Abstract:
This study aimed at preparing and assessing the potential of cow dung biochar (CDB) in adsorption of selected pesticides
(tebuconazole, λ-cyhalothrin and α-cypermethrin) and polycyclic aromatic hydrocarbons (PAHs) (naphthalene, phenanthrene
and anthracene) from water. CDB was prepared by low temperature pyrolysis (300–350 ℃) and characterized for surface
morphology, composition, crystallinity, phases and thermal properties before assessing its adsorption efficacy at different
conditions, isotherm models and regeneration capacity for the target pesticides and PAHs. The morphologies of the samples
indicated an amorphous structurewith –OH groups. The composite char had four phases of amorphous, transition, compos-
ite and turbostratic char phase while depicting high thermally stability. The adsorption capacities ranged between 78 and
91%. The optimal adsorption conditions were 20 ℃ at a pH range of 4.0–8.0 for 30 min. Temkins adsorption was the most
favored model. Chemisorption was exhibited for all sorbates except λ-cyhalothrin while following both pseudo-first order and
Akrami-Erovich models. The adsorption processes were spontaneous under room temperature conditions. The adsorbents
had an adsorption capacity of 63–80% for the third adsorption cycle indicating they would be regenerated successfully. As
a matter of fact, the prepared CBD showed potential for removal of the chemical pollutants’ removal.
Keywords Pesticides · PAHs · Cow dung biochar · Adsorption.
