Two treatment methodologies such as electro-coagulation coupled electro-flotation (EC -EF) and adsorption have been adopted to remove doxycycline hyclate (DCH) from the aqueous solution. An electro-coagulation (EC) coupled electro-flotation (EF) system has been designed in a closed reactor with a capacity of 1.5L on a laboratory scale. Electro-synthesis of alumina (electro-generated alumina, EGA) using aluminium electrodes with magnesium chloride as an electrolyte was achieved and used for the adsorption experiments. In both the treatment techniques, removal of DCH efficiency as a function of pH, initial DCH concentration and interfering electrolyte was studied. About 99% of DCH was removed at the end of 80 minutes in the range of pH 6 -8 by EC -EF process whereas the adsorption technique achieved about 73% (73 mg g -1 ) of DCH removal in the pH range of 3 -9 at the equilibrium time of 150 minutes.Current density of 5.39 mS cm -2 and EGA dose of 4 g L -1 was optimized respectively for the EC -EF and adsorption processes. The presence of accompanying electrolyte (NaCl) with DCH solution in the EC -EF process increased the electrical conductivity of 1.78 mS cm -1 and could achieve about 90% of DCH removal in the first 30 minutes. On the other hand, in the adsorption process, the participation of chloride (NaCl) as an interfering ion decreased the DCH removal to about 76%. Kinetic and isotherm models fitting the DCH removal dynamics in both the techniques have been checked for their validation. Characterization studies which include FTIR, SEM and XRD have also been done to explore the functional groups, surface morphology and crystalline nature of the solid materials.

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The molar conductivities of Et4NBr, n-Pr4NBr, n-Bu4NBr, and n-Bu4NBPh4 have been measured in N,N-dimethylformamide–methyl ethyl ketone (DMF–MEK) mixtures (34.5≥D≥20.10) over the maximum concentration range (2×D3×10−7 mol dm−3) along with the densities and viscosities of the solvent mixtures at 25 °C. The conductance data have been analyzed by using the Fuoss-1978 (F78) conductance equation and the results compared with those obtained from the Justice (J) and the Fuoss-Onsager-Skinner (FOS) equations. The molar conductivities at infinite dilution (Λ0), the thermodynamic association constant (KA) and the distance or the ion-size parameter (R or a°) are evaluated from these data. A better fit of the parameters was provided by the F78 equation which yielded KA and R values. The Λ0 and the KA values are found to increase with decrease in the dielectric constant of the medium and in a given solvent mixture they follow the order Et4NBr>n-Pr4NBr>n-Bu4NBr>n-Bu4NBPh4.

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Electrochemical treatment involving a coupled coagulation and floatation was performed in the removal of Doxycycline Hyclate (DCH) from aqueous solutions. All the experiments were carried out in an electrochemical reactor of 1.5 L which contained aluminium electrodes as cathode and anode. The removal of doxycycline hyclate (DCH) species by EC/EF was determined as a function of electrolysis time, pH, current intensity, flow rate and DCH concentration. From the observed results, it was corroborated that the DCH removal through the EC/EF process was excellent. The effective contribution from initial pH (7.03) and current intensity (5.39 mA cm -2 ) was very much remarkable and well apparent from flocs of good buoyancy. The removal of DCH was inversely proportional to spacing between electrodes (SBE) and circulating flow rate in the presence of the supporting NaCl electrolyte of 1 g L -1 . It was also highly promoted by the addition of NaCl in comparison to NaNO 3 and KCl to the electrolytic system. The compliance of four kinetic models was verified with DCH removal system. The free energy values from DKR model suggested the nature of bonding by chemical forces. Characterization by FTIR, SEM and XRD interpreted the assignments of various functional groups, surface morphology and crystalline incorporated amorphous nature, respectively of electro -generated flocs. The current efficiency and specific electrical energy consumption at optimized conditions of the EC/EF system were calculated.

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