Activated carbon (AC) is a versatile and extensively employed adsorbent in environmental remediation. It possesses distinct properties that can be enhanced to selectively target specific pollutants through modifications, including chemical impregnation or incorporation into composite materials. In this study, porous calcium alginate beads (PCAB) were synthesized by incorporating AC and natural alginate through ion gelation in a Ca(II) ion-containing solution, with the addition of sodium lauryl sulfate as a surfactant. The prepared PCAB was tested for Cu(II) removal. PCAB exhibited a spherical shape with higher porosity and surface area (160.19 m2. g−1) compared to calcium alginate beads (CAB) (0.04 m2. g−1). The adsorption kinetics followed the pseudo-first-order model for PCAB and the pseudo-second-order model for CAB. The Langmuir isotherm model provided the best fit for adsorption on PCAB, while the Freundlich model was suitable for CAB. Notably, PCAB demonstrated a maximum adsorption capacity of 75.54 mg.g−1, significantly higher than CAB's capacity of 9.16 mg. g−1. Desorption studies demonstrated that 0.1 M CaCl2 exhibited the highest efficiency (90%) in desorbing Cu(II) ions from PCAB, followed by 0.1 M HCl and 0.1 M NaCl. PCAB showed efficient reusability for up to four consecutive adsorption– desorption cycles. The fixed-bed column experiment confirmed the match with the Thomas model to the breakthrough curves with qTH of 120.12 mg.g−1 and 68.03 mg.g−1 at a flow rate of 1 mL.min−1 and 2 mL.min−1, respectively. This study indicated that PCAB could be an effective adsorbent for Cu(II) removal, offering insights for further application and design considerations.

Independence is a factor which has a significant impact on auditing quality, especially in the recent times where the marketplace is increasingly demanding transparency. The independence of auditors is assessed based on the main criteria such as the reliability of the audit opinions, the accuracy, truthfulness of financial reports, and the objectivity in the opinions of the auditor. The study investigates the effects of non-audit services (NAS) on auditor independence in emerging economies such as Vietnam. Non-audit services include taxation services, management advisory services and outsourcing internal audit services. Based on previously relevant researches, the authors develop hypotheses and a regression model about non-audit services (independent variables) and audit independence (dependent variable). The research collects data by 5-scale Likert questionnaire. The findings indicate the relationship between NAS and auditor independence. Specifically, the results reveal two main factors that have influence on auditor independence, namely, taxation services and management advisory services. The results of our research can be considered as new findings and can be compared to previous researches in Vietnam, which establishes a new viewpoint about the relationship between the NAS and the independence of the auditor. This result can be implemented for countries or jurisdictions which are similar to Vietnam.