Experimental Study On Forming Bentonite Adsorbent

Bentonite is a clay mineral of resource-rich in China, with a unique layered structure and strong adsorption capacity. Its physical and chemical properties are improved after the modification, effective adsorption of heavy metal ions, organic matter and other pollutants. Bentonite used in wastewater treatment has simple, effective, low-cost advantages. However, bentonite powder fine, with swelling, and form slurry with water, permeability can be poor, use of powdered bentonite wastewater treatment, solid-liquid separation is difficult, is not use to a wide range extended to the practical engineering applications.This article use Henan Xinyang pingqiao Licheng Factory sodium bentonite as raw material, add molding agent (porogen), through a certain preparation process, make the powdered sodium bentonite adsorbent into shape, to discuss the most good preparation process parameters, molding agent types and amounts; By X-ray diffraction and environmental scanning electron microscope analysis and comparison the raw materials bentonite with forming absorbent differences in physical and chemical properties, systematic study bentonite of raw materials and then molding adsorbent treatment heavy metals from wastewater Ni2 +, Cu2 + and Cr6 + effects of the factors conducted, compared the raw materials bentonite with forming absorbent adsorption to determine the forming absorbent the best conditions for adsorption of heavy metal wastewater, and explore the adsorption mechanism.Tantou Luoyang city in Henan metal smelting industrial park focused on heavy metal wastewater treatment plant as the basis to further explore the forming adsorbents in practical applications of value. This article also explore the feasibility program for saturated adsorbent and the final disposal of Microfiltration concentrate water, which lowered the heavy metal wastewater treatment costs, but also turning waste into treasure, the saturated absorbent material into the base to take full advantage of the construction, complete heavy metal wastewater treatment in the region to achieve zero emissions.The raw materials bentonite particle size is 200 mesh. By Preliminary tests selecting weathered coal and sodium carbonate as the forming agent, results showed that due to the use of weathered coal as forming agent, require the calcination temperature of 600°C, the time for more than 60min, destruction the montmorillonite structure in the bentonite, affecting the adsorption efficiency; Use of sodium carbonate for forming agent the molding temperature does not destroy the structure of montmorillonite, bentonite retained excellent adsorption properties on adsorption of methylene blue decolorization showed strong ability to choose the best adsorbent The preparation parameters, the adding amount of sodium carbonate 5%, calcination temperature is 550°C, calcination time 40min.Comparison on heavy metal ions adsorption shows that forming absorbent materials preparation process did not undermine the excellent properties of soil. Adsorption of Ni2+ containing waste waters the best conditions: m Ni / m bentonite as 9.39mg.g-1, vibration absorption 20min, pH 7.0, Ni2+ removal rate could reach 93.9%. The oscillation after adsorption, Ni2+ residual concentrations are reached (Integrated Wastewater Discharge Standard) GB8978-1996 level of emission requirements.Adsorption of wastewater containing Cu2+ optimum conditions for: m Cu / m bentonite as 8.99 mg.g-1, vibration absorption 20min, pH 7.0, Cu2+ removal rate could reach 89.9%. Forming sorbents Cr6+ adsorption result is not satisfactory, because of Cr6+ in the water as Cr2O72-anion form, and structure of silicon-oxygen negative charge repulsion phenomena. Forming adsorbent of heavy metal ions in wastewater and mechanism of the performance results show that the bentonite in water Ni2+ and Cu2+ adsorption are consistent with Langmuir adsorption isotherm equation also conforms to Freundlich adsorption isotherm equation.Forming adsorbent saturated, re-crushed, thrown into concentration reverse condensed water, then add other fillers, the water completely absorption into the saturated adsorbent, stir into the group, aging back, broken into a 3mm size of the particles, bentonite powder with its package, through a certain process of the appearance of glass, firing ceramic-based material, four times the cement mortar mix well prepared into a 250mm×250mm×60mm flooded road blocks, heavy metal ions penetration in line with " Identification standards of hazardous waste leaching toxicity of identification "(GB5085.3-2007), flooding good performance can be used as road blocks and the landscape.