Chelating agents for heavy metal removal

A compound comprising:

• wherein R1, R2, R3, R4, R5, and R6 are selected from the group consisting of hydrogen, alkyl, aryl, substituted alkyl, and substituted aryl;
• at least one of R1 and R2 is not hydrogen;
• at least one of R5, and R6 is not hydrogen;
• X1 and X2 are each independently selected from the group consisting of O, NR7, and S, wherein R7 is hydrogen, alkyl, aryl, substituted alkyl, or substituted aryl;
• and Y is a linking group selected from the group consisting of:
• alkylene, substituted alkylene, alkylidene, substituted alkylidene, arylene, or substituted arylene.

A compound comprising:

• wherein:
• a starred atom denotes a point of attachment;
• X1, X2 and X3 are independently selected from the group consisting of:
• O, NR3, and S;
• R1, R2, Y1, Y2, Y3, Y4, and Y5, are independently selected from the group consisting of hydrogen, alkyl, aryl, substituted alkyl, and substituted aryl;
• one of Y1, Y2, and Y3 is selected from the group consisting of:
• alkylene, oxy-alkylene, amino-alkylene, thio-alkylene, —(CH2)nC(═O)NH—, —(CH2)nC(═O)O—, arylene, substituted arylene, heteroarylene, and substituted heteroarylene;
• at least one of R1 and Y1 is not hydrogen;
• and at least one of R1, R2, Y1, Y2, Y4, and Y5 is hydrogen;
• and at least one of R1 and Y1 is not hydrogen.

A ligand attached to a glass fiber, wherein the ligand has structure:

• wherein:
• a starred atom denotes a point of attachment;
• N˜O denotes a bond that represents the Z or E isomeric form;
• X1 and X2 are independently selected from the group consisting of:
• O, NR4, and S;
• Y1, Y2, and Y3, R1, and R4 are independently selected from the group consisting of:
• hydrogen, alkyl, aryl, substituted alkyl, and substituted aryl;
• one of Y1, Y2, and Y3 is absent so that respective group X1, X2, or X3 to which it is bonded is attached directly to the resin, or one of Y1, Y2, and Y3 attaches the ligand to the resin and is selected from the group consisting of:
• alkylene, oxy-alkylene, amino-alkylene, thio-alkylene, —(CH2)nC(═O)NH—, —(CH2)nC(═O)O—, arylene, substituted arylene, heteroarylene, and substituted heteroarylene;
• at least one of R1, Y1, Y2, R4, and Y3 is hydrogen;
• and at least one of R1 and Y1 is not hydrogen.

A method of removing metal cations from an aqueous medium, comprising:

• passing the aqueous medium over a macroporous resin, attached to which is a ligand of structure:
• wherein:
• a starred atom denotes a point of attachment;
• N˜O denotes a bond that represents the Z or E isomeric form;
• X1 and X2 are independently selected from the group consisting of:
• O, NR4, and S;
• Y1, Y2, and Y3, R1, and R4 are independently selected from the group consisting of:
• hydrogen, alkyl, aryl, substituted alkyl, and substituted aryl;
• one of Y1, Y2, and Y3 is absent so that respective group X1, X2, or X3 to which it is bonded is attached directly to the resin, or one of Y1, Y2, and Y3 attaches the ligand to the resin and is selected from the group consisting of:
• alkylene, oxy-alkylene, amino-alkylene, thio-alkylene, —(CH2)nC(═O)NH—, —(CH2)nC(═O)O—, arylene, substituted arylene, heteroarylene, and substituted heteroarylene;
• at least one of R1, Y1, Y2, R4, and Y3 is hydrogen;
• and at least one of R1 and Y1 is not hydrogen.

An ion exchange apparatus comprising:

• a macroporous resin;
• and, attached to the resin a ligand having a structural formula:
• wherein:
• a starred atom denotes a point of attachment;
• N˜O denotes a bond that represents the Z or E isomeric form;
• X1, X2, X3 and X4 are independently selected from the group consisting of:
• O, NR4, and S;
• X1 is attached directly to the resin;
• Y2 and Y3 are independently selected from the group consisting of:
• alkylene, oxy-alkylene, amino-alkylene, thio-alkylene, arylene, substituted arylene, heteroarylene, and substituted heteroarylene;
• R1, R2 and R3 are independently selected from the group consisting of:
• hydrogen, alkyl, aryl, substituted alkyl, and substituted aryl;
• and n is from 1 to 5.