Functionalized C,N-Bipyrazole Receptor Grafted Onto Silica Surface for Arsenic (As) Adsorption and its Antibacterial Activity

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Taha, Nagham
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An-Najah National University
The ability of C,N- bipyrazole receptor grafted onto silica surface (SG2P) of adsorption arsenic (As) from aqueous solutions was studied. The effect of various parameter on the adsorption process was investigated. Such parameters included; PH, contact time, concentration of initial ions of arsenic in solution and dosage of adsorbent. The results obtained indicated the percentage removal of arsenic decreased with the increase of As concentration and pH, while the percentage removal increased with the increase of contact time, adsorbent dose and temperature. The removal efficiency for As(III) adsorption could reach 60% after 24hour was achieved at pH around 3, and temperature 25ºC, using 0.02g weight of dose, at initial concentration 10ppb for 10mL As(III) solution. The studied parameter result on adsorption showed the optimal conditions for arsenic adsorption process were pH around 3 (acidic solution), 45O C, initial concentration of arsenic ions was at 10 ppb, the optimal time interval was 20 minutes, and the dosage of adsorbent had maximum adsorption capacity at 0.15g. Two kinetics models were applied the adsorption process: pseudo-first order kinetic model and pseudo second order kinetic model. The results that adsorption process of arsenic harmonized pseudo second order model. The adsorption capacity of SG2P was studied using Freundlich and Langmiur models at equilibrium to determine the behavior of adsorption process, both models result showed favorable adsorption process. Thermodynamics parameters such standard enthalpy, standard entropy and standard free energy were calculated for SG2p adsorbent. The negative Go values indicate that the adsorption is spontaneous at these temperatures. The negative value of Ho reflects an exothermic adsorption and indicates that the adsorption is favored at low temperature. In the other hand, the positive value of ∆S° suggests that some structural changes occur on the adsorbent and the randomness at the solid/liquid interface in the adsorption system increases during the adsorption process. The antibacterial activity of SG2P was determined against two bacterial references strains using micro- broth dilution method. The references strains were Escherichia coli (ATCC25922) and Staphylococcus aureus (ATCC25932). The SG2P possessed limited antibacterial activity, where it was able to inhibit growth only at high concentration (MIC =1.5625 mg per ml).