Phosphorus removal from biodiesel by crystallization of magnesium ammonium phosphate

ABSTRACT

Excessive phosphorus content in biodiesel can adversely affect the combustion and emission processes. Phosphorus is also an important nutrient for the optimal growth of plants and the normal regulation of animal cells. The present study investigated Jatropha biodiesel. The phosphorus in the biodiesel was removed by the magnesium ammonium phosphate (MAP) crystallization method, using the response surface method (RSM) for the design of the phosphorus removal test and optimization of the key parameters of MAP synthesis, and the products synthesized under the optimized conditions were characterized. The results showed a 99.66% conversion rate of phosphorus in the phosphorus removal process, with no significant interaction between Mg²⁺:PO₄^3- (X₂) and NH₄⁺:PO₄^3- (X₃) during the phosphorus conversion process. The MAP yield was 47.67%, and a significant interaction between pH (X₁) and NH₄⁺:PO₄^3- (X₃) was observed during the MAP. The optimal conditions for MAP crystallization through RSM optimization were found to be pH 9.374 and a PO₄^3-:Mg²⁺:NH₄⁺ molar ratio of 1:2.889:3.000. A 94.13% phosphorus removal rate was observed under the optimized conditions, with a MAP yield of 49.09%, both of which were close to the predicted values of 95.00% and 49.45%, respectively. The synthesis products under the optimized conditions were characterized in detail and the synthesis of MAP was demonstrated.

KEYWORDS:

• Ion chromatography
• biodiesel
• phosphorus content
• phosphorus removal
• response surface method

Abbreviations

CCD	=	Central composite design
FTIR	=	Fourier Transform Interferometric Radiometer
FE-SEM	=	Field Emission Scanning Electron Microscope
FTIR	=	Fourier Transform Interferometric Radiometer
MAP	=	Magnesium ammonium phosphate
RSM	=	Response surface methodology
XRD	=	X-ray diffraction

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The work was supported by the National Natural Science Foundation of China [52166013]; Yunnan Fundamental Research Projects[202101AS070115]

Notes on contributors

Li Zhou

Li Zhou Conceptualization, Methodology, Software, Writing- Original draft preparation.

Fashe Li

Fashe Li Supervision, Data curation.

Wenchao Wang

Wengchao Wang Software, Reviewing and editing.

Hua Wang

Hua Wang Reviewing.