Salt is used to protect a salmon slab with a thickness of 4.8 mm. The initial salt concentration of the salmon and the salt concentration of brine solution are given as 0.012% and 15%, respectively. The diffusivity of salt in salmon slab is 8.78x10-11 m2/s. The convective mass transfer coefficient is given as 7.32x10-8 m/s and the equilibrium distribution coefficient can be assumed as 1. Calculate the required processing time to increase the salt concentration of the center point to 6%.