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°C, cHCl=3 mol·L−1, mHCHO:mCLS=7%, wCLS=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.