Utilization of waste lignin to prepare controlled-slow release urea

Abstract

Purpose The present work reports an economically attractive improvement in the area of producing particulate slow release nitrogen fertilizer using lignin as a waste effluent of pulp and paper manufacturing process. Methods An improved coating of modified lignin was applied on the surfaces of the individual urea particles. The Kraft and Sulfite black liquors obtained from two different paper pulping units and were used as sources of sulfate and sulfite lignin, respectively. Chemical modification of extracted lignin was performed through acetylation reaction by acetic acid/sodium metabisulfite to increase its hydrophobicity character. In a separate experiment, a thin layer of synthesized acetylated lignin was coated on granular urea by fluidized-bed technique. The nitrogen release of synthesized fertilizer in the water and soil was examined by the Kjeldahl method. Results The analysis of FTIR spectra indicated the changes in the functional groups of acetylated lignin. Petrographic photography and scanning electron microscopy (SEM) analyses demonstrated a uniform and homogeneous covering of the urea surface. The 7 day nitrogen release rate of urea coated by acetylated lignin in soil was obtained 36.3 and 45.3 % for Kraft and Sulfite lignin, respectively, whereas this value was 59 % for sulfur coated urea. Conclusions Using industrial wastewater as source of lignin gives satisfactory results for industrial applications and yields a quality green fertilizer product with reduced operation difficulties while considerably preserving the environment.Keywords Controlled release fertilizer Á Fluidized-bed coating Á Kraft and sulfite liquor Á Modified lignin coated urea Abbreviations CRF Controlled-release fertilizers FTIR Fourier transform infrared SCU Sulfur coated urea SEM Scanning electron microscopy

Properties of Coated Controlled Release Diammonium Phosphate Fertilizers Prepared with the Use of Bio‐based Amino Oil

“…Priamine compare the lower viscosity obtained when THF solvent was used. Therefore, high thickness, compacted and good adhesion between the granule and the coating were obtained by reducing the pores sizes which became smaller as the coating percentage increased (Behin and Sadeghi, 2016) (Fig. 3).…”

“…Indeed, its low viscosity conferred to the shell coatings a compact structure and covered all the cavities and cracks in the surface of the uncoated DAP fertilizers when the percentage of coating increased leading to a smooth surface (Fig 3f). With its good water repellency, hydrophobic nature, Priamine brings excellent barrier properties and thus moderated the P release rate (Behin and Sadeghi, 2016).…”

“…For each coating, the measurements were taken at four different locations and the average thickness was calculated (Table 1) (Behin and Sadeghi, 2016;Lubkowski et al , 2019). The thickness of different coatings based on Priamine were displayed in Fig.2S (ESI).…”

Preliminary Study on Sustainable NPK Slow-Release Fertilizers Based on Byproducts and Leftovers: A Design-of-Experiment Approach

“…The mechanism of controlled release is regulated first by the progressive degradation of the coating and second by the osmotic pressure inside the core; thereafter, high hydrophilic and environmentally green compounds must be considered to avoid the pollution of soil after coating degradation. In this sense, the more recent research is dedicated to the study of coating or matrix-based on natural materials, such as bentonite and cotton stalks, 11 lignin, 12 wheat straw, 13 chitosan and vegetal cellulose, 14 and chitosan and potato starch. 15 Studies so far demonstrated that the obtainment of a gradual controlled release over a period of 21 days is difficult because it is necessary to avoid too fast biodegradation of the coating due to very high hydrosolubility of the natural materials, and therefore, research must be focused on the need for greater control of the coating formulation.…”

Nitrogen Dynamics in Soil Fertilized with Slow Release Brown Coal-Urea Fertilizers

“…Considerable research efforts have been aimed at developing suitable mitigation strategies to reduce gaseous and leaching losses of N from intensively managed agricultural systems 7 – 10 . Mitigation strategies, such as using controlled release or enhanced efficiency fertilizers or combined application of organic and inorganic fertilizers to minimize the loss of N for improving its use efficiency by crops have been extensively studied in the last few decades 11 , 12 .…”