Deep Decontamination Of Cd²⁺ From Wastewater Onto Immobilized Spent Substrates Of Pleurotus Ostreatus

Spent substrates of mushroom(SSM) are solid wastes of edible mushrooms from industrial production. It bring about ecology pollution if the wastes were discharged to environment without any treatment. There are abundant of functional groups existing in surface of SSM, which are considered bisorption for removing heavy metal ions. The biosorption of spent substrates own many adventages compared with traditional treatment method for heavy metal wastewater, such as lower cost, lower energy consumption, less environmental pollution. But it is adverse to recycling and reusing if the powder of SSM was put in wastewater directly, which even lead to the biomass get corrupted and cause secondary pollution.SA-PVA is used to immobilize SSM in my study for making uniform biosorption ball. The immobilized SSM possesses the following merits: 1 、 It is convenient to recycle for spherical biosorption material, in order to load packed columns and used in practice production; 2 、 The SA-PVA immobilized biomass also has certain mechanical strength, and its internal structures are full of apertures with larger surface area. These traits is benefial for sufficient contacting between heavy metal ions and biomass; 3、There are abundant of functional groups for combining heavy metal ions provided by lignin、cellulose、mycelium which exist in SSM; 4、The material is also convenient to obtain and lower cost.The SA-PVA immobilized biomass are used to adsorbed Pb2+、Cu2+、Zn2+、Cd2+and study their adsorption single factors respectively. The result indicate that the adsorption capacity of immobilized SSM can reach to above 60mg/g, under the condition that pH is 5-6, adsorption temperature is above 25℃, initial concentration of heavy metal is range from 100-200mg/L.It is emphasis on Cd2+ adsorption by immobilized SSM in my study. The maximum of adsorption capacity on Cd2+ can reach to above 70mg/g under p H6, adsorption temperature 30℃and initial concentration of heavy metal is 100mg/L. The adsorption isotherm is concided with Langmuir absorption isotherm model and the correlation coefficient is identified to 0.998. It is showed that the bisorption of immobilized SSM is mainly monolayer chemisorptions. Furthermore,SEM, FTIR, XRD and BET were used to analyse the adsorption mechanism of Cd2+. The result showed that the specific surface area is 51.1546m2/g, and it mainly contain chemisorptions,electrostatic adsorption and complexation reactions on Cd2+ with functional groups such as the–OH,-NH, C=O and C-N which play key roles in biosorption. In adsorption-desorption experiments, HCl is used as eluent for Cd2+ loaded biomass. As the recycling times increase, theeluent rate of cadmium decrease accordingly. The rate of eluent only droped 15% compared with the first operation. Finally, large number of immobilized SSM was loaded to adsorption column,and the biosorption on Cd2+ of wastewater was carried on simulation of manufacturing operations under the optimum conditions. The result indicated that the immobilized SSM own higher adsorption capacity, easily recycling and lower cost, and possesss great potential of development and higher application value.