Preparation and application of irradiated polyvinyl alcohol/starch/pumice composites for adsorption of basic dye: Isotherm and kinetics study

Even at low concentrations, organic dye pollution entering water resources from the textile, paper, and pharmaceutical industry sectors poses a serious hazard to human and aquatic life. One of the most significant remediation methods is the adsorption method. In the present study, the uptake of basic violet 7 (BV7) synthetic dye was investigated utilizing Poly (vinyl alcohol)/starch/Pumice [poly (PVA/St/Pu)] composite films prepared by a simple casting of both PVA and St with Pu and then irradiated by electron beam (EB) source to prompt curing. Numerous characterization methods, such as SEM, FTIR, X-ray diffraction (XRD, and other measurements, were examined on the prepared sample. The tensile strength (TS) of all composites was increased by increasing the radiation dose up to 10 kGy. TS was increased by 3 php of Pu, and an overload of Pu led to a decrease in TS values. The elongation at break (Eb) of the prepared composite increased at 3 Pu, then decreased as the quantity of the pumice increased, while the Eb was decreased by irradiation. The effects of the produced polymeric films' composition and irradiation dose on the basic violet 7 (BV 7) dye adsorption were studied. It was found that the adsorption capacity of poly (PVA/St/9 php Pu-10 kGy) toward the BV 7 dye was 64.9 mg/g at the optimal conditions: pH = 11, contact time = 480 min., adsorbent dosage = 0.2 g., concentration = 150 mg/l, and temperature = 298 K. The adsorption process fitted with the pseudo-second-order model, Freundlich adsorption isotherms were found to be spontaneous and endothermic.

Kinetic studies and conditions optimizations for the removal of direct red 80 dye from wastewater using cotton calyx and iron oxide composite

This study focusses on the adsorption efficiency of cotton pod (Gossypium arboreum) for biosorption of direct red (DR) 80 dye. The effect of dye concentration, pH, shaking time, adsorbent dose and temperature was considered to evaluate the adsorption efficiency of the cheapest raw material on the removal of dye. Various concentrations (10–50 ppm) were examined and maximum percentage removal of the adsorbent was obtained at pH 1 with adsorbent dose of 0.9 g and shaking time of 60 min. To enhance the adsorption efficiency of the adsorbent, the cotton calyx was treated with FeSO4.7H2O and investigated the removal of the raw adsorbent and the composite. It was examined that the removal efficiency of the composite is more than that of raw adsorbent. The composite was more efficient as dye removal reached up to 97%. FTIR of the composite shows an additional peak at 650 cm−1 for presence of Fe-O group and confirmation of composite formation. SEM micrograph showed that the particles in composite are more packed compared to the raw adsorbent. Mathematical models were applied and kinetic studies also have been done to provide better results regarding to the experimental data. It is concluded that the prepared adsorbent could be used as a tool for the removal of toxic pollutants from textile wastewater.

Extraction of silica from fly-ash and fabrication of silica-clay composite for dye removal and kinetic studies

A facile and green approach to extract silica from the coal fly-ash waste is extremely critical for environmental sustainability and economically suitable. In this study, we have used acid-alkali coupled approach to improvised the proficiency of the extraction process. The sodium hydroxide (NaOH) soaking results the formation of the sodium silicate (Na2SiO3) solution then pure silica was obtained by heating at high temperature; this coupled route-way results better yield of silica (SiO2) which is ∼ 40 g. The efficiency of pure silica is not enough to remove toxic effluents from the aqueous media. A highly versatile approach of composite formation was adopted to fabricate silica-clay composite using kaolinite-clay and extracted silica. Both materials, extracted silica and its silica-clay composite were analyzed using scanning electron microscopy (SEM), energy dispersive X-ray (EDX) method, X-ray diffraction technique (XRD) and Fourier transform infra-red spectroscopy (FTIR). The silica-clay composite showed plate-tubular like morphology with enormous binding sites available for the sorption pollutants like organic dyes. It has shown excellent sorption of methylene blue (MB) efficiency of 131.5 mg/g, while silica furnished the sorption of 70.5 mg/g. Results revealed that the synthesized material could probably have better potential for dye removal from industrial effluents.

Ultrasonic supported dye removal by a novel biomass

Sumac Leaves (Rhus Coriaria L), were used as a possible adsorbent of Basic Blue 3 (BB3) removal. The main affecting parameters on adsorption such as concentration, pH and temperature were investigated. Adsorption equilibrium was reached in 30 min. The ultrasonic effect was also enhanced the dyestuff removal. Adsorption capacity was rised from 0.566 to 1.826 mg/g, as rising the concentration from 4 μg/mL to 10 μg/mL. Several isotherm models including Langmuir, Freundlich and Temkin were applied for explaining the adsorption mechanism. Temkin and Langmuir isotherm models describe the system well. Pseudo first order, pseudo second order and intra particle kinetics were evaluated. Pseudo second order diffusion model supports the adsoprption and also intra particle diffusion plays an important role for BB3 removal. Thermodynamics of the adsorption were commented. −2219.5 J/mol of Gibbs energy showed us a spontaneous and physical adsorption.

Ionizing radiation based advanced oxidation process for reactive orange 122 dye degradation and kinetics studies

In the current study, the degradation of reactive orange 122 (RO 122) dye was carried out under UV and gamma irradiation in presence of H2O2. The effect of variables such as UV exposure time, gamma-ray absorbed dose, initial concentration of dye and oxidant dose were investigated. The removal of 64.10, 58.84 and 55.46 (%) was observed for 50, 100 and 150 (mg/L) dye concentrations, respectively using UV radiation time of 150 (min). The degradation was enhanced to 80.39, 69.95 and 67.01 (%) when UV radiation was employed in the presence of H2O2 (0.5 mL/L) for above concentrations respectively. The degradation was further improved to 97, 92.54 and 81.32 (%) using 5 kGy absorbed dose along with H2O2 (0.5 mL/L). The reduction in chemical oxygen demand (COD) was 77, 64 and 57 (%) using UV/H2O2 (0.5 mL/L), while 63, 56 and 53 (%) in case of gamma/H2O2 for aforementioned concentrations. The removal efficiency (G-value), dose constants (k), dose indispensable for 50, 90 and 99 (%) degradation (D 0.5, D 0.90, and D 0.99) after the treatment with gamma radiation were determined. The G-value was noted as 0.46–0.0711 for 50–150 mg/L dye concentration for gamma irradiated samples which improved to 0.57–0.1204 for above mentioned concentrations in presence of H2O2. The FTIR analysis showed that all the peaks were disappeared using gamma/H2O2 at 5 kGy absorbed dose except a minor peak of −CO stretching. The degradation mechanism of dye followed pseudo-first-order kinetics. A significant decrease in peak area was observed by the HPLC analysis after treating the dye samples with gamma/H2O2 (0.5 mL/L) at absorbed dose of 5 kGy which has proven the process efficiency for dye degradation.

Adsorption kinetics for the removal of toxic Congo red dye by polyaniline and citrus leaves as effective adsorbents

This study focusses on the synthesis of polyaniline (PANI) and polyaniline base adsorbent utilizing Citrus limon leaves (CL) powder. The polyaniline base adsorbent with C. limon was synthesized using the same process as polyaniline synthesis, but with the addition of leaves powder. PANI and PANI based adsorbent with C. limon leaves powder (PANI/CL) were characterized by Fourier Transform Infra-Red (FTIR), UV-Visible spectroscopy and Scanning Electron Microscopy (SEM). This synthesized material was employed for the removal of congo red (CR) dye from industrial wastewater. Furthermore, the Langmuir, Temkin and Freundlich isotherms were also applied to evaluate experimental results. PANI is an efficient adsorbent for CR removal with 71.9 mg/g, while PANI/CL is an efficient adsorbent with 80 mg/g removal of dye according to a comparison of maximal adsorption capabilities. The data concludes that the prepared adsorbents could possibly be employed for the removal of toxic dyes from industrial effluents at large scale and ultimately could help in improving the environment.

Kinetics of acid blue 40 dye degradation under solar light in the presence of CuO nanoparticles synthesized using Citrullus lanatus seeds extract

In view of eco-benign nature of green synthesis, in the present investigation, the CuO NPs are prepared using Citrullus lanatus seeds extract and photocatalytic degradation efficiency for Acid Blue 40 (AB-40) was evaluated. The CuO NPs were characterized by XRD (X-ray diffraction), SEM (scanning electron microscopy), EDX (energy dispersive X-ray), and FT-IR (Fourier transform infrared) techniques. The synthesized CuO NPs was in face centered monoclinic crystalline form with particle size in 40–60 nm range. The photocatalytic degradation potential of CuO NPs was assessed for acid blue 40 (AB-40) dye degradation and catalyst dose, concentration of dye, radiation exposure time and pH are considered for dye removal. The CuO NPs exhibited auspicious efficiency, an 84.89% dye removal was attained at optimal conditions and dye degradation followed BMG (Behnajady–Modirshahla–Ghanbery) kinetics model. Results revealed CuO NPs synthesized using C. lanatus seeds extract is photoactive catalyst and green route can be employed for CuO NPs fabrication for photocatalytic applications.

Biochar caged zirconium ferrite nanocomposites for the adsorptive removal of Reactive Blue 19 dye in a batch and column reactors and conditions optimizaton

Biochar caged zirconium ferrite (BC-ZrFe2O5) nanocomposites were fabricated and their adsorption capacity for Reactive Blue 19 (RB19) dye was evaluated in a fixed-bed column and batch sorption mode. The adsorption of dye onto BC-ZrFe2O5 NCs followed pseudo-second-order kinetics (R 2 = 0.998) and among isotherms, the experimental data was best fitted to Sips model as compared to Freundlich and Langmuir isotherms models. The influence of flow-rate (3–5 mL min−1), inlet RB19 dye concentration (20–100 mg L−1) and quantity of BC-ZrFe2O5 NCs (0.5–1.5 g) on fixed-bed sorption was elucidated by Box-Behnken experimental design. The saturation times (C t /C o  = 0.95) and breakthrough (C t /C o  = 0.05) were higher at lower flow-rates and higher dose of BC-ZrFe2O5 NCs. The saturation times decreased, but breakthrough was increased with the initial RB19 dye concentration. The treated volume was higher at low sorbent dose and influent concentration. Fractional bed utilization (FBU) increased with RB19 dye concentration and flow rates at low dose of BC-ZrFe2O5 NCs. Yan model was fitted best to breakthrough curves data as compared to Bohart-Adams and Thomas models. Results revealed that BC-ZrFe2O5 nanocomposite has promising adsorption efficiency and could be used for the adsorption of dyes from textile effluents.

Kinetics of methylene blue dye adsorptive removal using halloysite nanocomposite hydrogels

In the present work, halloysite nano-clay (HNTs) based hydrogel was fabricated and their efficiency for the removal of methylene blue dye was studied. The hydrogel films were prepared with varying amount of halloysite nano-clay via facile solution casting method. Effect of halloysite clay on adsorption performance of composite was investigated. The hydrophobic thermoplastic synthetic polymer, polylactic acid (PLA) was blended with hydrophilic polymer polyvinyl alcohol (PVA) and HNTs to synthesize hydrogels. Swelling behavior and antimicrobial efficiency was also evaluated. The halloysite incorporating films showed excellent antibacterial activity. Swelling capacity of hydrogel with increased halloysite content was reduced due to increased crosslinking among polymer chains. Halloysite incorporated hydrogel exhibited higher adsorption ability as compared to film comprising of only PVA and PLA and dye removal followed pseudo first order kinetics. Film with 0.03 g HNTs rapidly attained adsorption-desorption equilibria and removed the dye completely within 30 min. Results confirmed that synthesized film could be potentially used for the removal of cationic dye and fabricated hydrogel film have promising potential for wastewater treatment since a higher adsorption capacity was observed for halloysite nano-clay incorporated hydrogel.

Greener approach to substitute chemical reduction clearing process for fabric dyed with Foron Blue E-BL 150, Foron Rubine RD-GFL and Foron Brilliant Yellow S-6GL using indigenous resources

Fabric dyed with disperse dyes followed a reduction clearing process (RCP)/chemical clearing process (CCP) to remove the unfixed dye from the fabric. In the clearing process, unfixed dyes and chemicals are discharged into streams. To combat this issue, an environment friendly approaches is explored that is a biological clearing using indigenous fungal strains of white-rot fungi (Pleurotus ostreatus and Ganoderma lucidum). In this context, fabrics dyed with three disperse dyes (Foron Blue E-BL 150, Foron Rubine RD-GFL and Foron Brilliant Yellow S-6GL) were considered. The fabric cleared with biological clearing process improved the quality of fabric versus chemically cleared fabric and among the tested strains, G. lucidum showed higher efficiency for color strength improvement. However, no significant difference in tensile and tear strength of all fabric samples was observed. The quality of effluents in clearing reduction process for three dyes was assessed and it was observed that water quality parameters including chemical oxygen demand (COD), total organic carbon (TOC), biological oxygen demand (BOD), total suspended solids (TSS), pH, dissolved oxygen (DO) and total dissolved solids (TDS) improved significantly and results revealed that the biological clearing approach can substitute chemical reduction clearing process for fabric dyed with dyes, which is greener and eco-friendly versus conventional processes to avoid unfixed dyes discharge in to water bodies.