Postconsumer
solid waste has received wide attention in the development
of raw materials for innovative products. In this paper, waste polystyrene
(WPS) foam was employed as a starting material to react with 3,3′,4,4′-biphenyltetracarboxylic
dianhydride (BPDA) to synthesize a series of hyper-cross-linked polymers
(HPB-s). The maximum adsorption capacities of the
hyper-cross-linked adsorbents were 3082.2 and 3279.4 mg g–1 for malachite green (MG) and safranine T, respectively. The kinetics
and isotherms were more consistent with the pseudo-second-order and
Freundlich models, and the thermodynamic data indicated that the adsorption
process was heat-absorbing and spontaneous. Furthermore, HPB-2 still
maintained a complete shape and a high adsorption capacity after five
adsorption–desorption cycles. More importantly, the adsorption
studies for three binary mixed dye systems showed that HPB-2 exhibited
efficient and selective adsorption behavior toward cationic dyes from
water. The present work demonstrates that HPB-2 has promising potential
in purifying dye wastewater.