Valorisation of agricultural waste derived biochars in aquaculture to remove organic micropollutants from water – experimental study and molecular dynamics simulations

Abstract

In this work, we evaluated the valorisation of agricultural waste materials by transforming coconut husks and shells, corncobs and rice straw into biochar for water treatment in aquaculture. We compared the biochars’ suitability for removal of organic micropollutants (acetaminophen, oxytetracycline, tetracycline, enrofloxacin, atrazine, diuron and diclofenac) from surface water needed for aquaculture. The biochars were prepared by three methods ranging from inexpensive drum kilns (200 °C) to pyrolysis with biogasfication (350–750 °C). Overall, antibiotics tetracycline and enrofloxacin were the most strongly sorbed micropollutants, and coconut husk biochar prepared at 750 °C was the best sorbent material. Molecular Dynamics simulations indicated that the major sorption mechanism is via π-π stacking interactions and there is a possibility of multilayer sorption for some of the micropollutants. We observed, a strong impact of ionic strength (salinity), which is an important consideration in coastal aquaculture applications. High salinity decreased the sorption for antibiotics oxytetracycline, tetracycline and enrofloxacin but increased diclofenac, atrazine and diuron sorption. We considered coconut husk biochar produced in drum kilns the most practical option for biochar applications in small-scale coastal aquacultures in South Asia. Pilot trials of canal water filtration at an aquaculture farm revealed that micropollutant sorption by coconut husk biochar under real-world conditions might be 10–500 times less than observed in the laboratory studies. Even so, biochar amendment of sand enhanced the micropollutant retention, which may facilitate subsequent biodegradation and improve the quality of brackish surface water used for food production in coastal aquaculture.

Synthesis of corncob biochar with high surface area by KOH activation for VOC adsorption: effect of KOH addition method

“…Toluene could combine with the carbonyl group as an electronic donor through the aromatic ring, which is an electronic acceptor, and form a stable donor acceptor complex 40 . Also, compounds containing an aromatic ring in their structure may donate π electrons to π‐electron acceptors on the biochar surface; π–π electron donor–acceptor interactions may be another significant sorption mechanism 41 . These FTIR results show that the carbon materials activated using the method of KOH addition had abundant surface oxygen‐containing functional groups.…”

“…40 Also, compounds containing an aromatic ring in their structure may donate π electrons to π-electron acceptors on the biochar surface; π-π electron donor-acceptor interactions may be another significant sorption mechanism. 41 These FTIR results show that the carbon materials activated using the method of KOH addition had abundant surface oxygen-containing functional groups.…”

Biomass carbon mining to develop nature-inspired materials for a circular economy

“… 199 DFT has also been used as an auxiliary method in characterizing both hydrochar and biochar, 200 demonstrating its ability to complement experimental results. In biochar, the adsorption properties of seaweed-derived biochar, 201 and the optimization of pollutant retention time, 202 has been some of the studies conducted. The need for designer hydrochars with applications in energy storage, catalysis, agriculture, and oil and gas industries calls for a strong effort on the development of atomistic models and new simulation techniques for porous carbon materials.…”

Biochar Derived from Palm Waste Supported Greenly Synthesized MnO2 Nanoparticles as a Novel Adsorbent for Wastewater Treatment

“…Adsorption onto biochars derived from biomass is considered an effective and environmentally friendly method to remove many of the contaminants from wastewater [13][14][15]. Biochar can be produced from biomass using thermochemical and biochemical technologies.…”