This review summarizes the chemical characteristics and environmental impact of LMP. As a low-cost absorbent or agent, the current progresses on LMP potential applications such as wastewater and air pollution, remediation of contaminated soils, and bio-treatment of organic waste are also reviewed in details.
2. Production and characteristics of LMP
2.1. LMP production
Pulp and paper plants are primary sources of LMP in the causticization process versus mechanical, chemi-mechanical and chemical methods, respectively. Kraft process, the most dominating chemical pulp, is used to dispose of wood Bikinin in spite of pollution problems posed by malodorous compounds. The flow sheet of LMP production in kraft pulp papermaking process has been shown by Martins et al. (2007), together with Eq. (1) (Cheng et al., 2009), as seen from Table 3.
In general, precipitated calcium carbonate (PCC) is generally produced from mined, crushed calcium carbonate (CaCO3) and calcium silicates, with a higher purity of CaCO3 than that of ground CaCO3 (GCC) from a controlled synthesis through calcination and hydratization, filtration and carbonation. There are several various types of PCC grades, but the purity of PCC is usually over 99 wt% with density of 2700 kg/m3 (Teir et al., 2005). In papermaking process, PCC could enhance paper bulk, brightness, light scattering and printability as a filler agent. However, the calcination of CaCO3 requires about the external heat of 2669 kJ/kg CaCO3 (with an initial temperature of 25 °C) at 900 °C (Teir et al., 2005), Consequently, it causes a high cost and energy consumption.