ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Treatment of toxic Imidacloprid pesticide-laden agricultural wastewater using low-grade coal-derived adsorbent

Smruti Smita Sahoo, Rushabh K. Kale, and Pradip Chowdhury

Department of Chemical Engineering, National Institute of Technology Rourkela, Rourkela, India

E-mail: chowdhuryp@nitrkl.ac.in

Received: 21 December 2022  Accepted: 3 June 2023

Abstract:

This work reports a systematic investigation on the treatment of toxic Imidacloprid pesticide-laden agricultural wastewater using low-grade coal-derived adsorbent. Following mechanical and chemical treatments, both run-of-mine (ROM) and prepared coal samples were analyzed using proximate analysis and gross caloric value (GCV) measurements followed by CHNS analysis. An ash content of 41% and GCV of 3270 kcal/kg were measured for Mahanadi Coal Fields (MCL 1, India) sample. Ultimate analysis of MCL1 sample yielded C: 62.34; H: 4.805; N: 1.406; and S: 0.95, respectively. Coal petrography established the presence of high vitrinite content (ca. 46%) in MCL1 sample. Surface morphology via SEM imaging showed improvement in the porous nature of treated coal samples, EDX mapping showed the heterogeneous composition with the presence of inorganic mineral impurities: Si, Al, and Zr. Powder XRD patterns corroborated the crystalline nature of raw and processed coals. FT-IR spectra of raw coal exhibited the presence of O–H stretch functional group at 1429 and 1100 cm⁻¹ due to the presence of alcohols, phenols, and carboxylic acids. The adsorbent, viz. activated carbon (AC), was prepared from the MCL1 sample via standard activation techniques. Alkali-treated product yielded maximum iodine number (1430 mg/g). Raman spectra of raw coal and AC showed I_d/I_g ratios at 0.69 and 0.86, respectively. The higher value for AC confirms the transformation. The surface area was improved from 33 (ROM) to 890 m²/g (AC). Batch studies on the removal of Imidacloprid were carried out on simulated solutions and agricultural wastewater. The presence of Imidacloprid in the agricultural effluent was approximately 20 ppm. Maximum removal percentage of ca. 92% was noted for the model contaminant, whereas for the real agricultural sample, the removal efficiency was ca. 88.9% within 60 min of experimental run. The adsorbent regeneration showed encouraging results with consistent repeatability in performance up to 4^th cycle.

Keywords: High ash coal; Activated carbon; Adsorption; Pesticide; Imidacloprid

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-023-02913-1

Chemical Papers 77 (10) 5961–5977 (2023)