@conference{
author = "Lopičić, Zorica and Antanasković, Anja and Šoštarić, Tatjana and Đošić, Marija and Milojković, Jelena and Bourgerie, Sylvain and Morabito, Domenico",
year = "2023",
abstract = "The concerns over the environmental and economic issues of the phosphates as eutrophication agents are continiously rising, due to their toxic
effects on the whole environment. The greatest risk arises from entering phosphates into water streams as the runoff from agricultural lands and
those from sewage water. Among the conventional methods used for phosphate removal, adsorption technology appeared as the most promising
one, due to its simplicity and economical feasibility. Another advantage of this technique is the possibility of sorbent regeneration with low amounts
of by-products, and possible reuse of regenerated sorbate in different applications, including agriculture. Amongst many sorbents widely used,
modified activated carbon (AC) is mostly used, but the application of modified AC raises costs of AC production/application. In the sense of this,
the search for cheaper sorbents with higher phosphate removal capacity is still needed. Biochar (BC) is a cost-effective and environmental friendly
stable solid material rich in carbon, resistant to decomposition and mineralization [1]. Although BC and AC are made from similar raw materials, BC
is usually produced at lower temperatures, resulting in a price of BC that is app. 1/6 of the price of the commercial AC [2]. In the last decade, BC is
receiving great attention as a promising sorbent for different pollutants from water streams, but the use of BC also supports the reduction of
greenhouse gases and its application into soils enhance the soil fertility. Many recent studies with unmodified BCs [3] have shown lower phosphate
removal ability, indicating negative surface charge as one of the factors influencing lower removal of negatively charged ions over a wide pH range.
In order to increase BCs sorption capacity toward phosphates, the introduction of some cationic species is often required. In this paper, synthesis
of MgO-biochar from waste lignocellulosic biomass was applied, in order to create highly porous nanocomposite material with efficient phosphate
removal. For this purpose, feedstock used to make the MgO-biochar nanocomposites were plum stones (PmS) obtained from the local factory,
where they have been disposed as a waste. After receiving, feedstock was air dried and milled into 0.1-0.5 mm particles. MgCl2·6H2O was used to
prepare a solution to pre-treat the PmS feedstock according to the procedure described in [4]. After immersing procedure, the oven dried mixture
was heated at 10 °C/min up to 500 °C under Ar flow for 1,5 h. For the purpose of sorbent characterisation, pHpzc, XRD, TG-DTG and FTIR analysis
were performed. The existence of Mg nanoparticles shifts the pHPZC from 6.7 to highly alkaline value of 10.7 which facilitates the electrostatic
interactions between the negatively charged PO43- ions and PmS-M-B. The diffraction peaks identified as MgO revealed that MgO particles were
highly crystalline, and uniformly deposited across the entire PmS-M-B surface. TGA analyses revealed four stage degradation, where the peaks for
the PmS-M-B shifted to the higer temperatures compared to the unmodified biochar (PmS-B) and higher residual mass after final combustion stage.
FTIR spectra have showed most band differences in the 1800–600 cm−1 range. The characterised MgO-biochar nanocomposite produced from
pyrolysis (PmS-M-B) was further used in sorption experiments. A stock phosphate solution was prepared using KH2PO4 and diluted to the required
concentrations. The adsorption isotherm of phosphate on the PmS-M-B was determined using the batch sorption technique by mixing 0.1 g of the
biochar sample with 50 mL of phosphate solutions of different concentrations ranging from 10 to 500 mg/L. The reaction vessels were shaken (150
rpm, 25 °C) and after the desired contact times (from 5 min to 24 h), the samples were filtered, phosphate concentrations in the liquid phase samples
were determined using MD 610 colorimeter (Lovibond, Germany), and the amount of PO43- adsorbed onto PmS-M-B was calculated. Data obtained
through the isothermal experiments were fitted using three commonly applied isotherms: Langmuir, Freundlich and Sips. Isotherm equilibrium
modelling revealed that the Sips isotherm provided the best model fit with maximum sorption capacity of 181.46 mg/g. This sorption capacity is
much higher than the most of the others reported in literature [5, 6] .A possible sorption mechanism of PO43 removal might be assigned to
electrostatic attraction and hydrogen bonding, Obtained results demonstrated that engineered MgO-biochar derived from waste PmS can be used
as a promising green material for removing phosphates from contaminated waters, providing opportunities in developing low-cost and highly
efficient material to resolve eutrophication issue. In the same time, environmental benefits might be multiple: decreasing environmental hazards by
reducing waste landfills, and also using exhausted sorbate in soil remediation and as a slow release fertilizer, confirming advantages of the biochars
amongst the other available adsorbents.",
publisher = "PROTEOMASS Scientific Society",
journal = "5th International Caparica Conference on Pollutant Toxic Ions and Molecules 2023",
title = "Engineered Biochar Made from Waste Plum Stones as Efficient Sorbent in Phosphate Removal",
pages = "176-176"
}
