Geopolymer is a porous inorganic material with a three-dimensional mesh structure, good mechanical properties, a simple preparation process (no sintering) and a low economic cost, and it is environmentally friendly. Geopolymer concrete has been widely used in the construction field, and many other studies have revealed that geopolymer will become one of the most promising inorganic materials with unique structure and properties. This paper provides a review of the development and current status of geopolymers and briefly explains the effects of material proportioning, experimental factors and activators on geopolymer performance. Because of the advantages of high specific surface area and high porosity, geopolymers could be used as adsorbent materials. This paper summarizes the research progresses of the adsorption of metal cations, anions, dyes, and gases by geopolymers, which emphasizes the geopolymer membranes in adsorption, and discusses the challenges and opportunities for the development of more efficient, sustainable and practical adsorption protocols.

We present here a novel conjugated aptamer-gold nanoparticle (Apt-AuNPs) fluorescent probe and its application for specific detection of recombinant human erythropoietin-α (rHuEPO-α). In this nanobiosensor, 12 nm AuNPs function as both a nano-scaffold and a nano-quencher (fluorescent energy acceptor), on the surface of which the complementary sequences are linked (as cODN-AuNPs) and pre-hybridized with carboxymethylfluorescein (FAM)-labeled anti-rHuEPO-α aptamers. Upon target protein binding, the aptamers can be released from the AuNP surface and the fluorescence signal is restored. Key variables such as the length of linker, the hybridization site and length have been designed and optimized. Full performance evaluation including sensitivity, linear range and interference substances are also described. This nanobiosensor provides a promising approach for a simple and direct quantification of rHuEPO-α concentrations as low as 0.92 nM within a few hours.

Bipolar membranes, a new type of composite ion exchange membrane, contain an anion exchange layer, a cation exchange layer and an interface layer. The interface layer or junction is the connection between the anion and cation exchange layers. Water is dissociated into protons and hydroxide ions at the junction, which provides solutions to many challenges in the chemical, environmental and energy fields. By combining bipolar membranes with electrodialysis technology, acids and bases could be produced with low cost and high efficiency. The interface layer or junction of bipolar membranes (BPMs) is the connection between the anion and cation exchange layers, which the membrane and interface layer modification are vital for improving the performance of BPMs. This paper reviews the effect of modification of a bipolar membrane interface layer on water dissociation efficiency and voltage across the membrane, which divides into three aspects: organic materials, inorganic materials and newly designed materials with multiple components. The structure of the interface layer is also introduced on the performance of bipolar membranes. In addition, the remainder of this review discusses the challenges and opportunities for the development of more efficient, sustainable and practical bipolar membranes.

Dithiocarbamate-grafted polyurethane (PU) composites were synthesized by anchoring dithiocarbamate (DTC) as a chelating agent to the polyethyleneimine-polydopamine (PE-DA)-functionalized graphene-based PU matrix (PE-DA@GB@PU), as a new adsorbent material for the recovery of Cu²⁺, Pb²⁺, and Cd²⁺ from industrial effluents. After leaching with acidic media to recover Cu²⁺, Pb²⁺, and Cd²⁺, dithiocarbamate-grafted PE-DA@GB@PU (DTC-g-PE-DA@GB@PU) was decomposed and PE-DA@GP was regenerated. The latter was used to recover Pd²⁺, Pt⁴⁺, and Au³⁺ from the copper leaching residue and anode slime. The present DTC-g-PE-DA@GB@PU and PE-DA@GB@PU composites show high adsorption performance, effective separation, and quick adsorption of the target ions. The morphologies of the composites were studied by scanning electron microscopy and their structures were investigated by Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy. The effects of pH values, contact time, and initial metal ion concentration conditions were also studied. An adsorption mechanism was proposed and discussed in terms of the FT-IR results.

A solid phase extraction procedure was developed for the separation and preconcentration of trace amounts of Au(III) in geological samples by using a polyurethane foam column modified with cytosine. The influence of the flow rate of the sample solution, the pH effect, eluent type, sorption capacity, and presence of matrix ions on the solid phase extraction procedure was investigated. The analytical results for international gold reference materials measured by this new method were in close agreement with those obtained by other well-established methods and values. Under the optimum conditions, the detection limit (3σ, n = 6) for the analyte was 6 ng L⁻¹, with an enrichment factor of 480. The equilibrium data were best represented by the Langmuir isotherm model, showing pseudo-first-order kinetics. The maximum adsorption capacity of Au(III) on the adsorbent was 98.9 mg g⁻¹.

Dopamine is an important neurotransmitter for organisms and affects their function, so monitoring and detecting dopamine levels are essential. Sensitivity and selectivity of electrochemical sensors for the detection of dopamine usually rely on hybrid nanocomposites. In this context, we designed a micro-regionally restricted hybrid nanocomposite by modulating the micro-nano structure. Using functional groups on nitrogen-doped reduced graphene oxide (N-rGO) to restrict the random growth of tungsten disulfide nanosheets, we obtained a 2D layered material with bidirectional structural support to achieve high specific surface and high activity for application in robust and novel dopamine electrochemical sensors. A facile electrochemical sensor for dopamine detection was fabricated by modifying a screen-printed carbon electrode with the nanocomposite. The sensor exhibits excellent performance of dopamine detection in the wide range of 1 μ mol l ⁻¹ –100 μ mol l ⁻¹ with a detection limit of 0.2 μ mol l ⁻¹ and a high sensitivity of 0.56 μ A μ mol ⁻¹ l ⁻¹ . The optimized sensor shows a good selectivity, satisfactory long-term stability and reproducibility towards DA and a separation of peak potential of 142 mV with uric acid. In addition, the prepared sensor provides favorable recovery in human serum and artificial cerebrospinal solution (aSCF), indicating great potentials in electrochemical detection and biological sensing applications.