On the Interactions and Synergism between Phases of Carbon⁻Phosphorus⁻Titanium Composites Synthetized from Cellulose for the Removal of the Orange-G Dye

Cellulose-based materials in tailoring a novel defective titanium‑carbon‑phosphorus hybrid composites for highly efficient photocatalytic activity

Until now, black titania has attracted much interest as a potential photocatalyst. In this contribution, we report the first demonstration of the effective strategy to fundamentally improve the photocatalytic performance using a novel sustainable defective titanium‑carbon-phosphorous (TCPH) hybrid nanocomposite. The prepared TCPH was used for photocatalytic degradation of the main organic pollutants, which is methyl orange (MO) dye. The physico-chemical properties of as-prepared samples were characterized by various techniques to observe the transformations after carbonization and the interaction between different composite phases. The existence of Ti+3 and oxygen vacancies at the surface, and a notable increase in surface area, are all demonstrated by TCPH, together with the distinct core-shell structure. These unique properties exhibit excellent photocatalytic performance due to the boosted charge transport and separation. The highest degradation efficiency of methyl orange (MO) was attained in the case of TCPH when compared with titanium-cellulose-phosphorous (TCeP) and titanium‑carbon-phosphorous (TCPN). Accordingly, the highest degradation efficiency was achieved by applying the optimal operational conditions of 1 g/L of TCPH catalyst, 10 mg/L of MO, pH of 7 and the temperature at 25 ± 3 °C after 3 min under LED lamp (365 nm) with light intensity 100 mW/cm2. The degradation mechanism was investigated, and the trapping tests showed the dominance of hydroxyl radicals in the degradation of MO. TCPH showed high stability under a long period of operation in five consecutive cycles, which renders the highly promising on an industrial scale. The fabrication of highly active defective titanium‑carbon-phosphorous opens new opportunities in various areas, including water splitting, and CO2 reduction.

Construction of attapulgite decorated cetylpyridinium bromide/cellulose acetate composite beads for removal of Cr (VI) ions with emphasis on mechanistic insights

Eco-friendly and renewable composite beads were constructed for efficient adsorptive removal of Cr (VI) ions. Attapulgite (ATP) clay decorated with cetylpyridinium bromide (CPBr) was impregnated into cellulose acetate (CA) beads, which were formulated through a simple and cost-effective solvent-exchange approach. FTIR, XRD, SEM, Zeta potential, and XPS characterization tools verified the successful formation of ATP-CPBr@CA beads. The composite beads displayed a spherical and porous shape with a positively charged surface (26.6 mV) at pH 2. In addition, higher adsorption performance was accomplished by ATP-CPBr@CA composite beads with ease of separation compared to their components. Meanwhile, equilibrium isotherms pointed out that the Langmuir model was optimal for describing the adsorption process of Cr (VI) with a maximal adsorption capacity of 302 mg/g. Moreover, the D-R isotherm model verified the physical adsorption process, while adsorption data obeyed the pseudo-second-order kinetic model. Further, XPS results hypothesized that the removal mechanism involves adsorption via electrostatic interactions, redox reaction, and co-precipitation. Interestingly, the ATP-CPBr@CA composite beads reserved tolerable adsorption characteristics with a maximum removal present exceeding 70% after reuse for seven successive cycles, proposing its feasible applicability as a reusable and easy-separable candidate for removing heavy metals from aquatic bodies.

The superior photocatalytic performance and DFT insights of S-scheme CuO@TiO2 heterojunction composites for simultaneous degradation of organics

The necessity to resolve the issue of rapid charge carrier recombination for boosting photocatalytic performance is a vigorous and challenging research field. To address this, the construction of a binary system of step-scheme (S-scheme) CuO@TiO₂ heterostructure composite has been demonstrated through a facile solid-state route. The remarkably enhanced photocatalytic performance of CuO@TiO₂, compared with single TiO₂, which can consequence in the more efficient separation of photoinduced charge carriers, reduced the band gap of TiO₂, improved the electrical transport performance, and improved the lifetimes, thus donating it with the much more powerful oxidation and reduction capability. A photocatalytic mechanism was proposed to explain the boosted photocatalytic performance of CuO@TiO₂ on a complete analysis of physicochemical, DFT calculations, and electrochemical properties. In addition, this work focused on the investigation of the stability and recyclability of CuO@TiO₂ in terms of efficiency and its physical origin using XRD, BET, and XPS. It is found that the removal efficiency diminishes 4.5% upon five recycling runs. The current study not only promoted our knowledge of the binary system of S-scheme CuO@TiO₂ heterojunction composite photocatalyst but also shed new light on the design of heterostructure photocatalysts with high-performance and high stability.

Role of Combined Na2HPO4 and ZnCl2 in the Unprecedented Catalysis of the Sequential Pretreatment of Sustainable Agricultural and Agro-Industrial Wastes in Boosting Bioethanol Production

Improper lignocellulosic waste disposal causes severe environmental pollution and health damage. Corn Stover (CS), agricultural, and aseptic packaging, Tetra Pak (TP) cartons, agro-industrial, are two examples of sustainable wastes that are rich in carbohydrate materials and may be used to produce valuable by-products. In addition, attempts were made to enhance cellulose fractionation and improve enzymatic saccharification. In this regard, these two wastes were efficiently employed as substrates for bioethanol production. This research demonstrates the effect of disodium hydrogen phosphate (Na₂HPO₄) and zinc chloride (ZnCl₂) (NZ) as a new catalyst on the development of the sequential pretreatment strategy in the noticeable enzymatic hydrolysis. Physico-chemical changes of the native and the pretreated sustainable wastes were evaluated by compositional analysis, scanning electron microscopy (SEM), X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). These investigations showed major structural changes after the optimized sequential pretreatment. This pretreatment not only influences the delignification process, but also affects the functionalization of cellulose chemical structure. NZ released a higher glucose concentration (328.8 and 996.8 mg/dl) than that of ZnCl₂ (Z), which released 203.8 and 846.8 mg/dl from CS and TP, respectively. This work led to the production of about 500 mg/dl of ethanol, which is promising and a competitor to other studies. These findings contribute to increasing the versatility in the reuse of agricultural and agro-industrial wastes to promote interaction areas of pollution prevention, industrialization, and clean energy production, to attain the keys of sustainable development goals.

The Interplay of Autoclaving with Oxalate as Pretreatment Technique in the View of Bioethanol Production Based on Corn Stover

Bio-based treatment technologies are gaining great interest worldwide, and significant efforts are being afforded to develop technology for the use of lignocellulosic biomass. The potential of corn stover (CS) as a feedstock for bioethanol production was investigated by creating an optimal pretreatment condition to maximize glucose production. The current study undertook the impact of novel physico-chemical pretreatment methods of CS, i.e., autoclave-assisted oxalate (CSOA) and ultrasound-assisted oxalate (CSOU), on the chemical composition of CS and subsequent saccharification and fermentation for bioethanol production. The delignification was monitored by physicochemical characterizations such as SEM, XRD, FTIR, CHNs, and TGA. The results evidenced that delignification and enzymatic saccharification of the CS pretreated by CSOA was higher than CSOU. The optimum enzymatic saccharification operating conditions were 1:30 g solid substrate/mL sodium acetate buffer at 50 °C, shaking speed 100 rpm, and 0.4 g enzyme dosage. This condition was applied to produce glucose from CS, followed by bioethanol production by S. cerevisiae using an anaerobic fermentation process after 72 h. S. cerevisiae showed high conversion efficiency by producing a 360 mg/dL bioethanol yield, which is considered 94.11% of the theoretical ethanol yield. Furthermore, this research provides a potential path for waste material beneficiation, such as through utilizing CS.

Nanocellulose: a bioadsorbent for chemical contaminant remediation

Chemical contaminants such as heavy metals, dyes, and organic oils seriously affect the environment and threaten human health. About 2 million tons of waste is released every day into the water system. Heavy metals are the largest contributor which cover about 31% of the total composition of water contaminants. Every day, approximately 14 000 people die due to environmental exposure to selected chemicals. Removal of these contaminants down to safe levels is expensive, high energy and unsustainable by current approaches such as oxidation, biodegradation, photocatalysis, precipitation, reverse osmosis and adsorption. A combination of biosorption and nanotechnology offers a new way to remediate these chemical contaminants. Nanostructured materials are proven to have higher adsorption capacities than the same material in its larger-scale form. Nanocellulose is very promising as a high-performance bioadsorbent due to its interesting characteristics of high adsorption capacity, high mechanical strength, hydrophilic surface chemistry, renewability and biodegradability. It has been proven to have higher adsorption capacity and better binding affinity than other similar materials at the macroscale. The high specific surface area and abundance of hydroxyl groups within lead to the possible functionalization of this material for decontamination purposes. Several research papers have shown the effectiveness of nanocellulose in the remediation of chemical contaminants. This review aims to provide an overview of the most recent developments regarding nanocellulose as an adsorbent for chemical contamination remediation. Recent advancements regarding the modification of nanocellulose to enhance its adsorption efficiency towards heavy metals, dyes and organic oils were highlighted. Moreover, the desorption capability and environmental issue related to every developed nanocellulose-based adsorbent were also tackled.

Cellulose acetate based Complexation-NF membranes for the removal of Pb(II) from waste water

This study investigates the removal of Pb(II) using polymer matrix membranes, cellulose acetate/vinyl triethoxysilane modified graphene oxide and gum Arabic (GuA) membranes. These complexation-NF membranes were successfully synthesized via dissolution casting method for better transport phenomenon. The varied concentrations of GuA were induced in the polymer matrix membrane. The prepared membranes M-GuA2–M-GuA10 were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, atomic force microscope and bio-fouling studies. Thermal stability of the membranes was determined by thermogravimetric analysis under nitrogen atmosphere. Dead end nanofiltration was carried out to study the perm- selectivity of all the membranes under varied pressure and concentration of Pb(NO₃)₂. The complexation-NF membrane performances were significantly improved after the addition of GuA in the polymer matrix membrane system. M-GuA8 membrane showed optimum result of permeation flux 8.6 l m⁻² h⁻¹. Rejection of Pb(II) ions was observed to be around 97.6% at pH 9 for all the membranes due to electrostatic interaction between CA and Gum Arabic. Moreover, with the passage of time, the rate of adsorption was also increased up to 15.7 mg g⁻¹ until steady state was attained. Gum Arabic modified CA membranes can open up new possibilities in enhancing the permeability, hydrophilicity and anti-fouling properties.

New Activated Carbon from Mine Coal for Adsorption of Dye in Simulated Water or Multiple Heavy Metals in Real Wastewater

Nano-activated carbon (NAC) prepared from El-Maghara mine coal were modified with nitric acid solution. Their physico-chemical properties were investigated in terms of methylene blue (MB) adsorption, FTIR, and metal adsorption. Upon oxidation of the AC_S with nitric acid, surface oxide groups were observed in the FTIR spectra by absorption peaks at 1750–1250 cm⁻¹. The optimum processes parameters include HNO₃/AC ratio (wt./wt.) of 20, oxidation time of 2 h, and the concentration of HNO₃ of 10% reaching the maximum adsorption capacity of MB dye. Also, the prepared NAC was characterized by SEM, EDX, TEM, Raman Spectroscopy, and BET analyses. The batch adsorption of MB dye from solution was used for monitoring the behavior of the most proper produced NAC. Equilibrium isotherms of MB dye adsorption on NAC materials were acquired and the results discussed in relation to their surface chemistry. Langmuir model recorded the best interpretation of the dye adsorption data. Also, NAC was evaluated for simultaneous adsorption of six different metal ions (Fe²⁺, Ni²⁺, Mn²⁺, Pb²⁺, Cu²⁺, and Zn²⁺) that represented contaminates in petrochemical industrial wastewater. The results indicated that the extracted NAC from El-Maghara mine coal is considered as an efficient low-cost adsorbent material for remediation in both basic dyes and metal ions from the polluted solutions.

Element-Doped Functional Carbon-Based Materials

Carbon materials are one of the most fascinating materials because of their unique properties and potential use in several applications. They can be obtained from agricultural waste, organic polymers, or by using advanced synthesizing technologies. The carbon family is very wide, it includes classical activated carbons to more advanced types like carbon gels, graphene, and so on. The surface chemistry of these materials is one of the most interesting aspects to be studied. The incorporation of different types of chemical functionalities and/or heteroatoms such as O, N, B, S, or P on the carbon surface enables the modification of the acidic–basic character, hydrophilicity–hydrophobicity, and the electron properties of these materials, which in turn determines the final application. This book collects original research articles focused on the synthesis, properties, and applications of heteroatom-doped functional carbon materials.

Synthesis and photocatalytic properties of three dimensional laminated structure anatase TiO2/nano-Fe0 with exposed (001) facets

Three dimensional laminated structure anatase TiO₂/nano-Fe⁰ with exposed (001) facets used as photocatalysts were synthesized by a two-step solvothermal route and a liquid phase reduction deposition method. The resulting samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, scanning electron microscopy, transmission electron microscopy and selected-area electron diffraction. Characterization and experimental results indicated that the three dimensional laminated structure of anatase TiO₂ was assembled by two dimensional TiO₂-sheets with a thickness of approximately 30 nm. The three dimensional laminated structure anatase TiO₂/nano-Fe⁰ photocatalysts with improved visible-light responsive capability, high charge-hole mobility, and low electron–hole recombination exhibited higher photocatalytic performance in the photocatalytic degradation of methylene blue. The composite of nano-Fe⁰ and TiO₂ could effectively promote the generation of hydroxyl radicals (˙OH) with a synergistic effect and Photo-Fenton theory. This study provided new insights into the fabrication and practical application of high-performance photocatalysts in degrading organic pollutants.

Three dimensional laminated structure anatase TiO₂/nano-Fe⁰ with exposed (001) facets were successfully synthesized, which exhibited higher photocatalytic performance in the photocatalytic degradation of methylene blue.

Conductive Black Titania Nanomaterials for Efficient Photocatalytic Degradation of Organic Pollutants

Abstract

Titanium dioxide (TiO2) as an important semiconductor is widely used in the fields of solar cell, solar thermal collectors, and photocatalysis, but the visible-light power harvest remains insufficient due to the little effective visible-light absorption and many carrier-recombination centers originating from the wide band gap structure. Herein, conductive black titania (BT) nanomaterials with crystalline-TiO2-core/amorphous-TiO2−x-shell structure prepared through two-zone Al-reduction route are found efficient in photocatalyzing the degradation of organic pollutants to environmentally friendly products under full solar and even visible light irradiation. The unique core–shell structure and numerous surface oxygen vacancies or Ti3+ species in the amorphous layer accompanying prominent physicochemical properties of narrow band gap, high carrier concentration, high electron mobility, and excellent separation and transportation of photoinduced e−−h+ pairs result in exceptional photocatalytic efficiency. The optimized BT-500 (pristine TiO2 treated at 500 °C during two-zone Al-reduction process) catalyst achieves superior photocatalytic degradation rates for toluene and ethyl acetate as well as an excellent photostability with high degradation efficiency of 93% for the 6th reuse.

Graphic Abstract

Phosphorylated micro- vs. nano-cellulose: a comparative study on their surface functionalisation, growth of titanium-oxo-phosphate clusters and removal of chemical pollutants

Phosphorylation imparts cellulose (amorphous or crystalline) with original surface reactivity to bridge metal oxide clusters and to scavenge for chemicals.