Page 239 - 00. Complete Version - Progress Report IPEN 2014-2016

Environmental Science and Technology | Progress Report 239

BESP). At IPEN, column tests with sludge and Al-substituted tobermorite, katoite, hydro-
sludge/soil mixtures have been established to calumite and zeolite hydroxysodalite by hy-
simulate field conditions and to evaluate the drothermal treatments of semi-dry flue gas
potential of leachate pollutants from sludge desulfurization, a waste generated from the
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 world-
wide coal and coal ash disposal is a serious
environmental concern. Only 30% of fly ash is Figure 8 (a/b). Con-
applied as raw material for cement and con- version of sugar-
cane waste ash (a)
crete production. The remaining solid wastes into Nanosilica (b)
are disposed in on-site ponds, nearby aban-
doned or active mine sites, or landfills. Reuse
of coal ash may provide a new source of rev-
enue for coal-fired power plants and may off-
set 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 ad- successfully extracted with 99.1% yield from
sorbents. The results obtained in the project sugarcane waste ash by a two-stage heating
showed that zeolites are highly efficient ma- process followed by precipitation. The results
terials for the removal of dyes and toxic met- suggest that sugarcane waste ash could be
als from aqueous solution. converted into a value-added product, mini-
mizing the environmental impact of dispos-
A simple synthetic route to the formation of al problems.