Ordered Mesoporous Carbons Modified Tin-covered Carbon Paste Electrode To Detect Cd²⁺,Zn²⁺ And Cu²⁺

In this paper,three kinds of tin covered ordered mesoporous materials modified carbon paste electrode?CPE?have been used to detect heavy metal ions,such as Cd²⁺,Zn²⁺,and Cu²⁺,by square wave anodic stripping voltammetry.This method combined the advantages that OMCs can conduct electrons quickly and the uniform pore diameters of OMCs cause good adsorption;the tin is environmentally friendly and can form a mixture with heavy metals to amplify the signal of peak current;and carbon paste electrode is contamination free,convenient to make and the surface can renew quickly.Also,this new method can analyst the concentrations of heavy metal ions in real samples.1.The preparation of the tin film CMK-3 modified carbon paste electrode and the detection of Cd?II?A tin film CMK-3 modified carbon paste electrode?Sn/CMK-3/CPE?that is a brand new electrode combined the ordered mesoporous carbons?OMCs?and tin film was used to detect trace cadmium.As one of the OMCs,CMK-3 has the distinct advantage of conducting electrons because the pore in them is regularly ordered and controllable with the pore diameters about 3.8-4 nm,this uniform pore diameter ensures good adsorption of CMK-3.Compared to the carbon paste electrode modified by CMK-3?CMK-3/CPE?,the CPE,and carbon paste electrode modified by the tin film?Sn/CPE?,the Sn/CMK-3/CPE has higher sensitivity and stability in the process of detecting Cd?II?.Under the optimum conditions(Mass of CMK-3,4.0 mg;pH,4.70;Sn?II?concentration,6.5 mg L^-1;deposition potential,-1.2 V;deposition time,300 s),the Sn/CMK-3/CPE indicated a wide linear range in the concentration range of 6.0–100.0?g L^-1?r=0.9980?with the detection limit of 0.8?g L^-1for Cd?II?.This novel sensor was applied to the detection of Cd?II?in river samples with good sensitivity and selectivity.So,the sensor can be used to detect Cd?II?in real samples with good results.2.The preparation of the carbon paste electrode of tin-covered SBA-15 and the detection of Zn???A tin-covered SBA-15 modified carbon paste electrode?Sn/SBA-15/CPE?was used to detect Zn???.As one of the ordered mesoporous silicon,SBA-15 has good advantages of conducting electrons because the pore in them is regularly ordered,controllable,and with the pore diameters 7-9nm,pore volume 0.65-0.7cm³ g^-1,specific square area 500-600 m² g^-1,moreover,the adsorptivity of SBA-15 for heavy metal ions and organic compounds is good.Compared with SBA-15 modified carbon paste electrode?SBA-15/CPE?,carbon paste electrode deposited by tin film?Sn/CPE?,the carbon paste electrode?CPE?,the Sn/SBA-15/CPE enhanced the sensitivity for detection of Zn?II?by square wave anodic stripping voltammetry?SWASV?.The following conditions were chosen as the most proper conditions,the Sn?II?concentration is 5.5 mg L^-1,the mass of SBA-15 is 4 mg,the pH of the hydrochloric acid solution is 4.5,the deposition potential is-1.55 V,and the deposition time is 300 s.The Sn/SBA-15/CPE indicated highly linear behavior in the concentration range of4.0–100.0?g L^-1?r=0.9985?with the detection limit of 0.15?g L^-1 for Zn?II?.The sensor shows good results in the process of detecting Zn?II?in lake samples with good sensitivity and selectivity,which proved that the sensor can be successfully applied to the detection of divalent zinc ions in practical samples.3.The preparation of the tin-covered carbon paste electrode combined N-doped CMK-3 and the detection of Cu???An original tin-covered carbon paste electrode combined N-doped CMK-3 was used to detect copper ions.As one kind of the ordered mesoporous carbons?OMCs?,N-doped CMK-3 has good advantages of conducting electrons and good adsorptivity,because the pore in them is regularly ordered,controllable,and with the pore diameters 7-9 nm,pore volume 0.65-0.7cm³ g^-1,specific square area 500-600 m² g^-1.The Sn/N-doped CMK-3/CPE enhanced the signal of peak current for detection of Cu?II?by square wave anodic stripping voltammetry,which is better than N-doped CMK-3 modified carbon paste electrode?N-doped CMK-3/CPE?,the bare carbon paste electrode?CPE?,and tin film modified carbon paste electrode?Sn/CPE?.The optimum conditions are as follows:the mass of N-doped CMK-3 is 4 mg,the Sn?II?concentration is 7.5 mg L^-1,the deposition potential is-1.3 V,and the deposition time is 350 s,the pH of the hydrochloric acid solution is 4.75.The Sn/N-doped CMK-3/CPE exhibited large linear range of 6.0–100.0?g L^-1?r=0.9998?with the detection limit of 0.073?mol L^-1 for Cu?II?.The outstanding sensor shows good sensitivity and selectivity in the process of detecting Cu?II?in river samples.Therefore,the sensor can be successfully applied to the detection of bivalent copper ions in practical samples..