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Functionalizing nanosilica (n-SiO2) particles with suitable active organic moiety leads to the formation of surfaces with precisely controlled physical and chemical characteristics. In this work, a novel nanosorbent (31 ± 2.4 nm), namely succinic acid functionalized nanosilica (n-SiO2@SA), was synthesized via a simple protocol using microwave irradiation to remove Cu(II) ions from aqueous media. The successful functionalization of n-SiO2 was confirmed by FTIR, and the thermal stability of n-SiO2@SA was investigated by TGA study. Other techniques, including HRTEM, DLS and zeta-potential, were utilized to investigate the chemical, surface, and morphological properties of the fabricated n-SiO2@SA. The response surface methodology (RSM) combined with three-level, three-factorial Box–Behnken design (BBD) was applied to optimize the multivariable sorption system using data obtained from 17 batch runs to reach 98.9% of Cu(II) ion removal. The predicted optimal conditions were as follows: contact time = 30 min, pH = 7.1, initial Cu(II) concentration = 317.5 mg L−1, and sorbent dose = 15 mg at which the maximum sorption capacities for n-SiO2 and n-SiO2@SA were 209.3 and 386.4 mg g−1, respectively, at 25 °C, thus supporting the validity of functionalization process. Non-linear regression and linear least-squares methods confirm the suitability of Langmuir model to describe the experimental endothermic, feasible, and chemisorption data, whereas the normalized standard deviation Δq% recommends the pseudo second-order kinetic model to represent the kinetic data. Real Cu-contaminated wastewaters were used to examine n-SiO2@SA nanosorbent for removing Cu(II) ions.

The adsorption of crystal violet (CV) dye onto magnetic alginate (MAlg) composite from aqueous solutions was studied. Experiments were carried out as function of contact time, dosage, temperature, pH, and CV concentration in the solutions. Optimum CV uptake was observed at equilibrium pH 7 and most of the CV was sorbed within 30 min. The equilibrium adsorption data were analyzed using two common adsorption models: Langmuir and Freundlich. The results revealed that Langmuir isotherm fit the experimental results well. The maximum adsorption capacity obtained from Langmuir isotherm equation was 0.113 mmol g−1at 298 ± 1 K. The kinetics adsorption of CV onto MAlg composite was investigated using the pseudo first-order and pseudo second-order kinetic models. The results showed that the adsorption of CV onto MAlg composite followed pseudo second-order kinetic model. Thermodynamic data indicated that the adsorption process is an endothermic and spontaneous reaction. Due to its outstanding adsorption capacities, MAlg composite is an excellent adsorbent for the removal of CV. The composite regeneration was greater than 98.6% with 0.01 mol/L HCl, and MAlg composite could be repeatedly utilized for CV removal with negligible loss in sorption capacity.