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Herein, we have reported a photocatalytic Bi 5 O 7 I, protonated g-C 3 N 4 heterojunction with directional charge transfer channels provided by tea waste biochar to achieve effective e - /h + pair isolation for the improved degradation of Methylene blue (MB) and Doxycycline hydrochloride (DCHCl). An S-scheme heterojunction was fabricated via the novel method that combined hydrothermal and ultrasonic dispersion, followed by an electrostatic self-assembly route. The as-fabricated Bi 5 O 7 I/protonated g-C 3 N 4 /Tea waste biochar heterojunction formed a strong contact at the interface, as supported by the electron microscopic results. As per the adsorption and photocatalytic degradation kinetics study, Bi 5 O 7 I/Tea waste biochar/protonated g-C 3 N 4 (40 wt%) heterojunction showed a higher adsorption rate of 41.56% and 32% for MB and DCHCl within 30 min in the dark. Also, 92.02% MB and 90.21% DCHCl degradation rates in 60 and 90 min, respectively, are approximately 43 and 32 times higher than bare Bi 5 O 7 I and protonated g-C 3 N 4 photocatalysts. The highest adsorption and degradation rate was achieved owing to the addition of Tea waste biochar and protonated g-C 3 N 4 in a controlled ratio, and the sufficient interfacial contact between Bi 5 O 7 I and protonated g-C 3 N 4 is for the improved isolation rate of e - /h + pairs as evidenced by zeta potential values photoluminescence spectra as well as from scanning and transmission electron microscopy. Moreover, Bi 5 O 7 I/Tea waste biochar/protonated g-C 3 N 4 (40 wt%) possessed high stability and recyclability after four consecutive cycles without much altering the degradation ability. Therefore, we believe that the as-fabricated Bi 5 O 7 I/Tea waste biochar/protonated g-C 3 N 4 (40 wt%) provides new insight into the highly efficient S-scheme mechanisms significant for accelerating multicomponent photocatalytic redox reactions; while forming an effective visible light responsive candidate for treating wastewater., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Batch adsorption experiments were carried out for the removal of methylene blue (MB) cationic dye from aqueous solution using organic/inorganic hydrogel nanocomposite of titania incorporated sodium alginate crosslinked polyacrylic acid (SA-cl-poly(AA)-TiO2). The hydrogel was prepared by graft copolymerization of acrylic acid (AA) onto sodium alginate (SA) biopolymer in the presence of a crosslinking agent, a free radical initiator and TiO2 nanoparticles. The hydrogel exhibited a high swelling capacity of 412.98g/g. The factors influencing adsorption capacity of the absorbents such as pH of the dye solutions, initial concentration of the dye, amount of absorbents, and temperature were investigated and used to propose a possible mechanism of adsorption. The adsorption process concurs with a pseudo-second-order kinetics and with Langmuir isotherm equation. A very high adsorption capacity (Qmax=2257.36 (mg/g)) and a correlation coefficient of 0.998 calculated from isotherm equations show the high efficiency of the absorbent and thus expected to be a good candidate as an absorbent for water treatment., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Abstract Pectin is one of the finest natural polymer which has drawn great attention because of its applications in different fields. Due to the quintessential structure of pectin, it can be transformed into variety of useful products. It can be utilized as a blend in many polymers to make a mixture or a composite material. Owing to considerable collection in chemical conformation and cross-linking mechanism, different pectin based hydrogels have been prepared for different characteristics in pharmaceutical and bio-medical sites. Inventive properties of hydrogels like volubility, swellability, solvability and hydrophilicity make them better alternative for wastewater treatment. Recently, pectin based hydrogels have demonstrated excellent performance to eliminate various metal ions and dyes from the polluted water. The adsorption characteristics of pectin based hydrogels can be upgraded by using nanoparticles, which prompts to the development of hydrogel nano-composites. In this review article, we have summarized a comprehensive assessment in the direction of using pectin based hydrogels to remove toxic pollutants from aqueous solution. Sodium acrylate-co-N-isopropylacrylamide based pectin hydrogel has demonstrated the maximum adsorption capacities of 265.49, 137.43, 54.86, 53.86, 51.72 and 50.01 mg g−1 for the adsorption of methyl violet, methylene blue, Pb(II), Cu(II), Co(II) and Zn(II) respectively. We have also discussed the pectin structure, properties and applications in this article. Graphical abstract Image 1081 Highlights • Hydrogel is used as sustainable noble material. • Structure and properties of pectin are described. • Pectin is produced from bio-waste materials. • Pectin based hydrogels are used in water purification. • The mechanical strength of pectin based hydrogel can be improved by incorporation of nanoparticles. [ABSTRACT FROM AUTHOR]

A sol-gel synthesis of nanocomposite adsorbent materials by dehydroxylation condensation of tetraethoxysilane (TEOS) in the presence of xanthan gum (XG) using base catalyst and ethanol as co-solvent is discussed. The synthesized nanocomposite material was evaluated for their ability to adsorb cationic dyes—methylene blue (MB) and bismarck brown Y (BB) from an aqueous solution. The XG/SiO 2 nanocomposite shows the ordered macro- and meso-porous structures and also exhibited large surface area, excellent chemical/mechanical stability and high binding capability for MB and BB dyes. Different parameters such as pH, adsorbent dose and initial concentration were studied. The adsorption behaviour of the nanocomposite was investigated by performing both kinetics and equilibrium studies under batch conditions. The maximum adsorption capacity ( Q max ) of the nanocomposite for MB and BB was found to be significantly high (432.90 mg g −1 and 448.43 mg g −1 , respectively). The time taken for the removal of 99.4% of MB and 87.2% of BB from 100 mg L −1 of dye solutions is only 35 min. Thus, the proposed XG/SiO 2 nanocomposite is a very promising adsorbent for the fast and efficient removal of dye from aqueous solutions. [ABSTRACT FROM AUTHOR]

Presently, the distinct charge transport and interface interaction of the S-scheme heterojunction has garnered significant interest. Herein, a S-scheme-based charge transportation Mo-doped Bi 2 WO 6 /WO 3 /Biochar heterojunction was synthesized in situ using a coprecipitation technique to improve methylene blue adsorption and photocatalytic reactive oxygen species production. The doped Mo altered the band gap of Bi 2 WO 6 to increase light absorption, which can facilitate electron-hole separation and transfer. Likewise, the S-scheme band structure improved sunlight utilization, enhanced the reduction and oxidation power of photogenerated electrons, and boosted charge carrier separation and transfer. Thus, due to the synergetic impact of doping and the S scheme band structure, the photocatalysts efficiently eliminated Methylene blue up to 87.5 % in 30 min of photoirradiation. Fabricated heterojunction Mo–Bi 2 WO 6 /WO 3 /Biochar photocatalyst have highest Kapp values 0.02816 min−1 while Mo–Bi 2 WO 6 /WO 3 , Mo–Bi 2 WO 6 , Bi 2 WO 6 , and WO 3 photocatalysts have 0.02816, 0.02273, 0.01527, 0.00643, and 0.00735 min−1, respectively which was 4.38 times greater than pristine Bi 2 WO 6. The study offers a novel perspective for the in-situ production of S-scheme heterojunction with doping to remove different types of contaminants. [Display omitted] • Fabrication of MO-doped Bi 2 WO 6 /WO 3 /Biochar heterojunction through Coprecipitation process. • Doping of Mo on Bi 2 WO 6 for enhanced photocatalytic activity. • S-scheme degradation Mechanism followed for MB dye degradation. • 87.5 % MB removal within 30 min of light irradiation. • ●OH and ●O 2 − are reactive species for MB removal. [ABSTRACT FROM AUTHOR]

Recently, there has been a significant increase in the interest of using photocatalysis for environmental clean-up applications. In this research, potassium, and phosphorus co-doped graphitic carbon nitride (KPCN) photocatalyst modified with graphene oxide (GO) and heterostructured with ZnFe 2 O 4 was synthesized via the hydrothermal method (KPCN/GO/ZnFe 2 O 4). The photoactivity of KPCN/GO/ZnFe 2 O 4 photocatalyst was examined for the photocatalytic degradation of target pollutants such as methylene blue (MB) dye, rhodamine B (RhB) dye, and tetracycline (TC) antibiotic. Furthermore, the chemical oxygen demand (COD) removal efficiency for real wastewater was determined to explore the practical application of KPCN/GO/ZnFe 2 O 4 photocatalyst. The degradation efficiencies of bare graphitic carbon nitride, KPCN, KPCN/GO, and KPCN/GO/ZnFe 2 O 4 photocatalysts for tetracycline antibiotics were 30%, 42%, 57%, and 87% within 60 min, respectively. Moreover, KPCN/GO/ZnFe 2 O 4 photocatalyst showed 71% COD removal efficiency within 240 min. The •OH and •O 2 − were the major reactive species in the photocatalytic process. Results showed that the degradation efficiencies of graphitic carbon nitride were greatly enhanced upon doping and further improved with the addition of GO and ZnFe 2 O 4. Doping improved light harvesting, GO enhanced the adsorption ability and heterojunction with ZnFe 2 O 4 enhanced the charge separation as well as the reusability of synthesized KPCN/GO/ZnFe 2 O 4 photocatalyst. [Display omitted] • Hydrothermal synthesis of non-toxic co-doped KPCN/GO/ZnFe 2 O 4 photocatalyst. • GO-supported S-scheme heterojunction for enhanced photocatalytic performance. • 96%, 93%, and 87% degradation efficiencies for RhB, MB, and TC, respectively. • 71% COD removal efficiency within 240 min. • Magnetic separation and excellent reusability even after 5 cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel CNTs@CuBi 2 O 4 /AgBiO 3 hydrothermally fabricated photocatalyst. • 97.94% of MB photocatalytic degradation by CNTs@CuBi 2 O 4 /AgBiO 3. • CNTs mediating the charge transfer in between CuBi 2 O 4 /AgBiO 3. • All solid state Z-scheme mechanism. A novel CNTs@CuBi 2 O 4 /AgBiO 3 , All-Solid State (ASS) Z-scheme photocatalyst was hydrothermally synthesized to explore visible light photocatalytic performance via methylene blue degradation. The ASS Z-scheme heterojunction exhibited 97.94% of degradation in 60 min in visible light. Besides, the photocatalytic activity of heterojunction remained 89.50% after 10 cycles, signifying high stability and reusability of heterojunction. The presence of CNTs on CuBi 2 O 4 /AgBiO 3 nanoparticles acted as an electron transfer bridge in-between CuBi 2 O 4 and AgBiO 3. The ASS Z-scheme-based photocatalytic mechanism considerably enhanced photo-exciton lifetime, longer stability, increased visible light absorption, and photocatalytic activity of fabricated CNTs@CuBi 2 O 4 /AgBiO 3. [ABSTRACT FROM AUTHOR]