Removal of arsenic from contaminated water: Phytoaccumulation and adsorbent-based removal by activated carbon prepared from Typha tripholia

Abstract

Aim: To assess the phytoaccumulation efficiency of arsenic in different parts of Typha tripholia (cattail) grown in the natural habitat of a pond located in Rada village of Bijua block, district Lakhimpur Kheri (U.P.) and to develop an adsorbent based removal technology by activated carbon prepared from Typha tripholia (ACTT) using physical activation. Methodology: Phytoaccumulation of arsenic was studied in cattail plants. Rhizomes and leaves of plants were used to prepare activated carbon. The morphological characterization and surface structure were studied by using different modern techniques like Scanning electron microscopy (SEM), Energy-dispersive X-ray (EDX), and Brunauer-Emmett- Teller (BET). The adsorption efficiency and removal of arsenic were studied by using different doses of ACTT, i.e., 0.5, 1.0, 1.5, 2.0, 2.5 g 100 m l-1 in the known solution of arsenate (30 ppb). Results: The arsenic concentration in pond water was 19 µg l-1, which was higher than the permissible limit (10 µg l-1) of WHO, while in the soil it was 123 µg kg-1. The maximum As concentration in the root was 360 µg kg-1, while in the stem and leaf, it was 20 µg kg-1 and 26 µg kg-1, respectively. Characteristics properties of ACTT showed amorphous nature and it contained 81.71 % carbon while other elements like oxygen (10.65 %), chloride (2.12 %) and potassium (5.52%) were also detected. The porosity of ACTT was 1.271 × 10-3 cc g-1 with pore volume 3.7 × 10-3 cc g-1, while the pore size, pore width, and pore diameter were 4.498 nm, 2.0208 nm and 4.498 nm, respectively. Removal of arsenic increased on increasing the dose of activated carbon, and the maximum adsorption (99.6%) was observed at 1.5 g 100-1 ml further it decreased. Interpretation: Thus, Typha tripholia may be used as phytoremediation, a plant-based green technology for the removal of As from contaminated water while ACTT acts as a good adsorbent for As, due to its large surface area and pore space and a high degree of surface reactivity. Key words: Arsenic removal, Activated carbon, Adsorption, Cattail, Phytoaccumulation