Comparative study of biochar prepared from cow dung and sewage sludge and its application as an adsorbent for organic pollutants removal in water

Abstract

In this research, the synthesis of biochar from cow dung and sewage sludge and its application for the removal of organic contaminants using methylene blue (MB) as the model molecule was evaluated. Experiments were performed using different concentrations of adsorbent and MB and were optimized by a response surface methodology (RSM). Dynamic models were adjusted to the experimental data and the regeneration of the bed was studied. The results showed that the optimal conditions to favor the adsorption of MB, in a fixed bed and making a comparison between the two biochar sources, were those where an adsorbent biochar concentration of 5 g and initial MB concentration of 10 mg L −1 were used. The biochar prepared from cow dung presented the best adsorption conditions. Under these conditions, the breaking time was 172.73 min. The models of Thomas, Bohart-Adams, and Yoon-Nelson were applied for the study in fixed-bed columns and it was observed that the models were adjusted satisfactorily. Regeneration was possible for three different cycles, slightly diminishing the performance of the bed with elution of HNO 3 . These results indicate that MB bed fixed adsorption on cow dung biochar is viable and suitable for water treatment.

Biochar for agronomy, animal farming, anaerobic digestion, composting, water treatment, soil remediation, construction, energy storage, and carbon sequestration: a review

“…In batch mode operation, variables affecting the removal process such as pH, adsorbent dose, initial concentration of the contaminant, and contact time have also been optimised (El-Azazy et al 2020 ; El-Azazy et al 2021b ; El-Azazy et al 2021c ; Bardestani et al 2019 ; Beakou et al 2017 ; Kalderis et al 2017 ; Lenin Sundar et al 2021 ; Roy et al 2018 ; Turk Sekulic et al 2018 ; Zhao et al 2021d ). Variables such as fixed-bed height, flow rate, the particle size of the biochar adsorbent, pH, and concentration of the inlet solution are optimised in continuous mode operation (Biswas et al 2020 ; Blagojev et al 2019 ; Levio-Raiman et al 2021 ; Sivarajasekar et al 2018 ; Suárez‐Vázquez et al 2021 ). As a result, the target response (output) will vary according to the input variables assessed.…”