Vijaya Kumar Bulasara

EXPERIMENTAL INVESTIGATION ON ADSORPTION OF AMIDO BLACK 10B DYE ONTO ZEOLITE SYNTHESIZED FROM FLY ASH

ABSTRACT This work presents experimental studies on adsorptive removal of Amido black 10B dye using a low-cost zeolite synthesized from fly ash to study the effect of various parameters, namely pH, temperature, agitation speed, adsorption time, zeolite loading, and dye concentration, on dye removal efficiency. Dye removal efficiency increased with increase in adsorbent dosage, adsorption time, and stirrer speed, and the optimal values of zeolite dose, adsorption time, and stirrer speed were found to be 10 g/L, 6 h, and 300 rpm respectively. On the other hand, dye removal efficiency decreased with increase in the initial dye concentration as well as temperature, indicating that the adsorption process is exothermic and is effective at low concentrations of adsorbate. Maximum dye removal was obtained at low pH values (between 2 and 5), indicating the fact that the zeolite surface is positively charged. Experimental data matched well with the pseudo-first-order kinetic model and the Freundlich equilibrium isotherm. The most important observation in this work is that zeolite synthesized from fly ash could act as a very effective adsorbent for the removal of amido black dye from its aqueous solutions.

Heat Transfer and Pressure Drop Characteristics of Dilute Alumina–Water Nanofluids in a Pipe at Different Power Inputs

This work addresses the effect of temperature on the thermophysical properties (i.e., density, viscosity, thermal conductivity, and specific heat capacity) of alumina–water nanofluid over a wide temperature range (25°C–75°C). Low concentrations (0–0.5% v/v) of alumina nanoparticles (40 nm size) in distilled water were used in this study. The pressure drop and the effective heat transfer coefficient of nanofluids were also estimated for different power inputs and at different flow rates corresponding to Reynolds numbers in the range of 1500–6000. The trends in variation of thermophysical properties of nanofluids with temperature were similar to that of water, owing to their low concentrations. However, the density, viscosity, and thermal conductivity of nanofluids increased, while the specific heat capacity decreased with increasing the nanoparticle concentration. The convective heat transfer coefficient of the nanofluid and the pressure drop along the test section increased with increasing the particle concentration and flow rate of nanofluid. Results showed that the heat transfer coefficient increases, while the pressure drop decreases slightly with increasing the power input. This is because of the fact that increasing power input to heater increases the bulk mean temperature of nanofluids, resulting in a decreased viscosity. The prepared nanofluids were found to be more effective under turbulent flow than in transition flow.

Preparation of kaolin-based low-cost porous ceramic supports using different amounts of carbonates

AbstractFlat ceramic membrane supports were prepared using kaolin as the major constituent with varying amounts of carbonates and sintered at 900°C. The prepared supports were subjected to SEM, XRD, and porosity tests. The supports prepared without using carbonates had the largest mean pore size with the lowest porosity. The porosity of membranes increased by increasing the amount of calcium carbonate. The supports prepared using calcium carbonate had wider pore size distribution on the surface than those prepared using sodium carbonate. Small amount (10%) of sodium carbonate acts as a pore modifier resulting in smaller mean pore size, while large amount (>20%) of sodium carbonate blocks the pores by forming a sodium silicate layer and results in nonporous support. Therefore, calcium carbonate should be preferred over sodium carbonate for preparing highly porous ceramic membranes.

Surface Modification of Synthesized Nanozeolite NaX with TEAOH for Removal of Bisphenol A

In the present study, the surface modification of a freshly synthesized nanozeolite NaX was done with tetraethylammonium hydroxide (TEAOH) and applied as an adsorbent for the removal of bisphenol A (BPA) from its aqueous solutions. The adsorbent was characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results indicated that the synthesized adsorbent can remove BPA rapidly and effectively because of its high surface area (572 m2/g) and small particle size (35 nm). Uptake of BPA was greatly influenced by pH, stirring rate, temperature, contact time, and adsorbent dose. The optimum values of these parameters were 10.5 pH, 250 rpm, 25°C, 2 h, and 0.6 g/L. The adsorption was found to be spontaneous and exothermic. The Freundlich isotherm model and pseudo-first-order kinetic model fitted the experimental results well. The monolayer and multilayer adsorption capacities were found to be 42.8 and 122.6 mg/g, respectively.

Removal of emerging contaminants daidzein and coumestrol from water by nanozeolite beta modified with tetrasubstituted ammonium cation

In present research, a simplistic hydrothermal method was adopted for one-step synthesis of nanozeolite beta (NZB) having an average particle size of 18nm with Si/Al ratio 46.67, surface area 328m2/g, pore volume 0.287cm3/g, and pore diameter 3.5nm. The surface of the synthesized NZB was modified with 0.5wt% hexadecyltrimethylammonium bromide (HDTMA-Br) and used as an adsorbent for the removal of two phytoestrogens daidzein and coumestrol from aqueous solutions. The surface properties and surface charge of NZB considerably changed after modification with HDTMA-Br, which resulted in enhanced removal of daidzein (92-98% from 7 to 27%) and coumestrol (93.5-99% from 5 to 9.2%). The surface modified zeolite beta (SMZB) has similar physical characteristics as of NZB with an average particle size of 20nm, surface area 299.8m2/g, pore volume 0.263cm3/g, and pore diameter 3.51nm. The influence of various parameters was examined by conducting a sequence of batch experiments. The adsorption equilibrium was achieved in less than 3h with saturation capacity of 40.74mg/g and 42.87mg/g for daidzein and coumestrol, respectively. The Freundlich isotherm and fractional order kinetic models represented the adsorption data very closely. The thermodynamic parameters indicated that sorption of both phytoestrogens onto SMZB is spontaneous and exothermic.

Synthesis and characterization of low-cost ceramic membranes from fly ash and kaolin for humic acid separation

Ceramic microfiltration membranes were prepared using five different compositions formulated with different amounts of fly ash and kaolin and sintered at 900 °C. The SEM analysis evidenced a large number of small pores on the surface of kaolin-rich membranes. The M4 membrane prepared using 25% fly ash and 50% kaolin was found to be optimum as it had a good combination of pore size (0.885 μm), porosity (42.7%), mechanical strength (43.6MPa), and chemical stability (<3% weight loss in acid and 0.02% in base), and this membrane was successfully applied in separation of humic acid from water. The permeate flux data fitted very closely with cake-filtration model, indicating the formation of a cake layer on membrane surface. Membrane fouling was found to be reversible and easily negated by cleaning and backflushing. The regenerated membrane showed better rejection of humic acid than fresh membrane with a flux recovery of above 80%.

Tailoring of nanozeolite NaX for enhanced removal of a phytoestrogen from its aqueous solutions

ABSTRACT This study represents the application of nanozeolite NaX (NZX) synthesized by hydrothermal treatment without addition of any expensive structure directing agent for the highly effectual adsorption of biochanin A from aqueous solution. The characteristics and surface morphology of NZX were determined using FT-IR, SEM, TEM, BET, and XRD. The adsorption performance of NZX was analyzed at different conditions such as temperature, pH, contact time, adsorbent dose, and initial adsorbate concentration. The adsorption mechanism was well verified by pseudo-second-order kinetic and Redlich–Peterson isotherm models. The thermodynamic parameters revealed that the removal process was exothermic and spontaneous.

Influence of pH and temperature of dip-coating solution on the properties of cellulose acetate-ceramic composite membrane for ultrafiltration

Polymer-ceramic composite membranes were prepared by dip coating technique using 5 wt.% cellulose acetate (CA) solution at different temperatures (15 °C, 25 °C and 40 °C). The effect of pH (2-12) of the polymeric solution on the properties of the membranes was studied using SEM, EDAX, FTIR, gas and liquid permeation. The thickness of the polymeric layer depended on the interaction of CA solution with the surface of ceramic support. Membrane permeability decreased with increase in pH because of decrease in pore size and porosity resulting from strong interaction of the polymer layer with the ceramic support. The porosity and mean pore size of the prepared membranes were found to be 28-60% and 30-47 nm (ultrafiltration range), respectively. The optimized membrane (pH 7) was used for ultrafiltration of oil in water emulsions (100 and 200 mg/L). Oil rejection of 99.61% was obtained for 100 mg/L of oil concentration in water.

Performance of a new ceramic microfiltration membrane based on kaolin in textile industry wastewater treatment

Abstract A ceramic microfiltration membrane with a porosity of 40.2%, mean pore diameter of 0.27 μm, and a flexural strength of 55 MPa was prepared and applied for treatment of two types of textile dye-bath effluents. The ceramic membrane had a water permeability of 1376 L/m2.h.bar and showed excellent corrosion resistance against basic medium. Considerable removal of COD (25%), TDS (31%), BOD (39%), turbidity (21%), sulphates (34%), chlorides (33%), and color (26%) from textile effluents was achieved in the microfiltration treatment along with complete (100%) removal of TSS. This study revealed that filtration of textile effluents using a sub-micron range ceramic membrane (0.27 μm) is more effective than traditional microfiltration membranes (2–10 μm). The flux data fitted well with the standard pore blocking model indicating that the removal of various contaminants is due to adsorption of solutes on the interior surfaces of membrane pores.

Heat transfer and pressure drop performance of alumina–water nanofluid in a flat vertical tube of a radiator

ABSTRACT This work presents experimental investigation on the effects of nanofluid inlet temperature (40–90°C), Reynolds number (12,000–30,000), particle concentration (0–1 vol.%), and air velocity (0.25–0.55 m/s) on thermal and flow characteristics of water-based alumina nanofluids in a flat vertical tube of a radiator. The specific heat capacity, viscosity, density, and thermal conductivity were measured experimentally. The heat transfer coefficient enhanced (up to 31%) with an increase in fluid inlet temperature, particle volume concentration, Reynolds number as well as air inlet velocity. The pressure drop increased with an increase in the particle volume concentration and Reynolds number, while it decreased slightly with an increase in the fluid inlet temperature. The friction factor and pumping power increased with particle concentration. The friction factor decreased, while the pumping power increased with sn increase in fluid flow rate.