Study On The Adsorption Performance Of Modified Silica Sand Towards Heavy Metal Ions

The treatment of wastewater containing heavy metal ions is one of the difficult issues in the process of industrial development. Adsorption is often used to remove the metal ions in wastewater. However, the regeneration and secondary pollution of the used sorbent is a great challenge. Since heavy metals are expensive and widely used in many fields, the treatment of metal ions contaminated wastewater should also consider the recycling and utilization of the recovered heavy metal ions.In this work, combining sol-gel with template method, tetraethyl orthosilicate(TEOS) as the silica source and cetyl trimethyl ammonium bromide(CTAB) as template to form porous silica layers on the surface of a parent silica sand(P-sand) which is used in glass production and water filtration. The surface area of the calined coated sand(C-sand) significantly increased. The C-sand was further functionalized by 3-aminopropyltriethoxysilane(APTES). The sample were characterized by SEM,TEM, FT-IR, XRD, DTA, and N2 sorption/desorption measurements. The adsorption of Cu2+,Ni2+,Cu2+/Cr3+ and ions from real copper electroplating wastewater of the APTES modified sand was studied. The used adsorbent contains the adsorbed ions were used for the preparation of color glasses.We first studied the influence of the amounts of CTAB, H2 O, TEOS, and NaOH concentration, reaction temperature and time, the surface area ofthe formed porous silica. The results show that the sample obtained with 1.08 g CTAB, 100 m L H2 O, 4.5 mLTEOS, 30 m L of 0.3 M NaOH at 60 oc for 3h has the largest surface area. Therefore, in this system 6 g silica sand was coated five times under the optimized conditions. The product has a surface area increases of 260.56 m2/g, 2895 times that of the original silica sand. Affter the aminofunctionalized, the surface area reduced to 150.13m2/g, 1668 times of the original silica sand.The influence of pH, adsorption temperature, and time, adsorbent dosage and initial concentration on the adsorption of the Cu2+ and Ni2+, Cr3+, and Cu2+/Cr3+ has been studied. It’s shown that the adsorption of Cu2+ and Ni2+ on amino modified sand follows the pseudosecond kinetic models and the Freundlich models.Under the optimal conditions, the adsorption of Cu2+ by the APTES-sand reaches 60%, the adsorption capacity of sand is 9.42mg/g; the adsorption of Ni2+ by the DM-sand reaches 84.89%, the adsorption capacity of sand is 4.97mg/g. These values are 67.67%, 10.15mg/g and 28.07%, 4.21mg/g in the cases of Cu2+ and Cr3+ions in the mixed of Cu2+/Cr3+ solution, respectively.The APTES-sand which has adsorbed Cu2+, Ni2+, Cu2+/Cr3+ ions were successfully used to make lake blue, brown and dark green glasses. Either the C-sand or APTES-sand absorbed Cr3+ ions can make green glass, but the latter glass has UV blocking effect.