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The present work develops an effective bioadsorbent of cross-linked chitosan-genipin/SiO 2 adsorbent (CHI-GNP/SiO 2). The developed CHI-GNP/SiO 2 was employed for the removal of organic dye (reactive orange 16, RO16) from simulated wastewater. The optimization of the fundamental adsorption variables (CHI-GNP/SiO 2 dose, time, and pH) via the Box-Behnken design (BBD) was attained for achieving maximal adsorption capacity and high removal efficiency. The good agreement between the Freundlich isotherms and empirical data of RO16 adsorption by CHI-GNP/SiO 2 indicates that the adsorption process follows a multilayer adsorption mechanism. The reasonable agreement between the pseudo-second-order model and the kinetic data of RO16 adsorption by CHI-GNP/SiO 2 was obtained. The maximum RO16 adsorption capacity (q max) of CHI-GNP/SiO 2 was identified to be 57.1 mg/g. The adsorption capacity of CHI-GNP/SiO 2 is attributed to its unique surface properties, including its highly porous structure and the presence of functional groups such as amino and hydroxyl groups. According to the results of this investigation, CHI-GNP/SiO 2 has the potential to be an adsorbent for the removal of acidic dyes from wastewater. • A cross-linked chitosan-genipin/SiO 2 adsorbent (CHI-GNP/SiO 2) was developed. • The CHI-GNP/SiO 2 was employed to remove reactive orange 16 (RO16) from wastewater. • The optimization of the adsorption variables via the Box-Behnken design (BBD) was attained. • The maximum RO16 adsorption capacity (q max) of CHI-GNP/SiO 2 was found to be 57.1 mg/g. [ABSTRACT FROM AUTHOR]

The present work develops an effective bioadsorbent of cross-linked chitosan-genipin/SiO 2 adsorbent (CHI-GNP/SiO 2). The developed CHI-GNP/SiO 2 was employed for the removal of organic dye (reactive orange 16, RO16) from simulated wastewater. The optimization of the fundamental adsorption variables (CHI-GNP/SiO 2 dose, time, and pH) via the Box-Behnken design (BBD) was attained for achieving maximal adsorption capacity and high removal efficiency. The good agreement between the Freundlich isotherms and empirical data of RO16 adsorption by CHI-GNP/SiO 2 indicates that the adsorption process follows a multilayer adsorption mechanism. The reasonable agreement between the pseudo-second-order model and the kinetic data of RO16 adsorption by CHI-GNP/SiO 2 was obtained. The maximum RO16 adsorption capacity (q max) of CHI-GNP/SiO 2 was identified to be 57.1 mg/g. The adsorption capacity of CHI-GNP/SiO 2 is attributed to its unique surface properties, including its highly porous structure and the presence of functional groups such as amino and hydroxyl groups. According to the results of this investigation, CHI-GNP/SiO 2 has the potential to be an adsorbent for the removal of acidic dyes from wastewater. • A cross-linked chitosan-genipin/SiO 2 adsorbent (CHI-GNP/SiO 2) was developed. • The CHI-GNP/SiO 2 was employed to remove reactive orange 16 (RO16) from wastewater. • The optimization of the adsorption variables via the Box-Behnken design (BBD) was attained. • The maximum RO16 adsorption capacity (q max) of CHI-GNP/SiO 2 was found to be 57.1 mg/g. [ABSTRACT FROM AUTHOR]

In this research, a highly efficient adsorbent biomaterial (hereinafter, CTS/PPS-HS) of chitosan/functionalized fruit stones (peach and plum) with H 2 SO 4 was produced for the adsorption of brilliant green (BG) dye from aquatic systems. The developed biomaterial was characterized by several techniques like SEM-EDX, FTIR, XRD, BET, and pH pzc. To systematically optimize the adsorption performance of CTS/PPS-HS, the Box-Behnken design (BBD) based on response surface methodology (RSM) was attained. The factors considered for optimization included A: CTS/PPS-HS dosage (0.02–0.08 g), B: pH (4–10), and C: removal time (10–60 min). The pseudo-first-order and Langmuir isotherm models exhibited excellent agreement with the experimental results of BG adsorption by CTS/PPS-HS. The outstanding adsorption capacity (409.63 mg/g) of CTS/PPS-HS was obtained. The remarkable adsorption of BG onto CTS/PPS-HS can be primarily attributed to electrostatic forces between the acidic sites of CTS/PPS-HS and the BG cations, accompanied by interactions such as π-π, Yoshida H-bonding, n-π, and H-bond interactions. The current data underscores the significant potential inherent in combining biomass with CTS polymer to create an exceptionally effective adsorbent biomaterial tailored for the elimination of cationic dyes. • Biocomposite of chitosan/functionalized fruit stones (peach and plum) with H 2 SO 4 (CTS/PPS-HS) was produced. • CTS/PPS-HS was applied for the adsorption of brilliant green (BG) dye from aquatic systems. • Box-Behnken design (BBD) was employed to optimize the adsorption of BG dye. • The pseudo-first-order and Langmuir models exhibited excellent agreement with the experimental results of BG adsorption. • The adsorption capacity (409.63 mg/g) of CTS/PPS-HS was obtained. [ABSTRACT FROM AUTHOR]

[Display omitted] • A cross-linked chitosan-glutaraldehyde/nano silica (CHS-GLA/n-Silica) was synthesized by a hydrothermal process. • The adsorptive property of CHS-GLA/n-Silica was evaluated for removal of AR88 dye. • The adsorption key parameters were optimized via the Box-Behnken design. • The Langmuir and Temkin isotherm models agreed well with the adsorption of AR88 by CHS-GLA/n-Silica. • The maximum adsorption capacity of CHS-GLA/n-Silica towards AR88 was found to be 115.9 mg/g. The facile synthesis of cross-linked chitosan-glutaraldehyde/nano silica (CHS-GLA/n-Silica) nanocomposite was accomplished in two steps including the functionalization of a natural biopolymer (CHS) with an inorganic nanomaterial (n-Silica), followed by a cross-linking process with glutaraldehyde (GLA). The ability of CHS-GLA/n-Silica to remove acid red 88 (AR88) dye from an aqueous system was optimized by the Box–Behnken design (BBD), taking into consideration the factors affecting adsorption (CHS-GLA/n-Silica dose (0.02–0.1 g/100 mL); time (10–60 min); and pH (4–10). The equilibrium behavior of AR88 by CHS-GLA/n-Silica is clearly illustrated by the Langmuir and Temkin isotherms. The kinetics of AR88 adsorption by CHS-GLA/n-Silica were appropriately described by a pseudo-second-order model. CHS-GLA/n-Silica displays an adsorption capacity of 115.9 mg/g. The electrostatic forces between the positively charged CHS-GLA/n-Silica and the AR88 anions, as along with n-π, and H-bond interactions, which accounts for the efficient adsorption of AR88 onto the CHS-GLA/n-Silica. This study demonstrates that CHS-GLA/n-Silica has promising potential as an adsorbent for the effective removal of synthetic dyes from wastewater. [ABSTRACT FROM AUTHOR]

This study aimed to develop a biocomposite (hereinafter, CHI/OP-H 2 SO 4) via the functionalization of chitosan (CHI) biopolymer by chemically modified orange peel (OP-H 2 SO 4). The physicochemical characteristics of CHI/OP-H 2 SO 4 were studied using methods such as pH pzc , XRD, FTIR, BET, and FESEM-EDX. The efficacy of the CHI/OP-H 2 SO 4 biocomposite in removing cationic dye (safranin O, SAF-O) from aqueous solutions was assessed. The Box-Behnken Design (BBD) based on response surface methodology (RSM) was employed to optimize the adsorption performance of CHI/OP-H 2 SO 4 , considering factors such as A: CHI/OP-H 2 SO 4 dose (0.02–0.08 g), B: pH (4–10), and C: time (10–60 min). The pseudo-first-order and Freundlich isotherm models align well with the experimental data of SAF-O adsorption by CHI/OP-H 2 SO 4. The excellent adsorption capacity for CHI/OP-H 2 SO 4 was recorded (321.2 mg/g). The notable adsorption of SAF-O onto CHI/OP-H 2 SO 4 is attributed primarily to electrostatic forces between the acidic groups of CHI/OP-H 2 SO 4 and the SAF-O cation, along with H-bonding, and n-π interactions. By transforming waste materials into valuable resources, this approach not only mitigates environmental impact but also produces a promising and sustainable adsorbent for the removal of cationic dyes, exemplified here by the effective removal of SAF-O dye. • A biocomposite of chitosan and functionalized orange peel with H 2 SO 4 (CHI/OP-H 2 SO 4) was synthesized. • The efficacy of the CHI/OP-H 2 SO 4 in removing SAF-O dye was assessed. • BBD-RSM was employed to optimize the SAF-O dye adsorption. • The Freundlich isotherm model aligns well with the experimental data of SAF-O adsorption. • The excellent adsorption capacity for CHI/OP-H 2 SO 4 was recorded (321.2 mg/g). [ABSTRACT FROM AUTHOR]

Herein, a natural material including chitosan (CTS) and algae (food-grade algae, FGA) was exploited to attain a bio-adsorbent (CTS/FGA) for enhanced methyl violet 2B dye removal. A study of the FGA loading into CTS matrix showed that the best mixing ratio between CTS and FGA to be used for the MV 2B removal was 50 %:50 % (CTS/FGA; 50:50 w /w). The present study employed the Box-Behnken design (RSM-BBD) to investigate the impact of three processing factors, namely CTS/FGA-(50:50) dose (0.02–0.1 g/100 mL), pH of solution (4–10), and contact time (5–15 min) on the decolorization rate of MV 2B dye. The results obtained from the equilibrium and kinetic experiments indicate that the adsorption of MV 2B dye on CTS/FGA-(50:50) follows the Langmuir and pseudo-second-order models, respectively. The CTS/FGA exhibits an adsorption capacity of 179.8 mg/g. The characterization of CTS/FGA-(50:50) involves the proposed mechanism of MV 2B adsorption, which primarily encompasses various interactions such as electrostatic forces, n-π stacking, and H-bonding. The present study demonstrates that CTS/FGA-(50:50) synthesized material exhibits a distinctive structure and excellent adsorption properties, thereby providing a viable option for the elimination of toxic cationic dyes from polluted water. • Chitosan (CTS) was composited with food-grade algae (FGA) to form a biocomposite (CTS/FGA). • CTS/FGA yielded enhanced methyl violet 2B (MV 2B) dye removal (179.8 mg/g). • Box-Behnken design (RSM-BBD) led to an optimized adsorption process. • MV 2B adsorption by CTS/FGA follows the Langmuir and pseudo-second-order models. • CTS/FGA is a sustainable biocomposite adsorbent via a facile synthesis. [ABSTRACT FROM AUTHOR]

In this study, chitosan/nano SiO 2 (CTS/NS) was chemically modified with bisphenol A diglycidyl ether (BADGE) cross-linker-assisted hydrothermal process to create an effective adsorbent, CTS-BADGE/NS, for the removal of reactive orange 16 (RO16) dye from aquatic systems. Box-Behnken design (BBD) was used to optimize the adsorption process by varying the adsorbent dose (0.02–0.1 g/100 mL), pH (4–10), and time (20–360 min). The adsorption isotherm results indicated that the Langmuir model fits the experimental data well, suggesting that the adsorption process involves a monolayer formation of RO16 on the surface of CTS-BADGE/NS. The kinetic modeling of RO16 adsorption by CTS-BADGE/NS demonstrated that the pseudo-first-order model fits the adsorption data. CTS-BADGE/NS achieved an adsorption capacity of 97.8 mg/g for RO16 dye at optimum desirability functions of dosage 0.099 g/100 mL, solution pH of 4.44, and temperature of 25 °C. Overall, the π-π electron donor-acceptor system significantly improved the adsorption performance of the CTS-BADGE/NS. The results of the regeneration investigation demonstrate that the CTS-BADGE/NS exhibits effective adsorption of RO16, even after undergoing five consecutive cycles. The results of this study suggest that the developed CTS-BADGE/NS composite can be a promising adsorbent for water purification applications. • Chitosan/nano SiO 2 (CTS/NS) was modified with bisphenol A diglycidyl ether (BADGE) to yield CTS-BADGE/NS. • CTS-BADGE/NS was applied for the removal of reactive orange 16 (RO16) dye. • Box-Behnken design (BBD) was used to optimize the adsorption process. • The Langmuir model fits the experimental data well. • CTS-BADGE/NS achieved an adsorption capacity of 97.8 mg/g. [ABSTRACT FROM AUTHOR]

Herein, a highly efficient and sustainable adsorbent of cross-linked chitosan-glyoxal/algae biocomposite (CHT-GLX/ALG) adsorbent was developed through an innovative hydrothermal cross-linking method. The CHT-GLX/ALG biocomposite was characterized using several complementary analytical methods that include CHN-O, XRD, FTIR, SEM-EDX, and pH pzc. This new adsorbent, named CHT-GLX/ALG, was utilized for the adsorption of a cationic dye (methyl violet 2B; MV 2B), from synthetic wastewater. The optimization of the dye adsorption process involved key parameters is listed: CHT-GLX/ALG dosage (from 0.02 to 0.1 g/100 mL), pH (from 4 to 10), and contact time (from 20 to 180 min) that was conducted using the Box-Behnken design (BBD). The optimal adsorption conditions for the highest decolorization efficiency of MV 2B (97.02 %) were estimated using the statistical model of the Box-Behnken design. These conditions include a fixed adsorbent dosage of 0.099 g/100 mL, pH 9.9, and a 179.9 min contact time. The empirical data of MV 2B adsorption by CHT-GLX/ALG exhibited favorable agreement with the Freundlich isotherm model. The kinetic adsorption profile of MV 2B by CHT-GLX/ALG revealed a good fit with the pseudo-second-order model. The maximum adsorption capacity (q max) for MV 2B by CHT-GLX/ALG was estimated at 110.8 mg/g. The adsorption of MV 2B onto the adsorbent can be attributed to several factors, including electrostatic interactions between the negatively charged surface of CHT-GLX/ALG and the MV 2B cation, as well as n-π and H-bonding. These interactions play a crucial role in facilitating the effective adsorption of MV 2B onto the biocomposite adsorbent. Generally, this study highlights the potential of CHT-GLX/ALG as an efficient and sustainable adsorbent for the effective removal of organic dyes. • A cross-linked chitosan-glyoxal/algae (CHT-GLX/ALG) was developed. • CHT-GLX/ALG is a sustainable adsorbent for methyl violet 2B (MV 2B). • Key adsorption parameters were optimized using the Box-Behnken design. • The adsorption kinetics of MV 2B follows the pseudo-second-order model. • The maximum monolayer adsorption capacity for MV 2B was 110.8 mg/g. [ABSTRACT FROM AUTHOR]

Herein, the polymer nanomatrix of chitosan/SiO 2 (CHI/n-SiO 2) was enriched with a π-π electron donor-acceptor system using diaromatic rings of benzil (BEZ) assisted via a hydrothermal process to obtain an effective adsorbent of chitosan-benzil/SiO 2 (CHI-BEZ/n-SiO 2). The polymer nanomatrix (CHI/n-SiO 2) and the resulting adsorbent (CHI-BEZ/n-SiO 2) were applied to remove the anionic acid red 88 (AR88) dye from aqueous media in a comparative mode. Box-Behnken design (BBD) was adopted to optimize AR88 adsorption onto CHI/n-SiO 2 and CHI-BEZ/n-SiO 2 with respect to variables that influence AR88 adsorption (adsorbent dose: 0.02–0.1 g/100 mL; pH: 4–10; and time: 10–90). The adsorption studies at equilibrium were conducted with a variety of initial AR88 dye concentrations (20–200 mg/L). The adsorption isotherm results reveal that the AR88 adsorption by CHI/n-SiO 2 and CHI-BEZ/n-SiO 2 are described by the Langmuir model. The kinetic adsorption profiles of AR88 with CHI/n-SiO 2 and CHI-BEZ/n-SiO 2 reveal that the pseudo-first-order model provides the best fit results. Interestingly, CHI-BEZ/n-SiO 2 has a high adsorption capacity (261.2 mg/g), which exceeds the adsorption capacity of CHI/n-SiO 2 (215.1 mg/g) that relates to the surface effects of SiO 2 and the functionalization of chitosan with BEZ. These findings show that CHI-BEZ/n-SiO 2 represents a highly efficient adsorbent for the removal of harmful pollutants from water, which outperforming the CHI/n-SiO 2 system. • Chitosan/SiO 2 (CHI/n-SiO 2) was functionalized with benzil to yield CHI-BEZ/n-SiO 2. • CHI/n-SiO 2 and CHI-BEZ/n-SiO 2 adsorbents afford removal of acid red 88 (AR88) dye. • Box-Behnken design (BBD) enabled optimized removal of AR88 by the adsorbents. • The adsorption capacity of CHI/n-SiO 2 for AR88 dye was 215.1 mg/g. • The adsorption capacity of CHI-BEZ/n-SiO 2 for AR88 dye was 261.2 mg/g. [ABSTRACT FROM AUTHOR]