Research Papers

Valorization of diatomaceous earth as an alternative activator for pumice–based geopolymer concrete: Experimental and multiple linear regression modeling

2026-09-02T07:11:54Z

Valorization of diatomaceous earth as an alternative activator for pumice–based geopolymer concrete: Experimental and multiple linear regression modeling Wafula, Dorothy; Shikuku, Victor; Saouma, Felix; Tome, Sylvain Geopolymer cement (GC) is gaining attention as a sustainable alternative to Portland cement due to its lower CO₂ emissions. However, GC formations rely on sodium silicate, which is expensive, and its production has a high carbon footprint. The development of alternative silica and aluminosilicate sources is therefore critical for improving the sustainability and economic viability of geopolymer concrete. This study focuses on the use of diatomaceous earth (DE) as an alternative silica source and examines the effect of the activator composition on the compressive strength of pumice-based geopolymer concrete, relative to commercial sodium silicate (CSS) as a control, using a one-step synthesis approach. The study evaluates the effects of curing temperature (30, 50, and 70 ◦C), sodium hydroxide concentration (6, 8, and 10 M), and silica mass in the activator (40, 80, and 100 g) on the compressive strength of the resulting geopolymer concrete. The compressive strengths for CSS and DE samples were comparable (<6%). The Multiple Linear Regression (MLR) model (y = 0.3319[NaOH]-0.0231 [DE]+0.0304[Temp]+0.4508) indicated that NaOH has the highest positive effect on compressive strength, while excessive silica content has a negative effect on the compressive strength of pumice-based geopolymer concrete. Compressive strength increased (~50%) from 2.8 to 4.41 MPa when NaOH concentration increased from 6 M to 10 M for DE samples, respectively. In contrast, an increase in silica mass from 40 g to 100 g reduced the strength by ~28.9% and ~38% for CSS and DE samples, respectively. The results indicate that at high NaOH concentration, low DE content and elevated temperatures, DE-based activator produced an activator with comparable results to CSS. In the absence of established geopolymer concrete standards in Kenya, a laboratory scale mix design was adopted to enable consistent comparison between DE and CSS based systems. Further research should focus on mix optimization and strategies to enhance strength development for broader construction applications and standardization.

The Effect of Psychological Empowerment on Employee Performance in Law Courts in Kenya: A Case Study of Vihiga Law Courts

2026-09-02T06:47:43Z

The Effect of Psychological Empowerment on Employee Performance in Law Courts in Kenya: A Case Study of Vihiga Law Courts Jemaiyo, Mary Mbiti; Omuyoyi, Maureen; Omondi, Atieno Margaret The study examined the effect of psychological empowerment on employee performance in law courts in Kenya, with specific reference to Vihiga Law Courts. The study was grounded on Douglas McGregor’s Theory X and Theory Y. A case study research design was adopted. The target population comprised 50 employees drawn from judges, magistrates, court reporters, legal secretaries, and court clerks. Inferential statistics, including linear regression analysis, were used to analyze data with the aid of SPSS version 21. The findings revealed that psychological empowerment has a statistically significant positive effect on employee performance. The results indicated that increases in psychological empowerment led to improved employee performance in law courts. The study also established that empowerment dimensions such as autonomy, competence, meaning, and impact enhance employee motivation and efficiency. The study concludes that psychological empowerment is a key determinant of employee performance in judicial institutions. It recommends that court management strengthen empowerment practices through participatory decision-making, delegation of responsibilities, staff training, and improved working conditions to enhance service delivery.

FINANCIAL CAPITAL REPORTING, MANUFACTURED CAPITAL REPORTING, ENVIRONMENTAL CAPITAL REPORTING AND FIRM VALUE OF LISTED COMPANIES IN KENYA

2026-09-02T06:11:10Z

FINANCIAL CAPITAL REPORTING, MANUFACTURED CAPITAL REPORTING, ENVIRONMENTAL CAPITAL REPORTING AND FIRM VALUE OF LISTED COMPANIES IN KENYA Omare, Dominic Abuga This study examines the effect of financial capital reporting, manufactured capital reporting, and environmental capital reporting on the firm value of companies listed on the Nairobi Securities Exchange. Using a balanced panel dataset of NSE listed firms observed annually over the period 2015 2022, the study applies a panel regression framework to account for repeated observations of the same firms over time and to control for unobserved firm specific characteristics that could confound the reporting value relationship. Secondary data are extracted using a structured data collection instrument and verified for completeness and consistency prior to estimation. The regression results indicate that financial capital reporting has a strong positive and statistically significant association with firm value, implying that improved disclosure and stewardship of financial capital is highly value relevant to investors. Manufactured capital reporting is also positively and significantly related to firm value, suggesting that clearer reporting on productive assets and operational capacity enhances market valuation. Environmental capital reporting shows a positive and statistically significant relationship with firm value, although the effect appears comparatively weaker, indicating that environmental disclosures are valued but may be more sensitive to firm specific conditions and sector characteristics. The findings support the conclusion that stronger multi capital reporting is associated with higher firm value among NSE listed firms. The study recommends strengthening the quality, consistency, and comparability of multi capital disclosures to enhance market confidence and valuation outcomes.

A review on the recent advances in the use of hydrochar for adsorption of methylene blue dye from aqueous systems

2026-02-23T08:45:51Z

A review on the recent advances in the use of hydrochar for adsorption of methylene blue dye from aqueous systems Onyango, Collins; Nyairo, Wilfrida; Shikuku, Victor This study reviewed the use of hydrochars in the adsorption of methylene blue, a toxic dye, from aqueous phases. Journal articles published predominantly between 2020 and 2025 were assessed. The articles were mainly identified through keyword searches on ScienceDirect, Scopus and Web of Science. The studies reported a high efficacy of hydrochars against the dye. Organic wastes were primarily used as a feedstock in the hydrothermal carbonization processes, aligning to the waste to resource principle, an efficient and cost effective route of synthesis of adsorbents. The pseudo-first order, pseudo-second order and the Elovich model best described the kinetic data while the Freundlich, Sips and Langmuir isotherms best fitted the experimental data, with model predicted adsorption capacities in the range of 30-1060 mg g− 1. All the reviewed studies reported a spontaneous and feasible adsorption process (negative ΔG), while the entropy (ΔS) and enthalpy (ΔH) values varied with feedstock used, the specific modification routes and modification conditions. Several systems retained between 65 and 95% capacity over five cycles with eluents such as HCl, ethanol and methanol. The mechanism of adsorption was reported by most of the studies to be through electrostatic interactions, hydrogen bonding and π-π interactions.