Physiochemical Characterization of Biochars from Six Feedstocks and Their Effects on the Sorption of Atrazine in an Organic Soil

Shagufta Gaffar,Krishnaswamy Jayachandran,Amin Rabiei Baboukani,Chunlei Wang,Saoli Chanda,Donald W Watts,Sanku Dattamudi,Jeffrey M Novak

doi:10.3390/agronomy11040716

Shagufta Gaffar, Krishnaswamy Jayachandran + Show 6 more

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https://doi.org/10.3390/agronomy11040716

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Abstract

Application of biochars in agricultural soils has the potential to reduce groundwater contamination of atrazine, a widely used herbicide in the US, therefore sustaining environmental quality and reducing human health issues. This study was conducted to characterize biochars produced from six feedstocks and investigate their ability to remove and retain atrazine in an organic-rich soil. Australian pine (AP), Brazilian pepper (BP), coconut husk (CH), cypress (Cy), loblolly pine (L), and pecan shell (P) feedstocks were pyrolyzed at 350 °C and 500 °C. Adsorption and desorption behaviors of atrazine were explained using Freundlich isotherms. Higher pyrolysis temperature increased specific surface area (5 times), total pore volume (2.5 times), and aromaticity (1.4 times) of the biochars. CH feedstock produced the most effective biochars (CH350 and CH500), which adsorb 8–12% more atrazine than unamended soils. CH350 biochar performed the best (Kd ads = 13.80, KOC = 153.63, Kd des = 16.98) and had significantly higher (p < 0.05) adsorption than unamended soil, possibly resulting from its highest cation exchange capacity (16.32 cmol kg−1). The Kd des values for atrazine desorption were greater than the Kd ads for adsorption, indicating retention of a considerable amount of atrazine by the biochar-amended soils following desorption.

Highlights

Atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-trithemazine) is a very common herbicide used in the United States to control pre- and post-emergence broadleaf weeds (Stellaria media, Taraxacum officinale, Lespedeza cuneata, etc.) in agricultural production
Detailed information on biochar yield, proximate analysis and physiochemical properties are presented in Tables 2 and 3 which show considerable variation between the twelve different biochars used in this study
Yield (%), volatile matter (VM) (%) and moisture (%) content of the biochars produced from pyrolysis of the six different feedstocks (Australian pine, AP; Brazilian pepper, BP; coconut husk, CH; cypress, Cy; loblolly pine, L; and pecan shell, P) decreased significantly (p < 0.05) as the temperature increased from 350 ◦ C to 500 ◦ C (Table 2)

Summary

Introduction

Atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-trithemazine) is a very common herbicide (triazine group) used in the United States to control pre- and post-emergence broadleaf weeds (Stellaria media, Taraxacum officinale, Lespedeza cuneata, etc.) in agricultural production. Atrazine and its metabolites, namely desethyl-atrazine (DEA; 2-amino-4-chloro-6-(isopropylamino)-s-triazine), deisopropyl-atrazine (DIA; 2-amino-4 chloro-6-(ethylamino)-s-triazine), and hydroxylatrazine (HA; 2-hydroxy-4-(ethylamino)-6-(isopropylamino)-s-triazine) have been commonly detected in soil, drinking water aquifers, shallow groundwater and in surface water This is an imperative area of concern because atrazine has been recognized as an endocrine disruptor compound in humans [4]. It has adverse effects on the immune and central nervous systems of other mammals and aquatic invertebrates [5]. An important issue remains to control the availability of atrazine in soil solution and its fate and transport in natural water resources

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