Synergetic removal of aqueous phenol by ozone and activated carbon within three-phase fluidized-bed reactor

Synergetic removal of aqueous phenol by decomposition with ozone and adsorption on activated carbon was experimentally investigated. To enhance phenol removal performance, two activated carbons (AC1 and AC2) with BET surface areas of 1106 and 1150 m² g^?1 and average pore diameters of 2.3 and 1.7 nm, respectively, were employed. While the slowest initial removal of phenol was achieved with introduction of ozone only, the much better removal of phenol was obtained with utilization of activated carbon with ozone. Some intermediate products, which were detected as total organic carbon (TOC), were found to remain even after phenol was completely decomposed. Regarding to higher mesopore fraction, AC1 could better remove intermediates than AC2. With the synergetic performance of AC1 and ozone it was found that the highest removal of phenol and TOC was up to 100% and 89%, respectively.     

含酚废水处理的吸附和臭氧氧化动力学模型

A three phase fluidized bed reactor was used to investigate the combined effect of adsorption and oxidation for phenolic wastewater treatment.Aqueous solutions containing 10 mg·L 1of phenol and ozone were continuously fed co-currently as upward flow into the reactor at constant flow rate of 2 and 1 L·min1,respectively.The phenolic treatment results in seven cases were compared:(a)O3 only,(b)fresh granular activated carbon(GAC),(c) 1st reused GAC,(d)2nd reused GAC,(e)fresh GAC enhanced with O3,(f)1st reused GAC enhanced with O3,and (g)2nd reused GAC enhanced with O3.The phenolic wastewater was re-circulated through the reactor and its concentration was measured with respect to time.The experimental results revealed that the phenolic degradation using GAC enhanced with O3 provided the best result.The effect of adsorption by activated carbon was stronger than the effect of oxidation by ozone.Fresh GAC could adsorb phenol better than reused GAC.All cases of adsorption on GAC followed the Langmuir isotherm and displayed pseudo second order adsorption kinetics.Finally,a differential equation for the fluidized bed reactor model was used to describe the phenol concentration with respect to time for GAC enhanced with O3.The calculated results agree reasonably well with the experimental results.     

Development of separation sharpness model for hydrocyclone

Hydrocyclones are mechanical devices used in classifying and separating many different types of materials. A classification function of the hydrocyclone has been continually developed for solid–liquid separation. In the classification process of solids from liquids, it is desirable to reduce the amount of misplaced material; therefore, the separation sharpness, α(alpha), is a parameter that helps in evaluating misplaced material and has been developed as a model to help the designer predict the performance of the classification. However, the problem with the separation sharpness model is that it cannot be used outside the range of conditions under which it was developed. Therefore, this research aimed to develop the separation sharpness model to predict more accurately and cover a wide range of conditions using the multiple linear regression method. The new regression model of separation sharpness was based on a wide range of both experimental and industrial data-sets of 431 tests collaborating with the additional experiments of 117 tests that were obtained from a total of 548 tests. The new model of separation sharpness can be used in the range of 30–762 mm hydrocyclone body diameters and feed solid concentrations in the range of 0.5 wt%–80 wt%. When compared with the experimental separation sharpness, the accuracy of the separation sharpness model prediction has an error of 4.53% and ~ of 0.973.     

Particle separation performance by use of electrical hydro-cyclone

A special electrical hydro-cyclone is developed and tested. In the underflow collection box of the hydro-cyclone, it has a central metal rod electrode and a cylindrical metal wall between which the desired DC electrical potential or no potential is applied. Effect of central rod diameter and length on separation cut size was examined. The aqueous suspensions of silica particles with a median diameter of 754 nm were tested using a 20 mm-diameter hydro-cyclone without underflow.

It was found that the zeta potential of particles increased proportionally with the value of pH. The electrical potential exhibits a stronger effect when the suspension indicates high pH value. The cut size decreases with the increase of initial pH values. This result is due to the increased negative zeta potential under high pH condition and negatively charged particles are easily collected by electrostatic force.

The cut size decreases with the increase of electrode diameter. The cut size becomes smallest under high pH, large electrode diameter and long electrode length conditions. For the negatively charged particles, the center electrode should be negative polarity and outer cylindrical wall should be positive. By use of the electrostatic force, the cut size decreases about 9.2% smaller compared to the standard case without electrostatic force.