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• A ring-opening and substitution synthesis of a CH-TETA derivative • CH-TETA derivative was utilized for the first time to recover Pd from ELP solutions • Maximum adsorption capacity and desorption rate were 121.95 mg g −1 and 39.68 %, respectively. • After desorption, a considerable amount of Pd remains on the adsorbent • Therefore, stable adsorbents like these can serve a purpose as a catalyst Palladium (Pd), a well-known noble metal for its exceptional physical and chemical properties, finds widespread applications in sectors including automotive, hydrogen purification, dentistry, coinage, and jewelry. The growing demand for Pd has led to resource scarcity. This feature necessitated upon the economically and environmentally viable means for the reclamation of the precious metal ions from secondary sources. This article delves into the Pd adsorptive-desorption trends associated with the triethylenetetramine cross-linked chitosan (CH-TETA) derivative in moderately complex solutions. The effect of moderate solution chemistry complexity, incorporating ammonium hydroxide (NH 4 OH) and ethylenediaminetetraacetic acid (EDTA), within the synthetic electroless plating (ELP) solutions was investigated. Batch adsorption experiments were conducted through a variation of process parameters namely solution pH, CH-TETA dosage, adsorption duration, initial Pd concentration, and temperature. CH-TETA demonstrates an impressive Pd adsorption capacity ranging from 43.53 to 117.08 mg g⁻¹ and is correspondingly accompanied by the metal removal efficiency range of 87.05 % to 39.03 %. Such promising performance has been ascertained for an initial Pd constitution of 50 to 300 mg L⁻¹. Despite constituting other additives in the adsorbate system, utilizing simple acidic and basic eluents, the CH-TETA derivative exhibited a reasonable recovery efficacy of 39.68 %. Thereafter, recovery of Pd can be further enhanced into two approaches. In these, the first refers to the utilization of various other methods such as thermal, electrochemical, ultrasound, and microwave-assisted regeneration from spent adsorbents. Secondly, a pre-treatment method can be adopted to remove the additives prior to the adsorption process. In summary, the recovery of precious metal ions from the spent adsorbents has been a challenging task. Based on the discussion, further improvements based on the findings of this article are possible by targeting relevant research methodologies in resin chemistry and regeneration methods. [Display omitted] [ABSTRACT FROM AUTHOR]

Novelty Statement - For the first time, CH-AZ resin competence has been evaluated for Pd(II) recovery and use application. - CH-AZ resin provided excellent Pd sorption characteristics but moderate desorption characteristics. - With good Pd loading even after desorption, Pd adsorbed CH-AZ resin can serve as excellent material to serve as value added product development from waste resources. Abstract This article targets the efficacy of chitosan cross-linked 3-Amino-1,2,4-triazole-5-thiol derivative for the recovery of Pd from synthetic electroless plating solutions (ELP) whose solution chemistry complexity is brought forward with ethylenediaminetetraacetic acid (EDTA), ammonium hydroxide (NH 4 OH), and surfactant (cetyl trimethyl ammonium bromide (CTAB)). Batch adsorption characteristics of the resin were investigated in the parametric range of 2–10 pH, 0.2–2 g L−1 adsorbent dosage, 5–1080 min contact time, 50–300 mg L−1 Pd concentration and 25–60 °C operating temperature. Equilibrium, kinetic and thermodynamic model fitness studies were also considered. Pd(II) adsorption characteristics were determined using NaOH, KOH and HCl solutions with variant eluent concentrations (0.1–2 N). The solution chemistry complexity has been evaluated to have profound impact in detrimentally influencing Pd sorption characteristics of the CH-AZ resin. The resin has been characterized to be highly effective for Pd removal from synthetic ELP solutions but with moderate efficacy towards the noble metal recovery and reuse. [ABSTRACT FROM AUTHOR]

Deliberating upon the role of solution chemistry in influencing the Pd(II) adsorption and desorption characteristics using chitosan based resins, this work addresses the competence of glutaraldehyde cross-linked chitosan (GCC) co-polymer resin for the removal and recovery of Pd(II) from synthetic electroless plating solutions. GCC copolymer adsorbent was prepared by grafting of fixed weight ratio (1/17) of medium molecular weight chitosan and glutaraldehyde (25% in H 2 O). Within the adsorption parametric range of 2–10 pH, 60–300 min contact time, 10–50 mg adsorbent dosage and 50–500 mg/L initial Pd(II) concentration, the solution chemistry associated to synthetic ELP solution has been evaluated to strongly reduce the adsorption capacity of the GCC resin. Batch equilibrium adsorption studies inferred upon the fitness of Langmuir isotherm with a monolayer adsorption capacity of 166.67 mg/g. Adsorption kinetics and thermodynamic parametric evaluations affirmed pseudo-second-order kinetics and spontaneous exothermic Pd(II) adsorption on the resin. Further, speciation analysis provided valuable insights by indicating greater favourability of Pd(NH 3 ) 4 2+ species (at pH = 8) than PdEDTA −2 (at lower pH) to foster chemisorption with the GCC resin. In summary, the observations affirmed that solution chemistry needs to be addressed in laboratory investigations to further industrial application and competitiveness of alternate resins. [ABSTRACT FROM AUTHOR]