Contact Time Research Articles

Pressure swing adsorption of Li exchange hierarchical X zeolite for pure hydrogen from binary gas mixture

This study reports the separation of pure hydrogen (H2) employing pressure swing adsorption (PSA). The Li-X and Li-hierarchical X (Li–H-X) zeolite were prepared by an ion exchange process. The sorbents were evaluated through several experiments including, breakthrough, empty bed contact time (EBCT), single-bed, and two-bed PSA with different steps. The effect of pressure, purity, and recovery relationship was developed. The high-pressure PSA study was performed at 4, 6, and 10 bar with varying feed flow rates to assess their efficacy in pure H2 separation using binary gas stream (H2/CO2, 75/25 vol.%). The breakthrough adsorption capacity of Li–H-X exhibited 3.4 mmol g−1 and 0.212 mmol g−1 of CO2 and H2, respectively. Li–H-X shows ∼8% higher CO2 sorption capacity than the Li-X sorbent at 1 bar and 300 K due to the large meso-microporous structure of the sorbent. The two-bed PSA purity and recovery were found higher than single-bed PSA. Using two-bed PSA, the Li–H-X achieved a 99.5% of purity, 92.9% of recovery, and 10.4 mL min−1 g−1 of productivity, which was ∼16% higher recovery and productivity than single-bed PSA at a flow rate of 1200 mL min−1 at 6 bar. With increasing the pressure and flow rate, the recovery of Li–H-X was enhanced up to 93.7% with 99.1%–99.9% H2 purity. The long-term PSA was run using Li–H-X sorbent for 7.5 h with 230 cycles with H2 purity between 98.5 and 99.5% at 6 bar. Interestingly, the adsorbent shows the scalability of PSA for efficient H2 separation for a binary mixture of H2/CO2.

Performance of magnetic nanocomposite based on xanthan gum-grafted-poly(acrylamide) crosslinked by borax for the effective elimination of amoxicillin from aquatic environments

This study evaluated the effectiveness of using nanocomposite (NCs) of xanthan gum grafted polyacrylamide crosslinked Borax - iron oxide nanoparticle (XG-g-pAAm-CL-Borax-IONP) to remove the amoxicillin antibiotic (AMX) from an aquatic environment. To confirm the structural characteristics of the prepared XG-g-pAAm-CL-Borax-IONP NCs, unique characterization methods (XRD, FT-IR, FE-SEM, EDX, BET, TGA, Zeta, and VSM) were used. Adsorption experimental setups were performed with the influence of solution pH (4–9), the effect of adsorbent dose (0.003–0.02 g), the effect of contact time (5–45 min), and the effect of initial AMX concentration (50–400 mg/L) to achieve the most efficient adsorption conditions. Based on the Freundlich isotherm model, XG-g-pAAm-CL-Borax-IONP NCs provided the maximum AMX adsorption capacity of 1183.639 mg/g. This research on adsorption kinetics also established that the pseudo-second-order model (R2 = 0.991) is outstanding compatibility with the experimental results. AMX adsorption on the NCs may occur through intermolecular hydrogen bonding, diffusion, and trapping into the polymer network. Even after five cycles, these NCs still displayed the best performance. Based on these results, XG-g-pAAm-CL-Borax-IONP NCs may be a viable material for the purification of AMX from contaminated water.

Double Droplets Impact an Inclined Superhydrophobic Surface.

The rebound dynamics of double droplets impacting an inclined superhydrophobic surface decorated with macro-ridges are investigated via lattice Boltzmann method (LBM) simulations. Four rebound regions are identified, that is, the no-coalescence-rebound (NCR), the partial-coalescence-rebound of the middle part bounces first (PCR-M), and the side part bounces first (PCR-S), as well as the complete-coalescence-rebound (CCR). The occurrence of the rebound regions strongly depends on the droplet arrangement, the center-to-center distance of the droplets, and the Weber number. Furthermore, the contact time is closely related to the rebound regions. The PCR-M region can significantly reduce the contact time because the energy dissipation in this region may decrease which can promote the rebound dynamic. Intriguingly, the contact time is also affected by the droplet arrangement; i.e., droplets arranged parallel to the ridge dramatically shorten the contact time since this arrangement increases the asymmetry of the liquid film. Therefore, for multidrop impact, the contact time can be effectively manipulated by changing the rebound region and the droplet arrangement. This work focuses on elucidating the wetting behaviors, rebound regions, and contact time of the multiple-droplet impacting an inclined superhydrophobic surface decorated with macro-ridges.

Ozone treatment of meat and meat products: a review

Ozone treatment is a non-thermal method for disinfection; ozone is a powerful oxidizing agent that has been shown to be effective in reducing microbial load, extending the shelf life of meat products. This mini-review covers the analysis of the antimicrobial ozone activity in different meats (beef, poultry, pork, seafood, etc.), emphasizing the ozone application methods (liquid or gaseous phase), the applied concentrations and contact times and the effects of ozone treatment on meat quality, safety, and sensory properties. It has been demonstrated that ozone is effective against a broad range of microorganisms, including both Gram-positive and Gram-negative bacteria, spores, and vegetative cells. The efficacy of ozone depends on various factors, such as concentration, type of treatment, temperature, and presence of organic material. Ozone treatment, known for its rapid decomposition and lack of residue, provides an environmentally friendly alternative to traditional chemical sanitizers. Ozone treatments exhibit promising results in enhancing the safety and extending the shelf life of meat products. According to the findings, the application of ozone is an effective technology for prolonging the shelf life of different types of meats and meat products, requiring careful establishment of conditions on a case-by-case basis.

Development of a novel MIL‐68‐NH2@MCC composite for enhanced and synergistic removal of methylene blue and Sm(III) from an aqueous environment

In this study, a pioneering composite material, MIL‐68‐NH2@MCC, was synthesized by integrating an indium‐based metal–organic framework (MIL‐68‐NH2) with microcrystalline cellulose (MCC), that could be prepared by recycling different natural products of cellulose. The surface characteristics of the novel MIL‐68‐NH2@MCC composite were meticulously examined through X‐ray diffraction (XRD), infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy‐dispersive X‐ray spectroscopy (EDX). Remarkably, MIL‐68‐ NH2@MCC demonstrated significantly improved efficiency in removing methylene blue (MB) dye and Sm(III) ions from aqueous solutions, surpassing the removal capabilities of its individual constituents, MIL‐68‐NH2 and MCC. This superior performance can be attributed to the synergistic interplay between MIL‐68‐ NH2 and MCC. We thoroughly investigated the influence of various parameters, including pH, contact time, initial concentration, and temperature. The experimental adsorption data for both MB and Sm(III) exhibited a good fit with the Langmuir isotherm model. The optimized MIL‐68‐NH2@MCC exhibited remarkable maximum adsorption capacities of 133.8 mg/g for MB and 72.1 mg/g for Sm(III). The adsorption kinetics followed a pseudo‐second‐order model with correlation coefficients of 0.9879 and 0.9875 for MB and Sm(III), respectively. The application of intraparticle diffusion and the Boyd kinetic models demonstrated that the film diffusion is the dominant factor influencing the rate of the adsorption process. The study also examined a possible mechanism for the adsorption of MB and Sm(III) on the optimized MIL‐68‐NH2@MCC surface. Ultimately, the results highlight the originality of our research in terms of the efficacy of the newly developed MIL‐68‐NH2@MCC composite as an eco‐friendly adsorbent. Besides, the developed adsorbent effectively removes MB and Sm(III) from different water solutions while exhibiting outstanding selectivity and reusability.

Importance of pyrolysis temperature and particle size on physicochemical and adsorptive properties of urban wood-derived biochar

Physicochemical properties of biochars made from urban wood waste at different pyrolysis temperatures (400-700 °C) and particle sizes (1-2 mm and 63-75 μm) were compared to their ability for heavy metals adsorption at various contact times (30-300 min) and adsorbent dosages (0.1-5 g L-1) in real landfill leachate. The yield, volatile matter, hydrogen and oxygen contents, and functional groups of biochars decreased with increasing pyrolysis temperature; while pH, electrical conductivity, ash, fixed carbon, and specific surface area (SSA) increased. FE-SEM images showed that the creation of pores on the surface of biochars increased significantly with increasing pyrolysis temperature. Moreover, particle size exhibited no significant effect on the properties of biochars (p>0.05), except for the SSA. The SSA of biochars with a particle size of 63-75 μm was significantly higher than that measured in 1-2 mm biochars. The adsorption efficiency of heavy metals from landfill leachate increases with increasing pyrolysis temperature, contact time and adsorbent dosage. Conversely, reducing the particle size increases the adsorption efficiency. The highest adsorption efficiency for Pb, Zn, Ni, Cd, and Mn was obtained as a result of using biochar pyrolyzed at 700 °C with a particle size of 63-75 μm (i.e., BC700/63-75) by 60.39%, 75.01, 64.36, 58.87%, and 71.15%, respectively. Pseudo second-order kinetic and the Langmuir isotherm were recognized as the most appropriate models to describe the adsorption process. The chemical adsorption was identified as the main mechanism for the adsorption of metal ions onto BC700/63-75.

Dry Reforming of CH4 Using a Microreactor

In the present study, a comparison of the dry reforming of a gas mixture containing methane, carbon dioxide and nitrogen without contaminants to a ruthenium-based Ru/Al2O3 catalyst was carried out in a microreactor for the first time. The influence of the contact time, temperature and composition of the feed on the conversion was exhaustively investigated. The optimal operating conditions were found to be a contact time of 80 milliseconds, a temperature of 700 °C and a CH4:CO2 ratio of 1. The assessment of diffusional limitations reveals that there is no resistance to mass transfer, which reveals the potential benefit of the determination of intrinsic reaction kinetics within a microreactor.

Preparation of thiourea derivative incorporated Ag3PO4 core shell for enhancement of photocatalytic degradation performance of organic dye under visible radiation light

Photocatalysis is a promising technique to reduce hazardous organic pollutants using semiconductors under visible light. However, previous studies have been concerned with the behavior of silver phosphate (Ag3PO4) as n-type semiconductors, and the problem of their instability is still under investigation. Herein, 4,4′-(((oxalylbis(azanediyl)) bis(carbonothioyl)) bis(azanediyl)) dibenzoic acid is synthesized by green method and used to enhance the photocatalytic behavior for Ag3PO4. The incorporated Ag3PO4 core–shell is prepared and characterized via XRD, FT-IR, Raman, TEM and BET. Besides, the thermal stability of the prepared core shell was investigated via TGA and DSC measurements. The optical properties and the energy band gap are determined using photoluminescence and DRS measurements. The photodegradation of methylene blue in the presence of the synthesized Ag3PO4 core–shell under visible light is examined using UV/Vis measurements. The effect of initial dye concentration and contact time are studied. In addition, the kinetic behavior of the selected dye during the photodegradation process shows a pseudo-first order reaction with rate constant of 0.015 min−1 for ZAg. The reusability of the Ag3PO4 core shell is evaluated, and the efficiency changed from 96.76 to 94.02% after three cycles, indicating efficient photocatalytic behavior with excellent stability.

Adsorption Behavior of Co2+, Ni2+, Sr2+, Cs+, and I- by Corrosion Products α-FeOOH from Typical Metal Tanks.

Throughout the nuclear power production process, the disposal of radioactive waste has consistently raised concerns about environmental safety. When the metal tanks used for waste disposal are corroded, radionuclides seep into the groundwater environment and eventually into the biosphere, causing significant damage to the environment. Hence, investigating the adsorption behavior of radionuclides on the corrosion products of metal tanks used for waste disposal is an essential component of safety and evaluation protocols at disposal sites. In order to understand the adsorption behavior of important radionuclides 60Co, 59Ni, 90Sr, 135Cs and 129I on α-FeOOH, the influences of different pH values, contact time, temperature and ion concentration on the adsorption rate were studied. The adsorption mechanism was also discussed. It was revealed that the adsorption of key nuclides onto α-FeOOH is significantly influenced by both pH and temperature. This change in surface charge corresponds to alterations in the morphology of nuclide ions within the system, subsequently impacting the adsorption efficiency. Sodium ions (Na+) and chlorate ions (ClO3-) compete for coordination with nuclide ions, thereby exerting an additional influence on the adsorption process. The XPS analysis results demonstrate the formation of an internal coordination bond (Ni-O bond) between Ni2+ and iron oxide, which is adsorbed onto α-FeOOH.

The valorization of Prunus mahaleb shell through acid modification for the sorption of Pb2+ removal from aqueous solution

AbstractThis study aimed to investigate the biosorption performance of acid-modified waste Prunus mahaleb (PMA) shells in the removal of Pb2+ ions from aqueous solutions. Changes in the morphological properties and functional components of PMA biosorbent were characterized using SEM–EDX, FT-IR, BET, and PZC analyses. The effect of various parameters such as initial Pb2+ concentration, pH, PMA dosage, contact time, and temperature on biosorption was investigated using a batch biosorption procedure. The maximum biosorption capacity, determined using the Langmuir isotherm, was calculated to be 119 mg g−1. It was found that the biosorption kinetic mechanism followed pseudo-second-order kinetics and intraparticle diffusion model. According to the determined thermodynamic parameters, the biosorption mechanism was found to be endothermic (ΔH° > 0), spontaneous (ΔS° > 0), and entropy-increasing (ΔG° < 0). The outcomes of the experiment were evaluated in comparison to other sorbents that have been previously commonly used in the literature. It was demonstrated that PMA could be a promising, environmentally friendly, cost-effective, and sustainable potential biosorbent for the removal of Pb2+ ions.

Synthesis of zero valent copper/iron nanoparticles using Piper betle leaves for the removal of pharmaceutical contaminant atorvastatin

In this study, bimetallic Cu–Fe nanoparticles were synthesized using the green approach with Piper betle leaves, and the removal efficiency of one of the pharmaceutical compounds, Atorvastatin, was investigated. UV, SEM, FTIR, EDAX, particle size, and zeta potential measurements were used to confirm nanoparticle fabrication. The removal efficiency of Atorvastatin (10 mg/L) by bimetallic Cu–Fe nanoparticles was 67% with a contact time of 30 min at pH 4, the adsorbent dosage of 0.2 g/L, and stirring at 100 rpm. Piper betle bimetallic Cu–Fe nanoparticles have demonstrated excellent stability, reusability, and durability, even after being reused five times. Furthermore, the synthesized bimetallic Cu–Fe nanoparticles demonstrated remarkable antimicrobial properties against gram-negative strains such as Escherichia coli and Klebsiella pneumoniae, gram-positive strains such as Staphylococcus aureus and Bacillus subtilis, and fungi such as Aspergillus niger. In addition, the antioxidant properties of the synthesized bimetallic Cu–Fe nanoparticles were assessed using the DPPH radical scavenging assay. The results indicated that the nanoparticles had good antioxidant activity. Thus, using Piper betle extract to make Cu–Fe nanoparticles made the procedure less expensive, chemical-free, and environmentally friendly, and the synthesized bimetallic Cu–Fe nanoparticles helped remove the pharmaceutical compound Atorvastatin from wastewater.

Efficient treatment of secondary treated refinery wastewater using sand biofiltration: Removal of hazardous organic pollutants

This study explored the potential of sand biofiltration for tertiary treatment of real refinery wastewater. The biofilter (2 cm (I.D.) x 15 cm (L)) operated on secondary treated refinery wastewater at flow rate of 1 mL/min had empty bed contact time (EBCT) of 47.12 min for one circulation. Maximum reduction in COD after 4, 8 and 12 times recirculation was 25 %, 52 % and 56 %; while the TOC reduction was 33 %, 43 % and 51 %, respectively, after biofilm development over 30 days. Quantification using two dimensional gas chromatography – time of flight mass spectrometry (GCxGC-TOF MS) revealed that several of the identified target compounds could not be detected in the wastewater after 12 recirculations. After 8 times recirculation, most of the compounds showed very high removal efficiency. For biofiltration over the flow rate range 2–10 mL/min, the reduction in COD and NH4+-N ranged from 62–73 % and 78–86 %, respectively, after 8 times recirculation. The nitrite concentration first increased and subsequently decreased, while the nitrate concentration continuously increased with increase in the number of recirculations. Solid phase micro-extraction (SPME) analysis of the aqueous phase using GCxGC-TOF MS and a semi-quantitative approach indicated that the removal of predominant classes of compounds was greater than 95 % after 8 times recirculation, with maximum reduction occurring in the first pass through the biofilter. Assimilable organic carbon (AOC) reduction was 98 % after 8 times recirculation. Metagenomic analysis revealed that Proteobacteria was the most dominant phylum in the biofilter. Many known polynuclear aromatic hydrocarbon (PAH) degraders, such as Sphingomonadales, Burkholderiales, Rhodobacterales and Rhodospirillales, were found in the biofilter leading to high removal efficiency of hazardous organic pollutants.

Rebound characteristics of a water droplet impacting on a superhydrophobic cone

Precise control of droplet rebound behavior on superhydrophobic surfaces is essential for various industrial applications like anti-icing and self-cleaning. However, current studies still lack a comprehensive understanding of this phenomenon. Herein, we conduct a numerical investigation on the rebound dynamics of water droplets impacting on superhydrophobic conical cones under various Weber numbers and cone angles. A phase diagram illustrating impact outcome transitions from non-impalement to impalement and ring bouncing is presented. A semi-empirical model is proposed to identify the impalement transition by correlating critical Weber number with cone angle. While ring bouncing reduces contact time by up to 47 % compared to flat surfaces, it is a transient regime due to low rebound velocity, causing the liquid ring to recontact the cone and eventually rebound from the cone tip in a conventional manner with a prolonged contact time. We also observe attractive phenomena upon ring bouncing, including periodically oscillating radial extension and rapid rotation. Shorter contact times in conventional bouncing are achieved at larger cone angles and lower Weber numbers by minimizing radial expansion and falling distance. Furthermore, a theoretical model that accurately predicts the contact time of ring bouncing is developed. It is demonstrated that rebound velocities in both conventional and ring bouncing rise as cone angle decreases, attributed to reduced viscous dissipation and surface energy. Notably, in conventional bouncing, rebound velocity increases by 63 % on average compared to flat surfaces when the cone angle is 60°.

Significant increase in the number of occupational exposures reported to the Dutch Poisons Information Centre (2016–2022): the importance of poison centre data in health surveillance

Introduction Exposure to hazardous substances in the workplace can result in injuries and fatalities. This study aimed to investigate the characteristics and trend of occupational exposures reported to the Dutch Poisons Information Centre and to investigate whether the COVID-19 pandemic had an impact on the trend. Methods A retrospective analysis of all acute occupational exposures reported to the Dutch Poisons Information Centre between 1 January 2016 and 31 December 2022 was performed. Data on patient and exposure characteristics, symptoms and treatment recommendations were analyzed. Results Between 2016 and 2022, the Dutch Poisons Information Centre received 5,508 calls regarding acute occupational exposures. The annual number of calls on acute occupational exposures almost doubled over the years studied (from 475 in 2016 to 936 in 2022). During and after the COVID-19 pandemic (March 2020-December 2022), the number of calls stabilized, but the upward trend was not significantly affected. There were an estimated 0.20 calls per 1,000 human exposure calls per month (95 per cent confidence interval: −0.14; 0.53). Victims were often exposed through multiple routes, with inhalation being the most common route (44 per cent), followed by ocular (32 per cent) and dermal contact (30 per cent). Acids (1,138 exposures) and alkalis (912 exposures) were often involved. The Dutch Poisons Information Centre had information on 6,334 patients, although the total number of exposed patients was not known as some victims did not seek medical assistance, or were treated by healthcare professionals who did not consult our Centre. At the time of contact, 13 per cent (n = 795) of the patients reported no symptoms, 76 per cent (n = 4,805) reported mild to moderate symptoms and 3 per cent (n = 183) reported potentially severe symptoms. Information on symptoms was missing for 9 per cent (n = 551) of the patients. Hospital observation and treatment were recommended for 5 per cent (n = 325) of the patients. Discussion This study highlights the necessity for poisoning prevention strategies to reduce the number of work-related incidents involving hazardous substances. Conclusion The continuing increase in the number of workplace incidents involving hazardous substances is of concern. A comprehensive and multidisciplinary approach should be taken to gain a full understanding of occupational exposure to hazardous substances and to identify risk factors.

Uncalcined Zn/Al Carbonate LDH and Its Calcined Counterpart for Treating the Wastewater Containing Anionic Congo Red Dye

In this investigation, Zn/Al carbonate layered double hydroxide (ZAC-LDH) and its derived material on calcination were synthesized for removing the anionic azo dye Congo red (CR) from wastewater. Numerous factors were methodically investigated, including temperature, adsorbent dosage, pH, starting Dye Concentration (DC), and contact time. The CR elimination percentage dropped as the initial DC increased from 25 mg/L to 100 mg/L at 30 °C for uncalcined LDH, and from 97.96% to 89.25% for calcined LDH. The pH analysis indicates that the highest level of dye removal was recorded within the acidic pH range through the electrostatic attraction mechanism. The sorption kinetics analysis results demonstrated that the pseudo-second-order kinetic model exhibited a stronger fit to both uncalcined LDH and CZA-LDH, with the maximum correlation coefficient value. The Van’t Hoff plots indicate the spontaneous nature of the physisorption process with a negative ΔG° (<−20 kJ/mol), while the endothermic adsorption process exhibited a positive ΔH°. The X-ray diffraction of calcined LDH reveals a significant intercalation of CR dye molecules, both prior to and following adsorption, showcasing a distinctive memory effect. The Brunauer–Emmett–Teller (BET) gas sorption measurements were performed to support the mesoporous nature of ZAC-LDH and CZA-LDH. The FTIR spectrum confirms the interaction of dye molecules on the surface of uncalcined and calcined LDH. These findings emphasize the efficacy of both the synthesized LDHs in removing CR dye, with CZA-LDH demonstrating superior efficiency compared to uncalcined LDH in the context of CR removal from wastewater.

Probing structural features in potato starch granules at moderate hydration through the modelling of 1H->13C polarization transfer kinetics

The structural arrangement of starch polymers in presence of water is known to impact the functional properties of starchy products. In this study, the hydration of potato starch granules was investigated at the molecular level through various 1H->13C polarization transfer solid-state Nuclear Magnetic Resonance (ss-NMR) experiments. The impact of increasing the water content from 12.3 % to 45.9 % was assessed using 13C Cross Polarization Magic Angle Spinning (CPMAS), Variable Contact Time (VCT-CPMAS), Variable Spin Lock (VSL-CPMAS), and T One Rho QUEnching (TORQUE) NMR sequences. Of these, VCT-CPMAS proved to be the most promising. When applied with an optimal number of contact times, it enabled the application of several mathematical models that provided detailed insights into the structuring of protons in the hydrated potato starch granules. At low hydration (12.3 %), the models enabled various structural domains to be distinguished, which we suggest are associated with helical and amorphous structures. At moderate hydration (45.9 %), we tested two fitting models. Two pools of protons were revealed, corresponding to loosely ordered structures on the scale of tens of nanometers. These findings suggest varying water distribution during starch hydration and are likely to indicate variable hydration levels in the multilamellar amorphous structures of starch granules.

Stability of Running Stride Biomechanical Parameters during Half-Marathon Race

This study explores the stability of biomechanical parameters of the running stride of male trained athletes during a half-marathon competition. Using a field-based descriptive design, eight male athletes from a local training group were monitored throughout an official half-marathon race under identical conditions, assessing biomechanical parameters including ground contact time (GCT), leg spring stiffness (LSS), vertical oscillation (VO), and stride length (SL) recorded via the Stryd Summit Power Meter. A repeated measures analysis of variance (RM ANOVA) was conducted to detect significant changes in biomechanical parameters as the race progressed. Results demonstrated minimal changes in all parameters, with no significant differences observed for GCT (F = 0.96, p = 0.38), VO (F = 0.23, p = 0.87), and SL (F = 1.07, p = 0.35), and a small (η2 = 0.004) yet statistically significant difference in LSS (F = 5.52, p = 0.03) between the first and second segments, indicating that athletes were able to maintain stable biomechanical parameters throughout the race. The conclusion highlights the need for personalized training programs tailored to the unique biomechanical adaptations and demands of endurance running.

Barefoot pressure distribution of diabetic patients and non-diabetic volunteer subjects after sensorimotor training with an unstable shoe construction

BackgroundForty-three percent of all diabetic foot ulcers occur under the medial forefoot due to a medial deviation of elevated pressures and premature forefoot ground contact in neuropathic diabetic patients. A 6-week sensorimotor training period with an unstable shoe construction reduces in-shoe peak pressures and contact times under the medial aspect of the forefoot. MethodsThe study was designed as a Randomised Control Trial with two diabetic groups (one served as intervention group and one as control group) and one non-diabetic intervention group. Measurements for barefoot pressure distribution and contact times were taken by means of an Emed® pressure measurement platform (Novel GmbH, Munich) before and after 6 weeks. During this time the diabetic and the non-diabetic intervention groups were required to wear an unstable shoe construction (Masai Barefoot Technology, MBT®) for at least four hours per day. FindingsResults for the non-diabetic intervention group showed significantly later contact times for the medial portion of the forefoot, resulting in shorter contact times. Peak pressure was also reduced under the medial aspect of the foot while it was increased under the lateral aspect of the foot. Changes for the diabetic intervention group followed the same pattern while the values of the diabetic control group shifted away from the reference values. InterpretationA 6-week sensorimotor training period with an unstable shoe construction can change barefoot peak pressures and contact times in non-diabetic subjects and in diabetic patients in the most endangered area, i.e. the medial forefoot.

Batch adsorption studies on copper removal from an aqueous solution using natural zeolite: Process optimization

Abstract The ability of natural zeolite to remove copper ions from an aqueous solution was examined. The research aims to optimize adsorption operational variables, which include the amount of zeolite, pH, contact time, and initial heavy metal concentration for copper removal using zeolite. The research was conducted in batch experiments. The ranges of operational conditions are as follows: 0.2 - 1.0 g of zeolite, pH 4 - 8, 2 - 60 minutes of contact time, and 5 - 50 mg/L of initial concentration of copper. The outcomes indicated that the percentage removal of copper using zeolite achieved the best performance at an optimized adsorbent dosage of 1.0 g, a pH of 6, a contact time of 20 minutes with 135 rpm, and an initial copper concentration of 5 mg/L. To sum up, zeolite is an efficient adsorbent that is capable of separating copper from water-based solutions.

Enhanced removal of lead and zinc by a 3D aluminium sulphate-functionalised graphene aerogel as an effective adsorption system

The discharge of heavy metals into the environment has adversely affected the aquatic ecosystem due to their toxic and non-biodegradable nature. In this research, a three-dimensional graphene oxide/carboxymethylcellulose/aluminium sulphate (GOCAS) aerogel was synthesised and evaluated as a novel means for lead and zinc removal. The GOCAS aerogel was prepared via ice-templating of graphene oxide with carboxymethylcellulose and aluminium sulphate as the crosslinking and functionalisation additives. Characterisation of the aerogel by various analytical techniques confirmed the successful integration of the chemical additives. The hydroxyl and sulphate groups in the aerogel were found to participate in the adsorption of both metals. The equilibrium of lead adsorption was found to correlate well to the Freundlich isotherm, while zinc adsorption fitted closely the Langmuir isotherm. The kinetic adsorption behaviour of both metals was best described as pseudo-second-order. The interactive influences of concentration, temperature, contact time and adsorbent dose on the metal removal were explored by a central composite design, and the optimum adsorption capacity for lead was determined to be 138.7 mg/g at a GOCAS dose of 20 mg, initial concentration of 100 mg/L, temperature of 50 °C and contact time of 45 min. The optimum adsorption capacity for zinc was 52.69 mg/g at 30 mg, 65 mg/L, 45 °C and 40 min. Furthermore, regeneration studies with hydrochloric acid eluant were successfully conducted for up to four adsorption-desorption cycles. Overall, this work demonstrates that GOCAS aerogel is a viable nanosorbent for the adsorption of lead and zinc from water systems.