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In this study, the influence of different operating regimes on drop behaviour in an L-shaped pulsed sieve-plate column has been investigated and the effects of pulsation intensity and phase superficial velocities on drop diameters are evaluated. The toluene-water system with 0.03 L/L (3 vol%) acetone as a mass transfer agent is used. Experimental observations reveal that with increasing pulsation intensity, drop sizes slightly decrease and by reaching to the end of mixer-settler regime, they significantly decrease followed by a mild decrease in the dispersion regime. Moreover, it is observed that mean drop size firstly varies inversely as both phase superficial velocities change, while it slightly increases with further increase in superficial velocities. Finally, some of the most recommended correlations are compared to the experimental data. It is revealed that these correlations show the highest deviation in the lower end of the mixer-settler regime (> 40 %), while in the dispersion regime it becomes < 15 %, indicating that they are only applicable in the region of practical regimes. Accordingly, two of these correlations are modified in order to cover different operating regimes by means of two correlations proposed to predict the transition regime in each section of the column. The AARE values of the modified correlations are found to be < 14.7 %. [ABSTRACT FROM AUTHOR]

Tetracycline (TC) batch adsorption was investigated in a synthesized aqueous solution using activated carbon (AC) prepared from apricot shell. The adsorbent was produced via a chemical activation method using phosphoric acid. The specific surface area, total pore volume, and average pore diameter were 307.6 m2 g-1 0.191 cm3 g-1, and 1.957 nm, respectively. Our analysis revealed that the material produced primarily consisted of mesopores (61.1%). The effect of adsorbent dosage, contact time, initial TC concentration, temperature, and initial pH of the solution on TC adsorption was studied. A thermodynamics analysis revealed that the adsorption process is endothermic and spontaneous. Adsorption isotherms were investigated, and it was shown that the Freundlich model was the best fit for the adsorption equilibrium data. The maximum adsorption capacity of TC onto activated carbon was 308.33 mg g-1, and the adsorption kinetics perfectly matched those of the pseudo-second order model. It was concluded that adsorption of TC is controlled by both intra-particle diffusion and film diffusion mechanisms. The results showed the successful application of synthesized activated carbon for effective removal of TC. [ABSTRACT FROM AUTHOR]

In this paper, continuous fixed-bed studies were carried out to investigate the feasibility of using tea waste (TW) as a low-cost adsorbent for the removal of Congo red (CR) from aqueous solution. Effects of various parameters, such as mass of the adsorbent, flow rate, influent dye concentration, and initial pH were investigated. It was found that the amount of the column adsorption capacity was at about 3 mg/g. Three commonest models, namely Adams–Bohart, Thomas, and Yoon–Nelson models have been employed to predict the adsorption breakthrough curves of CR onto TW. The Adams–Bohart model satisfactorily predicts the initial parts of the adsorption process with the correlation coefficient at about 0.9. The Thomas and Yoon–Nelson models were found to be in reasonable agreement with the experimental data. In addition, the bed depth service time (BDST) model was applied at different bed depths. The results revealed that the experimental data greatly described using BDST model. It was concluded that the fixed-bed adsorption column with TW adsorbent can be used as a wastewater treatment for the removal of CR. [ABSTRACT FROM PUBLISHER]