利用6种不同的解吸剂对吸附了Pb~(2+)和Cd~(2+)的固定香菇小球进行解吸。结果表明，HC1溶液做解吸剂最佳，可以分别在90 min和60 min内将大量的Pb~(2+)和Cd~(2+)从聚乙烯醇-海藻酸钠(PVA-SA)固定香菇小球上解吸出来。利用模拟二级动力学方程描述HCl溶液对PVA-SA固定香菇小球上Pb~(2+)和Cd~(2+)的解吸过程，决定系数R~2分别为0.996 9和0.998 9。Cd~(2+)的解吸率在HCl浓度为0.1 mol?L~(-1)时达到平衡，解吸率为80%;Pb~(2+)的解吸率在HCl浓度为1.0 mol?L~(-1)时达到最大，为99.01%。微观形态研究表明，未吸附重金属的PVA-SA固定香菇小球表面粗糙多孔，小球通过物理性吸附或形成无机沉淀将重金属沉积在细胞壁上后，表面变得密实。经HCl解吸后的PVA-SA固定香菇小球表面粗糙度和孔隙度都恢复到吸附前的状态。PVA-SA固定香菇小球对Pb~(2+)和Cd~(2+)进行吸附后，利用HCl进行解吸，再吸附，如此3次循环使用后，其吸附率略有降低，但仍可达到85.24%和69.07%。

Aiming to improve the industrial and mine sewage treatment by using immobilized Lentinus edodes, a kind of cheap biosorbent, this paper is focused on the study of the desorption process of Pb~(2+) and Cd~(2+) by immobilized Lentinus edodes, so as to find a method for recycling heavy metals. In proceeding with our study, we have first of all investigated such important parameters, as the sort of desorbent, equilibrium time and the concentration of the desorbent. The experimental results from our research indicate that among the six desorbents(H_2SO_4, HNO_3, HCl, Na_2CO_3, NaHCO_3, NH_4Cl), HCl and HNO_3 could desorb more Pb~(2+) and Cd~(2+) from the immobilized Lentinus edodes than the other four, with the effect of HCl being better for the desorption behavior. Desorbing Pb~(2+) and Cd~(2+) with HCl, the equilibrium time was 90 min and 60 min respectively. With the pseudo-second-order model well fitted for Pb~(2+) and Cd~(2+) desorption data, and the correlation coefficient0.996 9 and 0.998 9, respectively, the desorption ratio of Pb~(2+) tends to reach its maximum limit of 99.01% when the concentration of HCl is 1 mol?L~(-1), while that of Cd~(2+) reaches its maximum limit of 80.81% at the concentration of HCl being 0.1 mol?L~(-1). According to the scanning electronic microscope and the energy spectrum observation, the surface of polyvinyl alcohol-Na-alginate (PVA - SA) immobilized Lentinus edodes beads is rough and porous before the absorption. By the physical adsorption or/and forming inorganic sediment, heavy metals were adsorbed on the cell walls of immobilized beads after adsorption. In addition, the Pb~(2+) and Cd~(2+) crystal was found on PVA - SA immobilized Lentinus edodes after absorption. And the surface of PVA - SA immobilized beads would become close-grained. But after desorption with HCl, the surface of the beads would return to be rough and porous again. Then the recycled beads could be used for absorbing heavy metals again. Thus Pb~(2+) and Cd~(2+) biosorption ratios for PVA - SA immobilized Lentinus edodes could still reach 85.24% and 69.07% respectively after the three times of regeneration.