Lead Adsorption Properties Of The Adsorbent Prepared From Sludge

The research took the dewatered sludge as raw material, adding proper blast furnace slagas additive, to make sludge-based adsorbent in high temperature and anoxic condition. Theoptimal process conditions were chosen through orthogonal experiment and single factorexperiment. Performance of the adsorbent was tested with simulative wastewater fromlaboratory. In order to study the absorption mechanism, electron microscope scanning,infrared spectrum and adsorption kinetics analysis were used.（1） Preparation technology. The preparation conditions were chosen through orthogonalexperiment and single factor experiment. The pyrolysis temperature was500℃, The ratio ofdewatered sludge and blast furnace slag was6:4, the particle size was about0.550mm and thepyrolysis time was1.5h. The iodine number of the sludge-based adsorbent was338.32mg/g.Its yield was63.16%and specific surface area was257.78m²/g.（2） Performance analysis. The adsorbent was used to treat the simulated heavy metalwastewater. The removal rate of the sludge-based adsorbent to Pb²⁺was increasing with thetime, pH and the increase of dosing quantity. And it tended to balance gradually. The removalrate of the sludge-based adsorbent to Pb²⁺could get94.6%in a condition of that thetemperature was25℃,pH was5, initial concentration of Pb²⁺was40mg/L, absorber dosagewas3g/L, absorber time was60min.（3） Mechanism analysis. Though surface characteristic analysis, infrared spectrum andpore characteristics analyzer to analyses the adsorbent which made under proper preparationconditions. The results show that the surface of the sludge-based adsorbent was rough. Itspore structure was clear. The infrared spectrum show that the absorption peaks of acidicoxygenous group such as hydroxy and carbonyl would appear at3500cm and1700cm. Thesestructures and surface characteristics were conducive to the application of sludge-basedadsorbent in wastewater treatment. The adsorption kinetics of the sludge-based adsorbent toPb²⁺was in line with pseudo-second-order kinetic equation. The diffusion inside particles was a controlling step of adsorption rate, but not the only one. Langmuir Isothermal Equation wasmore preferably to describe such adsorptions than Freundlich Isothermal Equation.