Removal of NO3-N in alkaline rare earth industry effluent using modified coconut shell biochar

Abstract

Coconut shell biochar (CSB) was selected as raw material to obtain two kinds of modified biochars by pickling and iron modification. The pickling coconut shell biochar (PCSB) and pickling-iron modified coconut shell biochar (PICSB) were used as adsorbents to remove NO3-N in alkaline rare earth industry effluent. The results showed that pickling smoothed the surface of CSB, and α-FeOOH was formed on the surface of PCSB because of FeCl3 solution modification. Suitable adsorbent dosages of PCSB and PICSB were both 2.0 g/L. The NO3-N adsorption process by PCSB and PICSB both reached equilibrium at 30 min. The quasi-first-order kinetic model shows good fit to the NO3-N adsorption by PCSB. Whereas, the quasi-second-order kinetic model is more suitable for PICSB adsorbing NO3-N. The adsorption mechanisms of PICSB for NO3-N removal were ligand exchange and electrostatic attraction, and that of PCSB for NO3-N removal was electrostatic attraction. The NO3-N adsorption amounts of PCSB and PICSB decreased with increasing adsorption temperature and pH. The maximum NO3-N adsorption amounts of PCSB and PICSB were 15.14 mg/L and 10.75 mg/L respectively with adsorbent dosage of 2.0 g/L, adsorption time of 30 min, adsorption temperature of 25 ± 1 °C, and initial solution pH of 2.01.

Increasing Surface Functionalities of FeCl3-Modified Reed Waste Biochar for Enhanced Nitrate Adsorption Property

“…Adel et al [12] obtained a lower adsorption ability of biochar after iron modification, which might be because the original conocarpus waste had fewer functional groups for binding with Fe 3+ /Fe 2+ . The high adsorption capacity could be explained by the combination of various modification processes and, thus, there being more adsorption sites for nitrate [18,34,35]. Therefore, the iron-modified biochar prepared in our study was preferable in terms of nitrate adsorption.…”

“…In order to systematically investigate the behavior of nitrate ad 600, different kinetic models for nitrate adsorption were analyzed ( sum of squares (RSS), chi-square analysis (χ 2 ) and coefficient of d employed to evaluate the goodness of fit for various kinetic and i 3). HCl-Fe-modified coconut shell biochar 1.0 mol/L HCl for 2 h, 1.0 mol/L FeCl 3 for 6 h adsorbent 2.0 g/L, 30 min, initial concentration 32.10 mg-N/L, initial pH 2.01 15.14 [35] Fe-Al-modified coconut shell biochar 1.0 mol/L HCl for 1 h, 1.0 mol/L FeCl 3 and 1.0 mol/L AlCl 3 for 6 adsorbent 2.0g/L, 50 mL solution, 24 h, acid condition 34.2 [34] FeO-modified conocarpu biochar 1 mol/L FeCl 2 /FeCl 3 for 2 h, 600 • C for 4 h adsorbent 10.0 g/L, 2 h, initial concentration 25 mg-N/L, initial pH 6 1.26 [12] Iron-modified wheat straw biochar 450 • C, 1 mol/L FeCl 3 adsorbent 10.0 g/L, 2 h, initial concentration 50 mg-N/L, initial pH 6 2.47 [16] Iron-modified reed biochar 27.20 Present study…”

Adsorption and desorption of nutrients from abattoir wastewater: modelling and comparison of rice, coconut and coffee husk biochar

“…For example, in a study conducted by Thao et al. (2021) , rice husk biochar was found to have a nitrate adsorption capacity of 0.129 mg/g ( Aghoghovwia et al., 2020 ), studied Pine wood biochar and found 15.2 mg/g, and ( You et al., 2019 ) studied Coconut shell biochar and found 15.14 mg/g. However ( Thao et al., 2021 ), investigated Rice husk biochar and found 0.2477 (mg/g) ( Gierak and Łazarska, 2017 ), investigated Commercial carbon and found 0.2348 (mg/g), and ( A Hanafi, 2016 ) investigated Activated carbon from rice straw and found 1.1 (mg/g).…”

Efficient Nitrate Adsorption from Groundwater by Biochar-Supported Al-Substituted Goethite

“…Indeed, like hematite, goethite could be used to modify biochar [32][33][34]. There is a large number of studies that have proved the feasibility of biochar-supported goethite to remove oxyanions, such as anionic As(III) [34,35], As(V) [32,33], phosphate [36][37][38][39], Cr(VI) [40], and nitrate [41]. Prior to the above studies, Hsi and Langmuir have found goethite presented with a point of zero charge (PZC) of 8.9, while hematite had a PZC of 7.5 [42].…”

“…In addition, the dispersion of goethite particles on the biochar surface resulted in more adsorption sites, and avoided the deterioration of adsorption due to the agglomeration of pristine goethite particles in solution [43]. You et al prepared biochar-supported goethite to remove nitrate in alkaline rare-earth industry effluent and successfully removed nitrate, with a maximum adsorption amount of 10.75 mg/g [41]. Therefore, biochar-supported goethite could provide benefits for nitrate removal from groundwater.…”