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In order to avoid the secondary pollution of the toxic residue of chemical crosslinking agent accompanied by chemical hydrogel adsorbent and enhance the adsorption performance of physical hydrogel, chitosan/calcium alginate/bentonite (CTS/CA/BT) composite physical hydrogel was constructed. The formation mechanism and structure of the composite hydrogel were determined by FTIR, XRD and SEM. Adsorption performances of the hydrogel toward Pb2+, Cu2+ and Cd2+ in water under different condition as well as multi-ion competitive sorption were investigated. The adsorption processes were described with the canonical adsorption kinetics and isotherms models. With the utilization of XPS analysis and adsorption thermodynamics analysis, it was found that the adsorptions were spontaneous physico-chemical adsorptions. The results showed that the maximum adsorption capacity of the hydrogel for Pb2+, Cu2+ and Cd2+ reached up to 434.89, 115.30 and 102.38 mg·g−1, respectively, better than those of other physical hydrogels or chitosan/bentonite composite. Moreover, the composite hydrogel improved the collectability of bentonite and showed a good reusability. The modification of bentonite and the formation of hydrogel were completed simultaneously, which greatly simplifies the operation process compared with the prior similar works. These suggest that the CTS/CA/BT composite hydrogel has promising application prospects for removal of heavy metal ions from water.

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g‐C3N4 (g‐CN) with edge grafting of 4‐(1H‐imidazol‐2‐yl) benzoic acid (IBA) and NiS cocatalysts is fabricated via a one‐pot chemical condensation of monomers with urea and subsequent photodeposition. The successful copolymerization of the IBA in g‐CN (g‐CN/IBA) is easily identified by 13C NMR spectra, Fourier transformed infrared spectra, and UV–vis absorption spectra. As a result, the acquired copolymer composites exhibit greatly enhanced visible‐light photocatalytic performance for H2 evolution, in comparison with the undoped g‐CN. The g‐CN‐IBA photocatalyst with the optimal loading amounts of NiS displays an outstanding hydrogen‐evolution rate of 2948.52 µmol g‐1 h‐1 under visible light (λ > 420 nm). The maximum apparent quantum efficiency of g‐CN/IBA‐3%NiS is 3.20% at 450 nm. The enhanced activity can be attributed to the synergism of edge grafting of 4‐(1H‐Imidazol‐2‐yl) benzoic acid and loading of NiS cocatalysts, which not only shows a remarkable redshift of the optical‐absorption compared to g‐CN, effectively improving the absorption in the visible range, but also effectively avoids recombination and drives the favorable separation of photogenerated carriers in plane. This work provides a protocol for simultaneously increasing the active sites of light absorption and surface reactions of g‐CN‐based photocatalysts to maximize photocatalytic hydrogen production activity.