| Nickel is widely applied in electroplating, printed circuit boards, materials and soon. Besides, the industry dischange amount of nickel wastewater every day. Thenickel can be induced carcinogenesis,"Metal pollution comprehensive prevention andcontrol10-25planning" also explicitly indicate that the nickel wastewater as thesecond kind of pollutant as the concentration of nickel(Ⅱ) must low the1mg/L.Thecurrently situation of wastewater is 'many, small, scatted and disorderly'; it is moreharm for human if not to regulate the wastewater. How to find out a method ofcheapness, easy operation and effectiveness to removal nickel wastewater, which iskey of solving the problem.The currently technology of removal nickel(Ⅱ) are precipitation, extraction,oxidation reduction method, adsorption, ion exchange resin, biomoval, etc.Precipitation is the common method used by small company to run metal wastewater,becase of its simpleness, easy operation and cost low. Whereas, it is a problem torecover nickel form complex wastewater by conventional precipitation in orde to meetthe standard of government. Many rereacher pay attention to the chelatingprecipitation due to which was used to remove the nickel from complex wastewater.the restriction that was applied to marcket is the chelator of lower toxicity, stableness,efftiveness and cheapness. Recently, it is common to use disulfur or thio-nitrogenligand. Though, the disulfur cheator easy to releas H2S in strong acid amdunstableness which was exposed to the air. The thio-nitrogen cheator was also easyoxidated to nitrosation, which ceased to be effective.For this reason, three kind of chelator5-methyl-2-sulfydrylbenzyl alcohol(MSL),5-methyl-2-sulfydrylbenzoic acid(MSD),4-methyl-2-chlorophenthiol-(MCP) weredeveloped to overcome such shortcoming in removal nickel(Ⅱ) wastewater. Theresult of experiment as follow:(1) MSL was invented by the4-methylphenthiol and formaldehyde in theAlkaline environment, which was also characterized by FI-infrared spectrum. What ismore, this paper studied the reaction condition toward yeid, the pH and the quality ofMSL and mixed agent toward removal nickel wastewater, the regeneration ratio of MSL.Result showed the best condition: the molar ratio of4-methylphenthiol andformaldehyde was1:1.5, the quality of NaOH was20%times than4-methylphenthiol, temperature was50℃, time was12hours. When the pH=9, thequality of MSL was added1.15times of the stoichiometric amount or the quality ofmixture agent(not separate MSL)17.8times than the nickel quality, the Nickel orewastewater was deal with the best effect. At the same time, when8mol/L HCl wasused to release MSL, the regeneration efficiency beyond98%.(2) MSD was synthesized by4-methylphenthiol and oxalyl chloride with theanhydrous aluminium chloride catalysis, which also was detected by FI-infraredspectrum. The optimum condition of the reaction, the effece of the pH and the qualityof MSD, decomposition ratio were all investigated. Result show as following: molarratio of4-methylphenthiol, oxalyl chloride and aluminium chloride was1.1:1:2.2,temperature was25℃and reaction time was2hours. What is more, the pH=9, thequality of MSD was used1.2times of the stoichiometric amount,which were the besteffect to remove the nickel ore wastewater. Meanwhile, when the chelatingprecipitation was decomposed by10mol/L HCl, the regeneration efficiency beyond97%.(3) MCP was compounded by4-methylphenthiol and sulfuryl chloride, which wasconfirmed by the FI-infrared spectrum. What is more, this paper studied the reactioncondition toward yeid, the pH and the quality of MCP toward removal nickelwastewater and the regeneration ratio of MSL.The result show as follow: The bestreacting molar ratio of4-methylphenthiol and thionyl chloride is1:1.3, thetemperatrue is40℃and the reaction times is2hours. The optimal treatment conditionof nickel ore wastewater is pH=9,1.1times dosage than theoretical mole amount.Besides, the nickel can be regenerated by12mol/L HCl, and regeneration efficiencybeyond98%. |
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