| The electronic industries that it calls potential sunrise industry have been becoming pushing factors of modern industry's advancement in the last decades.Meanwhile,the average lifetime of electronic products has been reduced dramatically,leading to massive production of electronic wastes(E-waste).However,printed circuit board is the integral component of any electronic equipment as it electrically connects and mechanically supports the other electronic components.Its basic structure is the copper-clad laminate,which consists of glass-reinforced epoxy resin and a number metallic materials including precious metals.WPCB generally includes two parts of metallic fractions(MF,>30%)and non-metallic fractions(NMF).This work studied the disposal of the non-metallic fractions from waste printed circuit boards(NMF-WPCB).The content of this disposal process included chemical treatment,thermal process(pyrolysis and combustion)and biomass(Rice husk)of pyrolysis with NMF-WPCB.The NMF-WPCB mainly consists of plastics with high content of Br,glass fibers and metals(e.g.,Cu).This work researched the pyrolysis and combustion of NMF-WPCB chemical pretreated by alkalis,acids and alkali-salts.Copper(Cu,2.5%),calcium(Ca,28.7%),and aluminum(Al,6.9%)were the main metal constituents.Meanwhile,the silicon(Si,28.3%)and the bromine(Br,26.4%)were the predorminant non-metallic constituents.The heavy metal such as Cu was significantly reduced by 92.4%using the HCl leaching process pretreatment.The organic Br in the plastics can be converted to HBr and other gases via the pyrolysis and combustion process.The alkali pretreatment was benefit for the Br fixation in the char.In particular,the Br fixation efficiency can reach up to 53.6%by the NaOH pretreatment combined with the pyrolysis process,since the formed HBr reacted with NaOH to generate NaBr.Compared with the pyrolysis process,most of Br in the solid phase can be transferred to the liquid and gas phase in the combustion process.The gaseous organic-Br can cause serious environmental pollution.Therefore,the HCl leaching combined with the NaOH pretreatment has a high potential to be used for the pyrolysis disposal of NMF-WPCB environmentally friendly.According to the method,the NMF has been chemical pretreated named by PNMF.Additionly,this paper has studied on co-pyrolysis of PNMF with rice husk(RH).The normal methods to determine activation energy and most probable mechanism function and pre-exponential factor in the thermal analysis kinetic(Coats-Redfern method)were described and the residue was characterized.The results that different heating rate has different effects on activated energy,and the higher the heating rate,the greater the activation energy.In a addition,the co-pyrolysis of PNMF with RH can improve the fuel property and thermolysis efficiency as well as adjust the activation energy.As a result,the co-pyrolysis of the biomass(RH)with PNMF is promising and environment friendly technology to E-waste and waste recycling use of agriculture. |
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