Development Of Novel Polycarboxylic Polymer Adsorbents And Application For The Recovery Of Rare And Precious Metals

In view of the current situation of the recovery of rare and precious metal resources,in this paper new polycarboxylic acid-based polymer adsorbents were developed,and their adsorption properties were studied.Carboxymethyl groups connected to the N-site of DEAE(CMDEAEC)and to the HOsite of cellulose(CM-DEAEC)have different adsorption selectivities.CMDEAEC adsorbs metal ions through the zwitterionic(carboxymethyl)triethylammonium inner salt groups forming complexes with them and has a special selectivity for Pd(II)at high chloride ion concentration and low p H.CM-DEAEC adsorbs metal ions through its carboxyl groups and exhibits good adsorption and separation of Ga(III).Therefore,CMDEAEC and CMDEAEC have great potential to be used for the recovery of rare and precious metal from secondary resources.Carboxymethyldiethylammoniumethyl cellulose(CMDEAEC)and carboxymethyl-2-diethylaminoethyl cellulose(CM-DEAEC)were synthesized to change the separation order of gold,platinum and palladium.At a 3M chloride ion concentration and in the p H range from 1.0 to 3.0,CMDEAEC can first adsorb and separate Pd(II)before Au(III)and Pt(IV)without being affected by the other metal ions.On the other hand,at a 0.1 M chloride ion concentration and p H 2,CM-DEAEC can first absorb and separate Pt(IV)before Au(III)and Pd(II)without being affected by the coexisting metal ions.Therefore,CMDEAEC can be used for analytical applications,and it can effectively solve the problem that rapid analysis and efficient separation of gold jewelry contained possibly Pd impurities.And CMDEAEC can be used for secondary resources recovery,such as it for first separating Pt,then recovering Au,Pd from Au-Pt-Pd alloy waste.Carboxymethyl-diethylammoniumethyl cellulose(CMDEAEC),a low-cost cellulosebased ionic liquid that possesses a nanoscale particle size and good swellability,was prepared through a one-step reaction.CMDEAEC exhibits high selectivity for Au(III).The adsorption process follows the Langmuir isotherm model and the pseudo-second-order kinetics model.CMDEAEC has excellent desorption and reusable properties.In conclusion,as an efficient,low-cost,easily obtained and environmentally friendly adsorbent,CMDEAEC is expected to be used for the selective recovery of gold.A phase-transfer adsorbent PAA-N2-DGA that was synthesized using a two-step reaction has a high selectivity for Th(IV).The maximum Th(IV)sorption capacity onto PAA-N2-DGA was 719.4 mg/g.PAA-N2-DGA exhibited an extremely fast adsorption rate with an adsorption equilibrium time of 1 min.In addition,PAA-N2-DGA can quickly process large volumes of sample.PAA-N2-DGA can also be rapidly separated like a solid adsorbent.Therefore,PAA-N2-DGA is an adsorbent that truly achieves rapid extraction separation.