Removal of Carbofuran from Drinking Water Using Natural Rutile

Abstract

Water bodies contaminated with pesticides is a major constrain faced by every agriculture
based country. Providing safe potable drinking water to public has proved to be a challenge in
such situations. Rutile is found in enormous concentrations in the Pulmoddai beach sand
deposit, and is exported as raw material since 1968, without utilising the deposit for any other
purpose.

There were number of reports published regarding the photocatalytic effect of rutile and use
of pure titanium dioxide to remove pesticides globally, but according to the available
literature, no studies on the potential effect of natural rutile sand in Sri Lanka has been
carried out for water purification facility. Therefore, this is the first record on profitable
utilisation of the rutile mineral deposit for development of water treatment technology in Sri
Lanka. The naural rutile sand for the experiment was supplied from the mineral deposit of
Pulmoddai, Eastern Province.

The photocatalytic activity of natural rutile sand was induced by providing ultra violet (UV)
illumination. In vitro laboratory experiments were carried out to assess the photocatalytic
ability of natural rutile sand on carbofuran. The results revealed the potential photocatalytic
degradation of carbofuran by natural rutile sand. The carbofuran removal efficiency of
natural rutile was compared with pure titanium dioxide (TiO2). The results showed that
removal rates of carbofuran by natural rutile sand with UV illumination was 72%, whereas
pure granular/powder TiO2 showed 74% and 76% of degradation of carbofuran respectively.
When carbofuran was exposed to only UV light treatment, 33% of carbofuran reduction was
detected.

Based on the results obtained, a filter model was designed using natural rutile sand and
evaluated the potential use of natural rutile sand to remove carbofuran. The filter model
showed that there were 46%, 50%, 61%, 65% and 71% removal of carbofuran at 60, 120,
180, 240 and 300 minutes respectively, for a water circulation rate of 500l /h.

The study showed that there is an enormous potential of utilising natural rutile sand to
remove hazardous pesticides from water and the result will help to improve a water filter in
future as well.

Keywords: Carbofuran, Photocatalysis, Rutile, Water purification