Development Of Bio-Ash Supported Nanocomposites For The Photocatalytic Treatment Of Acid Red 88 And Methylene Blue
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Date
2018-11-01
Authors
Lum, Pei Teng
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
To date, the wide scale application of photocatalysis, a new innovative and promising
technology for the environmental remediation of textile dye pollutants, is experiencing
the technical challenges of particles self-agglomeration and post-separation difficulty.
Arising research pertaining to the immobilization of photocatalysts onto different
supporting materials have been promoted. Giving insight into the huge generation of
agricultural bio-ash and highlighting of their low economical value, the development
of a series of bio-ash supported nanocomposites by using simple physical coating and
hydrothermal techniques has been attempted. Bio-ash including incense ash (IA),
durian shell ash (DSA) and coffee residue ash (CA) was adopted to be the low-cost
precursors for the preparation of bio-ash supported SnO2 and ZnO nanocomposites,
with different ash impregnation ratio from 1:1 to 1:5. Surface morphology analysis,
pore structural measurement, detection of surface functional groups and evaluation of
point of zero charge (pHzpc) were carried out. The photocatalytic performance was
examined with respect to the batch photocatalytic degradation of Acid Red 88 (AR 88)
and Methylene Blue (MB) by varying the operational parameters, catalyst loading,
initial dye concentration and irradiation time, and solution pH. Surface morphological
studies revealed that the deposition of catalysts onto the surface of different bio-ash
was successfully attained. Examination of the porosity development suggested that the
capability of bio-ash to improve the overall surface area. Fourier-Transform Infrared
Spectroscopy (FT-IR) spectrum ascertained the homogenous deposition of SnO2 and
ZnO photocatalysts on the surface of bio-ash. Results illustrated the best
photodegradation efficacy was achieved at the optimum catalyst loading of 0.03 g/100
mL for SnO2/CA, 0.04 g/100 mL for SnO2/IA and SnO2/DSA nanocomposites, and
0.40 g/100 mL for ZnO/IA, ZnO/DSA, and ZnO/CA nanocomposites, respectively.
Acidic medium favors to the photocatalytic removal of AR 88, while the basic
condition prefers to the photodegradation of MB. Increasing initial concentration from
100-500 mg/L for AR 88 and from 50-400 mg/L for MB demonstrated the significant
influences on the removal efficacy, and a longer irradiation time was acquired for the
complete removal process. Kinetic analysis revealed that the linearity of the
photocatalytic plots was well described by the first order model. Reusability test
indicated high durability of these newly prepared nanocomposites, with greater than
85% of degradation efficiency even after five regeneration cycles. This study provided
a new insight in the preparation of valuable bio-ash supported nanocomposites for the
effective purification of textile dye pollutants.