| Pyrite slag is the production of sulfuric acid roasting pyrite slag. With the development of the sulfuric acid industry, pyrite slag piled up like a mountain, not only occupying a lot of land, but also causing serious environmental pollution.In this paper, pyrite slag as an adsorbent are used to remove chromium ions in wastewater. We studied the chemical composition, phase composition, structural characteristics and properties of the pyrite slag and explore the removal of chromium ions in water and its influencing factors, and other related properties.The original pyrite slag wasmodified by hydrochloric acid, using electronic X-ray fluorescence analyzer, scanning microscope (SEM), X-ray diffraction (XRD) and other equipment to analyze the composition, phase and morphology of the pyrite slag material and hydrochloric acid-modified pyrite slag.The main components of the original sample and hydrochloric acid-modified pyrite slag were Fe2O3 and SiO2, also containing a little Al2O3, CaO and ZnO, etc.The original pyrite slag microstructure is given priority to with irregular particles, structure being more compact, and the existence of large bond body, etc.Hydrochloric acid-modified pyrite slag although there is a bond of larger particles, but particles become more small, uniform, more show uneven surface;The original sample and modified pyrite slag main phase were hematite, magnetite and quartz.We prepared modified pyrite slag into granular adsorbent by centrifugal granulation.We adopt the method of orthogonal experiment to study the influence of the caking agent configuration, the proportion of materials, time of ball mill, the dosage of pore-forming agent on the adsorbent shaping. The results show that when the rate of binder is 400:40, material proportion is 50:60, ball grinding time for 30 min and pore-forming agent content is 40%, the loss rate of the sample is the minimum and pyrite slag spherical particles is most uniform. For the pyrite slag adsorbent, we studied the influence of concentration of modifying hydrochloric acid, respectively, pyrite slag adding amount, adsorption time,initial concentration of the chromium ion solution and pH on the absorption effect of the pyrite slag.In 100ml simulated wastewater of chromium ion concentration of 20mg/L, adsorbent of pyrite cinder modified by 0.2 mol/L HCL additive amount of 4 g, adsorption time for 44 h, pH of 7, chromium ion removal effect is thebest, being more than 99%.For different concentrations of chromium ion solution, we drawed the pyrite slag adsorbent of Cr6+ isothermal adsorption curve, and the experimental data were fitted with the Langmuir adsorption isotherm equation and the Freundlich adsorption isotherm equation.The adsorption isotherm of pyrite slag Cr6+and the Langmuir adsorption isotherm equation is fittingwell. It showed that pyrite slag adsorbent Cr6+adsorption capacity is 1.37mg/g and pyrite slag Cr6+ adsorption are mainly chemical adsorption and physical adsorption is complementary. Adsorption is the joint outcome of chemical adsorption and physical adsorption.Different desorbent were used to desorb and regenerate the pyrite slag saturated sorbent; the adsorption rate of the sample desorbed by hydrochloric acid and then treated by sodium hydroxide is up to 79.36%. |
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