Optimization of synthesis of spherical lignosulphonate resin and its structure characterization

Calcium lignosulphonate was used to synthesize a spherical lignosulphonate resin in a cheap and non-toxic disperse medium by reversed phase suspension polymerization. The process conditions were optimized by orthogonal experiments. Under the optimal conditions (T=95 degrees C, C-HCl=3 mol.L-1, M-HCHO : M-CLS=7%, W-CLS=50%), globulation took about 20 min and the product was featured with excellent spherical shape, narrow particle size range, 61.20% of water retention capacity, 0.83 mmol.ml(-1) of total volume exchange capacity and 3.46 mmol.g(-1) of total exchange capacity. The results of Scanning Electron Micrograph and Scanning Probe Micrograph indicate that spherical lignosulphonate resin has a rugged surface with porous microstructure in the gel skeleton. The average pore size of dry samples was determined to be 10.46 nm by the BET method.