Removal Of Heavy Metals And Organics By Composite Nano-biomaterial

Nowadays, an increasing amount of toxic inorganic and organic wastes are beingdischarged into the environment, causing serious water, air, and soil pollution. Thecompound pollutions of heavy metals and organics have aroused wide public concernbecause they are more harmful to human beings and are more difficult to remove.Cd（II） is one of the most toxic heavy metals. It accumulates easily in living organismsand is harmful to the kidneys, liver, and the skeletal system.2,4-Dichlorophenol（2,4-DCP）, causes strong caustic and denaturing effects on organisms, includingirritation of the skin and the mucous membrane. The composite pollutants containingCd（II） and2,4-DCP can be more toxic and more difficult to remove than the singleone. Although many studies have investigated the disposal of heavy metals orchlorophenols respectively, little research has focused on the simultaneous removal ofthese two kinds of pollutants.Biosorption is a cost-efficient technique and no second pollution for treatinglarge volumes of waste streams. P. chrysosporium has been reported as an effectivebiomass used for adsorbing heavy metals. TiO₂nanoparticle is one of the mostpopular photocatalysts because of its high physical and chemical stability, nontoxicity,and low cost. Nitrogen-doped TiO₂nanoparticles were loaded onto P. chrysosporiumimmobilizing with sodium alginate gel to dispose of waste water containing Cd（II）and2,4-DCP in this article.The effects of contact time, pH, and initial concentrations were examined inbatch experiments. The current study demonstrated that the removal efficiencies weremaintained at a high level:84.2%for Cd（II） and78.9%for2,4-dichlorophenol（2,4-DCP） in the wide pH range of4.0to7.0in60h. The removal capacity ofimmobilized P. chrysosporium loaded with nitrogen-doped TiO₂nanoparticles （PTNs）was strongly affected by the initial Cd（II） and2,4-DCP concentrations.In order to investigate the removal pathways and mechanisms of immobilized P.chrysosporium loaded with nitrogen-doped TiO₂nanoparticles （PTNs）, scanningelectron microscopy （SEM）, energy-dispersive X-ray analysis （EDAX）, Fouriertransform infrared spectrometry （FT-IR）, and gas chromatography-mass spectrometry（GC-MS） were used. The hyphae of PTNs became tight, and a large amount ofcrystals adhered to them after the reaction. Results of Energy dispersive X-ray analysis revealed amino acids and proteins were involved in binding metal ions.Fourier transform infrared spectroscopy showed that carboxyl, amino, and hydroxylgroups on the surface of PTNs were responsible for the biosorption. In thedegradation process,2,4-DCP was broken down into o-chlorotoluene and4-hexene-1-ol. These results showed that PTNs could increase the resistance of P.chrysosporium to the toxic effects of pollutants and shorten its degradation time, thusPTNs is promising for simultaneous removal of Cd（II） and2,4-DCP from wastewater.