Study On The Adsorptive Performance Of Porous Cellulose Acetate/Zeolite Composite Fiber In Fixed-bed Column And The Application

Sorption appears as a simple and low-cost method, with a great potential ofbecoming an actual alternative to conventional ones, overcoming the problems ofinsufficient efficiency and difficult waste handling. However, the most adsorbentwas packed in a bed column with the small particle size to increase the specificsurface area and achieve high removal rate, which led to the problem of easy lossand difficult separation. Cellulose acetate/zeolite composite fiber was packed in thecolumn to adsorb the heavy metal ions Cu²⁺and organic dye methylene blue （MB）.The Thomas model and the bed depth service time （BDST） model were used to fitthe column sorption data. The efficacy and adsorption mechanism were also studied,and then the composite fiber was applied for the removal of copper fromelectroplating wastewater.The column sorption data obtained at different depth Z, initial concentration C₀,velocity v, and pH was studied. The results showed that, with Z increasing, the plotsof breakthrough curve moved to the right and the breakthrough time increased;while the plots moved leftward with an increase of C₀and v. The pH value was5.5in the adsorption process of Cu²⁺and the pH value was10.0in the adsorptionprocess of MB.At a higher of Z, C₀, v, total amount of Cu²⁺sent to the column （wtotal） waslarger; as Z rising, the removal percent （Y%）、the maximum column capacity （qtotal）、the equilibrium uptake qeq（exp）as well as the penetration time tband the saturationtime teall moved up; with C₀and v increasing, all the parameters above changed inthe opposite trend.The Thomas model that consist of two parameters （q0and kt） was applied todescribe the breakthrough curves. It was shown that the calculated breakthroughcurve agreed well with the measured ones. In the adsorption of Cu²⁺, when Zincreased, q0went up and ktwas reduced; when C₀and v was higher, q0and ktchanged in the opposite trend. During the adsorption process of MB, ktgraduallybecame smaller, while when C₀=50mg/L and v=5.4mL/min, the value of q0and ktwere maximal.The data obtained from the BDST model showed that the calculatedbreakthrough curve agreed well with the measured ones. With Z increasing, Kadecreased, while N0gradually increased. The predicted value of C₀’=80ppm andv’=8.6mL/min was similar to the actual results. The blank fiber had an obviously lower efficiency in the removal of Cu²⁺.The presence of NaCl had a greate effect in the removal process.The column was successfully applied for the removal of copper from the actualcopperplating wastewater. The column regeneration studies were carried out forthree sorption-desorption cycles. The tesults showed that, the adsorption capacitydecreased after the first regeneration, while the decrease was smaller after thesecond cycle. Short time was needed in the desorption and the regeneration timewas shortened.