Abstract

Synthesis of zeolite fromcrop waste and its application for pesticide removal

Author(s): Uzaira Rafique, Nosheen Ayub

Sustainable development is renowned as promising culture and multifaceted methodology comprising environmental, ecological, scientific, economic, social and political issues of global significance. The key aspects of sustainable development from an energy and chemical perspective are to develop more renewable forms of energy and products to reduce pollution. Agricultural residues attract widespread attention for renewable energy generation and also for their large scale combustion. The combustion of these products results in the generation of ashes which is a source of silica for the synthesis of adsorbents like zeolites. The present study aims at synthesis of zeolite from waste of agricultural areas to propose a system of waste management. To achieve the objectives, waste wheat (straws) and chemically (Cetyl trimethylammoniumbromide CTAB) modified wheat was mixed with spent aluminium foil solution, separately to obtain Si-Al zeolites. The synthesized product is characterized by Fourier transform infra-red spectroscopy (FTIR) and X-ray diffraction (XRD). The adsorption efficiency of synthesized zeolite was assessed by removal of pesticide (2, 4- Dichlorophenoxyacetic acid). FTIR peaks of Si-O-(Si) and Si-O-(Al) at 1200-400 cm-1 confirmed the synthesis of aluminosilicate zeolite. Characterization of materials under XRD revealed crystalline morphology and nano-sized particles (0.24 nm) of synthesized zeolites. The two newly synthesized zeolites were applied as adsorbents for the removal of selected pesticides (2, 4-D (herbicide) and carbaryl (insecticide)) used on agricultural fields. The results indicated that modified zeolites are better adsorbents with percent removal of 5 and 15 orders higher for carbaryl and 2,4-D, respectively. This is attributed to the enhanced surface area and porosity due to surfactant (CTAB) addition. The sequence of removal on Zeolites suggests that basic insecticide (carbaryl) is less efficiently removed than acidic 2, 4-D. The study proposes novel agro-based adsorbents for management of pesticides in agricultural settings.