119
a ball mill reactor. Debromination is done by substituting hydroxide or elimination
of hydrogen bromide. Once decabromodiphenyl ethane is removed, the residue is
suitable for mechanical recycling. After the removal of brominated organic compounds, the quality of fuel products is upgraded and their environmental effects are
decreased.
Dehalogenation of solid plastics is increased by adding additives during
mechanochemical treatment process. Generally, additives like alkali metal oxides
(calcium oxide, sodium hydroxide), iron powders, and quartz (silica) are employed
as catalytic adsorbents. Since, these materials are unsustainable, novel method was
developed through simultaneous grinding of plastics in the midst of sustainable
resources (e.g., biopolymers, biowastes, eco-friendly minerals) through mechanochemical treatment for clean fuel synthesis was elaborated in Fig. 6.4.
6.3.3 Hydrothermal Process
Thermal conduct of waste electrical and electronic equipment plastics emerged as a
suitable skill by degrading organo-bromine compounds, also in situ and secure
exclusion of bromine constituents from the oil products. The supercritical fluid
technology has emerged as a potential technique for chemical recycling of plastic
wastes. Supercritical fluids act as a better chemical medium under optimum conditions for depolymerization, hydrolysis, hydrogenation, and dehydrogenation with
properties like low viscosity, low dielectric content, high mass transport coefficient,
and higher diffusivity (Shibasaki et al. 2004; Zhang et al. 2013).
Hydrothermal treatment was preferred for clean fuel production because of its
higher efficiency than pyrolysis of biomass and sewage waste (Yu et al. 2016; Shen
et al. 2016). Reactor corrosion and higher energy utilization is the only drawback in
supercritical fluid method (Guo et al. 2009). Selection of appropriate supercritical
fluid and enhancers, price and operating parameters, etc. are the common challenges
faced during the hydrothermal treatment process.
Hydrothermal process is of two major types: (i) hydrothermal liquefaction and
(ii) hydrothermal gasification. The quality of final product is decided by the operating parameters and environment (Yan et al. 2010). Dehalogenation by hydrothermal
treatment method has been studied in recent days for plastics compounds (Starnes
2012). Solid fuel properties are significantly increased by unification of biomass
through hydrothermal conditions.
6.3.4 Pyrolysis
Pyrolysis is an environment-friendly and economically feasible technique for waste
electrical and electronic equipment plastic treatment than landfilling and incineration. Emission of toxic gases into the environment is lesser than incineration process
6 Chemical Recycling of Electronic-Waste for Clean Fuel Production
a ball mill reactor. Debromination is done by substituting hydroxide or elimination
of hydrogen bromide. Once decabromodiphenyl ethane is removed, the residue is
suitable for mechanical recycling. After the removal of brominated organic compounds, the quality of fuel products is upgraded and their environmental effects are
decreased.
Dehalogenation of solid plastics is increased by adding additives during
mechanochemical treatment process. Generally, additives like alkali metal oxides
(calcium oxide, sodium hydroxide), iron powders, and quartz (silica) are employed
as catalytic adsorbents. Since, these materials are unsustainable, novel method was
developed through simultaneous grinding of plastics in the midst of sustainable
resources (e.g., biopolymers, biowastes, eco-friendly minerals) through mechanochemical treatment for clean fuel synthesis was elaborated in Fig. 6.4.
6.3.3 Hydrothermal Process
Thermal conduct of waste electrical and electronic equipment plastics emerged as a
suitable skill by degrading organo-bromine compounds, also in situ and secure
exclusion of bromine constituents from the oil products. The supercritical fluid
technology has emerged as a potential technique for chemical recycling of plastic
wastes. Supercritical fluids act as a better chemical medium under optimum conditions for depolymerization, hydrolysis, hydrogenation, and dehydrogenation with
properties like low viscosity, low dielectric content, high mass transport coefficient,
and higher diffusivity (Shibasaki et al. 2004; Zhang et al. 2013).
Hydrothermal treatment was preferred for clean fuel production because of its
higher efficiency than pyrolysis of biomass and sewage waste (Yu et al. 2016; Shen
et al. 2016). Reactor corrosion and higher energy utilization is the only drawback in
supercritical fluid method (Guo et al. 2009). Selection of appropriate supercritical
fluid and enhancers, price and operating parameters, etc. are the common challenges
faced during the hydrothermal treatment process.
Hydrothermal process is of two major types: (i) hydrothermal liquefaction and
(ii) hydrothermal gasification. The quality of final product is decided by the operating parameters and environment (Yan et al. 2010). Dehalogenation by hydrothermal
treatment method has been studied in recent days for plastics compounds (Starnes
2012). Solid fuel properties are significantly increased by unification of biomass
through hydrothermal conditions.
6.3.4 Pyrolysis
Pyrolysis is an environment-friendly and economically feasible technique for waste
electrical and electronic equipment plastic treatment than landfilling and incineration. Emission of toxic gases into the environment is lesser than incineration process
6 Chemical Recycling of Electronic-Waste for Clean Fuel Production