Page 15 - PR 2014 2016 08 Environmental Science and Technology

Environmental Science and Technology | Progress Report 231

Paulo (SABESP). At IPEN, column tests with of Al-substituted tobermorite, katoite, hy-
sludge and sludge/soil mixtures have been drocalumite and zeolite hydroxysodalite by
established to simulate field conditions and to hydrothermal treatments of semi-dry flue gas
evaluate the potential of leachate pollutants desulfurization, a waste generated from the
from sludge and mixtures. desulfurization system of coal-fired power sta-
tion, has been demonstrated. All synthesized
Studies and development materials present ionic exchange capacity and

of recycling technologies could be used as low-cost adsorbent.
reuse of materials

Development of value-added
materials from wastes: Environmental
characterization and application

Brazilian coals are richer in ash (~ 50 wt.%)
and poorer in carbon when compared to
worldwide coal and coal ash disposal is a
serious environmental concern. Only 30% of Figure 8 (a/b).
fly ash is applied as raw material for cement Conversion of
sugarcane waste ash
and concrete production. The remaining solid (a) into Nanosilica (b)
wastes are disposed in on-site ponds, nearby
abandoned or active mine sites, or landfills.
Reuse of coal ash may provide a new source of
revenue for coal-fired power plants and may
offset expenses associated with its disposal. In
the environmental aspect, the increased use Brazil is the largest producer of sugarcane in
of coal ash can reduce energy consumption, the world. In the harvest 2015/16, 665.6 mil-
reduce the need for additional landfill space, lion of tons of sugarcane were produced. The
and conserve natural resources. processing of sugarcane to produce sugar and
ethanol generates various agricultural wastes,
In our group, we have been developing especially straw and bagasse. About 50% of
nanoporous zeolites synthesized from coal these residues are used as a source of energy
fly ash by conventionally hydrothermal treat- and the burning generates 1-4% ash. Another
ment and fusion method. Pure zeolites X and line of research has been developed focusing
A, surfactant-modified zeolites and zeolitic the conversion of sugarcane waste ash into
materials were synthesized and characterized. nanosilica (Fig. 8). Pure amorphous silica was
In addition, zeolites were used as low-cost successfully extracted with 99.1% yield from
adsorbents. The results obtained in the proj- sugarcane waste ash by a two-stage heating
ect showed that zeolites are highly efficient process followed by precipitation. The results
materials for the removal of dyes and toxic suggest that sugarcane waste ash could be
metals from aqueous solution. converted into a value-added product, mini-
mizing the environmental impact of disposal
A simple synthetic route to the formation problems.