Lanthanum-copper Composite Oxide Compounds And Research On The Removal From Wastewater

At present, eutrophication caused by excess phosphorus discharged into water bodies is becoming more serious. At the same time, phosphorus resource is limited on earth, It has larger scientific and practical values that phosphorus removal form wastewater and phosphorus recovery. Based on the lanthanum has more adsorptive ability for phosphate and preliminary studies, a novel phosphorus adsorbent has been prepared, hoping to provide new technologies for phosphorus removal from wastewater. In this study, lanthanum-copper composite oxide was developed by co-precipitation method with NaOH as precipitant. In addition, their ability to remove phosphate and regeneration were investigated.The best lanthanum-copper composite oxide was obtained when the adsorbent with copper molar mass fraction was3%, the preparation temperature was70℃, the reaction time was120min, and calcined at120℃for1hour. Copper content and calcination temperature had a greater impact on the adsorption amount of adsorbent. The results showed that:the lanthanum-copper composite oxide with the copper content of3%had high degree of dispersion and adsorbent calcined at400℃had a better adsorption ability. The adsorption mechanismn of phosphorus removal by lanthanum-copper composite oxide were both electrostatic adsorption and ion exchange adsorption.The factors affecting phosphate adsorption capacity of lanthanum-copper composite oxide were studied. The results showed that:shaking can make adsorption process faster, shake adsorption reach adsorption equilibrium after24h. The ratio of phosphate removal up to100%when the adsorbent dosage at0.75g·L-1and1.0g·L-1for solution of phosphate concentration50mg·L-1and80mg·L-1. pH4～6was determined as the better pH working range for lanthanum-copper composite oxide, that acidic conditions was more conducive to phosphorus adsorption. Phosphate uptake increased as the initial concentration increase with adsorbent additive amount for a fixed value, but the ratio of phosphate removal decreased. The experimental results indicate that the fitness of kinetic models for phosphate adsorption on lanthanum-copper composite oxide followed the order of:pseudo second-order equation> the pseudo first-order equation> Elovich equation. The adsorption isotherm was showed as Langmuir-type. Regeneration experiments showed that:The regeneration temperature has a great influence on the regeneration rate of adsorbent. The sample thermal decomposition reacted vigorously and the regeneration rate was gradually increased from800℃-1400℃. When the temperature reached at1500℃, the regeneration rate decreased slightly. The results indicated that high temperature lead to the new crystal phase generated, it was not conducive to the adsorption of phosphate. The thermal decomposition reaction was almost complete after12h, the maximum reproduction rate of the sample was58.6%.