginate-cellulose composites was investigated in this study. Extracted cellulose has been utilized to synthesize calcium alginate impregnated composite beads for fluoride remediation process in batch and fluidized-bed reactors. Physiochemical characteristics were analyzed by FTIR, SEM, TGA and BET. From the BET properties analysis, the surface area of prepared composite beads was 87.13 m2/g. The point zero charge (PZC) value of composite beads was attained at pH 7.32. The relationship between biosorption efficiency and independent variables have been observed to evaluate the effects on the fluoride biosorption efficiency of composites and its components. The hypothetical development of the removal technique has been explained using various nonlinear model-fitting methods to evaluate Isotherm study, bio-sorption Kinetics, Thermodynamic parameters and Mass transfer study. Maximum monolayer adsorption capacity (qm) obtained by following Langmuir model for fluoride removal was found to be 23.809 mg/g at 30 °C using adsorbent dosage of 2 g/L for an initial fluoride concentration of 6 mg/L. The optimized condition for fluoride adsorption experiment was observed by evaluating response surface methodology (RSM) was pH-5.67, dose 1.89 g/L and time 85.71 min and removal was found as 82.79%. Experimental data of fluidized-bed study were evaluated by designing mathematical modeling. Fluidization velocities was adjusted in between Umf and 2Umf for optimizing external mass transfer and adsorbent loss. Regeneration study of fluoride loaded biosorbent and cost analysis of composite production have been estimated.

Metal-oxide coated Graphene oxide nano-composite for the treatment of pharmaceutical compound in photocatalytic reactor: Batch, Kinetics and Mathematical Modeling using Response Surface Methodology and Artificial Neural Network.

Titanium dioxide (TiO2) photocatalyst has gained constant interest in the treatment of wastewater because of its greater stability, lower cost, low-toxicity, high efficiency, and more reactivity under UV radiation. On the other hand, Graphene oxide (GO) possesses high electron mobility, and therefore when GO is combined with TiO2, the photocatalytic activity of TiO2 is increased. In this study, nano-composite was synthesized in a hydrothermal reactor using two types of TiO2 nanoparticles (TiO2 consisting of a mixture of rutile and anatase phase (Type 1) and bioreduced TiO2 (Type 2)) and the efficiency of both the TiO2-GO nanocomposite to remove the drug Carbamazepine (CBZ) was investigated. The TiO2-GO nanocomposite with the Type 1 TiO2 exhibited greater efficiency hence further studies were conducted with that composite. The efficiency of TiO2-GO nanocomposite for the purpose of removing CBZ were investigated in presence of different types of incident radiation like Solar radiation, white light and three type of Ultraviolet radiation (A, B, C). The removal of the drug by TiO2-GO composite has been optimized using response surface methodology and artificial neural network. From this study, the maximum reduction was observed was 91.2% and whereas in case of the RSM optimization study the maximum removal that was observed was 91.7%. The validation of the RSM model was done using the mathematical analysis of the model equation of RSM. Different kinetics models was also analyzed using the experimental data and it was observed that it followed pseudo-second-order kinetics. The optimization using ANN also showed a close interaction with the experimental results.

Enhanced biosorption of fluoride by extracted nanocellulose/polyvinyl alcohol composite in batch and fixed-bed system: ANN analysis and numerical modeling.

The present investigation attempted to examine the defluoridation feasibility onto the extracted nanocellulose/PVA polymer composites. Nanocellulose were derived from sugarcane bagasse and blended with PVA (polyvinyl alcohol) polymer matrix. The defluoridation potential of nanocellulose/PVA was observed to be significantly dependent on the various operational factors including pH, time interval, etc. the Temkin isotherm (R2 = 0.989) as well as the Langmuir isotherm equation (R2 = 0.982) could well fit with the investigational data. Following the Langmuir isotherm, the maximum monolayer adsorption capacity for fluoride elimination at 25°C was obtained as 11.363 mg g-1. The nature of rate-limiting steps involved in defluoridation process might be effectively predicted by pseudo-second-order kinetics. Values of thermodynamic state properties achieved as of the thermodynamic analysis showed that the defluoridation process was spontaneous, exothermic, and feasible. The diffusion and mass transfer study were estimated by following the Boyd's model. Average effective diffusion coefficient (De) at various initial fluoride concentrations (4-10 mg L-1) was obtained as 15.3343×10-7 m2s-1 and the estimated magnitude of the mass-transfer coefficient (Kf) was 0.0346×10-9 m s-1 (temperature = 298 K, C0= 6 mgL-1). An ANN (artificial neural network) model applied to optimize and simulate the defluoridation procedure. Furthermore, continuous flow column reactor was conducted to investigate the practical applicability of composites in the defluoridation process. The Yoon-Nelson and the Thomas model exhibited excellent conformity with the breakthrough curves. Nanocellulose/PVA satisfactorily eliminated fluoride from its aqueous solution and can be considered as a suitable bio-sorbent for defluoridation.

Adsorption Characteristics of Activated Carbon for the Reclamation of Eosin Y and Indigo Carmine Colored Effluents and New Isotherm Model.

The adsorption response of eosin Y and indigo carmine acid dyes on activated carbon as a function of system temperature for a fixed concentration was investigated at various temperatures via adsorption isotherms and their thermodynamic quantities such as enthalpy, entropy, and Gibbs free energy changes. The adsorption data were exploited to develop a new adsorption isotherm. The new isotherm was developed with the spirit of solid-liquid phase equilibrium and regular solution theory. The proposed model has four adjustable constants and correlates adsorption isotherm in terms of the system temperature and melting temperature of the dye. The effect of pH on the removal of acid dyes was reported. The pH variation was observed to affect the adsorption efficiency. The removal of eosin Y and indigo carmine decreased from 99.4% to 82.6% and 92.38% to 79.48%, respectively, when the pH of the solution varied from 2 to 12. The thermodynamic analysis of the process reveals that the process of the removal of acid dyes is exothermic and spontaneous. Moreover, the kinetics parameters of the batch process are reported.

Treatment of malachite green dye containing solution using bio-degradable Sodium alginate/NaOH treated activated sugarcane baggsse charcoal beads: Batch, optimization using response surface methodology and continuous fixed bed column study.

In this study, carbonized material was produced using sodium hydroxide treated Sugar cane bagasse (SB), and synthesized materials ware used to prepare Sodium Alginate/SBAC composite beads which were further used as an adsorbent to remove malachite green dye (MG) present in water. Physiochemical characteristics of composite beads were analyzed using FTIR, SEM, TGA, and BET. Adsorption equilibrium data showed excellent fit to the Freundlich model (R2 = 0.994) than to the Langmuir model (R2 = 0.925). Adsorption kinetics study indicated that the MG removal process would be better described by the pseudo-second-order kinetic model. The thermodynamic study suggested the spontaneous and endothermic nature of MG adsorption. By using response surface methodology, the optimum conditions for MG adsorption on composite beads were found to be 115.43 min, 0.3 g/L and pH 8 for contact time, adsorbent mass, and pH respectively and MG adsorption efficiency was 97.88%. The fixed-bed column data were evaluated using several kinetic models and among them, Thomas model showed the best agreement with investigation results. These results revealed that synthesized composite beads have a high affinity toward MG and it could be reasonable, eco-friendly adsorbent for dye removal from wastewater.

Assessment on the decolourization of textile dye (Reactive Yellow) using Pseudomonas sp. immobilized on fly ash: Response surface methodology optimization and toxicity evaluation.

This study focuses on the investigation of removal of textile dye (Reactive Yellow) by a combined approach of sorption integrated with biodegradation using low cost adsorbent fly ash immobilized with Pseudomonas sp. To ensure immobilization of bacterial species on treated fly ash, fly ash with immobilized bacterial cells was characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and fluorescence microscopy. Comparative batch studies were carried out using Pseudomonas sp, fly ash and immobilized Pseudomonas sp on flyash and were observed that immobilized Pseudomonas sp on flyash acted as better decolourizing agent. The optimized pH, temperature, and immobilized adsorbent dosage for highest percentage of dye removal were observed to be pH 6, 303 K, 1.2 g/L in all the cases. At optimum condition, the highest percentage of dye removal was found to be 88.51%, 92.62% and 98.72% for sorption (flyash), biodegradation (Pseudomonas sp) and integral approach (Pseudomonas sp on flyash) respectively. Optimization of operating parameters of textile dye decolourization was done by response surface methodology (RSM) using Design Expert 7 software. Phytotoxicity evaluation with Cicer arietinum revealed that seeds exposed to untreated dye effluents showed considerably lower growth, inhibited biochemical, and enzyme parameters with compared to those exposed to treated textile effluents. Thus this immobilized inexpensive technique could be used for removal of synthetic dyes present in textile wastewater.

Integral approach of sorption coupled with biodegradation for treatment of azo dye using Pseudomonas sp.: batch, toxicity, and artificial neural network.

The present study investigated the removal of azo dye (crystal violet) by adsorption (using a low-cost adsorbent fly ash), biodegradation (using bacterial species, Pseudomonas sp.), and an integrated approach of sorption coupled with biodegradation (using fly ash immobilized with Pseudomonas sp.) on a comparative scale. To ascertain immobilization of bacteria on fly ash, immobilized bacterial cells were characterized by energy-dispersive X-ray spectroscopy, scanning electron microscopy, Fourier-transform-infrared spectroscopy, and fluorescence microscopy. Batch studies were conducted for optimization of the process parameters for ensuring maximum dye removal. The optimum pH, temperature, and initial dye concentration for the highest percentage of dye removal were found to be pH 7, 37 °C, and 50 mg/L in all the three cases. Under optimized conditions, the highest percentage of dye removal was found to be 89.24, 79.64, and 99.04% for biodegradation, sorption, and integrated approach of sorption and biodegradation, respectively. Finally, phytotoxicity studies carried out with the treated water on Cicer arietinum seeds also carried proved that these processes and the adsorbent did not exert any toxic effects on the seeds. Artificial neural network modeling revealed a close interaction between theoretically predicted and experimentally obtained results and with an error of around 1.1%. Thus, this novel, environmentally sustainable and economically viable technique may be applied for effective removal of crystal violet from industrial wastewater.

Extraction of dye from aqueous solution in rotating packed bed.

The influence of centrifugal acceleration on mass transfer rates in liquid-liquid extraction was investigated experimentally in rotating packed bed (RPB) contactor. The extraction of methyl red using xylene was studied in the equipment. The effect of rotational speed (300-900rpm), flow rate of the aqueous (4.17-20.8×10(-6)m(3)/s), and organic phase (0.83-2.5×10(-6)m(3)/s) on the mass transfer performance was examined. The maximum stage efficiency attained was ∼0.98 at aqueous to organic flow rate ratio of 10. The results suggest that contactor volume required to carry out a given separation can be reduced by an order of magnitude with RPB in comparison to conventional extractors.