title: Synthesis and characterization of agricultural controllable humic acid superabsorbent.
abstract: Humic acid superabsorbent polymer (P(AA/AM-HA)) and superabsorbent polymer (P(AA/AM)) were synthesized by aqueous solution polymerization method using acrylic acid (AA), acrylamide (AM) and humic acid (HA) as raw material. The effects of N,N'-methylenebisacrylamide (MBA) crosslinking agent, potassium peroxydisulfate (KPS) initiator, reaction temperature, HA content, ratio of AA to AM, concentration of monomer and neutralization of AA on water absorption were investigated. Absorption and desorption ratios of nitrogen fertilizer and phosphate fertilizer were also investigated by determination of absorption and desorption ratio of NH4(+), PO4(3-) on P(AA/AM-HA) and P(AA/AM). The P(AA/AM-HA) and P(AA/AM) were characterized by Fourier translation infrared spectroscopy, biological photomicroscope and scanning electron microscopy (SEM). The optimal conditions obtained were as follows: the weight ratio of MBA to AA and AM was 0.003; the weight ratio of KPS to AA and AM was 0.008; the weight ratio of HA to AA was 0.1; the mole ratio of AM to AA is 0.1; the mole ratio of NaOH to AA is 0.9; the reaction temperature was 60°C. P(AA/AM-HA) synthesized under optimal conditions, has a good saline tolerance, its water absorbency in distilled water and 0.9 wt.% saline solution is 1180 g/g and 110 g/g, respectively. P(AA/AM-HA) achieves half saturation in 6.5 min. P(AA/AM-HA) is superior to P(AA/AM) on absorption of NH4(+), PO4(3-). The SEM micrograph of P(AA/AM-HA) shows a fine alveolate structure. The biological optical microscope micrograph of P(AA/AM-HA) shows a network structure. Graft polymerization between P(AA/AM) and HA was demonstrated by infrared spectrum. The P(AA/AM-HA) superabsorbent has better absorbing ability of water and fertilizer, electrolytic tolerance and fewer cost than P(AA/AM) superabsorbent.
authors: School of Chemical Engineering, University of Science and Technology Liaoning, Liaoning 114051, China.  gaolijuan@ustl.edu.cn
authors: Lijuan
authors: L
authors: Gao
authors: School of Chemical Engineering, University of Science and Technology Liaoning, Liaoning 114051, China.
authors: Shiqiang
authors: S
authors: Wang
authors: School of Chemical Engineering, University of Science and Technology Liaoning, Liaoning 114051, China. Electronic address: zhao_xuefei@sohu.com.
authors: Xuefei
authors: X
authors: Zhao
mesh_terms: D065966:Absorption, Physicochemical; D020106:Acrylamide; D000179:Acrylates; D000383:Agriculture; D005308:Fertilizers; D006812:Humic Substances / Q000032:analysis; D008855:Microscopy, Electron, Scanning; D017680:Potassium Compounds / Q000737:chemistry; D012972:Sodium Hydroxide / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013431:Sulfates / Q000737:chemistry; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D000179:Acrylates; D005308:Fertilizers; D006812:Humic Substances; D017680:Potassium Compounds; D013431:Sulfates; D014867:Water; D020106:Acrylamide; D012972:Sodium Hydroxide; C009007:potassium persulfate; C036658:acrylic acid
keywords: adsorption capacity; lignite humic acid; removal rate; superabsorbent polymer; water absorbency