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Article

Sorption-Desorption of Phosphorus on Manure- and Plant-Derived Biochars at Different Pyrolysis Temperatures

by
Nighet Musa
1,
Khalid Saifullah Khan
1,*,
Joseph C. Blankinship
2,
Shahzada Sohail Ijaz
1,
Zahid Akram
3,
Mona S. Alwahibi
4,
Mohammad Ajmal Ali
4 and
Munazza Yousra
5
1
Institute of Soil and Environmental Sciences, Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi 46300, Pakistan
2
Department of Environmental Science, The University of Arizona, Tucson, AZ 85719, USA
3
Department of Plant Breeding and Genetics, Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi 46000, Pakistan
4
Department of Botany and Microbiology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
5
Land Resources Research Institute, National Agricultural Research Centre, Islamabad 45500, Pakistan
*
Author to whom correspondence should be addressed.
Sustainability 2024, 16(7), 2755; https://doi.org/10.3390/su16072755
Submission received: 5 February 2024 / Revised: 14 March 2024 / Accepted: 24 March 2024 / Published: 27 March 2024
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Abstract

:
Sustainable phosphorus (P) management is essential to preventing mineral fertilizer losses, reducing water pollution, and addressing eutrophication issues. Phosphorus sorption and mobility are strongly influenced by the properties of biochar, which are determined by pyrolysis temperature and type of feedstock. This understanding is crucial for optimizing biochar application for soil nutrient management. Therefore, a batch sorption-desorption experiment was conducted to examine P sorption-desorption in plant-based (parthenium, corn cobs) and manure-based (farmyard manure, poultry manure) biochars prepared at both 400 °C and 600 °C. Manure-based biochars demonstrated higher P sorption at 400 °C, with less sorption at 600 °C, while plant-based counterparts exhibited lower sorption capacities. Phosphorus desorption, on the other hand, increased at 600 °C, particularly in manure-based biochars. The scanning electron microscopy (SEM) and Fourier-transform infrared spectra (FTIR) analysis suggested that a lower pyrolysis temperature (400 °C) enhances P sorption due to higher specific surface area and different functional groups. Additionally, the manure-based biochars, which were enriched with calcium (Ca) and magnesium (Mg), contributed to increased P sorption. In summary, P sorption is enhanced by a lower carbonization (400 °C) temperature. Although manure-based biochars excel in retaining P, their effectiveness is limited to shorter durations. In contrast, plant-based biochars showcase a prolonged capacity for P retention.

1. Introduction

Phosphorus (P) is a vital nutrient in plant nutrition. It is needed to perform critical physiological functions such as photosynthesis, respiration, seed production, and root growth [1]. Because P is a non-renewable resource, its scarcity limits agricultural yields worldwide despite constant soil replenishment with fertilizers [2]. The recovery efficiency of applied P is less than 20% in most soils [3], and the rest of unutilized P accumulates in soils, resulting in environmental degradation to soil quality [4]. A release of surplus P from fertilizers and agricultural runoff into water bodies has resulted in significant eutrophication, triggering algae outbreaks and a deterioration in water quality, ultimately leading to the failure of ecosystems [5]. It is crucial to practice sustainable P management to preserve crop output while reducing negative environmental effects. Phosphorus is retained in soils by two different processes: sorption and desorption. It is crucial to understand both of these processes in order to increase P availability [6].
A number of adsorbents, such as polymer adsorbents, zeolites, alumina, and synthetic materials, can be added to contaminated water to effectively remove P [7]. Another organic amendment that has been recommended for use as a P sorbent is biochar [8], which is a carbon-rich compound produced from biomass pyrolysis [9]. Biochar has numerous advantages over other adsorbent materials, like great thermal stability, low cost, easy availability of biomasses, and an abundance of surface functional groups that retain P [5]. The main pathways through which P adsorbs to biochar surfaces are the electrostatic attraction of phosphate ions (PO43−) with positively charged biochar surfaces [10,11], the pore-filling of high-specific-surface-area biochars, the anion-exchange capacity of biochars [12], and calcium (Ca) and magnesium (Mg) precipitation [13].
The degree of P sorption is directly proportional to the functional groups, specific surface area, surface charge, and pore structures of biochar [14]. However, these properties of biochar are governed by two main factors: (i) conditions for pyrolysis, including residence duration, heating rate, and temperature [15,16], and (ii) the type of biomass used [17]. Biochars produced from the same biomass at various pyrolysis temperatures can have very different physical and chemical properties such as functional groups, cation-exchange capacity, porosity, and surface area [18]. Though many studies have addressed the influence of pyrolysis temperature on biochar properties, the optimal temperature for pyrolysis to produce biochar is a topic of debate. Thus, identifying the most effective biomass feedstock and maximizing pyrolysis conditions are crucial for using biochar in agriculture [19,20]. However, there has been little exploration of the pyrolytic conversion of animal waste to evaluate its P-sorption capacity. Therefore, a detailed study on P sorption-desorption of plant and animal-based biochars under the same pyrolysis conditions is needed to assess their potential benefits and limitations for agricultural use.
The use of agricultural wastes as sorbents is a sustainable and environmentally friendly approach to address various pollution issues. Agricultural waste materials, which are abundant and often considered byproducts of farming activities, can be repurposed as effective sorbents for different contaminants [21]. Parthenium hysterophorus L., often known as parthenium weed, is a noxious weed that has now invaded 46 countries [22]. It may flourish in many different types of climatic regions and tolerate drought and salt stress [23,24]. The swift emergence and dispersal of invasive parthenium pose a threat to human health and lower agricultural production [25]. Around the world, scientists are currently working to create biological, pharmacological, cultural, and physical strategies to manage this aggressive weed. One of the management strategies is its utilization as biochar [26]. In the same way, animal manure production has surpassed more than a million tons per day in countries like Pakistan. This massive waste is left for spontaneous decomposition that generates methane or is burnt in the open air, resulting in the emission of smoke, CO2, and other particles that degrade environmental quality [27].
The intensive use of low-value organic waste produced in huge quantities from the agriculture and livestock sectors could lead to less environmental pollution and greater economic benefits. However, the literature lacks a detailed study of these materials to access P-sorption-desorption capacity under the same pyrolytic conditions. Therefore, this study was conducted with the following objectives: (1) to determine and compare the P-sorption capacities of manure- vs. plant-based biochars pyrolyzed at different temperatures and (2) to determine and compare the P desorption capacities of adsorbed P by the same biochars.

2. Materials and Methods

2.1. Feedstock Collection

Parthenium weed, corn cobs, farmyard manure, and poultry manure were used as feedstocks for biochar production. Parthenium weed was collected from lawns, landscape areas of housing societies, parks, and open fields of Rawalpindi City (33.5651° N, 73.0169° E). Corn cobs were collected from peddlers in Rawalpindi. After collection, the biomass of parthenium weed and corn cobs were washed and cut into pieces approximately 1 cm in length. Poultry manure was collected as waste material from the Poultry Research Institute, Rawalpindi. This material consisted of a variable mixture of bedding materials such as sawdust, rice husk, bird excreta, and feed spills. Farmyard manure was picked from the Arid Agriculture University Animal Research Farm, Koont (33.1166° N, 73.0111° E). All feedstocks were dried in an oven at 65 °C for 24 h.

2.2. Biochar Production

The feedstock of all materials was pyrolyzed in a muffle furnace at 400 °C and 600 °C. The heating rate was 30 °C/min, and the residence time after attaining the desired temperature was 1 h. Samples were removed from the furnace when the temperature dropped to 200 °C. Containers were kept in a desiccator for cooling. After cooling, the biochar was crushed and sieved until it was 1 mm in size. The resultant biochars were stored in plastic bottles and labeled according to feedstock type and pyrolysis temperature as outlined in Table 1.

2.3. Biochar Characterization

The electrical conductivity (EC) and pH of biochars were quantified in deionized water at a 20:1 (DI/BC) ratio after agitating the samples for 1 h [28]. The American Standard Test Method [29] was used to determine the cation-exchange capacity (CEC) of biochar. Nutrient concentrations of total nitrogen (N), P, potassium (K), Ca, and Mg in biochars were extracted after the digestion of 0.5 g of biochar with concentrated HNO3:HClO4 (2:1) at 180 °C for 2 h [30]. Following the development of a yellow color using the vanadate-molybdate technique, the concentration of P was determined using a UV–visible spectrophotometer (UV-1201, Shimadzu, Tokyo, Japan) [31]. Potassium was measured on a flame photometer [31]. Calcium and Mg were measured using atomic absorption spectroscopy. The organic carbon (C) concentration of the biochar samples was determined by burning to ash in the muffle furnace at 500 °C for 4–5 h, as described by Brake [32]. The specific surface area (SSA) of biochars was measured using the ethylene glycol monoethyl ether (EGME) method [33]. The Fourier-transform infrared spectra (FTIR) of biochars were examined using 2 mg of the ground sample in a KBr pellet. The FTIR scan was performed at a resolution of 4 cm−1, averaging 10 scans at 1 cm−1 intervals. The biochar’s morphology was assessed using measurements made with a BEL Japan, Inc. (Toyonaka, Japan) scanning electron microscope (SEM). The bulk density (BD) of biochars was calculated using the core method [34]. Biochar porosity was determined using the difference in densities, as explained by Pastor-Villegas, et al. [35].

2.4. Phosphorus Sorption Experiment

A sorption experiment was conducted using the methodology described by Zaho, et al. [36]. Two grams of each biochar sample was placed in 50 mL polyvinyl chloride centrifuge tubes and then suspended in 20 mL of 0.01 M KCl solution containing 0, 25, 50, 100, 200, 400, and 600 mg L−1 P added as KH2PO4. To stop microbiological growth, 0.5 mL of chloroform was put into the centrifuge tubes. Samples were centrifuged for 10 min at 3800 rpm after being equilibrated for 24 h at room temperature on a horizontal shaker table. The clear supernatant solution was then obtained and filtered using Whatman No. 42 filter paper and analyzed for P using the ammonium molybdate/ascorbic acid method [37]. Determining the sorbed P involved subtracting the initial P concentration from the equilibrium solution’s concentration (after shaking). Parameters for Freundlich (Equation (1)) and Langmuir isotherms (Equation (2)) were calculated by the following equations:
q = K F C ( 1 n )
q = K L bC 1 + K L C
where q is the sorbed P (mg g−1 of P), C is the equilibrium P concentration in supernatant solution after shaking (mg L−1), KF is Freundlich partitioning coefficient, 1/n is sorption intensity, b is maximum sorption capacity (mg g−1 of P), and KL is the Langmuir constant.

2.5. Phosphorus Desorption Experiment

Immediately following the completion of the sorption studies, a desorption experiment was carried out. The sorption batch study samples were extracted using 50 mL of 0.5 M NaHCO3 at a 1:50 ratio after being repeatedly cleaned with isobutyl alcohol [38]. Samples were agitated for 30 min on a horizontal shaker and then centrifuged for 5 min to produce a clear supernatant solution. Extractants were obtained to examine bicarbonate extractable P (available P) using the ammonium molybdate/ascorbic acid method described above. An implementation diagram of batch sorption and desorption procedure is shown in Figure 1.
The amount of P in the equilibrium solution (Ct mg L−1) was determined as the net amount of P desorbed by the biochar, and the ratio between the amounts of P adsorbed and P desorbed on biochar was used to compute the percentage of P desorption (P des. %).
P   des .   ( % ) = Ct × V W × Q
where Q is the amount of P adsorbed (mg g−1); Ct is the equilibrium P concentration (mg L−1); W is the sample weight (g), and V is the solution volume (L) of KH2PO4.

2.6. Statistical Analysis

The sorption data were fitted to the Freundlich (Equation (1)) and Langmuir isotherm model (Equation (2)) using the solver add-in function of Microsoft Excel version 2402. All the treatments were analyzed in triplicate. The mean values with standard deviation were computed using Statistix 8.1.

3. Results

3.1. Physicochemical Properties

Pyrolyzing raw feedstock produced alkaline biochars (Table 2) except for CCB, which had a pH of 6.93 at 400 °C, and the higher temperature (600 °C) further enhanced biochar alkalinity to 9.87. Among different feedstocks, the pH values of PB (8.33 and 10.14) were highest at both temperatures, followed by PMB (8.26 and 9.87) and FYMB (8.07 and 9.61). Similarly, the EC of biochars increased with increasing thermal carbonization from 400 °C to 600 °C. The highest EC was reported with PB among feedstocks at both temperatures, i.e., 0.93 dS m−1 at 400 °C and 1.01 dS m−1 at 600 °C (Table 2). These results suggest higher chances of inducing soil salinity when utilizing parthenium-based biochar.
Conversely, CEC decreased with an increase in temperature (Table 2). Plant-based biochars (PB and CCB) had a higher CEC (ranging between 50.7 and 77.6 cmolc kg−1) at both temperatures compared to manure-based biochars (FYMB and PMB), which had a CEC ranging between 41.7 and 58.8 cmolc kg−1. When considering manure-based biochars versus plant-based biochars, the latter exhibited higher porosity (ranging between 46.8 and 76.6%). The porosity of biochars was significantly influenced by pyrolysis temperature. Higher temperatures (600 °C) led to a 9–14% decrease in porosity for manure-based biochars and a more substantial (35–36%) decrease for plant-based biochars.

3.2. Elemental Composition

For all feedstock types, the changes in biochar elemental concentrations with rising pyrolysis temperatures followed the same trend (Table 3). The N content decreased with increasing pyrolysis temperature, whereas P, K, Ca, and Mg contents in all feedstocks increased significantly with an increase in temperature. The highest N, P, Ca, and Mg contents were reported with manure biochars (PMB followed by FYMB) at both temperatures. The PB had significantly higher N, P, Ca, and Mg levels compared to CCB.
Biochars from plant materials had significantly higher C contents than manure-based biochars. Within feedstock types, plant-based biochar C content increased more notably at the higher temperature compared to the lower temperature (57.1–64.5% at 400 °C and 74.3–74.7% at 600 °C). However, the inverse was observed in manure biochar (44.4–58.8% at 400 °C and 45.6–48.8% at 600 °C.

3.3. FTIR Spectra Analysis

The spectral analysis of FTIR was used to analyze biochar functional groups. The spectrum of lower-pyrolysis-temperature (400 °C) biochars (except CCB-400) had peak intensities at the following wavelengths: 2960 cm−1, 2850 cm−1, 2345 cm−1, 1750 cm−1, 1600 cm−1, 1260 cm−1, 1100 cm−1, 1020 cm−1, 875 cm−1, 800 cm−1, and 670 cm−1 (Figure 2a). Methyl stretching of C-H was found at 2850 and 2960 cm−1. The wavelengths at which absorption first manifested in the range of 1600 cm−1 and 1750 cm−1 were allotted as C=C (cyclic alkenes) and C=O, respectively. Absorbance at 1000–1100 cm−1 was regarded as C-O stretches and P-containing functional groups. However, the intensity in this region was relatively low, especially for FYMB-400. The band located at 875 cm−1 was ascribed to aromatic C H out-of-plane bending, suggesting a higher level of aromaticity in this sample. A band at 800 cm−1 was termed Si-O, which was contained in every biochar encompassed. Figure 2b shows that at higher carbonization temperatures (600 °C), the spectra of FTIR became less complex, indicating fewer functional groups on biochars.

3.4. Scanning Electron Microscopy and SSA

The condensed products of pyrolysis were determined using scanning electron micrographs. Variations in the pyrolysis procedures of different feedstocks resulted in variations in surface morphologies (Figure S1). A comparison of temperature showed that surface morphology was influenced by temperature. The surface of all biochars at 400 °C was smooth, but an increase in temperature (600 °C) caused irregular-shaped particles on the surface. The CCB had better-defined pores, while the rest of the biochars had less-defined and less-uniform pore structures. The specific surface area (SSA) decreased with the rise in pyrolysis temperature. Among materials, the highest SSA (1353.6 m2 g−1) was reported with CCB-400, which dropped to 352.4 m2 g−1 at 600 °C (Table 2).

3.5. Effect of Feedstock Type on Phosphorus Sorption and Desorption

The correlation coefficients (R2) suggest that the Langmuir isotherm model (R2 = 0.94–0.99) was more suitable for fitting P sorption using all types of biochars compared to the Freundlich isotherm model (R2 = 0.92–0.99). It was observed that all biochars, regardless of pyrolysis conditions, could sorb P (Table 4, Figure 3). On comparing biochars of different feedstock types, both the manure-based biochars (FYMB and PMB) had higher P-sorption capacity (3.49 mg g−1 and 3.47 mg g−1, respectively) than plant-based biochars. On the other hand, the PB had a relatively higher P-sorption capacity (2.99 mg g−1) than other plant-based biochar.
Phosphorus desorption for all treatments increased with increasing initial P concentrations (Figure 4). The maximum percentage of desorbed P (70%) was reported in FYMB at the highest initial P (600 mg L−1) concentration. Among all feedstocks, the order of percent of desorbed P at the highest initial P concentration can be summarized as FYMB > PMB > CCB > PB. The lower binding energy (KL) of FYMB, PMB, and CCB explained the reason for the high P desorption of these materials.

3.6. Effect of Pyrolysis Temperature on Phosphorus Sorption and Desorption

Considering the amount of P sorbed onto each biochar (Table 4, Figure 3), it is evident that the pyrolysis temperature significantly affected the P-sorption capacity. A lower pyrolysis (400 °C) temperature favored the P-sorption capacity on all biochars. However, raising the pyrolysis from 400 °C to 600 °C led to the loss of P-sorption capacity, reducing it to 6%, 6%, 16%, and 20% in PB-600, CCB-600, FYMB-600, and PMB-600, respectively.
The extent of P liberation from the sorbate is indicated by the ratio of the amount of desorbed P to the total amount of sorbed P. All the biochars prepared at 600 °C had a higher percentage of P desorption compared to those designed at 400 °C (Figure 4). Overall, 5–10% more desorption was reported with biochars produced at 600 °C compared to 400 °C.

4. Discussion

This study was conducted to explore the potential feedstocks and suitable pyrolysis temperature for enhancing the P-sorption capacity of biochars, which ultimately can enhance P utilization efficiency in soil. The outcomes of this investigation suggest that the sorption of P on biochar is a complex process that cannot be fully described by a single mechanism. Several investigations have revealed that surface precipitation, ligand exchange, and electrostatic sorption are the main processes involved in the P adsorption process using biochar [39,40].
Specific surface area (SSA) is regarded as an important parameter for predicting the sorption capacity of any material. Materials with a high SSA have a larger surface area available for interaction with their surroundings, which can result in higher sorption capacities. This is because the surface area is where most sorption processes occur, including adsorption, absorption, and ion exchange. Biochars produced at 400 °C, irrespective of feedstock, had significantly high P-sorption capacity. One reason for higher sorption at 400 °C was likely due to greater specific surface area. There are some studies [41,42,43] that concluded that the surface area of biochars increases with an increase in pyrolysis temperature. However, the decrease in surface area with higher pyrolysis temperature can also be supported by studies [44,45]. The possible mechanism of this behavior is that the porous structure of the biochar being produced may be destroyed at high temperatures due to melting, which could clog part of the pores and cause the material to have a low surface area [46]. This phenomenon was observed by Soinne, et al. [47], correlating the diminished surface area of biochar derived from a mixture of Norway spruce and Scots pine with its lower P-sorption capacity.
When biochars prepared at 400 °C and 600 °C were observed by SEM, there were well-distinguished morphological differences, and the presented structures showed soft and fragmented pieces at 600 °C (Figure S1). These results imply that the physical interaction of porous adsorption is one of the contributors to PO43− sorption in all biochars because the more SSA increases, the more chemical adsorptive sites will be exposed for P adsorption. The correlation between the rise in pyrolysis temperature and the decrease in P sorption is supported by the findings of Jung, et al. [48], who found that the P-sorption capacity of Undaria pinnatifida root biochar diminished with pyrolysis temperatures surpassing 400 °C.
FTIR spectral analysis is crucial for determining the functional groups that contribute to the P-sorption capacity of biochar. According to Sarkhot, et al. [49], there are two different types of hydrogen bonding responsible for the unique bonding of biochars with P: (i) a bond between the proton of H2PO4− and phenolic end groups (C=O) of biochar, and (ii) a bond between protons from the surface -OH group of biochar and un-protonated oxygen of H2PO4−. Therefore, in the present study, a higher P-sorption capacity of lower-pyrolysis-temperature (400 °C) biochars was likely caused by C=C (peaked around 1600 cm−1) and C=O (peaked around 1700 cm−1) bonds (Figure 2a). These results are supported by Matin, Jalali, Antoniadis, Shaheen, Wang, Zhang, Wang, and Rinklebe [20], who reported higher P sorption in walnut biochar compared to almond biochar due to the presence of C=O and C=C bonds. Pyrolysis at 600 °C nearly removed functional groups from biochar (Figure 2b), which seemed to be one reason for lower P sorption on higher-pyrolysis-temperature biochar. This is likely because a higher pyrolysis temperature alleviates the dehydration reaction, which suggests a decrease in polar functional groups [50].
While considering the effects of feedstock type on P sorption, manure-based biochars were shown to have a greater P-sorption capacity. High cation-exchange capacity (CEC) values of biochar indicate an ability to sorb cations but not anions. Biochar surfaces are frequently negatively charged, which repels negatively charged ions like P, as shown by Yao, et al. [51] and Lawrinenko and Laird [52]. Therefore, the SSA of the adsorbent and the creation of metal–ion complexes are the primary factors regulating P sorption from aqueous solutions. Comparatively, a higher P sorption of manure-based biochars, despite having a lower surface area, pointed to a different possible mechanism for P sorption, which is that P could precipitate with Ca and Mg. As Ca and Mg were present in relatively higher abundances in manure-based biochars, the precipitation of P by Ca likely occurred in each of them to some extent (Table 3). The presence of Ca in solution could change the P species (i.e., from H2PO4− and HPO42−) to an ion pair (i.e., CaHPO40 [53]. This ion pair could easily adsorb on a negatively charged surface more so than other negatively charged species, i.e., H2PO4− and HPO42− [54]. An increase in P sorption due to Ca and Mg has been reported by many studies such as [55], which compared wheat straw, hardwood, and willow wood biochar and found higher P sorption in willow wood biochar because of the presence of 10-times-higher Ca and Mg content. Similar findings were reported by Jung, et al. [56], where peanut shell biochar had a higher level of P removal from water due to higher Ca and Mg content than soybean stover and bamboo wood biochars. Also, Yao, et al. [57] demonstrated that biochars made from sugar beet tailings that had undergone anaerobic digestion had higher phosphate adsorption, which was probably caused by the surface MgO present.
A reversible process of sorption that determines the fate of P is the desorption of P from biochar. The lower binding energy and higher P desorption rate of manure-based biochars compared to plant-based ones confirms more physical adsorption of P on animal biochars. Gong, et al. [58] specified that it is challenging to desorb chemically adsorbed nutrients from the biochar, but physically adsorbed nutrients can readily be desorbed. Similarly, a rise in carbonization temperature reduced the P binding energy of biochar, resulting in a high P desorption rate at 600 °C. These outcomes demonstrate that biochar prepared at 400 °C had a higher P-sorption capacity and a lower desorption rate. Therefore, a temperature of 400 °C is more favorable for producing biochar with a high capacity for P sorption.

5. Conclusions

Our study investigated the sorption and desorption mechanisms of biochar to understand the relationship between sorbed and available P. We found that the properties of biochar were significantly influenced by the type of feedstock used, leading to variations in their capacities for P sorption and desorption. The research findings suggest that biochars derived from manure exhibit higher capacities for both P sorption and desorption when compared to plant-based biochars. The principal mechanism driving P sorption in manure biochars appears to be the precipitation of P with Ca and Mg present in the biochars, whereas plant-based biochars primarily rely on a pore-filling mechanism. Furthermore, our study highlights the significant influence of pyrolysis temperature on biochar characteristics, particularly SSA and functional groups. Biochars produced at a lower carbonization temperature (e.g., 400 °C) exhibit higher SSA and stronger FTIR peaks, resulting in enhanced P-sorption capacity. Therefore, we propose that biochars prepared at 400 °C are more effective for retaining P in agricultural systems. However, it is important to note that while manure-based biochars retain more P, their retention capacity diminishes more quickly compared to plant-based biochars.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/su16072755/s1, Figure S1: Scanning electron microscopy (SEM) images of biochars prepared from different feedstocks at 400 °C and 600 °C. Here a = PB-400; b = PB-600; c = CCB-400; d = CCB-600; e = FYMB-400; f = FYMB-600; g = PMB-400 and h = PMB-600.

Author Contributions

Conceptualization, Investigation, Validation, N.M., K.S.K., J.C.B. and S.S.I.; Supervision, K.S.K.; Writing-original draft, N.M.; Methodology, Formal analysis, Data collection, N.M. and J.C.B.; Writing—review and editing, N.M., K.S.K., J.C.B., S.S.I., Z.A., M.S.A., M.A.A. and M.Y. All authors have read and agreed to the published version of the manuscript.

Funding

Financial support for this research was provided by the Higher Education Commission of Pakistan [grant number 315-19507-2AV3-113] and the Researchers Supporting Project Number (RSP2024R306), King Saud University, Riyadh, Saudi Arabia.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Data will be given on request.

Acknowledgments

The authors extend their appreciation to the Higher Education Commission (HEC), Pakistan, and the Researchers Supporting Project Number (RSP2024R306), King Saud University, Riyadh, Saudi Arabia.

Conflicts of Interest

The authors state that they have no known conflicting financial interests or personal connections that would have seemed to have an impact on the work that was published in this article.

Abbreviations

P, phosphorus; P, parthenium biochar; CCB, corn cobs biochar; FYMB, farmyard manure biochar; PMB, poultry manure biochar; SSA, specific surface area; EGME, ethylene glycol monoethyl ether; FTIR, Fourier-transform infrared spectra; SEM, scanning electron microscope.

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Figure 1. Implementation diagram of batch sorption and desorption procedure.
Figure 1. Implementation diagram of batch sorption and desorption procedure.
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Figure 2. Infrared Spectroscopy (FTIR) for biochars prepared from different feedstocks at (a) 400 °C and (b) 600 °C.
Figure 2. Infrared Spectroscopy (FTIR) for biochars prepared from different feedstocks at (a) 400 °C and (b) 600 °C.
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Figure 3. Phosphorus sorption Langmuir isotherms of biochars prepared from different feedstocks at 400 °C and 600 °C where (a) = PB-400 and PB-600; (b) = CCB-400 and CCB-600; (c) = FYMB-400 and FYMB-600 and (d) = PMB-400 and PMB-600.
Figure 3. Phosphorus sorption Langmuir isotherms of biochars prepared from different feedstocks at 400 °C and 600 °C where (a) = PB-400 and PB-600; (b) = CCB-400 and CCB-600; (c) = FYMB-400 and FYMB-600 and (d) = PMB-400 and PMB-600.
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Figure 4. Phosphorus desorption (%) of biochars prepared from different feedstocks at 400 °C and 600 °C pyrolysis temperatures where (a) = PB-400 and PB-600; (b) = CCB-400 and CCB-600; (c) = FYMB-400 and FYMB-600 and (d) = PMB-400 and PMB-600.
Figure 4. Phosphorus desorption (%) of biochars prepared from different feedstocks at 400 °C and 600 °C pyrolysis temperatures where (a) = PB-400 and PB-600; (b) = CCB-400 and CCB-600; (c) = FYMB-400 and FYMB-600 and (d) = PMB-400 and PMB-600.
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Table 1. Labelling scheme for biochar storage.
Table 1. Labelling scheme for biochar storage.
BiocharFeedstockPyrolysis Temperature
PB-400Parthenium biochar400 °C
CCB-400Corn cob biochar400 °C
FYMB-400Farmyard manure biochar400 °C
PMB-400Poultry manure biochar400 °C
PB-600Parthenium biochar600 °C
CCB-600Corn cob biochar600 °C
FYMB-600Farmyard manure biochar600 °C
PMB-600Poultry manure biochar600 °C
Table 2. Physicochemical properties of biochars made from various feedstocks at 400 °C and 600 °C pyrolysis temperatures.
Table 2. Physicochemical properties of biochars made from various feedstocks at 400 °C and 600 °C pyrolysis temperatures.
BiocharspH (1:20)SSA (m2g−1)EC (dS m−1)CEC (cmolc kg−1)Bulk Density (g cm3)Porosity (%)
PB-4008.33 ± 0.02719 ± 6.890.93 ± 0.0068.7 ± 0.430.27 ± 0.0172.7 ± 2.40
PB-60010.14 ± 0.01361 ± 4.601.01 ± 0.0153.9 ± 1.700.59 ± 0.0146.8 ± 4.25
CCB-4006.93 ± 0.02934 ± 3.280.0 6± 0.0077.6 ± 0.290.22 ± 0.0276.6 ± 2.55
CCB-6009.87 ± 0.05352 ± 7.810.33 ± 0.0250.7 ± 0.510.474 ± 0.0248.5 ± 5.20
FYMB-4008.07 ± 0.03344 ± 3.750.18 ± 0.0044.4 ± 1.840.48 ± 0.0358.9 ± 4.02
FYMB-6009.61 ± 0.01238 ± 2.520.17 ± 0.0041.7 ± 0.950.54 ± 0.0250.3 ± 2.27
PMB-4008.26 ± 0.01551 ± 5.060.60 ± 0.0058.8 ± 0.500.55 ± 0.0253.3 ± 2.11
PMB-6009.87 ± 0.03300 ± 2.710.44 ± 0.0246.8 ± 0.750.54 ± 0.0248.4 ± 5.62
The mean ± standard deviation for three determinates; SSA = (Specific surface area) analyzed by EGME; EC = Electrical conductivity; CEC = Cation-exchange capacity; PB = Parthenium biochar; CCB = Corn cobs biochar; FYMB = Farmyard manure biochar; PMB = Poultry manure biochar.
Table 3. Elemental composition of biochar prepared from different feedstocks at 400 °C and 600 °C.
Table 3. Elemental composition of biochar prepared from different feedstocks at 400 °C and 600 °C.
BiocharsC (%)N (g kg−1)P (g kg−1)K (g kg−1)Ca (g kg−1)Mg (g kg−1)
PB-40064.5 ± 0.213.11 ± 0.051.84 ± 0.0450.1 ± 0.2511.4 ± 0.404.46 ± 0.24
PB-60074.3 ± 0.192.81 ± 0.024.42 ± 0.1458.8 ± 0.9519.3 ± 0.249.94 ± 0.33
CCB-40057.1± 0.342.91 ± 0.021.07 ± 0.0112.3 ± 0.352.72 ± 0.041.82 ± 0.01
CCB-60074.7 ± 0.121.91 ± 0.022.30 ± 0.0218.1 ± 1.023.73 ± 0.032.16 ± 0.03
FYMB-40055.3 ± 1.734.22 ± 0.031.88 ± 0.0213.0 ± 0.5821.3 ± 0.2910.0 ± 0.59
FYMB-60045.6 ± 0.993.12 ± 0.034.44 ± 0.0321.8 ± 0.3339.1 ± 0.6720.3 ± 0.18
PMB-40054.5 ± 1.016.33 ± 0.034.46 ± 0.0834.3 ± 0.4520.9 ± 0.5415.1 ± 0.21
PMB-60048.8 ± 0.454.82 ± 0.027.24 ± 0.1444.9 ± 0.5840.4 ± 0.1324.8 ± 0.70
The mean ± standard deviation for three determinates.
Table 4. Phosphate sorption parameters of the isotherms described by the Langmuir and Freundlich equation of biochars prepared from different feedstocks at 400 °C and 600 °C pyrolysis temperatures.
Table 4. Phosphate sorption parameters of the isotherms described by the Langmuir and Freundlich equation of biochars prepared from different feedstocks at 400 °C and 600 °C pyrolysis temperatures.
BiocharLangmuirFreundlich
KLQmaxR2LKFnR2F
PB-4000.0062.990.950.1001.950.95
PB-6000.0052.820.940.0721.790.92
CCB-4000.0042.620.980.0661.840.95
CCB-6000.0042.470.980.0291.510.95
FYMB-4000.0043.490.990.0581.630.97
FYMB-6000.0043.180.980.0551.660.99
PMB-4000.0043.470.970.0641.800.96
PMB-6000.0042.770.970.0731.000.97
Qmax is the adsorption maximum (mg g−1), KL is a constant related to the binding of Langmuir, R2L means correlation coefficient for the Langmuir isotherm model, n is a dimensionless constant and nothing related to the intensity of the absorption, KF is the Freundlich constant. R2F is the correlation coefficient for the Freundlich isotherm model.
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Musa, N.; Khan, K.S.; Blankinship, J.C.; Ijaz, S.S.; Akram, Z.; Alwahibi, M.S.; Ali, M.A.; Yousra, M. Sorption-Desorption of Phosphorus on Manure- and Plant-Derived Biochars at Different Pyrolysis Temperatures. Sustainability 2024, 16, 2755. https://doi.org/10.3390/su16072755

AMA Style

Musa N, Khan KS, Blankinship JC, Ijaz SS, Akram Z, Alwahibi MS, Ali MA, Yousra M. Sorption-Desorption of Phosphorus on Manure- and Plant-Derived Biochars at Different Pyrolysis Temperatures. Sustainability. 2024; 16(7):2755. https://doi.org/10.3390/su16072755

Chicago/Turabian Style

Musa, Nighet, Khalid Saifullah Khan, Joseph C. Blankinship, Shahzada Sohail Ijaz, Zahid Akram, Mona S. Alwahibi, Mohammad Ajmal Ali, and Munazza Yousra. 2024. "Sorption-Desorption of Phosphorus on Manure- and Plant-Derived Biochars at Different Pyrolysis Temperatures" Sustainability 16, no. 7: 2755. https://doi.org/10.3390/su16072755

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