Study On The Treatment Of Heavy Metal Nickel Ions In Industrial Wastewater

As a kind of heavy metal material, Nickel is closely related to human lives and widely used in steel, nickel-based alloys, electroplating and battery and other fields. However, its emissions have been strictly controlled under national environmental standards owing to its hazards. Therefore, how to effectively remove nickel from industrial sewage has become an imperative environmental issue in today's industrial manufacturing industry. Compared with other heavy metal removal methods, chemical precipitation and adsorption methods have a wider application prospect on account of their simple operation and low cost. This dissertation focuses on the treatment with nickel in the industrial sewage. A systematic study has been conducted and the main research results are listed as follows:(1) The precipitation method of Ca(OH)2 and DDTC-Na is applied in the treatment with industrial sewage with nickel complex, and the step chemical precipitation method is used to treat nickel complex in industrial sewage. Some parameters are measured to study their effects on the experiment, namely the pH value of the precipitate, the dosage of Ca(OH)2 and of DDTC-Na. In the first step of precipitation, Ca(OH)2 is used to adjust the pH value of sewage to maintain 11.5-12.5, and then most nickel in the sewage will be precipitated. In the second step of precipitation, when the pH value of sewage reaches 6-8 and the dosage of DDTC-Na m?:m ???=1:7, the result will be the best. This method of treatment with industrial sewage with nickel complex can reach 0.5mg/L of the national emission standard.(2) NaOH activation method is used to prepare porous carbon materials, and the porous carbon materials'absorption on Ni(?)) is studied. With rice husks as raw materials, NaOH is used as an activator to prepare porous carbon materials so as to absorb heavy metal nickel ions from aqueous solution. Alkali/carbon ratio, activation time, activation temperature and other activation conditions are measured to study their effects on the porous carbon materials'absorption on Ni(?)). Besides, the effects on absorption capacity by some parameters like the pH value of the solutions, adsorption time, and the initial concentration of Ni(?) solutions are also studied. The results have shown that the absorption capacity reaches its best when alkali/carbon ratio is 3, activation time 2 hours, and activation temperature 800?. The porous carbon materials' adsorption on nickel ions more conforms to the Langmuir isotherm mode, since it is mainly monolayer adsorption with its maximum adsorption capacity of 75.3mg/g. When the initial pH value is 7.0, it will reach the absorption equilibrium after 200mins' reaction. When the porous carbon materials are characterized by BET absorption, EDS, XRD and FTIR, the results show that there is SiO2 except C in the porous carbon materials, that the most probable aperture is 0.62nm, and that the specific area is 1192m2/g. Ni2+ will be parsed out of H2SO4 solutions by putting porous carbon loaded with nickel ions in the solutions, which realizes the reuse of the porous carbon materials. The results show that the absorption capacity of porous carbon materials can still maintain 90% of its initial capacity after five cycles. Therefore, the porous carbon materials are an effective absorption material for the removal of nickel ions from solutions.(3) KMnO4 and NaOH activation method is used to prepare manganese doped porous carbon materials and their absorption on Ni(?) is studied. With rice husks as raw material, KMnO4 and NaOH are used as activators to produce manganese doped porous carbon materials so as to absorb heavy metal nickel ions from solutions. Besides, the effects on absorption capacity by some parameters like the concentration of KMnO4 solution, the pH value of the solutions, adsorption time, and the initial concentration of Ni(?) solutions are also studied. The results have shown that when the concentration of KMnO4 solution is 1%, the prepared manganese doped porous carbon materials reach their best absorption capacity on Ni(?), which more conforms to the Langmuir isotherm mode with its maximum absorption of 128.2 mg/g. When the manganese doped porous carbon materials are characterized by BET absorption, EDS,XRD and FTIR, the results show that the content of SiO2 decreases, and that most probable aperture is 0.58nm, and that the specific area is 1537m2/g.